TEXAS INSTRUMENTS INA121 Technical data

®

INA121

INA121

FET-Input, Low Power

INSTRUMENTATION AMPLIFIER

INA121

FEATURES

● LOW BIAS CURRENT: ±4pA

● LOW QUIESCENT CURRENT:

● LOW INPUT OFFSET VOLTAGE:

● LOW INPUT OFFSET DRIFT:

±450µA

±200µV

±2µV/°C

● LOW INPUT NOISE:
20nV/√Hz at f = 1kHz (G =100)

● HIGH CMR: 106dB

● WIDE SUPPLY RANGE:

±2.25V to ±18V

● LOW NONLINEARITY ERROR: 0.001% max

● INPUT PROTECTION TO

±40V

● 8-PIN DIP AND SO-8 SURFACE MOUNT

APPLICATIONS

● LOW-LEVEL TRANSDUCER AMPLIFIERS

Bridge, RTD, Thermocouple

● PHYSIOLOGICAL AMPLIFIERS

ECG, EEG, EMG, Respiratory

● HIGH IMPEDANCE TRANSDUCERS

● CAPACITIVE SENSORS

● MULTI-CHANNEL DATA ACQUISITION

● PORTABLE, BATTERY OPERATED SYSTEMS

● GENERAL PURPOSE INSTRUMENTATION

2

R

G

1

8

3

Over-Voltage

Protection

Over-Voltage

Protection

A

A

–

V

IN

+

V

IN

DESCRIPTION

The INA121 is a FET-input, low power instrumenta­tion amplifier offering excellent accuracy. Its versatile
three-op amp design and very small size make it ideal
for a variety of general purpose applications. Low bias
current (±4pA) allows use with high impedance
sources.

Gain can be set from 1V to 10,000V/V with a single
external resistor. Internal input protection can with­stand up to ±40V without damage.

The INA121 is laser-trimmed for very low offset
voltage (±200µV), low offset drift (±2µV/°C), and
high common-mode rejection (106dB at G = 100). It
operates on power supplies as low as ±2.25V (+4.5V),
allowing use in battery operated and single 5V sys­tems. Quiescent current is only 450µA.

Package options include 8-pin plastic DIP and SO-8
surface mount. All are specified for the –40°C to
+85°C industrial temperature range.

V+

7

INA121

1

2

25kΩ

25kΩ

40kΩ40kΩ

A

3

40kΩ40kΩ

G = 1 +

6

V

O

5

Ref

50kΩ

R

G

SBOS078

4

V–

International Airport Industrial Park • Mailing Address: PO Box 11400, Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706 • Tel: [phone] • Twx: 910-952-1111

Internet: http://www.burr-brown.com/ • FAXLine: [phone] (US/Canada Only) • Cable: BBRCORP • Telex: 066-6491 • FAX: [phone] • Immediate Product Info: [phone]

®

©1997 Burr-Brown Corporation PDS-1412A Printed in U.S.A. May, 1998

1

INA121

SPECIFICATIONS: VS = ±15V

At TA = +25°C, VS = ±15V, RL = 10kΩ, and IA reference = 0V, unless otherwise noted.

INA121P, U INA121PA, UA
PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX UNITS
INPUT

Offset Voltage, RTI ±200±200/G ±500±500/G ±300±200/G

vs Temperature ±2±2/G ±5±20/G ✻ ±15±20/G µV/°C
vs Power Supply V
Long-Term Stability ±0.5 ✻ µV/mo

