LT6656 Datasheet

Linear Technology/Analog Devices

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Datasheet

LT6656
1
6656fc
For more information www.linear.com/LT6656
TYPICAL APPLICATION
Output Voltage Temperature Drift
TEMPERATURE (°C)
–40
2.498
2.499
V
OUT
(V)
2.500
2.501
2.502
2.503
–20 0 20 40
6652 TA01b
60 80
38 TYPICAL UNITS
LT6656-2.5
Basic Connection
DESCRIPTION
1µA Precision Series
Voltage Reference
The LT
®
6656 is a tiny precision voltage reference that
draws less than 1µA of supply current and can operate
with a supply voltage within 10mV of the output voltage.
The LT6656 offers an initial accuracy of 0.05% and tem-
perature drift of 10ppm/°C. The combined low power and
precision characteristics are ideal for portable and battery
powered instrumentation.
The LT6656 can supply up to 5mA of output drive with
65ppm/mA of load regulation, allowing it to be used as
the supply voltage and the reference input to a low power
ADC. The LT6656 can accept a supply voltage up to 18V
and withstand the reversal of the input connections.
The LT6656 output is stable with 1µF or larger output
capacitance and operates with a wide range of output
capacitor ESR.
This reference is fully specified for operation from –40°C
to 85°C, and is functional over the extreme temperature
range of –55°C to 125°C. Low hysteresis and a consistent
temperature drift are obtained through advanced design,
processing and packaging techniques.
The LT6656 is offered in the 6-lead SOT-23, (2mm ×
2mm) DFN, and 8-lead LS8 Packages. The LS8 is a 5mm
× 5mm surface mount hermetic package that provides
outstanding stability.
FEATURES
APPLICATIONS
n Ultralow Supply Current: 850nA
n Low Drift
A Grade: 10 ppm/°C Max
B Grade: 20 ppm/°C Max
n High Accuracy
A Grade: 0.05% Max
B Grade: 0.1% Max
n Long-Term Drift: 15ppm/√kHr (LS8 Package)
n No Humidity Sensitivity (LS8 Package)
n High Output Drive Current: 5mA Min
n Low Dropout Voltage: 10mV Max
n Fully Specified from –40°C to 85°C
n Operational from –55°C to 125°C
n Wide Supply Range to 18V
n Reverse Input/Output Protection
n Available Output Voltage Options:
1.25V, 2.048V, 2.5V, 3V, 3.3V, 4.096V and 5V
n Available in Low Profile (1mm) ThinSOT™,
(2mm × 2mm) DFN and High Stability Hermetic
(5mm × 5mm) LS8 Packages
n Precision A/D and D/A Converters
n Portable Gas Monitors
n Battery- or Solar-Powered Systems
n Precision Regulators
n Low Voltage Signal Processing
n Micropower Remote Sensing
2.51V ≤ V
IN ≤ 18V
0.1µF 1µF
V
OUT
2.5V
6656 TA01a
LT6656-2.5
VIN VOUT
GND
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property
of their respective owners.
LT6656
2
6656fc
For more information www.linear.com/LT6656
ABSOLUTE MAXIMUM RATINGS
Input Voltage ........................................................... ±20V
Output Voltage ........................................... 0.3V to 20V
Output Voltage Above Input Voltage .........................20V
Specified Temperature Range (Note 2)
Commercial ............................................. 0°C to 70°C
Industrial .............................................40°C to 85°C
(Note 1)
ORDER INFORMATION
TAPE AND REEL (MINI) TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE
LT6656ACS6-1.25#TRMPBF LT6656ACS6-1.25#TRPBF LTFNK 6-Lead Plastic TSOT-23 0°C to 70°C
LT6656BCS6-1.25#TRMPBF LT6656BCS6-1.25#TRPBF LTFNK 6-Lead Plastic TSOT-23 0°C to 70°C
LT6656AIS6-1.25#TRMPBF LT6656AIS6-1.25#TRPBF LTFNK 6-Lead Plastic TSOT-23 –40°C to 85°C
LT6656BIS6-1.25#TRMPBF LT6656BIS6-1.25#TRPBF LTFNK 6-Lead Plastic TSOT-23 –40°C to 85°C
LT6656ACS6-2.048#TRMPBF LT6656ACS6-2.048#TRPBF LTFNN 6-Lead Plastic TSOT-23 0°C to 70°C
LT6656BCS6-2.048#TRMPBF LT6656BCS6-2.048#TRPBF LTFNN 6-Lead Plastic TSOT-23 0°C to 70°C
LT6656AIS6-2.048#TRMPBF LT6656AIS6-2.048#TRPBF LTFNN 6-Lead Plastic TSOT-23 –40°C to 85°C
LT6656BIS6-2.048#TRMPBF LT6656BIS6-2.048#TRPBF LTFNN 6-Lead Plastic TSOT-23 –40°C to 85°C
LT6656ACS6-2.5#TRMPBF LT6656ACS6-2.5#TRPBF LTFGW 6-Lead Plastic TSOT-23 0°C to 70°C
LT6656BCS6-2.5#TRMPBF LT6656BCS6-2.5#TRPBF LTFGW 6-Lead Plastic TSOT-23 0°C to 70°C
LT6656AIS6-2.5#TRMPBF LT6656AIS6-2.5#TRPBF LTFGW 6-Lead Plastic TSOT-23 –40°C to 85°C
LT6656BIS6-2.5#TRMPBF LT6656BIS6-2.5#TRPBF LTFGW 6-Lead Plastic TSOT-23 –40°C to 85°C
LT6656ACS6-3#TRMPBF LT6656ACS6-3#TRPBF LTFNQ 6-Lead Plastic TSOT-23 0°C to 70°C
LT6656BCS6-3#TRMPBF LT6656BCS6-3#TRPBF LTFNQ 6-Lead Plastic TSOT-23 0°C to 70°C
LT6656AIS6-3#TRMPBF LT6656AIS6-3#TRPBF LTFNQ 6-Lead Plastic TSOT-23 –40°C to 85°C
LT6656BIS6-3#TRMPBF LT6656BIS6-3#TRPBF LTFNQ 6-Lead Plastic TSOT-23 –40°C to 85°C
LT6656ACS6-3.3#TRMPBF LT6656ACS6-3.3#TRPBF LTFNS 6-Lead Plastic TSOT-23 0°C to 70°C
LT6656BCS6-3.3#TRMPBF LT6656BCS6-3.3#TRPBF LTFNS 6-Lead Plastic TSOT-23 0°C to 70°C
LT6656AIS6-3.3#TRMPBF LT6656AIS6-3.3#TRPBF LTFNS 6-Lead Plastic TSOT-23 –40°C to 85°C
LT6656BIS6-3.3#TRMPBF LT6656BIS6-3.3#TRPBF LTFNS 6-Lead Plastic TSOT-23 –40°C to 85°C
Operating Temperature Range (Note 2).. 55°C to 125°C
Output Short Circuit Duration ......................... Indefinite
Junction Temperature .......................................... 150°C
Storage Temperature Range (Note 3) ..... 65°C to 150°C
Lead Temperature (Soldering, 10 sec.)
