LT6656AIS6-5 [Linear]
1μA Precision Series Voltage Reference; 1μA精准串联电压基准型号: | LT6656AIS6-5 |
厂家: | Linear |
描述: | 1μA Precision Series Voltage Reference |
文件: | 总18页 (文件大小:558K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
LT6656
1µA Precision Series
Voltage Reference
FeaTures
DescripTion
The LT®6656 is a small 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.
n
Low Drift
A Grade: 10 ppm/°C Max
B Grade: 20 ppm/°C Max
High Accuracy
n
A Grade: 0.05% Max
B Grade: 0.1% Max
n
n
n
n
n
n
n
n
Ultralow Supply Current: 850nA
High Output Drive Current: 5mA Min
Low Dropout Voltage: 10mV Max
Fully Specified from –40°C to 85°C
Operational from –55°C to 125°C
Wide Supply Range to 18V
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.
Reverse Input/Output Protection
Available Output Voltage Options:
1.25V, 2.048V, 2.5V, 3V, 3.3V, 4.096V and 5V
Thermal Hysteresis: 25ppm
The LT6656 output is stable with 1µF or larger output
capacitance and operates with a wide range of output
capacitor ESR.
n
n
Low Profile (1mm) ThinSOT™ Package
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.
applicaTions
n
Precision A/D and D/A Converters
n
Portable Gas Monitors
n
The LT6656 is offered in the 6-lead SOT-23 package.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. ThinSOT is
a trademark of Linear Technology Corporation. All other trademarks are the property of their
respective owners.
Battery- or Solar-Powered Systems
n
Precision Regulators
n
Low Voltage Signal Processing
n
Micropower Remote Sensing
Typical applicaTion
Output Voltage Temperature Drift
LT6656-2.5
2.503
38 TYPICAL UNITS
Basic Connection
2.502
2.501
2.500
2.499
2.498
LT6656-2.5
V
OUT
2.51V ≤ V ≤ 18V
V
V
OUT
IN
IN
2.5V
GND
0.1µF
1µF
6656 TA01a
–40 –20
0
20
40
60
80
TEMPERATURE (°C)
6652 TA01b
6656fa
ꢀ
LT6656
absoluTe MaxiMuM raTings
pin conFiguraTion
(Note 1)
TOP VIEW
Input Voltage........................................................... 20V
Output Voltage........................................... –0.3V to 20V
Output Voltage Above Input Voltage .........................20V
Specified Temperature Range
GND* 1
GND 2
NC 3
6 V
OUT
5 NC
4 V
IN
S6 PACKAGE
6-LEAD PLASTIC TSOT-23
= 150°C, θ = 230°C/W
Commercial ............................................. 0°C to 70°C
Industrial .............................................–40°C to 85°C
Operating Temperature Range ............... –55°C to 125°C
Output Short Circuit Duration ......................... Indefinite
Junction Temperature .......................................... 150°C
