Datasheet AD8293G80 Datasheet (ANALOG DEVICES)

Low Cost, Zero-Drift In-Amp

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FEATURES

Small package: 8-lead SOT-23 Reduced component count

Incorporates gain resistors and filter resistors Low offset voltage: 20 μV maximum Low offset drift: 0.3 μV/°C maximum Low gain drift: 25 ppm/°C maximum High CMR: 140 dB typical Low noise: 0.7 μV p-p from 0.01 Hz to 10 Hz Single-supply operation: 1.8 V to 5.5 V Rail-to-rail output Available in 2 fixed-gain models

APPLICATIONS

Current sensing Strain gauges Laser diode control loops Portable medical instruments Thermocouple amplifiers

with Filter and Fixed Gain

AD8293G80/AD8293G160

FUNCTIONAL BLOCK DIAGRAM

7 5 6

FILT+V

+5

7 5

S

IN-AMP

R2

REFGND

OUT

R3

5kΩ

ADC OUT

AD8293Gxx

Figure 1.

C2

6

FILT+V

OUT

R2

R3

5kΩ

AD8293Gxx

32

ADC OUT

4

OUTPUT TO ADC WITH ANTI ALIASING FILTER

4

C3

+3.3V

ADC

REF

S

+IN

8

R1

IN-AMP

4kΩ

–IN

1

REFGND

32

0.1µF

LOAD

I

1.8V

DC-DC

R

SHUNT

+IN

8

R1

4kΩ

–IN

1

Figure 2. Measuring Current Using the AD8293G80/AD8293G160

07451-001

10µF0.1µF

07451-002

GENERAL DESCRIPTION

The AD8293G80/AD8293G160 are small, low cost, precision instrumentation amplifiers that have low noise and rail-to-rail outputs. They are available in two fixed-gain models: 80 and 160. They incorporate the gain setting resistors and filter resistors, reducing the number of ancillary components. For example, only two external capacitors are needed to implement a 2-pole filter. The AD8293G80/AD8293G160 also feature low offset voltage, offset drift, and gain drift coupled with high commonmode rejection. They are capable of operating on a supply of

1.8 V to 5.5 V.

With a low offset voltage of 20 µV (AD8293G160B), an offset voltage drift of 0.3 µV/°C, and a voltage noise of only 0.7 µV p-p (0.01 Hz to 10 Hz), the AD8293G80/AD8293G160 are ideal for applications where error sources cannot be tolerated.

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners.

Table 1. AD8293Gxx Models and Gains

Model Gain

AD8293G80 80 AD8293G160 160

Precision instrumentation, position and pressure sensors, medical instrumentation, and strain gauge amplifiers benefit from the low noise, low input bias current, and high commonmode rejection. The small footprint and low cost are ideal for high volume applications.

The small package and low power consumption allow the maximum channel density and the minimum board size required for portable systems. Designed for ease of use, these instrumentation amplifiers, unlike more traditional ones, have a buffered reference, eliminating the need for an additional op amp to set the reference voltage to midsupply.

The AD8293G80/AD8293G160 are specified over the industrial temperature range from −40°C to +85°C. The AD8293G80/ AD8293G160 are available in a halogen-free, Pb-free, 8-lead SOT-23.

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REVISION HISTORY

8/08—Revision 0: Initial Version

Theory of Operation ...................................................................... 10

High PSR and CMR ................................................................... 10

1/f Noise Correction .................................................................. 10

Applications Information .............................................................. 11

Overview ..................................................................................... 11

Reference Connection ............................................................... 11

Output Filtering .......................................................................... 11

Clock Feedthrough ..................................................................... 12

Power Supply Bypassing ............................................................ 12

Input Overvoltage Protection ................................................... 12

Outline Dimensions ....................................................................... 13

Ordering Guide .......................................................................... 13

Rev. 0 | Page 2 of 16

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SPECIFICATIONS

ELECTRICAL CHARACTERISTICS

VCC = 5.0 V, VCM = −0 V, V specifications guaranteed by characterization.