TSOT-23 (Note 4) ..............................................300°C
GND* 1
GND 2
NC 3
6 V
OUT
5 NC
4 VIN
TOP VIEW
S6 PACKAGE
6-LEAD PLASTIC TSOT-23
TJMAX = 150°C, θJA = 230°C/W
*CONNECT PIN TO DEVICE GND (PIN 2)
TOP VIEW
VIN
NC
VOUT
NC
GND
GND*
DC PACKAGE
6-LEAD (2mm × 2mm) PLASTIC DFN
4
5
7
GND*
6
3
2
1
TJMAX = 125°C, θJA = 102°C/W
EXPOSED PAD (PIN 7) MUST BE CONNECTED TO GND
1
2
3
NC
NC
GND*
7
6
5
NC
VOUT
VOUT
4
GND
8
VIN
TOP VIEW
LS8 PACKAGE
8-PIN LEADLESS CHIP CARRIER (5mm × 5mm)
TJMAX = 150°C, θJA = 125°C/W
*CONNECT PIN TO DEVICE GND (PIN 4)
PIN CONFIGURATION
LEAD FREE FINISH
LT6656
3
6656fc
For more information www.linear.com/LT6656
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL (MINI) TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE
LT6656ACS6-4.096#TRMPBF LT6656ACS6-4.096#TRPBF LTFNV 6-Lead Plastic TSOT-23 0°C to 70°C
LT6656BCS6-4.096#TRMPBF LT6656BCS6-4.096#TRPBF LTFNV 6-Lead Plastic TSOT-23 0°C to 70°C
LT6656AIS6-4.096#TRMPBF LT6656AIS6-4.096#TRPBF LTFNV 6-Lead Plastic TSOT-23 –40°C to 85°C
LT6656BIS6-4.096#TRMPBF LT6656BIS6-4.096#TRPBF LTFNV 6-Lead Plastic TSOT-23 –40°C to 85°C
LT6656ACS6-5#TRMPBF LT6656ACS6-5#TRPBF LTFNX 6-Lead Plastic TSOT-23 0°C to 70°C
LT6656BCS6-5#TRMPBF LT6656BCS6-5#TRPBF LTFNX 6-Lead Plastic TSOT-23 0°C to 70°C
LT6656AIS6-5#TRMPBF LT6656AIS6-5#TRPBF LTFNX 6-Lead Plastic TSOT-23 –40°C to 85°C
LT6656BIS6-5#TRMPBF LT6656BIS6-5#TRPBF LTFNX 6-Lead Plastic TSOT-23 –40°C to 85°C
LT6656ACDC-1.25#TRMPBF LT6656ACDC-1.25#TRPBF LFNM 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C
LT6656BCDC-1.25#TRMPBF LT6656BCDC-1.25#TRPBF LFNM 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C
LT6656AIDC-1.25#TRMPBF LT6656AIDC-1.25#TRPBF LFNM 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C
LT6656BIDC-1.25#TRMPBF LT6656BIDC-1.25#TRPBF LFNM 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C
LT6656ACDC-2.048#TRMPBF LT6656ACDC-2.048#TRPBF LFNP 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C
LT6656BCDC-2.048#TRMPBF LT6656BCDC-2.048#TRPBF LFNP 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C
LT6656AIDC-2.048#TRMPBF LT6656AIDC-2.048#TRPBF LFNP 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C
LT6656BIDC-2.048#TRMPBF LT6656BIDC-2.048#TRPBF LFNP 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C
LT6656ACDC-2.5#TRMPBF LT6656ACDC-2.5#TRPBF LFGX 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C
LT6656BCDC-2.5#TRMPBF LT6656BCDC-2.5#TRPBF LFGX 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C
LT6656AIDC-2.5#TRMPBF LT6656AIDC-2.5#TRPBF LFGX 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C
LT6656BIDC-2.5#TRMPBF LT6656BIDC-2.5#TRPBF LFGX 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C
LT6656ACDC-3#TRMPBF LT6656ACDC-3#TRPBF LFNR 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C
LT6656BCDC-3#TRMPBF LT6656BCDC-3#TRPBF LFNR 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C
LT6656AIDC-3#TRMPBF LT6656AIDC-3#TRPBF LFNR 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C
LT6656BIDC-3#TRMPBF LT6656BIDC-3#TRPBF LFNR 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C
LT6656ACDC-3.3#TRMPBF LT6656ACDC-3.3#TRPBF LFNT 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C
LT6656BCDC-3.3#TRMPBF LT6656BCDC-3.3#TRPBF LFNT 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C
LT6656AIDC-3.3#TRMPBF LT6656AIDC-3.3#TRPBF LFNT 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C
LT6656BIDC-3.3#TRMPBF LT6656BIDC-3.3#TRPBF LFNT 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C
LT6656ACDC-4.096#TRMPBF LT6656ACDC-4.096#TRPBF LFNW 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C
LT6656BCDC-4.096#TRMPBF LT6656BCDC-4.096#TRPBF LFNW 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C
LT6656AIDC-4.096#TRMPBF LT6656AIDC-4.096#TRPBF LFNW 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C
LT6656BIDC-4.096#TRMPBF LT6656BIDC-4.096#TRPBF LFNW 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C
LT6656ACDC-5#TRMPBF LT6656ACDC-5#TRPBF LFNY 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C
LT6656BCDC-5#TRMPBF LT6656BCDC-5#TRPBF LFNY 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C
LT6656AIDC-5#TRMPBF LT6656AIDC-5#TRPBF LFNY 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C
LT6656BIDC-5#TRMPBF LT6656BIDC-5#TRPBF LFNY 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C
LEAD FREE FINISH PART MARKING* PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE
LT6656AILS8-1.25#PBF656125 8-Lead (5mm × 5mm) Ceramic LCC –40°C to 85°C
LT6656BILS8-1.25#PBF656125 8-Lead (5mm × 5mm) Ceramic LCC –40°C to 85°C
TRM = 500 pieces. *Temperature grades are identified by a label on the shipping container.