Storage Temperature Range (Note 2)..... –65°C to 150°C
Lead Temperature (Soldering, 10 sec.)
T
JMAX
JA
*CONNECT PIN TO DEVICE GND (PIN 2)
(Note 3).................................................................300°C
orDer inForMaTion
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
LTFNK
PACKAGE DESCRIPTION
SPECIFIED TEMPERATURE RANGE
LT6656ACS6-1.25#PBF
LT6656BCS6-1.25#PBF
LT6656AIS6-1.25#PBF
LT6656BIS6-1.25#PBF
LT6656ACS6-2.048#PBF
LT6656BCS6-2.048#PBF
LT6656AIS6-2.048#PBF
LT6656BIS6-2.048#PBF
LT6656ACS6-2.5#PBF
LT6656BCS6-2.5#PBF
LT6656AIS6-2.5#PBF
LT6656BIS6-2.5#PBF
LT6656ACS6-3#PBF
LT6656BCS6-3#PBF
LT6656AIS6-3#PBF
LT6656ACS6-1.25#TRPBF
LT6656BCS6-1.25#TRPBF
LT6656AIS6-1.25#TRPBF
LT6656BIS6-1.25#TRPBF
LT6656ACS6-2.048#TRPBF
LT6656BCS6-2.048#TRPBF
LT6656AIS6-2.048#TRPBF
LT6656BIS6-2.048#TRPBF
LT6656ACS6-2.5#TRPBF
LT6656BCS6-2.5#TRPBF
LT6656AIS6-2.5#TRPBF
LT6656BIS6-2.5#TRPBF
LT6656ACS6-3#TRPBF
LT6656BCS6-3#TRPBF
LT6656AIS6-3#TRPBF
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
0°C to 70°C
LTFNK
0°C to 70°C
LTFNK
–40°C to 85°C
–40°C to 85°C
0°C to 70°C
LTFNK
LTFNN
LTFNN
LTFNN
LTFNN
LTFGW
LTFGW
LTFGW
LTFGW
LTFNQ
LTFNQ
LTFNQ
LTFNQ
LTFNS
0°C to 70°C
–40°C to 85°C
–40°C to 85°C
0°C to 70°C
0°C to 70°C
–40°C to 85°C
–40°C to 85°C
0°C to 70°C
0°C to 70°C
–40°C to 85°C
–40°C to 85°C
0°C to 70°C
LT6656BIS6-3#PBF
LT6656BIS6-3#TRPBF
LT6656ACS6-3.3#PBF
LT6656BCS6-3.3#PBF
LT6656AIS6-3.3#PBF
LT6656BIS6-3.3#PBF
LT6656ACS6-3.3#TRPBF
LT6656BCS6-3.3#TRPBF
LT6656AIS6-3.3#TRPBF
LT6656BIS6-3.3#TRPBF
LTFNS
0°C to 70°C
LTFNS
–40°C to 85°C
–40°C to 85°C
LTFNS
6656fa
ꢁ
LT6656
orDer inForMaTion
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
LTFNV
PACKAGE DESCRIPTION
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
SPECIFIED TEMPERATURE RANGE
0°C to 70°C
LT6656ACS6-4.096#PBF
LT6656BCS6-4.096#PBF
LT6656AIS6-4.096#PBF
LT6656BIS6-4.096#PBF
LT6656ACS6-5#PBF
LT6656BCS6-5#PBF
LT6656AIS6-5#PBF
LT6656ACS6-4.096#TRPBF
LT6656BCS6-4.096#TRPBF
LT6656AIS6-4.096#TRPBF
LT6656BIS6-4.096#TRPBF
LT6656ACS6-5#TRPBF
LT6656BCS6-5#TRPBF
LT6656AIS6-5#TRPBF
LT6656BIS6-5#TRPBF
LTFNV
0°C to 70°C
LTFNV
–40°C to 85°C
–40°C to 85°C
0°C to 70°C
LTFNV
LTFNX
LTFNX
0°C to 70°C
LTFNX
–40°C to 85°C
–40°C to 85°C
LT6656BIS6-5#PBF
LTFNX
Consult LTC Marketing for parts specified with wider operating temperature ranges.
*The temperature and performance grades are identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard 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/