Impedance, Differential 10

Common-Mode V

Input Voltage Range See Text and Typical Curves ✻

= ±2.25V to ±18V ±5±20/G ±50±150/G ✻✻µV/V

S

12

|| 1 ✻ Ω || pF

= 0V 10

O

12

|| 12 ✻ Ω || pF

Safe Input Voltage ±40 ✻ V
Common-Mode Rejection V

= –12.5V to 13.5V

CM

G = 1 78 86 7 2 ✻ dB

G = 10 91 100 85 ✻ dB

G = 100 96 106 90 ✻ dB

G = 1000 106 ✻ dB

BIAS CURRENT V

vs Temperature See Typical Curve ✻

= 0V ±4 ±50 ✻✻pA

CM

Offset Current ±0.5 ✻ pA

vs Temperature See Typical Curve ✻

NOISE, RTI R
Voltage Noise: f = 10Hz G = 100 30 ✻ nV/√Hz

S

= 0Ω

f = 100Hz G = 100 21 ✻ nV/√Hz
f = 1kHz G = 100 20 ✻ nV/√Hz
f

= 0.1Hz to 10Hz G = 100 1 ✻ µVp-p

Current Noise: f = 1kHz 1 ✻ fA/√Hz

GAIN

Gain Equation 1 + (50kΩ/R
Range of Gain 1 10,000 ✻✻V/V
Gain Error V

= –14V to 13.5V

O

G = 1 ±0.01 ±0.05 ✻ ±0.1 %

) ✻ V/V

G

G = 10 ±0.03 ±0.4 ✻ ±0.5 %

G = 100 ±0.05 ±0.5 ✻ ±0.7 %

Gain vs Temperature

(1)

G = 1000 ±0.5 ✻ %

G = 1 ±1 ±10 ✻✻ppm/°C
G > 1 ±25 ±100 ✻✻ppm/°C

Nonlinearity V

= –14V to 13.5V

O

G = 1 ±0.0002 ±0.001 ✻ ± 0.002 % of FSR

G = 10 ±0.0015 ±0.005 ✻ ± 0.008 % of FSR

G = 100 ±0.0015 ±0.005 ✻ ±0.008 % of FSR

G = 1000 ±0.002 ✻ % of FSR

OUTPUT

Voltage: Positive R

Negative R
Positive R
Negative R

Capacitance Load Drive 1000 ✻ pF

= 100kΩ (V+)–0.9 ✻ V

L

= 100kΩ (V–)+0.15 ✻ V

L

= 10kΩ (V+)–1.5 (V+)–0.9 ✻✻ V

L

= 10kΩ (V–)+1 (V–)+0.25 ✻✻ V

L

Short-Circuit Current ±14 ✻ mA

FREQUENCY RESPONSE

Bandwidth, –3dB G = 1 600 ✻ kHz

G = 10 300 ✻ kHz

G = 100 50 ✻ kHz

G = 1000 5 ✻ kHz
Slew Rate V
Settling Time, 0.01% G = 1 to 10 20 ✻ µs

= ±10V, G ≤ 10 0.7 ✻ V/µs

O

G = 100 35 ✻ µs

G = 1000 260 ✻ µs
Overload Recovery 50% Input Overload 5 ✻ µs

POWER SUPPLY

Voltage Range ±2.25 ±15 ±18 ✻✻ ✻ V
Quiescent Current I

= 0V ±450 ±525 ✻✻µA

O

TEMPERATURE RANGE

Specification –40 85 ✻✻°C
Operating –55 125 ✻✻°C
Storage –55 125 ✻✻°C
Thermal Resistance,

8-Lead DIP 100 ✻ °C/W

θ

JA

SO-8 Surface Mount 150 ✻ °C/W

✻ Specification same as INA121P, U.
NOTE: (1) Temperature coefficient of the “Internal Resistor” in the gain equation. Does not include TCR of gain-setting resistor, R

±1000±1000/G

.

G

µV

®

INA121

2

PIN CONFIGURATION

Top View 8-Pin DIP and SO-8

ELECTROSTATIC
DISCHARGE SENSITIVITY

Top View

This integrated circuit can be damaged by ESD. Burr-Brown
recommends that all integrated circuits be handled with

1

R

G

–

2

V

IN

+

3

V

IN

4

V–

8

R

G

7

V+

6

V

O

5

Ref

appropriate precautions. Failure to observe proper handling
and installation procedures can cause damage.

ESD damage can range from subtle performance degradation
to complete device failure. Precision integrated circuits may
be more susceptible to damage because very small parametric
changes could cause the device not to meet its published
specifications.