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on lead based finish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
This product is only offered in trays. For more information go to: http://www.linear.com/packaging/
LT6656
4
6656fc
For more information www.linear.com/LT6656
AVAILABLE OPTIONS
OUTPUT VOLTAGE INITIAL ACCURACY
TEMPERATURE
COEFFICIENT
SPECIFIED TEMPERATURE RANGE
0°C TO 70°C –40°C TO 85°C
ORDER PART NUMBER* ORDER PART NUMBER*
1.250V 0.05% 10ppm/°C LT6656ACS6-1.25 LT6656AIS6-1.25
0.05% 10ppm/°C N/A LT6656AILS8-1.25
0.10% 20ppm/°C LT6656BCS6-1.25 LT6656BIS6-1.25
0.10% 10ppm/°C LT6656ACDC-1.25 LT6656AIDC-1.25
0.10% 15ppm/°C N/A LT6656BILS8-1.25
0.20% 20ppm/°C LT6656BCDC-1.25 LT6656BIDC-1.25
2.048V 0.05% 10ppm/°C LT6656ACS6-2.048 LT6656AIS6-2.048
0.10% 20ppm/°C LT6656BCS6-2.048 LT6656BIS6-2.048
0.10% 10ppm/°C LT6656ACDC-2.048 LT6656AIDC-2.048
0.20% 20ppm/°C LT6656BCDC-2.048 LT6656BIDC-2.048
2.500V 0.05% 10ppm/°C LT6656ACS6-2.5 LT6656AIS6-2.5
0.10% 20ppm/°C LT6656BCS6-2.5 LT6656BIS6-2.5
0.10% 10ppm/°C LT6656ACDC-2.5 LT6656AIDC-2.5
0.20% 20ppm/°C LT6656BCDC-2.5 LT6656BIDC-2.5
3.000V 0.05% 10ppm/°C LT6656ACS6-3 LT6656AIS6-3
0.10% 20ppm/°C LT6656BCS6-3 LT6656BIS6-3
0.10% 10ppm/°C LT6656ACDC-3 LT6656AIDC-3
0.20% 20ppm/°C LT6656BCDC-3 LT6656BIDC-3
3.300V 0.05% 10ppm/°C LT6656ACS6-3.3 LT6656AIS6-3.3
0.10% 20ppm/°C LT6656BCS6-3.3 LT6656BIS6-3.3
0.10% 10ppm/°C LT6656ACDC-3.3 LT6656AIDC-3.3
0.20% 20ppm/°C LT6656BCDC-3.3 LT6656BIDC-3.3
4.096V 0.05% 10ppm/°C LT6656ACS6-4.096 LT6656AIS6-4.096
0.10% 20ppm/°C LT6656BCS6-4.096 LT6656BIS6-4.096
0.10% 10ppm/°C LT6656ACDC-4.096 LT6656AIDC-4.096
0.20% 20ppm/°C LT6656BCDC-4.096 LT6656BIDC-4.096
5.000V 0.05% 10ppm/°C LT6656ACS6-5 LT6656AIS6-5
0.10% 20ppm/°C LT6656BCS6-5 LT6656BIS6-5
0.10% 10ppm/°C LT6656ACDC-5 LT6656AIDC-5
0.20% 20ppm/°C LT6656BCDC-5 LT6656BIDC-5
*See Order Information section for complete part number listing.
LT6656
5
6656fc
For more information www.linear.com/LT6656
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the specified
temperature range, otherwise specifications are at TA = 25°C. VIN = VOUT + 0.5V (for LT6656-1.25, VIN = 2.2V), CL = 1μF, IL = 0,unless
otherwise noted.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Output Voltage Error LT6656ACS6, LT6656AIS6, LT6656AILS8
LT6656BCS6, LT6656BIS6, LT6656BILS8
LT6656ACDC, LT6656AIDC
LT6656BCDC, LT6656BIDC
–0.05
–0.1
–0.1
–0.2
0.05
0.1
0.1
0.2
%
%
%
%
Output Voltage Temperature Coefficient (Note 5) LT6656A
LT6656B
l
l
5
12
10
20
ppm/°C
ppm/°C
Line Regulation VIN = (VOUT + 0.5V) to 18V
LT6656-2.048, LT6656-2.5, LT6656-3,
LT6656-3.3, LT6656-4.096, LT6656-5
l
2 25
40
ppm/V
ppm/V
VIN = 2.2V to 18V
LT6656-1.25
l
2 25
40
ppm/V
ppm/V
Load Regulation (Note 6) IL = 5mA, Sourcing
LT6656-2.048, LT6656-2.5, LT6656-3,
LT6656-3.3, LT6656-4.096, LT6656-5
l
65 150
375
ppm/mA
ppm/mA
IL = 5mA, Sourcing
LT6656S6-1.25, LT6656DC-1.25
l
80 175
425
ppm/mA
ppm/mA
IL = 5mA, Sourcing
LT6656LS8-1.25
l
135 250
500
ppm/mA
ppm/mA
Dropout Voltage (Note 7) VIN – VOUT, ∆VOUT Error ≤ 0.1%
IL = 0
LT6656-2.048, LT6656-2.5, LT6656-3,
LT6656-3.3, LT6656-4.096, LT6656-5
l
3
10
40
mV
mV
IL = 5mA, Sourcing
LT6656-2.048, LT6656-2.5, LT6656-3,
LT6656-3.3, LT6656-4.096, LT6656-5
l
250 370
500
mV
mV
Minimum Input Voltage IL = 0, ∆VOUT Error ≤ 0.1%
LT6656-1.25
0°C ≤ TA ≤ 70°C
–40°C ≤ TA ≤ 85°C
l
l
1.35
1.5
1.6
1.8
V
V
V
Supply Current
l
0.85 1.0
1.5
µA
µA
Output Short Circuit Current Short VOUT to GND
Short VOUT to VIN
18
4
mA
mA
Input Reverse Leakage Current VIN = –18V, VOUT = GND 80 µA
Reverse Output Current VIN = GND, VOUT = 18V 30 µA
Output Voltage Noise (Note 8) 0.1Hz to 10Hz
10Hz to 1kHz, LT6656-1.25
10Hz to 1kHz, LT6656-2.5
10Hz to 1kHz, LT6656-5
30
50
80
140
ppmP-P
µVRMS
µVRMS
µVRMS
Turn-On Time LT6656-1.25, 0.1% Settling
LT6656-2.5, 0.1% Settling
LT6656-5, 0.1% Settling
15
30
60
ms
ms
ms
Long Term Drift of Output Voltage (Note 9) LT6656S6, LT6656DC
LT6656LS8
50
15
ppm/√kHr
ppm/√kHr
Hysteresis (Note 10) LT6656S6, LT6656DC
∆T = 0°C to 70°C
∆T = –40°C to 85°C
25
70
ppm
ppm
LT6656LS8
∆T = 0°C to 70°C
∆T = –40°C to 85°C
15
55
ppm
ppm
LT6656
6
6656fc
For more information www.linear.com/LT6656
ELECTRICAL CHARACTERISTICS
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LT6656C is guaranteed to meet specified performance from
0°C to 70°C. The LT6656C is designed, characterized and expected to
meet specified performance from –40°C to 85°C but is not tested or
QA sampled at these temperatures. The LT6656I is guaranteed to meet
specified performance from –40°C to 85°C. By design, the LT6656 is
guaranteed functional over the operating temperature range of –55°C to
125°C.
Note 3: If the LT6656 is stored outside of the specified temperature range,
the output may shift due to hysteresis.
Note 4: The stated temperature is typical for soldering of the leads during
manual rework. For detailed IR reflow recommendations, refer to the
Applications section.
Note 5: Temperature coefficient is measured by dividing the maximum
change in output voltage by the specified temperature range.
Note 6: Load regulation is measured with a pulse from no load to the
specified load current. Output changes due to die temperature change
must be taken into account separately.
Note 7: Excludes load regulation errors.
Note 8: Peak-to-peak noise is measured with a 3-pole highpass filter at
0.1Hz and a 4-pole lowpass filter at 10Hz. The unit is enclosed in a still-air
environment to eliminate thermocouple effects on the leads. The test
time is 10 seconds. RMS noise is measured on a spectrum analyzer in a
shielded environment.
Note 9: Long term stability typically has a logarithmic characteristic and
therefore, changes after 1000 hours tend to be much smaller than before
that time. Total drift in the second thousand hours is normally less than
one third that of the first thousand hours with a continuing trend toward
reduced drift with time. Long-term stability will also be affected by
differential stresses between the IC and the board material created during
board assembly.
Note 10: Hysteresis in output voltage is created by mechanical stress
that differs depending on whether the IC was previously at a higher or
lower temperature. Output voltage is always measured at 25°C, but
the IC is cycled to the hot or cold temperature limit before successive
measurements. For instruments that are stored at well controlled
temperatures (within 20 or 30 degrees of operational temperature)
hysteresis is usually not a dominant error source. Typical hysteresis is the
worst-case of 25°C to cold to 25°C or 25°C to hot to 25°C, preconditioned
by one thermal cycle.