available opTions
SPECIFIED TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
TEMPERATURE
COEFFICIENT
OUTPUT VOLTAGE
INITIAL ACCURACY
ORDER PART NUMBER**
ORDER PART NUMBER**
1.250V
0.05%
0.1%
10ppm/°C
20ppm/°C
LT6656ACS6-1.25
LT6656BCS6-1.25
LT6656AIS6-1.25
LT6656BIS6-1.25
2.048V
2.500V
3.000V
3.300V
4.096V
5.000V
0.05%
0.1%
10ppm/°C
20ppm/°C
LT6656ACS6-2.048
LT6656BCS6-2.048
LT6656AIS6-2.048
LT6656BIS6-2.048
0.05%
0.1%
10ppm/°C
20ppm/°C
LT6656ACS6-2.5
LT6656BCS6-2.5
LT6656AIS6-2.5
LT6656BIS6-2.5
0.05%
0.1%
10ppm/°C
20ppm/°C
LT6656ACS6-3
LT6656BCS6-3
LT6656AIS6-3
LT6656BIS6-3
0.05%
0.1%
10ppm/°C
20ppm/°C
LT6656ACS6-3.3
LT6656BCS6-3.3
LT6656AIS6-3.3
LT6656BIS6-3.3
0.05%
0.1%
10ppm/°C
20ppm/°C
LT6656ACS6-4.096
LT6656BCS6-4.096
LT6656AIS6-4.096
LT6656BIS6-4.096
0.05%
0.1%
10ppm/°C
20ppm/°C
LT6656ACS6-5
LT6656BCS6-5
LT6656AIS6-5
LT6656BIS6-5
**See Order Information section for complete part number listing.
6656fa
ꢂ
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
LT6656A
LT6656B
–0.05
–0.10
0.05
0.10
%
%
l
l
Output Voltage Temperature Coefficient (Note 4)
Line Regulation
LT6656A
LT6656B
5
10
20
ppm/°C
ppm/°C
12
V
IN
= (V
+ 0.5V) to 18V
2
25
40
ppm/V
ppm/V
OUT
l
LT6656-2.048, LT6656-2.5, LT6656-3,
LT6656-3.3, LT6656-4.096, LT6656-5
V
= 2.2V to 18V
2
25
40
ppm/V
ppm/V
IN
l
l
LT6656-1.25
Load Regulation (Note 5)
Dropout Voltage (Note 6)
I = 5mA, Sourcing
65
150
375
ppm/mA
ppm/mA
L
LT6656-2.048, LT6656-2.5, LT6656-3,
LT6656-3.3, LT6656-4.096, LT6656-5
I = 5mA, Sourcing
80
3
175
425
ppm/mA
ppm/mA
L
l
l
l
LT6656-1.25
V
L
– V , ∆V
Error ≤ 0.1%
OUT
IN
OUT
I = 0
10
40
mV
mV
LT6656-2.048, LT6656-2.5, LT6656-3,
LT6656-3.3, LT6656-4.096, LT6656-5
I = 5mA, Sourcing
250
370
500
mV
mV
L
LT6656-2.048, LT6656-2.5, LT6656-3,
LT6656-3.3, LT6656-4.096, LT6656-5
Minimum Input Voltage
I = 0, ∆V
Error ≤ 0.1%
L
OUT
LT6656-1.25
0°C ≤ T ≤ 70°C
1.35
0.85
1.5
1.6
1.8
V
V
V
l
l
A
–40°C ≤ T ≤ 85°C
A
Supply Current
1.0
1.5
µA
µA
l
Output Short Circuit Current
Short V
Short V
to GND
18
4
mA
mA
OUT
OUT
to V
IN
Input Reverse Leakage Current
Reverse Output Current
V
IN
V
IN
= –18V, V
= GND, V
= GND
80
30
µA
µA
OUT
OUT
= 18V
Output Voltage Noise (Note 7)
0.1Hz to 10Hz
30
50
ppm
P-P
RMS
RMS
RMS
10Hz to 1kHz, LT6656-1.25
10Hz to 1kHz, LT6656-2.5
10Hz to 1kHz, LT6656-5
µV
µV
µV
80
140
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 8)
Hysteresis (Note 9)
50
ppm/√kHr
∆T = 0°C to 70°C
∆T = –40°C to 85°C
25
70
ppm
ppm
6656fa
ꢃ
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.
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 8: 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 2: If the parts are stored outside of the specified temperature range,
the output may shift due to hysteresis.
Note 3: The stated temperature is typical for soldering of the leads during
manual rework. For detailed IR reflow recommendations, refer to the
Applications section.
Note 4: Temperature coefficient is measured by dividing the maximum
Note 9: 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.
change in output voltage by the specified temperature range.
Note 5: 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 6: Excludes load regulation errors.
Note 7: 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
Typical perForMance characTerisTics
Output Voltage Temperature Drift
Typical VOUT Distribution
Supply Current vs Input Voltage
100
10
1
200
180
160
140
120
100
80