Table 2. A Grade

AD8293G80A AD8293G160A Parameter Symbol Conditions Min Typ Max Min Typ Max Unit

COMMON-MODE REJECTION CMR

NOISE PERFORMANCE

Voltage Noise e

Voltage Noise Density en f = 1 kHz 35 35 nV/√Hz

INPUT CHARACTERISTICS

Input Offset Voltage VOS 9 50 9 50 μV

vs. Temperature ΔVOS/ΔT −40°C ≤ TA ≤ +85°C 0.02 0.3 0.02 0.3 μV/°C Input Bias Current IB −40°C ≤ TA ≤ +85°C 0.4 2 0.4 2 nA Input Offset Current IOS 4 4 nA Input Operating Impedance

Differential 50||1 50||1 MΩ||pF

Common Mode 10||10 10||10 GΩ||pF Input Voltage Range 0 VCC − 1.7 0 VCC − 1.7 V

DYNAMIC RESPONSE

Small Signal Bandwidth Slew Rate SR Filter limited Filter limited Settling Time

2

t

0.1% 500 Hz filter, VO = 2 V step 1.9 1.9 ms

0.01% 2.4 2.4 ms

Internal Clock Frequency 60 60 kHz

GAIN 80 160

Gain Error VO = 0.075 V to 4.925 V 0.3 1 0.3 1 % Gain Drift −40°C ≤ TA ≤ +85°C 5 25 5 25 ppm/°C Nonlinearity VO = 0.075 V to 4.925 V 0.003 0.03 0.003 0.03 % FS

OUTPUT CHARACTERISTICS

Output Voltage High VOH

Output Voltage Low VOL 0.075 0.075 V Short-Circuit Current ISC ±35 ±35 mA

REFERENCE CHARACTERISTICS

V

Range 0.8 VCC − 0.8 0.8 VCC − 0.8 V

REF

REF Pin Current I

POWER SUPPLY

Operating Range 1.8 5.5 1.8 5.5 V Power Supply Rejection PSR VCC = 1.8 V to 5.5 V, VCM = 0 V 94 120 94 120 dB Supply Current ISY I

−40°C ≤ TA ≤ +85°C 1.5 1.5 mA

TEMPERATURE RANGE

Specified Range −40 +85 −40 +85 °C

1

Higher bandwidths result in higher noise.

2

Settling time is determined by filter setting.

= 3.3 V, VIN = V

REF

f = 0.01 Hz to 10 Hz 0.7 0.7 μV p-p

n p-p

1

BW Filter limited 500 500 Hz

s

0.01 1 0.01 1 nA

REF

− V

INP

V

CM

−40°C ≤ T

= 0 mA, VIN = 0 V 1.0 1.3 1.0 1.3 mA

O

, TA = 25°C, tested at ADC OUT, unless otherwise noted. Temperature

INN

= 0 V to 3.3 V,

≤ +85°C

A

Rev. 0 | Page 3 of 16

94 140 94 140 dB

−

V

CC

0.075

−

V

CC

0.075

V

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VCC = 2.7 V to 5.0 V, VCM = −0 V, V otherwise noted. Temperature specifications guaranteed by characterization.

Table 3. B Grade (Tested and Guaranteed over a Wider Supply Range to More Stringent Specifications Than the A Grade)

AD8293G80B AD8293G160B Parameter Symbol Conditions Min Typ Max Min Typ Max Unit

COMMON-MODE REJECTION CMR

NOISE PERFORMANCE

Voltage Noise e Voltage Noise Density en f = 1 kHz 35 35 nV/√Hz

INPUT CHARACTERISTICS

Input Offset Voltage VOS 5 30 3 20 μV

vs. Temperature ΔVOS/ΔT −40°C ≤ TA ≤ +85°C, VCC = 5 V 0.02 0.3 0.02 0.3 μV/°C

vs. Temperature ΔVOS/ΔT −40°C ≤ TA ≤ +85°C, VCC = 2.7 V 0.01 0.5 0.01 0.5 μV/°C Input Bias Current IB −40°C ≤ TA ≤ +85°C 0.4 2 0.4 2 nA Input Offset Current IOS 4 4 nA Input Operating Impedance

Differential 50||1 50||1 MΩ||pF

Common Mode 10||10 10||10 GΩ||pF Input Voltage Range 0 VCC − 1.7 0 VCC − 1.7 V

DYNAMIC RESPONSE

Small Signal Bandwidth

1

BW

Slew Rate SR Filter limited Filter limited Settling Time

2

t

0.1%

0.01% 2.4 2.4 ms

Internal Clock Frequency 60 60 kHz

GAIN 80 160

Gain Error VO = 0.075 V to 4.925 V 0.3 0.5 0.3 0.5 % Gain Drift −40°C ≤ TA ≤ +85°C 5 25 5 25 ppm/°C Nonlinearity VO = 0.075 V to 4.925 V 0.003 0.009 0.003 0.009 % FS

OUTPUT CHARACTERISTICS

Output Voltage High VOH

Output Voltage Low VOL 0.075 0.075 V Short-Circuit Current ISC V V

REFERENCE CHARACTERISTICS

V

Range 0.8 VCC − 0.8 0.8 VCC − 0.8 V

REF

REF Pin Current I

POWER SUPPLY

Operating Range 1.8 5.5 1.8 5.5 V Power Supply Rejection PSR VCC = 1.8 V to 5.5 V, VCM = 0 V 100 120 100 120 dB Supply Current ISY I

−40°C ≤ TA ≤ +85°C 1.5 1.5 mA

TEMPERATURE RANGE

Specified Range −40 +85 −40 +85 °C

1

Higher bandwidths result in higher noise.