TYPICAL PERFORMANCE CHARACTERISTICS
Output Voltage Temperature Drift Typical VOUT Distribution Supply Current vs Input Voltage
100
10
1
0.1
INPUT VOLTAGE (V)
0
SUPPLY CURRENT (µA)
10 186 14
6656 G17
20
8 164 122
TA = 125°C
TA = 85°C
TA = 25°C
TA = –40°C
TA = –55°C
1.25V OPTION
TEMPERATURE (°C)
–60 –40
–1000
0
1000
2000
3000
5000
6000
7000
8000
9000
4000
–20 0 20 40
60 12010080
ALL OPTIONS
25 TYPICAL UNITS
NORMALIZED AT 25°C
CL = 1µF
IL = 0
OUTPUT VOLTAGE ERROR (%)
–0.10
0.10
NUMBER OF UNITS
200
20
180
140
100
60
160
120
80
40
0
6656 G02
–0.02–0.06 0.060.020
ALL OPTIONS
CL = 1µF
IL = 0
TA = 25°C
LT6656
7
6656fc
For more information www.linear.com/LT6656
TYPICAL PERFORMANCE CHARACTERISTICS
Power Supply Rejection Ratio
vs Frequency
Dropout Voltage vs Load Current
Load Regulation (Sourcing) Load Regulation (Sinking)
Line Regulation
Supply Current vs Input Voltage
100
10
1
0.1
INPUT VOLTAGE (V)
0
SUPPLY CURRENT (µA)
10 186 14
6656 G03
20
8 164 122
TA = 125°C
TA = 85°C
TA = 25°C
TA = –55°C
2.048V TO 5V OPTIONS
2.5V OPTION SHOWN
VON MOVES WITH VOLTAGE OPTION
VON
0.1µ 1m
10m
100µ10µ
1000
100
10
1
LOAD CURRENT (A)
DROPOUT VOLTAGE (mV)
6656 G04
TA = 125°C
TA = 85°C
TA = 25°C
TA = –55°C
2.048V TO 5V OPTIONS
VIN – VOUT
INITIAL VIN = VOUT + 0.5V
∆VOUT = 0.1%
750
500
250
0
–750
–500
–250
OUTPUT VOLTAGE CHANGE (ppm)
6656 G05
TA = 125°C
TA = 85°C
TA = 25°C
TA = –55°C
2.048V TO 5V OPTIONS
VIN = VOUT + 0.5V
CL = 1µF
0.1µ 1m
10m
100µ10µ
LOAD CURRENT (A)
10µ
1m
100µ
5.0
2.0
1.5
3.0
2.5
4.0
3.5
4.5
1.0
0.5
0
–0.5
LOAD CURRENT (A)
OUTPUT VOLTAGE CHANGE (%)
6656 G06
TA = 85°C, 125°C
TA = 25°C
TA = –40°C
TA = –55°C
ALL OPTIONS
VIN = VOUT + 0.5V
CL = 1µF
1000
900
800
700
600
500
400
300
200
100
0
–200
–100
INPUT VOLTAGE (V)
0
OUTPUT VOLTAGE CHANGE (ppm)
10 186 14
6656 G08
20
8 164 122
TA = 125°C
TA = 85°C
TA = 25°C
TA = –55°C
ALL OPTIONS
IL = 0
CL = 1µF
2.5V OPTION SHOWN
VON MOVES WITH
VOLTAGE OPTION
VON
FREQUENCY (Hz)
POWER SUPPLY REJECTION RATIO (dB)
6656 G09
90
80
70
60
50
40
30
10
20
010 1k
10k
100
VIN = VOUT + 0.5V
CL = 1µF
IL = 0
1.25V OPTION
2.5V OPTION
5V OPTION
Minimum Supply Voltage
vs Load Current
2.0
1.8
1.6
1.4
1.2
0.8
1.0
MINIMUM SUPPLY VOLTAGE (V)
6656 G18
1.25V OPTION
INITIAL VIN = 2.2V
∆VOUT = 0.1%
TA = 125°C
TA = 85°C
TA = 25°C
TA = –40°C
TA = –55°C
0.1µ 1m
10m
100µ10µ
LOAD CURRENT (A)
Load Regulation (Sourcing)
500
250
0
–1000
–750
–500
–250
OUTPUT VOLTAGE CHANGE (ppm)
6656 G19
TA = 125°C
TA = 85°C
TA = 25°C
TA = –40°C
TA = –55°C
1.25V OPTION
VIN = 1.75V
CL = 1µF
0.1µ 1m
10m
100µ10µ
LOAD CURRENT (A)
Power Supply Rejection Ratio
vs Frequency
FREQUENCY (Hz)
POWER SUPPLY REJECTION RATIO (dB)
6656 G20
90
80
70
60
50
40
30
10
20
–10
0
10 1k
10k
100
2.5V OPTION
VIN = 3V
IL = 0, CL = 1µF
IL = 0, CL = 10µF
IL = 1mA, CL = 1µF
IL = 1mA, CL = 10µF
LT6656
8
6656fc
For more information www.linear.com/LT6656
Output Impedance vs Frequency
FREQUENCY (Hz)
OUTPUT IMPEDANCE (Ω)
6656 G21
10k
1k
100
10
110 1k
10k
100
VIN = VOUT + 0.5V
CL = 1µF
IL = 0
1.25V OPTION
2.5V OPTION
5V OPTION
TYPICAL PERFORMANCE CHARACTERISTICS
Reverse Output Current
Reverse Input Current
0 15
20
105
100
10
1
OUTPUT VOLTAGE (V)
REVERSE OUTPUT CURRENT (µA)
6656 G12
TA = 125°C
TA = 85°C
TA = 25°C
TA = –55°C
ALL OPTIONS
VIN = GND
INPUT VOLTAGE (V)
REVERSE INPUT CURRENT (µA)
6656 G11
1000
100
10
1
00 –2 –4 –6 –8
–20
–18–16–14–12–10
TA = 125°C
TA = 85°C
TA = 25°C
TA = –55°C
ALL OPTIONS
VOUT = GND
Output Noise Voltage Spectrum
vs Load Capacitance
FREQUENCY (Hz)
NOISE VOLTAGE (µV/√Hz)
6656 G15
40
35
30
25
20
15
10
5
01 100
1k
10
2.5V OPTION
VIN = 3V
IL = 0 CL = 47µF
CL = 4.7µF
CL = 0.47µF
Output Noise 0.1Hz to 10Hz
Output Voltage Noise Spectrum
vs Load Current
OUTPUT NOISE (20ppm/DIV)
TIME (1s/DIV)
6656 G13
ALL OPTIONS
VIN = VOUT + 0.5V
CL = 1µF
IL = 0
FREQUENCY (Hz)
NOISE VOLTAGE (µV/√Hz)
6656 G14
16
14
12
10
8
6
4
2
010 1k
10k
100
2.5V OPTION
VIN = 3V
CL = 1µF
IL = 0
IL = 10µA
IL = 250µA
IL = 1mA
Ground Current vs Load Current
LOAD CURRENT (A)
GROUND CURRENT (µA)
6656 G07
1000
100
10
1
10µ 1m
10m
100µ
TA = 125°C
TA = 85°C
TA = 25°C
TA = –55°C
ALL OPTIONS
VIN = VOUT + 0.5V
CL = 1µF
Output Impedance vs Frequency
FREQUENCY (Hz)
OUTPUT IMPEDANCE (Ω)
6656 G22
10k
1k
100
10
110 1k
10k
100
2.5V OPTION
VIN = 3V
IL = 0, CL = 1µF
IL = 0, CL = 10µF
IL = 100µA, CL = 1µF
IL = 100µA, CL = 10µF
Output Voltage Noise Spectrum
FREQUENCY (Hz)
NOISE VOLTAGE (µV
RMS
/√Hz)
6656 G24
30
25
20
15
10
5
010 1k
10k
100
VIN = VOUT + 5V
CL = 1µF
IL = 0
1.25V OPTION
2.5V OPTION
5V OPTION
LT6656
9
6656fc
For more information www.linear.com/LT6656
TYPICAL PERFORMANCE CHARACTERISTICS
Long-Term Drift Long-Term Drift (LS8)
HOURS
0
LONG TERM DRIFT (ppm)
200
150
50
–50
–150
100
0
–100
–200 500 900300 700
6656 G16
1000
400 800200 600100
ALL OPTIONS
CL = 1µF
IL = 0
5 TYPICAL PARTS
SOLDERED ONTO PCB
Integrated 10Hz to 1kHz Noise
vs Load Current
0.1µ 1m
10m
100µ10µ
250
150
200
100
50
0
LOAD CURRENT (A)
INTEGRATED NOISE (µV
RMS
)
6656 G23
CL = 0.47µF
CL = 1µF
CL = 10µF
CL = 47µF
2.5V OPTION
Integrated 10Hz to 1kHz Noise
vs Load Current
0.1µ 1m
10m
100µ10µ
500
400
200
100
300
0
LOAD CURRENT (A)
INTEGRATED NOISE (µV
RMS
)
6656 G25
VIN = VOUT + 0.5V
CL = 1µF
1.25V OPTION
2.5V OPTION
5V OPTION
TIME (HOURS)
0
OUTPUT VOLTAGE CHANGE (ppm)