10000
9000
8000
7000
6000
5000
4000
3000
2000
1000
0
T
T
T
T
T
= 125°C
= 85°C
1.25V OPTION
ALL OPTIONS
25 TYPICAL UNITS
NORMALIZED AT 25°C
ALL OPTIONS
A
A
A
A
A
C
L
= 1µF
L
= 25°C
I
= 0
= –40°C
= –55°C
C
I
= 1µF
= 0
T
= 25°C
A
L
L
60
40
20
0.1
–1000
0
0
2
4
6
8
10 12 14 16 18 20
–0.10
–0.06
–0.02 0 0.02
0.06
0.10
–60 –40 –20
0
20 40 60 80 100 120
INPUT VOLTAGE (V)
TEMPERATURE (°C)
OUTPUT VOLTAGE ERROR (%)
6652 G01
6656 G17
6656 G02
6656fa
ꢄ
LT6656
Typical perForMance characTerisTics
Minimum Supply Voltage
vs Load Current
Dropout Voltage vs Load Current
Supply Current vs Input Voltage
100
10
1
2.0
1.8
1.6
1.4
1.2
1.0
0.8
1000
100
10
T
T
T
T
= 125°C
= 85°C
= 25°C
= –55°C
2.048V TO 5V OPTIONS
1.25V OPTION
2.048V TO 5V OPTIONS
A
A
A
A
INITIAL V = 2.2V
V
– V
IN
= 0.1%
IN OUT
∆V
INITIAL V = V
+ 0.5V
OUT
OUT
IN
∆V
= 0.1%
OUT
V
ON
T
T
T
T
T
= 125°C
= 85°C
A
A
A
A
A
T
T
T
T
= 125°C
= 85°C
= 25°C
= –55°C
A
A
A
A
2.5V OPTION SHOWN
MOVES WITH VOLTAGE OPTION
= 25°C
V
= –40°C
= –55°C
ON
0.1
1
0
2
4
6
8
10 12 14 16 18 20
0.1µ
1µ
10µ
100µ
1m
10m
0.1µ
1µ
10µ
100µ
1m
10m
INPUT VOLTAGE (V)
LOAD CURRENT (A)
LOAD CURRENT (A)
6656 G03
6656 G18
6656 G04
Load Regulation (Sourcing)
Load Regulation (Sourcing)
Load Regulation (Sinking)
500
250
750
500
250
0
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
1.25V OPTION
2.048V TO 5V OPTIONS
ALL OPTIONS
V
C
= 1.75V
V
C
= V
+ 0.5V
V
C
= V + 0.5V
IN
L
IN
L
OUT
IN
OUT
= 1µF
= 1µF
= 1µF
L
0
T
T
T
T
= 85°C, 125°C
= 25°C
A
A
A
A
–250
–500
–750
–1000
= –40°C
= –55°C
–250
–500
–750
T
T
T
T
T
= 125°C
= 85°C
A
A
A
A
A
T
T
T
T
= 125°C
= 85°C
= 25°C
= –55°C
A
A
A
A
= 25°C
= –40°C
= –55°C
–0.5
0.1µ
1µ
10µ
100µ
1m
10m
0.1µ
1µ
10µ
100µ
1m
10m
10µ
100µ
1m
LOAD CURRENT (A)
LOAD CURRENT (A)
LOAD CURRENT (A)
6656 G19
6656 G05
6656 G06
Power Supply Rejection Ratio
vs Frequency
Power Supply Rejection Ratio
vs Frequency
Line Regulation
1000
900
800
700
600
500
400
300
200
100
0
90
80
70
60
50
40
30
20
10
0
90
80
70
60
50
40
30
20
10
0
ALL OPTIONS
T
T
T
T
= 125°C
= 85°C
= 25°C
= –55°C
V
C
I
= V + 0.5V
OUT
2.5V OPTION
V = 3V
IN
A
A
A
A
IN
L
L
I
= 0
L
= 1µF
L
C
= 1µF
= 0
2.5V OPTION SHOWN
MOVES WITH
V
ON
VOLTAGE OPTION
V
ON
I
L
I
L
I
L
I
L
= 0, C = 1µF
L
= 0, C = 10µF
L
1.25V OPTION
2.5V OPTION
5V OPTION
= 1mA, C = 1µF
L
= 1mA, C = 10µF
L
–100
–200
–10
0
2
4
6
8
10 12 14 16 18 20
10
100
1k
10k
10
100
1k
10k
INPUT VOLTAGE (V)
FREQUENCY (Hz)
FREQUENCY (Hz)
6656 G08
6656 G09
6656 G20
6656fa
ꢅ
LT6656
Typical perForMance characTerisTics
Ground Current vs Load Current
Output Impedance vs Frequency
Output Impedance vs Frequency
10k
1k
10k
1k
1000
100
10
V
C
I
= V
+ 0.5V
OUT
2.5V OPTION
ALL OPTIONS
IN
L
L
= 1µF
V
= 3V
V
C
= V
+ 0.5V
IN
IN
L
OUT
= 0
= 1µF
100
10
1
100
10
1
I
L
I
L
I
L
I
L
= 0, C = 1µF
L
T
T
T
T
= 125°C
= 85°C
= 25°C
= –55°C
A
A
A
A
= 0, C = 10µF
L
1.25V OPTION
2.5V OPTION
5V OPTION
= 100µA, C = 1µF
L
= 100µA, C = 10µF
L
1
10
100
1k
10k
10
100
1k
10k
10µ
100µ
1m
10m
FREQUENCY (Hz)
FREQUENCY (Hz)
LOAD CURRENT (A)
6656 G21
6656 G22
6656 G07
Reverse Output Current
Output Noise 0.1Hz to 10Hz
Reverse Input Current
1000
100
10
100
10
1
ALL OPTIONS
ALL OPTIONS
ALL OPTIONS
V
= GND
V
= GND
V
C
L
= V
+ 0.5V
OUT
IN
IN
L
OUT
= 1µF
I
= 0
1
T
T
T
T
= 125°C
= 85°C
= 25°C
= –55°C
T
T
T
T
= 125°C
= 85°C
= 25°C
= –55°C
A
A
A
A
A
A
A
A
0
0
–2 –4 –6 –8 –10 –12 –14 –16 –18 –20
0
5
10
15
20
TIME (1s/DIV)
6656 G13
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