2

Settling time is determined by filter setting.

= VCC/2, VIN = V

REF

= 5 V, VCM = 0 V to 3.3 V;

V

CC

−40°C ≤ T = 2.7 V, VCM = 0 V to 1 V;

V

CC

−40°C ≤ T

f = 0.01 Hz to 10 Hz 0.7 0.7 μV p-p

n p-p

Filter limited; measured at

− V

INP

≤ +85°C

A

≤ +85°C

A

, TA = 25°C, tested at OUT with 10 kΩ load and ADC OUT, unless

INN

110 140 110 140 dB

106 140 106 140 dB

500 500 Hz

ADC OUT

s

500 Hz filter, V

= 2 V step;

O

1.9 1.9 ms

measured at ADC OUT

V

CC

0.075

= 5 V ±35 ±35 mA

CC

= 2.7 V ±25 ±25 mA

CC

0.01 1 0.01 1 nA

REF

= 0 mA, VIN = 0 V 1.0 1.3 1.0 1.3 mA

O

Rev. 0 | Page 4 of 16

V

0.075

−

V

−

CC

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ABSOLUTE MAXIMUM RATINGS

Table 4.

Parameter Rating

Supply Voltage 6 V Input Voltage +V Differential Input Voltage1 ±V Output Short-Circuit Duration to GND Indefinite Storage Temperature Range (RJ Package) −65°C to +150°C Operating Temperature Range −40°C to +85°C Junction Temperature Range (RJ Package) −65°C to +150°C Lead Temperature (Soldering, 10 sec) 300°C

1

Differential input voltage is limited to ±5.0 V, the supply voltage, or

whichever is less.

SUPPLY

Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

THERMAL RESISTANCE

θJA is specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages.

Table 5.

Package Type θ

8-Lead SOT-23 (RJ) 211.5 91.99 °C/W

1

θJA is specified for the nominal conditions, that is, θJA is specified for the

device soldered on a circuit board.

1

θJC Unit

JA

ESD CAUTION

Rev. 0 | Page 5 of 16

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PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

AD8293Gxx

1

–IN

2

GND

3

REF

DC OUT

TOP VIEW

(Not to Scale)

Figure 3. Pin Configuration

8

+IN

+V

7

S

6

OUT

54

FILT

07451-003

Table 6. Pin Function Descriptions

Pin No. Mnemonic Description

1 −IN Inverting Input Terminal (True Differential Input) 2 GND Ground 3 REF Reference Voltage Terminal (Drive This Terminal to Level-Shift the Output) 4 ADC OUT Output with Series 5 kΩ Resistor for Use with an Antialiasing Filter 5 FILT Place a capacitor across FILT and OUT to limit the amount of switching noise at the output (see Applications Information) 6 OUT Output Terminal Without Integrated Filter 7 +VS Positive Power Supply Terminal 8 +IN Noninverting Input Terminal (True Differential Input)

Rev. 0 | Page 6 of 16

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TYPICAL PERFORMANCE CHARACTERISTICS

TA = 25°C, VCC = 5 V, and V

60

40

= VCC/2; G = 80, C2 = 1300 pF, and C3 = 39 nF; G = 160, C2 = 680 pF, and C3 = 39 nF, unless otherwise specified.

REF

G = 160

VCC = 2.7V, 5V FILTER = 500Hz

60

G = 160

40

VCC = 2.7V, 5V FILTER = 10kHz

20

GAIN (dB)

0

–20

–40

10 1 00 1k 10k 100k

G = 80

FREQUENCY (Hz)

Figure 4. Gain vs. Frequency

180

VCC = 2.7V, 5V GAIN = 80, 160

160

FILT ER = 500Hz

140

120

100

CMR (dB)

80

60

40

20

10 100 1k 10k 1 00k

FREQUENCY (Hz)

Figure 5. Common-Mode Rejection (CMR) vs. Frequency

4

(0.02V, 3.3V)