0
50
100
900800
6656 G26
–50
–100
–200 200 400 600
100 1000
300 500 700
–150
200 1.25V OPTION
VIN = 2V
CLOAD =1µF
ILOAD = 0
150
35 TYPICAL PARTS
SOLDERED ONTO PCB
LT6656
10
6656fc
For more information www.linear.com/LT6656
PIN FUNCTIONS
(TSOT-23/DFN)
GND* (Pin 1/Pin 3): Internal Function. This pin must be
tied to ground.
GND (Pin 2/Pin 2): Device Ground.
NC (Pins 3, 5/Pins 1, 5): Not Internally Connected. May
be tied to VIN, VOUT, GND or floated.
VIN (Pin 4/Pin 6): Power Supply. The minimum supply
varies with output load and voltage option, see the Dropout
Voltage specification in the Electrical Characteristics table
for further details. The maximum input voltage is 18V.
Bypass VIN with a 0.1µF capacitor to ground.
VOUT (Pin 6/Pin 4): Output Voltage. A minimum output
capacitor of 1µF is required for stable operation.
GND*(Exposed Pad Pin 7, DFN Only): This pin must be
tied to ground.
(LS8)
NC (Pins 1, 2, 7): Not Internally Connected. May be tied
to VIN, VOUT, GND or floated.
GND* (Pin 3): Internal Function. This pin must be tied
to ground.
GND (Pin 4): Device Ground.
VOUT (Pin 5): Output Voltage. A minimum output capacitor
of 1µF is required for stable operation.
VOUT (Pin 6): Output Voltage. Tie to pin 5 for best load
regulation.
VIN (Pin 8): Power Supply. Bypass VIN with a 0.1µF
capacitor to ground.
BLOCK DIAGRAM
NC
NC
6656 BD
BANDGAP ERROR
AMP
GND
VIN
TSOT-23/DFN
GND*
VOUT
NC
6656 BD (LS8)
BANDGAP ERROR
AMP
GND
VIN
LS8
NC
NC
GND*
VOUT
VOUT
3 4
5
6
7
8
2
1
LT6656
11
6656fc
For more information www.linear.com/LT6656
APPLICATIONS INFORMATION
Long Battery Life
Series references have a large advantage over shunt style
references. Shunt references require a resistor from the
power supply to operate. This resistor must be chosen
to supply the maximum current that can be demanded by
the load. When the load is not operating at this maximum
current, the shunt reference must always sink this current,
resulting in high dissipation and shortened battery life.
The LT6656 series reference does not require a current
setting resistor and is specified to operate with any supply
from 1.5V to 18V, depending on the output voltage option,
load current and operating temperature (see Dropout
Voltage and Minimum Input Voltage in the Typical Perfor-
mance Characteristics). When the load does not demand
current, the LT6656 reduces its dissipation and battery life
is extended. If the reference is not delivering load current,
it dissipates only a few µW, yet the same connection can
deliver 5mA of load current when required.
Start-Up
To ensure proper start-up, the output voltage should be
between –0.3V and the rated output voltage. If the output
load may be driven more than 0.3V below ground, a low
forward voltage schottky diode from the output to ground
is required. The turn-on characteristics can be seen in
Figure 1.
Figure 1. LT6656-2.5 Turn-On Characteristics, CL = 1µF
Figure 2. Transient Load Test Circuit
V
IN
3V
2N7000
R2
CIN
0.1µF CL
F
VGEN
3V
6656 F02
R1
LT6656-2.5
1V/DIV
VIN
VOUT
1ms/DIV 6656 F01
Output Voltage Options
The performance of the LT6656 is consistent for the 2.048V
to 5V options. The 1.25V option has slightly reduced load
regulation, and unlike the higher voltage options, the
minimum operating supply voltage is limited by internal
circuitry rather than the output voltage.
Parameters that are based on changes in the output voltage,
such as load regulation and hysteresis, remain proportional
to the output voltage and are specified in relative units,
for example, parts per million (ppm). Parameters that
are not based on changes in the output voltage, such as
supply current and reverse input current, are the same
for all options.
The bandwidth of the LT6656 decreases with higher output
voltage. This causes parameters that are affected by both
bandwidth and output voltage, such as wideband noise
and output impedance, to increase less with higher output
voltage.
Bypass and Load Capacitance
The LT6656 voltage reference needs a 0.1μF input bypass
capacitor placed within an inch of the input pin. An ad-
ditional 2.2μF capacitor should be used when the source
impedance of the input supply is high or when driving
heavy loads. The bypassing of other local devices may
serve as the required components. The output of the
LT6656 requires a capacitance of 1µF or larger. The LT6656
is stable with a wide variety of capacitor types including
ceramic, tantalum and electrolytic due to its low sensitivity
to ESR (5Ω or less).
The test circuit in Figure 2 was used to test the response
and stability of the LT6656 to various load currents. The
resultant transient responses can be seen in Figure 3 and
Figure 4. The large scale output response to a 500mV input
step is shown in Figure 5 with a more detailed photo and
description in the Output Settling section.
LT6656
12
6656fc
For more information www.linear.com/LT6656
Output Settling
The output of the LT6656 is primarily designed to source
current into a load, but is capable of sinking current to
aid in output transient recovery. The output stage uses a
class B architecture to minimize quiescent current and
has a crossover dead band as the output transitions from
sourcing to sinking current.