6656 G11
6656 G12
Output Voltage Noise Spectrum
vs Load Current
Output Noise Voltage Spectrum
vs Load Capacitance
Output Voltage Noise Spectrum
30
25
20
15
10
5
16
14
12
10
8
40
35
30
25
20
15
10
5
V
C
I
= V
+ 5V
OUT
2.5V OPTION
2.5V OPTION
I
L
I
L
I
L
I
L
= 0
IN
L
L
= 1µF
V
C
= 3V
V
I
= 3V
= 10µA
= 250µA
= 1mA
IN
L
IN
L
C = 47µF
L
= 0
= 1µF
= 0
5V OPTION
C
= 4.7µF
C
L
6
= 0.47µF
4
L
2.5V OPTION
2
1.25V OPTION
1k
0
0
0
10
100
10k
10
100
1k
10k
1
10
100
1k
FREQUENCY (Hz)
FREQUENCY (Hz)
FREQUENCY (Hz)
6656 G24
6656 G14
6656 G15
6656fa
ꢆ
LT6656
Typical perForMance characTerisTics
Integrated 10Hz to 1kHz Noise
vs Load Current
Integrated 10Hz to 1kHz Noise
vs Load Current
Long-Term Drift
500
400
300
200
100
0
250
200
150
100
50
200
150
100
50
V
C
= V
+ 0.5V
OUT
2.5V OPTION
ALL OPTIONS
IN
L
= 1µF
C = 1µF
L
L
I
= 0
0
5V OPTION
–50
–100
–150
–200
2.5V OPTION
C
C
C
C
= 0.47µF
= 1µF
= 10µF
= 47µF
L
L
L
L
1.25V OPTION
5 TYPICAL PARTS
SOLDERED ONTO PCB
0
0.1µ
1µ
10µ
100µ
1m
10m
0.1µ
1µ
10µ
100µ
1m
10m
0
100 200 300 400 500 600 700 800 900 1000
LOAD CURRENT (A)
LOAD CURRENT (A)
HOURS
6656 G25
6656 G23
6656 G16
pin FuncTions
GND* (Pin 1): Internal Function. This pin must be tied
to ground.
NC (Pin 5): Not internally connected. May be tied to V ,
OUT
IN
V
, GND or floated.
GND (Pin 2): Device Ground.
V
(Pin 6): Output Voltage. An output capacitor of 1µF
OUT
minimum is required for stable operation.
NC (Pin 3): Not internally connected. May be tied to V ,
IN
V , GND or floated.
OUT
V
(Pin 4): Power Supply. Bypass V with a 0.1µF
IN
IN
capacitor to ground.
block DiagraM
V
IN
NC
V
OUT
ERROR
AMP
BANDGAP
NC
GND
GND
6656 BD
6656fa
ꢇ
LT6656
applicaTions inForMaTion
Long Battery Life
Output Voltage Options
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, theshuntreferencemustalwayssinkthiscurrent,
resulting in high dissipation and shortened battery life.
TheperformanceoftheLT6656isconsistentforthe2.048V
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.
Parametersthatarebasedonchangesintheoutputvoltage,
suchasloadregulationandhysteresis,remainproportional
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 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.
ThebandwidthoftheLT6656decreaseswithhigheroutput
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.
Start-Up
Bypass and Load Capacitance
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.
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
LT6656requiresacapacitanceof1µForlarger. TheLT6656
is stable with a wide variety of capacitor types including
ceramic,tantalumandelectrolyticduetoitslowsensitivity
to ESR (5Ω or less).
V
IN
1V/DIV
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
Figure4.Thelargescaleoutputresponsetoa500mVinput
step is shown in Figure 5 with a more detailed photo and
description in the Output Settling section.
V
OUT
6656 F01
1ms/DIV
Figure 1. LT6656-2.5 Turn-On Characteristics, CL = 1µF
R2
V
IN
LT6656-2.5
3V
V
GEN
3V
C
IN
C
L
1µF
R1
0.1µF
2N7000
6656 F02
Figure 2. Transient Load Test Circuit
6656fa
ꢈ
LT6656
applicaTions inForMaTion
Thesettlingtimeistypicallylessthan8msforoutputloads
up to 5mA, however the time required to settle when the
loadisturnedofforinresponsetoaninputtransientcanbe
significantly longer due to the dead band (shown in Figure
7). Duringthisintervaltheoutputstageisneithersourcing
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.