ABSOLUTE MAXIMUM RATINGS

Supply Voltage .................................................................................. ±18V

Analog Input Voltage Range ............................................................. ±40V

Output Short-Circuit (to ground) .............................................. Continuous

Operating Temperature ................................................. –55°C to +125°C

Storage Temperature ..................................................... –55°C to +125°C

Junction Temperature.................................................................... +150°C

Lead Temperature (soldering, 10s)............................................... +300°C

NOTE: (1) Stresses above these ratings may cause permanent damage.
Exposure to absolute maximum conditions for extended periods may degrade
device reliability.

(1)

PACKAGE/ORDERING INFORMATION

PACKAGE SPECIFIED

PRODUCT PACKAGE NUMBER(1) RANGE MARKING NUMBER(2) MEDIA
Single

INA121P 8-Pin DIP 006 –40°C to +85°C INA121P INA121P Rails
INA121PA 8-Pin DIP 006 –40°C to +85°C INA121PA INA121PA Rails
INA121U SO-8 Surface-Mount 182 –40°C to +85°C INA121U INA121U Rails

" " " " " INA121U/2K5 Tape and Reel

INA121UA SO-8 Surface-Mount 182 –40°C to +85°C INA121UA INA121UA Rails

" " " " " INA121UA/2K5 Tape and Reel

NOTES: (1) For detailed drawing and dimension table, please see end of data sheet, or Appendix C of Burr-Brown IC Data Book. (2) Models with a slash (/) are
available only in Tape and Reel in the quantities indicated (e.g., /2K5 indicates 2500 devices per reel). Ordering 2500 pieces of “INA121U/2K5” will get a single
2500-piece Tape and Reel. For detailed Tape and Reel mechanical information, refer to Appendix B of Burr-Brown IC Data Book.

DRAWING TEMPERATURE PACKAGE ORDERING TRANSPORT

The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN assumes
no responsibility for the use of this information, and all use of such information shall be entirely at the user’s own risk. Prices and specifications are subject to change
without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not authorize or warrant
any BURR-BROWN product for use in life support devices and/or systems.

3

INA121

®

TYPICAL PERFORMANCE CURVES

At TA = +25°C, VS = ±15V, unless otherwise noted.

60

G = 1000V/V

50
40

G = 100V/V

30
20

G = 10V/V

Gain (dB)

10

0

G = 1V/V

–10
–20

1k 10k 1M 10M100k

GAIN vs FREQUENCY

Frequency (Hz)

COMMON-MODE REJECTION

120

100

80

60

40

20

Common-Mode Rejection (dB)

0

10 100 10k 100k 1M1k

vs FREQUENCY

G = 1000V/V

G = 100V/V

G = 10V/V

G = 1V/V

Frequency (Hz)

POSITIVE POWER SUPPLY REJECTION

120

100

80

60

40

Power Supply Rejection (dB)

20

0

10 100 10k 100k 1M1k

INPUT COMMON-MODE RANGE

vs OUTPUT VOLTAGE, V

15

10

5

0

–5

Common-Mode Voltage (V)

–10

V

D/2

V

D/2

+

V

CM

–15

–15 –10 0 5 15–5

vs FREQUENCY

Frequency (Hz)

+15V

+
–

+
–

Ref

–15V

Output Voltage (V)

G = 1V/V

= ±15V

S

V

O

G = 1000V/V

G = 100V/V

G = 10V/V

G = 1
G ≥ 10

10

NEGATIVE POWER SUPPLY REJECTION

120

G = 100V/V

100

80

G = 1000V/V

G = 10V/V

G = 1V/V

60

40

Power Supply Rejection (dB)

20

0

10 100 10k 100k 1M1k

INPUT COMMON-MODE RANGE

vs OUTPUT VOLTAGE, V

5
4
3
2

G ≥ 10

G = 1

1

0
–1
–2
–3

Common-Mode Voltage (V)