APPLICATIONS INFORMATION
Figure 5. Output Response to 0.5VP-P Step on VIN, CL = 1µF, IL = 0
The settling time is typically less than 8ms for output loads
up to 5mA, however the time required to settle when the
load is turned off or in response to an input transient can be
significantly longer due to the dead band (shown in Figure
7). During this interval the output stage is neither sourcing
nor sinking current so the settling time is dominated by
the ability of the application circuit to discharge the output
capacitor to the voltage at which the sourcing circuitry
in the output stage reactivates. Larger load currents will
decrease the settling time and higher output capacitance
will increase the settling time.
In application circuits where the LT6656 is experiencing
a load step greater than 5µA, such as an ADC reference
and supply implementation, the settling time will typically
remain less than 8ms, regardless of the output settling
from a previous load step.
The settling time can be estimated by the following
equation:
Settling time
2(Deadband)(C
L
)
I
L
+(VOUT )(0.8ms/V)
The deadband is ≈7mV for the 2.5V option, is proportional
to the voltage option (i.e., ≈14mV for the 5V option) and
can double due to variations in processing.
The graph in Figure 6 shows the settling time versus load
step with no load and with a constant 2µA load applied.
Note the settling time can be longer with load steps that
are not large enough to activate the sinking side of the
output stage.
2.7V
2.5V
V
OUT
2.3V
3.25V
VIN
2.75V
5ms/DIV 6656 F05
Figure 6. Output Settling Time to 0.05% vs Load Step
LOAD STEP (mA)
OUTPUT SETTLING TIME (ms)
6656 F06
0.001 1
10
0.10.01
2.5V OPTION
VIN = 3V
CL = 1µF
IL = LOAD
STEP TO 2µA
∆IL = LOAD
STEP TO ZERO
∆IL = ZERO TO
LOAD STEP
30
25
20
15
10
5
0
2.52V
2.50V
V
OUT
2.48V
1mA
IOUT
2mA
5ms/DIV 6656 F04
2.52V
2.50V
V
OUT
2.48V
0µA
IOUT
100µA
5ms/DIV 6656 F03
Figure 3. Transient Response, 0µA to 100µA Load Step
(R2 = 24.9k, R1 = Open)
Figure 4. Transient Response, 1mA to 2mA Load Step
(R1 = R2 = 2.49k)
LT6656
13
6656fc
For more information www.linear.com/LT6656
IL = 0
VOUT
10mV/DIV
IL = 5µA
3.25V
VIN 2.75V
5ms/DIV 6656 F07
Figure 7. Detailed Output Response to a 0.5V Input Step,
CIN = CL = 1µF
APPLICATIONS INFORMATION
The photo in Figure 7 shows the output response to a 0.5V
input step in both a no-load and 5µA load condition. In
the no-load condition only the bias current of the internal
bandgap reference (about 400nA) is available to discharge
the output capacitor.
Output Noise
Low frequency noise is proportional to the output voltage
and is insensitive to output current and moderate levels
of output capacitance.
Wideband noise increases less with higher output voltage
and is proportional to the bandwidth of the output stage,
increasing with higher load current and lower output
capacitance.
Peaking in the noise response is another factor contribut-
ing to the output noise level for a given frequency range.
Noise peaking can be reduced by increasing the size of the
output capacitor when driving heavier loads, or conversely,
reducing the size of the output capacitor when driving
lighter loads. Noise plots in the Typical Performance Curves
section show noise spectrum with various load currents
and output capacitances.
Internal Protection
The LT6656 incorporates several internal protection
features that make it ideal for use in battery powered
systems. Reverse input protection limits the input cur-
rent to typically less than 40µA when either the LT6656
or the battery is installed backwards. In systems where
the output can be held up by a backup battery with the
input pulled to ground, the reverse output protection of
the LT6656 limits the output current to typically less than
30µA. The current versus reverse voltage is shown in the
Typical Performance Characteristics section.
Long-Term Drift
Long-term drift cannot be extrapolated from accelerated
high temperature testing. This erroneous technique gives
drift numbers that are wildly optimistic. A more realistic
way to determine long-term drift is to measure it over the
time interval of interest. The LT6656 drift data was taken
over 100 parts that were soldered onto PC boards in a
typical application configuration. The boards were then
placed into a constant temperature oven with TA = 30°C,
their outputs scanned regularly and measured with an
8.5 digit DVM. The parts chosen in the Long Term Drift
curves in the Typical Performance Characteristics section
represent high, low and typical units.
Hysteresis
Hysteresis on the LT6656 is measured in two steps, for
example, from 25°C to –40°C to 25°C, then from 25°C to
85°C to 25°C, for the industrial temperature range. After
preconditioning by one thermal cycle, this two-step cycle
is repeated several times and the maximum hysteresis
from all the partial cycles is noted.
Results over both commercial and industrial temperature
ranges are shown in Figure 8 and Figure 9. The parts cycled
over the higher temperature range have a higher hysteresis
than those cycled over the lower range.
Power Dissipation
The LT6656 will not exceed the maximum junction tem-
perature when operating within its specified temperature
range of –40°C to 85°C, maximum input voltage of 18V
and specified load current of 5mA.
IR Reflow Shift
The different expansion and contraction rates of the mate-
rials that make up the LT6656 package may induce small
stresses on the die that can cause the output to shift during
LT6656
14
6656fc
For more information www.linear.com/LT6656
APPLICATIONS INFORMATION
Figure 12. Lead Free Reflow Profile Due to IR Reflow
Figure 9. LT6656 S6, DC –40°C to 85°C Hysteresis
Figure 11. LT6656 LS8 –40°C to 85°C Hysteresis
Figure 10. LT6656 LS8 0°C to 70°C Hysteresis
HYSTERESIS (ppm)
–160 –120 –40–80
NUMBER OF UNITS
20
18
14
12
8
4
16
10
6
2
0
6656 F09
160
12040 800
–40°C TO 25°C
85°C TO 25°C
2.5V OPTION
VIN = 3V
CL = 1µF
IL = 0
Figure 8. LT6656 S6, DC 0°C to 70°C Hysteresis
HYSTERESIS (ppm)
–60 –40 –20
NUMBER OF UNITS
30
25
15
5
20
10
0
6656 F08
6040200
2.5V OPTION
VIN = 3V
CL = 1µF
IL = 0
0°C TO 25°C
70°C TO 25°C
IR reflow. Common lead free IR reflow profiles reach over
250°C, considerably more than lead solder profiles. The
higher reflow temperature of the lead free parts exacerbates
the issue of thermal expansion and contraction causing
the output shift to generally be greater than with a leaded
reflow process.
The lead free IR reflow profile used to experimentally
measure the output voltage shift in the LT6656-2.5 is
shown in Figure 12. Similar results can be expected us-
ing a convection reflow oven. Figures 13 and 14 show the
change in output voltage that was measured for parts that
were run through the reflow process for 1 cycle and also 3
cycles. Additional drift of the LT6656 after IR reflow does
not vary significantly.