0µA
I
OUT
100µA
2.52V
2.50V
2.48V
V
OUT
6656 F03
5ms/DIV
Figure 3. Transient Response, 0µA to 100µA Load Step
(R2 = 24.9k, R1 = Open)
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.
1mA
I
OUT
2mA
The settling time can be estimated by the following
equation:
2.52V
2.50V
2.48V
V
OUT
2(Deadband)(CL)
Settling time≈
+(VOUT)(0.8ms/V)
IL
6656 F04
5ms/DIV
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.
Figure 4. Transient Response, 1mA to 2mA Load Step
(R1 = R2 = 2.49k)
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.
3.25V
V
IN
2.75V
2.7V
2.5V
2.3V
30
2.5V OPTION
V
OUT
V
C
= 3V
IN
L
= 1µF
25
20
15
10
5
∆I = LOAD
L
STEP TO ZERO
6656 F05
5ms/DIV
Figure 5. Output Response to 0.5VP-P Step on VIN, CL = 1µF, IL = 0
∆I = LOAD
L
STEP TO 2µA
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.
∆I = ZERO TO
L
LOAD STEP
0
0.001
0.01
0.1
LOAD STEP (mA)
1
10
6656 F06
Figure 6. Output Settling Time to 0.05% vs Load Step
6656fa
ꢀ0
LT6656
applicaTions inForMaTion
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.
3.25V
V
IN
2.75V
I
= 0
L
V
Long-Term Drift
OUT
10mV/DIV
I
= 5µA
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
L
6656 F07
5ms/DIV
Figure 7. Detailed Output Response to a 0.5V Input Step,
CIN = CL = 1µF
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
bandgapreference(about400nA)isavailabletodischarge
the output capacitor.
= 30°C,
placed into a constant temperature oven with T
A
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.
Output Noise
Hysteresis
Low frequency noise is proportional to the output voltage
and is insensitive to output current and moderate levels
of output capacitance.
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. This
two-stepcycleisrepeatedseveraltimesandthemaximum
hysteresis from all the partial cycles is noted. Unlike other
commonly used methods for specifying hysteresis, this
ensures the worst-case hysteresis is included, whether it
occurs in the first temperature excursion or the last.
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
outputcapacitorwhendrivingheavierloads,orconversely,
reducing the size of the output capacitor when driving
lighterloads.NoiseplotsintheTypicalPerformanceCurves
section show noise spectrum with various load currents
and output capacitances.
Results over both commercial and industrial temperature
rangesareshowninFigure8andFigure9.Thepartscycled
overthehighertemperaturerangehaveahigherhysteresis
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.
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
IR Reflow Shift
The different expansion and contraction rates of the mate-
rials that make up the LT6656 package may induce small
stressesonthediethatcancausetheoutputtoshiftduring
6656fa
ꢀꢀ
LT6656
applicaTions inForMaTion
30
300
225
150
75
380s
2.5V OPTION
0°C TO 25°C
70°C TO 25°C
T
= 260°C
P
V
C
= 3V
IN
RAMP
DOWN
= 1µF
25
20
15
10
5
L
= 0
T = 217°C
L
I
L
T
= 200°C
S(MAX)
t
T
= 190°C
P
S
30s
T = 150°C
t
L
RAMP TO
150°C
130s
40s
120s
4
0
0
–60 –40 –20
0
20
40
60
0
2
6
8
10
MINUTES
HYSTERESIS (ppm)
6656 F10
6656 F08
Figure 10. Lead Free Reflow Profile Due to IR Reflow
Figure 8. 0°C to 70°C Hysteresis
7
20
18
16
14
12
10
8
2.5V OPTION
3 CYCLES
1 CYCLE
2.5V OPTION
–40°C TO 25°C
85°C TO 25°C
V
C
I
= 3V
V
C
I
= 3V
IN
IN
6
5
4
3
2
1
0
= 1µF
= 1µF
L
= 0
L
= 0
L
L
6
4
2
0
0
20
60
100
140
180
220
–160 –120 –80 –40
0
40 80 120 160
CHANGE IN OUTPUT VOLTAGE (ppm)
HYSTERESIS (ppm)
6656 F11
6656 F09
Figure 9. –40°C to 85°C Hysteresis
Figure 11. Output Voltage Shift Due to IR Reflow,
Peak Temperature = 260°C
IR reflow. Common lead free IR reflow profiles reach over
250°C, considerably more than lead solder profiles. The
higherreflowtemperatureoftheleadfreepartsexacerbates
the issue of thermal expansion and contraction causing
the output shift to generally be greater than with a leaded
reflow process.
