LTC6915
Zero Drift, Precision
Instrumentation Amplifier with
Digitally Programmable Gain
FeaTures
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DescripTion
The LTC
®
6915 is a precision programmable gain instru-
mentation amplifier. The gain can be programmed to 0,
1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, or 4096
through a parallel or serial interface. The CMRR is typi-
cally 125dB with a single 5V supply with any programmed
gain. The offset is below 10µV with a temperature drift of
less than 50nV/°C.
The LTC6915 uses charge balanced sampled data tech-
niques to convert a differential input voltage into a single
ended signal that is in turn amplified by a zero-drift op-
erational amplifier.
The differential inputs operate from rail-to-rail and the
single-ended output swings from rail-to-rail. The LTC6915
can be used in single power supply applications as low as
2.7V, or with dual ±5V supplies. The LTC6915 is available
in a 16-lead SSOP package and a 12-lead DFN surface
mount package.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners
14 Levels of Programmable Gain
125dB CMRR Independent of Gain
Gain Accuracy 0.1% (Typ)
Maximum Offset Voltage of 10µV
Maximum Offset Voltage Drift: 50nV/°C
Rail-to-Rail Input and Output
Parallel or Serial (SPI) Interface for Gain Setting
Supply Operation: 2.7V to ±5.5V
Typical Noise: 2.5µV
P-P
(0.01Hz to 10Hz)
16-Lead SSOP and 12-Lead DFN Packages
applicaTions
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Thermocouple Amplifiers
Electronic Scales
Medical Instrumentation
Strain Gauge Amplifier
High Resolution Data Acquisition
Typical applicaTion
Differential Bridge Amplifier with Gain Programmed through the Serial Interface
LTC6915 SSOP PACKAGE
3 IN
+
3V
2 IN
R < 10k
RESISTOR
ARRAY
REF 13
11 PARALLEL_SERIAL
4-BIT
LATCH
HOLD_THRU 5
V
+
16
3V
0.1µF
Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7
8-BIT
SHIFT-REGISTER
SHDN
DGND
V
–
6915 TA01
+
C
S
C
H
OUT 15
SENSE 14
C
F
_
–
MUX
6 CS(D0)
7 D
IN
(D1)
8 CLK(D2)
9 D
OUT
(D3)
µP
TO OTHER
DEVICES
1
10
4
6915fb
1
LTC6915
absoluTe MaxiMuM raTings
(Note 1)
Total Supply Voltage (V
+
to V
–
) ................................. 11V
Input Current........................................................ ±10mA
|V
IN+
– V
REF
| ........................................................5.5V
|V
IN –
– V
REF
| ........................................................5.5V
|V
+
– V
DGND
| ........................................................5.5V
|V
DGND
– V
–
| ........................................................5.5V
Digital Input Voltage........................................... V
–
to V
+
Operating Temperature Range
LTC6915C .............................................. –0°C to 70°C
LTC6915I .............................................–40°C to 85°C
LTC6915H .......................................... –40°C to 125°C
Junction Temperature
(GN Package) .................................................... 150°C