HYSTERESIS (ppm)
–60 –40 –20
NUMBER OF UNITS
20
15
5
10
0
6656 F10
6040200
1.25V OPTION
VIN = 2V
CL = 1µF
IL = 0
0°C TO 25°C
70°C TO 25°C
HYSTERESIS (ppm)
–160 –120 –40–80
NUMBER OF UNITS
20
15
10
5
0
6656 F11
16012040 800
–40°C TO 25°C
85°C TO 25°C
1.25V OPTION
VIN = 2V
CL = 1µF
IL = 0
0246
MINUTES
8
0
75
150
225
300
6656 F12
10
120s
40s
tP
30s
TP = 260°C
RAMP
DOWN
RAMP TO
150°C
TS = 190°C
T = 150°C
tL
130s
TL = 217°C
TS(MAX) = 200°C
380s
LT6656
15
6656fc
For more information www.linear.com/LT6656
Figure 13. ∆VOUT Due to IR Reflow,
Peak Temperature = 260°C, SOT-23
Figure 14. ∆VOUT Due to IR Reflow,
Peak Temperature = 260°C, DFN
APPLICATIONS INFORMATION
short as possible to minimize the voltage drops caused
by load and ground currents. Excessive trace resistance
directly impacts load regulation.
Humidity Sensitivity
Plastic mold compounds absorb water. With changes in
relative humidity, plastic packaging materials change the
amount of pressure they apply to the die inside, which
can cause slight changes in the output of a voltage refer-
ence, usually on the order of 100ppm. The LS8 package is
hermetic, so it is not affected by humidity, and is therefore
more stable in environments where humidity may be a
concern. However
, PC board material may absorb water
and apply mechanical stress to the LT6656LS8. Proper
board materials and layout are essential.
For best stability, the PC board layout is critical. Change
in temperature and position of the PC board, as well as
aging, can alter the mechanical stress applied to compo-
nents soldered to the board. FR4 and similar materials also
absorb water, causing the board to swell. Even conformal
coating or potting of the board does not always eliminate
this effect, though it may delay the symptoms by reduc-
ing the rate of absorption. Removing power and ground
planes in the PC board under the voltage reference can
improve the stability significantly.
Figure 15a shows a tab cut through the PC board on three
sides of an LT6656, which significantly reduces stress
on the IC, as described in Application Note 82. For even
better performance, Figure 15b shows slots cut through
the PC board on all four sides. The slots should be as
long as possible, and the corners just large enough to
accommodate routing of traces. It has been shown that
for PC boards designed in this way, humidity sensitivity
can be reduced to less than 35ppm for a change in relative
humidity of approximately 60%. Mounting the reference
near the center of the board, with slots on four sides, can
further reduce the sensitivity to less than 10ppm.
An additional advantage of slotting the PC board is that the
LT6656 is thermally isolated from surrounding circuitry.
This can help reduce thermocouple effects and improve
accuracy.
CHANGE IN OUTPUT VOLTAGE (ppm)
0 6020
NUMBER OF UNITS
7
6
4
2
1
5
3
0
6656 F13
220180140100
SOT-23
3 CYCLES
1 CYCLE
2.5V OPTION
VIN = 3V
CL = 1µF
IL = 0
CHANGE IN OUTPUT VOLTAGE (ppm)
–160
NUMBER OF UNITS
6
8
10
160
6656 F14
4
2
5
7
9
3
1
0–80 080 240
DFN
3 CYCLES
1 CYCLE
2.5V OPTION
VIN = 3V
CL = 1µF
IL = 0
PC Board Layout
The mechanical stress of soldering a surface mount volt-
age reference to a PC board can cause the output voltage
to shift and temperature coefficient to change.
To reduce the effects of stress-related shifts, position
the reference near the short edge of the PC board or in a
corner. In addition, slots can be cut into the board on two
sides of the device. See Application Note AN82 for more
information. http://www.linear.com
The input and output capacitors should be mounted close
to the package. The GND and VOUT traces should be as
LT6656
16
6656fc
For more information www.linear.com/LT6656
APPLICATIONS INFORMATION
LS8
6656 F15a
Figure 15a. 3-Sided PCB Cutout
Figure 15b. 4-Sided PCB Cutout
LS8
6656 F12b
LT6656
17
6656fc
For more information www.linear.com/LT6656
TYPICAL APPLICATIONS
Regulator Reference
The robust input and output of the LT6656 along with its
high output current make it an excellent precision low
power regulator as well as a reference. The LT6656 would
be a good match with a small, low power microcontroller.
Using the LT6656 as a regulator reduces power consump-
tion, decreases solution size and increases the accuracy
of the microcontrollers on board ADC.
Low Power ADC Reference
Low power ADCs draw only a few µAs during their idle
period and well over 100µA during conversions. Despite
these surges of current, the ADC in reality can have very
low power consumption. Figure 17 shows the LTC2480,
a low power delta sigma ADC. When the ADC is disabled
its quiescent current (IQ) is roughly 1µA, during conver-
sion the IQ jumps up to 160µA. In reality, the power con-
sumption is not only based on the IQ during conversion,
but the real power consumption of the ADC is set by the
conversion time and the sample rate. The LTC2480 shown
in Figure 17 has a conversion time of 160ms which sets
the maximum sample rate of 6 samples per second. The
maximum sample rate also sets the maximum current
consumption to 160µA, but at slower sample rates the
ADC will have significantly lower average current draw.
If the ADC is sampled at 1 sample per second the aver-
age current drawn by the ADC during a 1 second interval
would only be 26.4µA. When taking into consideration the
current drawn by the reference, the total current draw is
only 27.4µA. This system is greatly simplified because
the precision reference does not need to be cycled on and
off to save power. Furthermore, leaving the reference on
continuously eliminates concern for turn-on settling time.