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 lead free IR reflow profile used to experimentally
measure the output voltage shift in the LT6656-2.5 is
shown in Figure 10. Similar results can be expected using
a convection reflow oven. Figure 11 shows the change
in output voltage that was measured for parts that were
run through the reflow process for 1 cycle and also 3
cycles. The results indicate that the standard deviation
of the output voltage increases with a positive mean shift
of 120ppm. While there can be up to 220ppm of output
voltage shift, additional drift of the LT6656 after IR reflow
does not vary significantly.
The input and output capacitors should be mounted close
to the package. The GND and V
short as possible to minimize the voltage drops caused
by load and ground currents. Excessive trace resistance
directly impacts load regulation.
traces should be as
OUT
6656fa
ꢀꢁ
LT6656
Typical applicaTions
Regulator Reference
Low Power ADC 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 microcontroller’s on board ADC.
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 13 shows the LTC2480, a
low power delta sigma ADC. When the ADC is disabled its
quiescentcurrent(I )isroughly1µA,duringconversionthe
Q
I jumps up to 160µA. In reality, the power consumption
Q
is not only based on the I during conversion, but the real
Q
LT6656-2.5
power consumption of the ADC is set by the conversion
timeandthesamplerate. TheLTC2480showninFigure13
has a conversion time of 160ms which sets the maximum
samplerateof6samplespersecond.Themaximumsample
ratealsosetsthemaximumcurrentconsumptionto160µA,
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 average current drawn by the ADC
during a 1 second interval would only be 26.4µA. When
taking into consideration the current drawn by the refer-
ence, the total current draw is only 27.4µA. This system is
greatlysimplifiedbecausetheprecisionreferencedoesnot
need to be cycled on and off to save power. Furthermore,
leaving the reference on continuously eliminates concern
for turn-on settling time.
3V ≤ V ≤ 18V
IN
OUT
IN
MCU
V /V
CC REF
0.1µF
10µF
5
6
7
2
3
1
PB0/AIN0/A /MOSI
REF
PB1/INT0/A /MISO/OC1A
IN1
PB2/ADC1/SCK/T0/INT0
PB3/ADC2
PB4/ADC3
PB5/RESET/ADC0
GND
6656 TA02
Figure 12. Microcontroller Reference and Regulator
LT6656-5
5.1V ≤ V ≤ 18V
IN
OUT
IN
4.7µF
0.1µF
REF
V
CC
+
–
IN
IN
CS
SCK
SDO
DIFFERENTIAL INPUT
±V • 0.5 (±±.5Vꢀ
LTC±480
REF
AT 1sps, I = ±7.4µA
Q
6656 TA05
Figure 13. Low Power ADC Reference
6656fa
ꢀꢂ
LT6656
Typical applicaTions
Extended Supply Range Reference
V
CC
UP TO 160V
330k
MMBT5551
IN
BZX584C12
0.1µF
V
OUT
OUT
LT6656-2.5
2.2µF
1µF
6656 TA03
Boosted Output Current Reference
3.6V ≤ V ≤ 18V
CC
+
2207
10µF
2N2905
1µF
0.1µF
IN
V
OUT
OUT
LT6656-2.5
40mA MAX
6656 TA04
Micropower Regulator, IQ = 2µA, Sink Up to 8mA
3V ≤ V ≤ 18V
CC
LT6656-2.5
IN
OUT
+
–
0.1µF
1µF
LT6003
2.5V
6656 TA06
ADC Reference and Bridge Excitation Supply
3.3V ≤ V ≤ 5.5V
CC
LT6656-3.3
3.8V ≤ V ≤ 18V
IN
OUT
IN
0.1µF
1µF
0.1µF
10µF
10k
10k
10k
V
V
CC
REF
–
+
IN
CS
SCK
SDO
0.1µF
0.1µF
LTC2452
IN
6656fa
ꢀꢃ
LT6656
Typical applicaTions
Low Power Precision High Voltage Supply Monitor, IQ = 1.4µA, High Voltage Supply Load = 10µA