–4
–5

VS = ±5V

= ±2.5V

V

S

–5

–4 –3 –2 –1 0 1 2 3 4 5

vs FREQUENCY

Frequency (Hz)

G ≥ 10

G = 1

Output Voltage (V)

= ±5V, ±2.5V

S

®

INA121

4

TYPICAL PERFORMANCE CURVES (CONT)

INPUT BIAS CURRENT

vs COMMON-MODE INPUT VOLTAGE

1m

100µ

10µ

10p

1p

–10µ

–100µ

–1m

–20 –15 –10 –5 0 5 10 15 20

Common-Mode Voltage (V)

Input Bias Current (A)

At TA = +25°C, VS = ±15V, unless otherwise noted.

10k

INPUT BIAS CURRENT vs TEMPERATURE

1k

100

10

I

1

Bias Current (pA)

0.1

B

I

OS

0.01
–75 –50 –25 0 25 50 75 100 125

Temperature (°C)

INPUT OVER-VOLTAGE V/I CHARACTERISTICS

1

0.8

0.6

0.4

0.2

–0.2
–0.4

Input Current (mA)

–0.6
–0.8

Flat region represents
normal linear operation.

0

G = 1V/V

–1

–50 –40 –30 –20 –10 10 20 30 40050

G = 1000V/V

V

IN

Input Voltage (V)

I

IN

G = 1V/V

G = 1000V/V

+15V

–15V

1000

SETTLING TIME vs GAIN

0.01%

100

0.1%

Settling Time (µs)

10

1 10 100 1000

Gain (V/V)

QUIESCENT CURRENT AND SLEW RATE

500

475

450

425

Quiescent Current (µA)

400

375

–75 –50 –25 0 25 50 75 100 125

vs TEMPERATURE

I

Q

Temperature (°C)

SR

1.4

1.2

1

0.8

0.6

0.4

±15

±14

±13

Slew Rate (V/µs)

±12

Short-Circuit Current (µA)

±11

±10

–75 –50 –25 0 25 50 75 100 125

5

SHORT-CIRCUIT CURRENT

vs TEMPERATURE

+I

SC

–I

SC

Temperature (°C)

INA121

®

TYPICAL PERFORMANCE CURVES (CONT)

At TA = +25°C, VS = ±15V, unless otherwise noted.

OUTPUT VOLTAGE SWING vs OUTPUT CURRENT

V+
(V+) –0.3
(V+) –0.6
(V+) –0.9
(V+) –1.2
(V+) –1.5
(V–) +1.5
(V–) +1.2
(V–) +0.9

Output Voltage Swing (V)

(V–) +0.6
(V–) +0.3

(V–)

0 ±2 ±4 ±6 ±8 ±10

10

8
6
4
2

0
–2
–4
–6

Offset Voltage Change (µV)

–8

–10

0

+85°C

+25°C
–40°C, –55°C

+125°C

+125°C

+85°C

Output Current (mA)

INPUT OFFSET VOLTAGE WARM-UP

100

200

Time (µs)

+25°C

–40°C, –55°C

300

400

500

MAXIMUM OUTPUT VOLTAGE vs FREQUENCY

30

25

G = 1

20

15

10

5

Peak-to-Peak Output Voltage (Vp-p)

0

100 1k 10k 100k 1M

18
16
14
12
10

8
6

Percent of Units (%)

4
2
0

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10

G = 10 to 100

G = 1000

Frequency (Hz)

INPUT OFFSET VOLTAGE DRIFT

PRODUCTION DISTRIBUTION

Typical production
distribution of
packaged units.

Offset Voltage Drift (µV/°C)

INPUT-REFERRED NOISE VOLTAGE

1000

100

10

Voltage Noise (nV/√Hz)

1

1 10 1k 10k100

®

INA121

vs FREQUENCY

Frequency (Hz)

G = 1

G = 10

G = 1000

(BW Limit)

G = 100

VOLTAGE NOISE 0.1 TO 10Hz

INPUT-REFERRED, G ≥ 100

0.5µV

1s/div

6