0.1µF 10µF
LT6656-2.5
3V ≤ VIN ≤ 18V
6656 F16
PB0/AIN0/AREF/MOSI
MCU
5
PB1/INT0/AIN1/MISO/OC1A 6
PB2/ADC1/SCK/T0/INT0 7
PB3/ADC2 2
PB4/ADC3 3
PB5/RESET/ADC0 1
VCC/VREF
GND
OUTIN
0.1µF
5.1V ≤ VIN ≤ 18V
4.7µF
6656 F17
DIFFERENTIAL INPUT
±VREF • 0.5 (±2.5V)
AT 1sps, IQ = 27.4µA
LT6656-5
IN OUT
SDOIN
CS
SCK
IN+
LTC2480
VCC
REF
Figure 16. Microcontroller Reference and Regulator
Figure 17. Low Power ADC Reference
LT6656
18
6656fc
For more information www.linear.com/LT6656
TYPICAL APPLICATIONS
Micropower Regulator, IQ = 2µA, Sink Up to 8mA
0.1µF
3V ≤ V
CC
≤ 18V
2.5V
F
6656 TA06
LT6656-2.5
IN OUT
+
LT6003
Boosted Output Current Reference
F
220
6656 TA04
10µF
3.6V ≤ V
CC
≤ 18V
VOUT
40mA MAX
2N2905
+
OUT
LT6656-2.5
IN
0.1µF
Extended Supply Range Reference
V
CC
UP TO 160V
V
OUT
2.2µF F
MMBT5551
6656 TA03
0.1µF
330k
BZX584C12
OUT
LT6656-2.5
IN
ADC Reference and Bridge Excitation Supply
0.1µF
3.8V
≤ VIN ≤ 18V
F
0.1µF
10µF
LT6656-3.3
IN OUT
0.1µF
0.1µF CS
SCK
SDO
IN
IN+
VREF VCC
LTC2452
10k10k
10k
3.3V ≤ V
CC
≤ 5.5V
LT6656
19
6656fc
For more information www.linear.com/LT6656
TYPICAL APPLICATIONS
Low Power Precision High Voltage Supply Monitor, IQ = 1.4µA, High Voltage Supply Load = 10µA
0.1µF
6.5V ≤ VCC ≤ 10V
VCC
F
LT6656-5
IN OUT
OVERVOLTAGE FLAG
6656 TA08
+
LTC1540
7
56
3
4
1, 2
100V
105V OVERVOLTAGE THRESHOLD
9.53M
475k
2-Terminal Current Source
0.1µF
F
LT6656-1.25
GND
IN OUT
6656 TA09
+
LT6003
+
R2
R1
VREF
R3
IV
R
R
R
OUT
REF
=+
1
2
31
Precision Current and Boosted Reference, IQ = 5.5µA
0.1µF F
LT6656-2.5
IN OUT
2.75V
3V ≤ VCC ≤ 16V
6656 TA10
+
LT6004
+
LT6004
200k
249k
1k
2M
2.5V
1µA OUT
VCC
2N5086
LT6656
20
6656fc
For more information www.linear.com/LT6656
PACKAGE DESCRIPTION
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
1.50 – 1.75
(NOTE 4)
2.80 BSC
0.30 – 0.45
6 PLCS (NOTE 3)
DATUM ‘A’
0.09 – 0.20
(NOTE 3) S6 TSOT-23 0302
2.90 BSC
(NOTE 4)
0.95 BSC
1.90 BSC
0.80 – 0.90
1.00 MAX 0.01 – 0.10
0.20 BSC
0.30 – 0.50 REF
PIN ONE ID
NOTE:
1. DIMENSIONS ARE IN MILLIMETERS
2. DRAWING NOT TO SCALE
3. DIMENSIONS ARE INCLUSIVE OF PLATING
4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
5. MOLD FLASH SHALL NOT EXCEED 0.254mm
6. JEDEC PACKAGE REFERENCE IS MO-193
3.85 MAX
0.62
MAX
0.95
REF
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
1.4 MIN
2.62 REF
1.22 REF
S6 Package
6-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1636)
LT6656
21
6656fc
For more information www.linear.com/LT6656
PACKAGE DESCRIPTION
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
2.00 ±0.10
(4 SIDES)
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WCCD-2)
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE
TOP AND BOTTOM OF PACKAGE
0.40 ±0.10
BOTTOM VIEW—EXPOSED PAD
0.56 ±0.05
(2 SIDES)
0.75 ±0.05
R = 0.125
TYP
R = 0.05
TYP
1.37 ±0.05
(2 SIDES)
1
3
64
PIN 1 BAR
TOP MARK
(SEE NOTE 6)
0.200 REF
0.00 – 0.05
(DC6) DFN REV B 1309
0.25 ±0.05
0.50 BSC
0.25 ±0.05
1.42 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
0.61 ±0.05
(2 SIDES)
1.15 ±0.05
0.70 ±0.05
2.55 ±0.05
PACKAGE
OUTLINE
0.50 BSC
PIN 1 NOTCH
R = 0.20 OR
0.25 × 45°
CHAMFER
DC6 Package
6-Lead Plastic DFN (2mm × 2mm)
(Reference LTC DWG # 05-08-1703 Rev B)
LT6656
22
6656fc
For more information www.linear.com/LT6656
PACKAGE DESCRIPTION
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
7
8
1
3
4
2
2.00 REF
R0.20 REF
6
5
7
8
6
5
1
2
3
4
4.20 ±0.10
4.20 SQ ±0.10
2.54 ±0.15
1.00 × 7 TYP
0.64 × 8 TYP
LS8 0113 REV B
R0.20 REF
0.95 ±0.10
1.45 ±0.10
0.10 TYP0.70 TYP
1
4
7
8
6
1.4
0.5
1.50 ±0.15
2.50 ±0.15
2.54 ±0.15
0.70 ±0.05 × 8
PACKAGE OUTLINE
0.5
5.00 SQ ±0.15
5.00 SQ ±0.15
5.00 SQ ±0.15
5.80 SQ ±0.15
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
NOTE:
1. ALL DIMENSIONS ARE IN MILLIMETERS
2. DRAWING NOT TO SCALE
3. DIMENSIONS PACKAGE DO NOT INCLUDE PLATING BURRS
PLATING BURRS, IF PRESENT, SHALL NOT EXCEED 0.30mm ON ANY SIDE
4. PLATING—ELECTO NICKEL MIN 1.25UM, ELECTRO GOLD MIN 0.30UM
5. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE
TOP AND BOTTOM OF PACKAGE
PIN 1
TOP MARK
(SEE NOTE 5)
2
3
LS8 Package
8-Pin Leadless Chip Carrier (5mm × 5mm)
(Reference LTC DWG # 05-08-1852 Rev B)
ABCDEF
XYY ZZ
e4
Q12345
TRAY PIN 1
BEVEL PACKAGE IN TRAY LOADING ORIENTATION
COMPONENT
PIN “A1
1.4
LT6656
23
6656fc
For more information www.linear.com/LT6656
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
REVISION HISTORY
REV DATE DESCRIPTION PAGE NUMBER
A 7/10 Voltage options added (1.25, 2.048, 3, 3.3), reflected throughout the data sheet 1 to 18
B 5/11 Added 6-lead DFN package reflected throughout the data sheet 1 to 20
C 11/13 Addition of 1.25V option in the LS8 package
Note 10 updated with additional explanation of hysteresis
Pin Functions updated to show pin numbers and LS8 package
Block Diagram updated to show pin numbers and LS8 package
Hysteresis section updated with additional explanation
Hysteresis graphs updated for SOT23 and LS8 packages
New section added for Humidity Sensitivity
1 to 4
6
10
10
13
14
15, 16
LT6656
24
6656fc
For more information www.linear.com/LT6656
LINEAR TECHNOLOGY CORPORATION 2010
LT 1113 REV C • PRINTED IN USA
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 FAX: (408) 434-0507 www.linear.com/LT6656
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Reference
0.05% Max, 10ppm/°C Max Drift, 1.25V, 2.5V, 4.096V, 5V, 10µA Maximum Supply
Current
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LT6003 1.6V, 1µA Precision Rail-to-Rail Op Amp 1µA Max Supply Current, 1.6V Minimum Operating Voltage, SOT-23 and DFN Packages
LT6650 Micropower Reference with Buffer Amplifier 0.05% Max, 5.6µA Supply, SOT-23 Package
LT6660 Tiny Micropower Series Reference 0.2% Max, 20ppm/°C Max, 20mA Output Current, 2mm × 2mm DFN
LT6700 Micropower, Low Voltage Dual Comparator
with 40mV Reference
6.5µA Supply Current, 1.4V Minimum Operating Voltage
TYPICAL APPLICATION
Reference Regulator for Micropower DAC, Total IQ = 4.8µA
0.1µF
5.1V ≤ V
IN ≤ 18V
10µF
VREF VCC
GND
CS
SCK
SDI
LTC1662
DAC A
DAC B
LT6656-5
IN OUT 5V
0V TO 5V OUTPUT
0V TO 5V OUTPUT
6656 TA07

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