(DFN Package) .................................................. 125°C
Storage Temperature
(GN Package) ..................................... –65°C to 150°C
(DFN Package) ................................... –65°C to 125°C
Lead Temperature (Soldering 10 sec).................... 300°C
pin conFiguraTion
TOP VIEW
IN
–
TOP VIEW
12 V
+
1
2
3
4
5
6
13
V
–
SHDN 1
IN
–
2
IN
+
3
V
–
4
HOLD_THRU 5
CS(D0) 6
D
IN
(D1) 7
CLK(D2) 8
16 V
+
15 OUT
14 SENSE
13 REF
12 NC
11 PARALLEL_SERIAL
10 DGND
9
D
OUT
(D3)
IN
+
V
–
CS(D0)
D
IN
(D1)
CLK(D2)
11 OUT
10 REF
9
8
7
PARALLEL_SERIAL
DGND
D
OUT
(D3)
DE12 PACKAGE
12-LEAD (4mm
×
3mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 160°C/W
EXPOSED PAD (PIN 13) IS V
–
, MUST BE SOLDERED TO PCB
GN PACKAGE
16-LEAD NARROW PLASTIC SSOP
T
JMAX
= 150°C,
θ
JA
= 135°C/W
orDer inForMaTion
LEAD FREE FINISH
LTC6915CDE#PBF
LTC6915IDE#PBF
LTC6915CGN#PBF
LTC6915IGN#PBF
LTC6915HGN#PBF
LEAD BASED FINISH
LTC6915CDE
LTC6915IDE
LTC6915CGN
LTC6915IGN
LTC6915HGN
TAPE AND REEL
LTC6915CDE#TRPBF
LTC6915IDE#TRPBF
LTC6915CGN#TRPBF
LTC6915IGN#TRPBF
LTC6915HGN#TRPBF
TAPE AND REEL
LTC6915CDE#TR
LTC6915IDE#TR
LTC6915CGN#TR
LTC6915IGN#TR
LTC6915HGN#TR
PART MARKING
6915
6915I
6915
6915I
6915H
PART MARKING*
6915
6915I
6915
6915I
6915H
PACKAGE DESCRIPTION
12-Lead (4mm
×
3mm) Plastic DFN
12-Lead (4mm
×
3mm) Plastic DFN
16-Lead Narrow Plastic SSOP
16-Lead Narrow Plastic SSOP
16-Lead Narrow Plastic SSOP
PACKAGE DESCRIPTION
12-Lead (4mm
×
3mm) Plastic DFN
12-Lead (4mm
×
3mm) Plastic DFN
16-Lead Narrow Plastic SSOP
16-Lead Narrow Plastic SSOP
16-Lead Narrow Plastic SSOP
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
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/
6915fb
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LTC6915
elecTrical characTerisTics
SYMBOL
PARAMETER
Gain Error (Note 2)
Gain Error (Note 2)
Gain Error (Note 2)
Gain Error (Note 2)
Gain Nonlinearity
V
OS
Input Offset Voltage (Note 3)
Average Input Offset Drift (Note 3)
I
B
I
OS
en
CMRR
Average Input Bias Current (Note 4)
Average Input Offset Current (Note 4)
Input Noise Voltage
Common Mode Rejection Ratio
V
+
= 3V, V
–
= 0V, V
REF
= 200mV
A
V
= 1 (R
L
=10k)
A
V
= 2 to 32 (R
L
= 10k)
A
V
= 64 to 1024 (R
L
= 10k)
A
V
= 2048, 4096 (R
L
= 10k)
A
V
= 1
V
CM
= 200mV
T
A
= –40°C to 85°C
T
A
= 85°C to 125°C
V
CM
= 1.2V
V
CM
= 1.2V
DC to 10Hz
A
V
= 1024, V
CM
= 0V to 3V, LTC6915C
A
V
= 1024, V
CM
= 0.1V to 2.9V, LTC6915I
A
V
= 1024, V
CM
= 0V to 3V, LTC6915I
A
V
= 1024, V
CM
= 0.1V to 2.9V, LTC6915H
A
V
= 1024, V
CM
= 0V to 2.97V, LTC6915H
V
S
= 2.7V to 6V
Sourcing 200µA
Sourcing 2mA
Sinking 200µA
Sinking 2mA
No Load at OUT, V
CM
= 200mV
No Load at OUT, Capacitive Load at
,
D
OUT
(C
L
) = 15pF Continuous CLK
Frequency = 4MHz,
CS
= LOW,
Gain Control Code = 0001
V
SHDN
= 2.7V (Hardware Shutdown)
V
SHDN
= 1V, Gain Control Code = 0000
(Software Shutdown)
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The
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denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C.