100V
105V OVERVOLTAGE THRESHOLD
V
CC
9.53M
3
4
7
+
6.5V ≤ V ≤ 10V
CC
OVERVOLTAGE FLAG
LTC1540
LT6656-5
6
IN
OUT
–
5
0.1µF
1µF 475k
1, 2
6656 TA08
2-Terminal Current Source
+
+
–
LT6003
R3
V
REF
R1
1µF
LT6656-1.25
GND
IN
OUT
0.1µF
R2
–
6656 TA09
VREF R2
¥
´
¶
IOUT
ꢀ
ꢁ1
µ
¦
§
R1 R3
Precision Current and Boosted Reference, IQ = 5.5µA
249k
V
CC
+
–
+
–
1k
2.75V
200k
2N5086
LT6004
LT6004
1µA OUT
3V ≤ V ≤ 16V
CC
2M
LT6656-2.5
IN
OUT
2.5V
0.1µF
1µF
6656 TA10
6656fa
ꢀꢄ
LT6656
package DescripTion
S6 Package
6-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1636)
2.90 BSC
(NOTE 4)
0.62
MAX
0.95
REF
1.22 REF
1.4 MIN
1.50 – 1.75
2.80 BSC
3.85 MAX 2.62 REF
(NOTE 4)
PIN ONE ID
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
0.30 – 0.45
6 PLCS (NOTE 3)
0.95 BSC
0.80 – 0.90
0.20 BSC
DATUM ‘A’
0.01 – 0.10
1.00 MAX
0.30 – 0.50 REF
1.90 BSC
0.09 – 0.20
(NOTE 3)
S6 TSOT-23 0302 REV B
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
6656fa
ꢀꢅ
LT6656
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
6656fa
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.
ꢀꢆ
LT6656
Typical applicaTion
Reference Regulator for Micropower DAC, Total IQ = 4.8µA
LT6656-5
5V
5.1V ≤ V ≤ 18V
IN
OUT
IN
0.1µF
10µF
V
V
CC
REF
0V TO 5V OUTPUT
0V TO 5V OUTPUT
DAC A
DAC B
CS
SCK LTC1662
SDI
GND
6656 TA07
relaTeD parTs
PART NUMBER DESCRIPTION
COMMENTS
LT1389
LTC1440
LT1460
Nanopower Precision Shunt Voltage Reference 0.05% Max 10ppm/°C Max, 800nA Supply
Micropower Comparator with Reference
Micropower Series Reference
3.7µA Max Supply Current, 1% 1.182V Reference, MSOP, PDIP and SO-8 Packages
0.075% Max, 10ppm/°C Max Drift, 2.5V, 5V and 10V Versions,MSOP, PDIP, SO-8,
SOT-23 and TO-92 Packages
LT1461
LT1495
LTC1540
LT1634
Micropower Precision LDO Series Reference
1.5µA Precision Rail-to-Rail Dual Op Amp
Nanopower Comparator with Reference
3ppm/°C Max Drift, 0°C to 70°C, –40°C to 85°C, –40°C to 125°C Options in SO-8
1.5µA Max Supply Current, 100pA Max IOS
600nA Max Supply Current, 2% 1.182V Reference, MSOP and SO-8 Packages
Micropower Precision Shunt Voltage
Reference
0.05% Max, 10ppm/°C Max Drift, 1.25V, 2.5V, 4.096V, 5V, 10µA Maximum Supply
Current
LT1790
LTC1798
LT6003
LT6650
LT6660
LT6700
Micropower Precision Series Reference
6µA Low Dropout Series Reference
1.6V, 1µA Precision Rail-to-Rail Op Amp
Micropower Reference with Buffer Amplifier
Tiny Micropower Series Reference
0.05% Max, 10ppm/°C Max, 60µA Supply, SOT23 Package
Available in Adjustable, 2.5V, 3V, 4.096V and 5V
1µA Max Supply Current, 1.6V Minimum Operating Voltage, SOT-23 Package
0.05% Max, 5.6µA Supply, SOT-23 Package
0.2% Max, 20ppm/°C Max, 20mA Output Current, 2mm × 2mm DFN
6.5µA Supply Current, 1.4V Minimum Operating Voltage
Micropower, Low Voltage Dual Comparator
with 40mV Reference
6656fa
LT 0710 REV A • PRINTED IN USA
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
ꢀꢇ
●
●
LINEAR TECHNOLOGY CORPORATION 2010
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
相关型号:
LT6656BCS6-2.048#TRMPBF
LT6656 - 1µA Precision Series Voltage Reference; Package: SOT; Pins: 6; Temperature Range: 0°C to 70°C
Linear
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