CONDITIONS
MIN
–0.075
–0.5
–0.6
–1
TYP
0
0
–0.1
–0.2
3
–3
MAX
0.075
0.5
0.6
1.0
15
±10
±50
±100
5
1.5
2.5
100
100
95
100
85
110
2.95
2.75
119
119
119
10
3
UNITS
%
%
%
%
ppm
µV
nV/°C
nV/°C
nA
nA
µV
P-P
dB
dB
dB
dB
dB
dB
V
V
50
300
1.3
1.65
mV
mV
mA
mA
V
+
= 3V, V
–
= 0V, V
REF
= 200mV
PSRR
Power Supply Rejection Ratio (Note 5)
Output Voltage Swing High (Referenced to V
–
)
Output Voltage Swing Low (Referenced to V
–
)
Supply Current, Parallel Mode
Supply Current, Serial Mode (Note 6)
116
2.98
2.87
18
130
0.88
1.1
Supply Current Shutdown
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125
2.7
4
180
µA
µA
V
SHDN Input High
SHDN Input Low
SHDN and HOLD_THRU Input Current (Note 2)
Internal Op Amp Gain Bandwidth
Slew Rate
Internal Sampling Frequency
V
+
= 5V, V
–
= 0V, V
REF
= 200mV
Gain Error (Note 2)
Gain Error (Note 2)
Gain Error (Note 2)
Gain Error (Note 2)
Gain Nonlinearity
A
V
= 1 (R
L
= 10k)
A
V
= 2 to 32 (R
L
= 10k)
A
V
= 64 to 1024 (R
L
= 10k)
A
V
= 2048, 4096 (R
L
= 10k)
A
V
= 1
1
5
200
0.2
3
V
µA
kHz
V/µs
kHz
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–0.075
–0.5
–0.6
–1
0
0
–0.1
–0.2
3
0.075
0.5
0.6
1
15
%
%
%
%
ppm
6915fb
3
LTC6915
elecTrical characTerisTics
V
OS
Input Offset Voltage (Note 3)
Average Input Offset Drift (Note 3)
Average Input Bias Current (Note 4)
I
OS
CMRR
Average Input Offset Current (Note 4)
Common Mode Rejection Ratio
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C.
V
CM
= 200mV
T
A
= –40°C to 85°C
T
A
= 85°C to 125°C
V
CM
= 1.2V
V
CM
= 1.2V
A
V
= 1024, V
CM
= 0V to 5V, LTC6915C
A
V
= 1024, V
CM
= 0.1V to 4.9V, LTC6915I
A
V
= 1024, V
CM
= 0V to 5V, LTC6915I
A
V
= 1024, V
CM
= 0.1V to 4.9V, LTC6915H
A
V
= 1024, V
CM
= 0V to 4.97V, LTC6915H
V
S
= 2.7V to 6V
Sourcing 200µA
Sourcing 2mA
Sinking 200µA
Sinking 2mA
No Load at OUT, V
CM
= 200mV
No Load at OUT, Capacitive Load at
,
D
OUT
(C
L
) = 15pF Continuous CLK
Frequency = 4MHz,
CS
= LOW,
Gain Control Code = 0001
V
SHDN
= 4.5V (Hardware Shutdown)
V
SHDN
= 1V, Gain Control Code = 0000
(Software Shutdown)
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–3
±10
±50
±100
µV
nV/°C
nV/°C
nA
nA
dB
dB
dB
dB
dB
dB
V
V
5
1.5
105
105
95
100
85
110
4.95
4.80
125
125
125
10
3
PSRR
Power Supply Rejection Ratio (Note 5)
Output Voltage Swing High
Output Voltage Swing Low
116
4.99
4.93
17
120
0.95
1.4
50
300
1.48
2
mV
mV
mA
mA
V
+
= 5V, V
–
= 0V, V
REF
= 200mV
Supply Current, Parallel Mode
Supply Current, Serial Mode (Note 6)
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Supply Current, Shutdown
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2
135
4.5
10
200
µA
µA
V
SHDN Input High
SHDN Input Low
SHDN and HOLD_THRU Input Current (Note 2)
Internal Op Amp Gain Bandwidth
Slew Rate
Internal Sampling Frequency
V
+
= 5V, V
–
= –5V, V
REF
= 0V
Gain Error (Note 2)
Gain Error (Note 2)
Gain Error (Note 2)
Gain Error (Note 2)
Gain Nonlinearity
V
OS
Input Offset Voltage (Note 3)
Average Input Offset Drift (Note 3)
I
OS
Average Input Bias Current (Note 4)
Average Input Offset Current (Note 4)
A
V
= 1 (R
L
= 10k)
A
V
= 2 to 32 (R
L
= 10k)
A
V
= 64 to 1024 (R
L
= 10k)
A
V
= 2048, 4096 (R
L
= 10k)
A
V
= 1
V
CM
= 0mV
T
A
= –40°C to 85°C
T
A
= 85°C to 125°C
V
CM
= 1V
V
CM
= 1V
1
5
200
0.2
3
V
µA
kHz
V/µs
kHz
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l
–0.075
–0.5
–0.6
–1
0
0
–0.1
–0.2
3
5
0.075
0.5
0.6
1
15
±20
±50
±100
%
%
%
%
ppm
µV
nV/°C
nV/°C
nA
nA
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4
1.5
10
3
6915fb
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LTC6915
elecTrical characTerisTics
CMRR
Common Mode Rejection Ratio
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C.
A
V
= 1024, V
CM
= –5V to 5V, LTC6915C
A
V
= 1024, V
CM
= –4.9V to 4.9V, LTC6915I
A
V
= 1024, V
CM
= –5V to 5V, LTC6915I
A
V
= 1024, V
CM
= –4.9V to 4.9V, LTC6915H
A
V
= 1024, V
CM
= –5V to 4.97V, LTC6915H
V
S
= 2.7V to 11V
Sourcing 200µA
Sourcing 2mA
Sinking 200µA
Sinking 2mA
No Load, V
CM
= 0mV
No Load at OUT, Capacitive Load at
,
D
OUT
(C
L
) = 15pF Continuous CLK
Frequency = 4MHz,
CS
= LOW,
Gain Control Code = 0001
V
SHDN
= 4V (Hardware Shutdown)
V
SHDN
= 1V, Gain Control Code = 0000
(Software Shutdown)
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105
105
100
100
90
110
4.97
4.90
123
123
123
dB
dB
dB
dB
dB
dB
V
V
–4.92
–4.70
1.6
2.48
V
V
mA
mA
PSRR
Power Supply Rejection Ratio (Note 5)
Output Voltage Swing High
Output Voltage Swing Low
Supply Current, Parallel Mode
Supply Current, Serial Mode (Note 6)
116
4.99
4.96
–4.98
–4.90
1.1
1.73
Supply Current, Shutdown
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160
4
25
240
µA
µA
V
SHDN Input High
SHDN Input Low
V
+
= 5V, V
–
= –5V, V
REF
= 0V
SHDN and HOLD_THRU Input Current (Note 2)
Internal Op Amp Gain Bandwidth
Slew Rate
Internal Sampling Frequency
Digital I/O, All Digital I/O Voltage Referenced to DGND
V
IH
V
IL
V
OH
V
OL
Digital Input High Voltage
Digital Input Low Voltage
Digital Output High Voltage
Digital Output Low Voltage
Digital Input Leakage
Timing, V
+
= 2.7V to 4.5V, V
–
= 0V (Note 7)
t
1
t
2
t
3
t
4
t
5
t
6
t
7
t
8
t
9
D
IN
Valid to CLK Setup
D
IN
Valid to CLK Hold
CLK Low
CLK High
CS/LD
Pulse Width
LSB CLK to
CS/LD
CS/LD
Low to CLK
D
OUT
Output Delay
CLK Low to
CS/LD
Low
C
L
= 15pF
Sourcing 500µA
Sinking 500µA
V
+
= 5V, V
–
= –5V, V
IN
= 0V to 5V
1
5
200
0.2
3
V
µA
kHz
V/µs
kHz
V
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2.0
0.8
V
+
– 0.3
0.3
±2
60
0
100
100
60
60
30
125
0
V
V
V
µA
ns
ns
ns
ns
ns
ns
ns
ns
ns
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