3

VCC = 5V, V

REF

= VCC/2

(4.98V, 3.3V)

20

GAIN (dB)

0

–20

10 100 1k 10k 100k

07451-004

FREQUENCY (Hz)

G = 80

07451-007

Figure 7. Gain vs. Frequency

180

VCC = 2.7V, 5V GAIN = 80, 160

160

FILT ER = 10kHz

140

120

100

CMR (dB)

80

60

40

20

10 100 1k 10k 100k

07451-005

FREQUENCY (Hz)

07451-008

Figure 8. Common-Mode Rejection (CMR) vs. Frequency

4

(0.02V, 3V)

3

(4.98V, 3V)

2

1

0

(0.02V, 0V) (4.98V, 0V)

INPUT COMMON-MODE VOLTAGE (V)

–1

–10123456

VCC = 2.7V,

V

REF

(2.68V, 1V)(0.02V, 1V)

= VCC/2

(2.68V, 0V)

OUTPUT VO LTAGE (V )

07451-018

Figure 6. Input Common-Mode Voltage Range vs. Output Voltage, G = 80

2

1

0

INPUT COMMON-MODE VO LTAGE (V)

–1

–10123456

(0.02V, 1V)

(0.02V, 0V)

VCC = 2.7V,

V

= VCC/2

REF

Figure 9. Input Common-Mode Voltage Range vs. Output Voltage, G = 160

Rev. 0 | Page 7 of 16

VCC = 5V, V

OUTPUT VO LTAGE (V )

= VCC/2

REF

(2.68V, 1V)

(2.68V, 0V)

(4.98V, 0V)

07451-019

AD8293G80/AD8293G160

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10

5

0

–5

–10

–15

INPUT OFFSET VOLTAGE (5mV/DIV)

–20

–25

–0.2 0 0.2 0. 4 0.6 0.8 1.0 1.2 1.4

POWER SUPPLY ON

GAIN = 160

GAIN = 80

TIME (ms)

4μV OFFSET

= 2.7V

V

CC

VCC = 5V

Figure 10. Input Offset Voltage vs. Turn-On Time, Filter = 500 Hz

1000

07451-010

10

POWER SUPPLY ON

5

4μV OFFSET

0

–5

–10

INPUT OFFSET VOLTAGE (5mV/DIV)

–15

–0.05 0 0.05 0.10 0.15 0.20

GAIN = 160

GAIN = 80

TIME (ms)

= 2.7V

V

CC

VCC = 5V

Figure 13. Input Offset Voltage vs. Turn-On Time, Filter = 10 kHz

07451-012

100

NOISE (nV/ Hz)

10

1

0.01 0.1 1 10 100 1k 10k 100k

FREQUENCY (Hz)

GAIN = 160

GAIN = 80

Figure 11. Voltage Noise Density

160

140

120

100

80

PSR (dB)

60

40

500Hz FILT ER 10kHz FILT ER

20

10 100 1k 10k 100k

GAIN = 160

GAIN = 80

FREQUENCY (Hz)

Figure 12. Power Supply Rejection (PSR) vs. Frequency

VOLTAGE NOISE (200nV/DIV)

TIME (10s/ DIV)

07451-009

07451-025

Figure 14. 0.01 Hz to 10 Hz Voltage Noise

0.30 VCC = 2.7V, 5V

G = 80, 160

0.25

0.20

0.15

10kHz FILT ER

0.10

0.05

50mV/DI

0

–0.05

500Hz FILT ER

–0.10

–0.15

07451-024

1ms/DIV

07451-011

Figure 15. Small Signal Step Response

Rev. 0 | Page 8 of 16

AD8293G80/AD8293G160

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VCC = 2.7V G = 80, 160

VCC = 5V G = 80, 160

10kHz FILT ER

500mV/DI

500Hz FILT ER

1ms/DIV

Figure 16. Large Signal Step Response

07451-013

10kHz FILTER

1V/DI

500Hz FILT ER

1ms/DIV

Figure 17. Large Signal Step Response

07451-017

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THEORY OF OPERATION

The AD8293G80/AD8293G160 are precision current-mode correction instrumentation amplifiers capable of single-supply operation. The current-mode correction topology results in excellent accuracy. Figure 18 shows a simplified diagram illustrating the basic operation of the AD8293G80/AD8293G160 (without correction). The circuit consists of a voltage-to-current amplifier (M1 to M6), followed by a current-to-voltage amplifier (R2 and A1). Application of a differential input voltage forces a current through External Resistor R1, resulting in conversion of the input voltage to a signal current. Transistor M3 to Transistor M6 transfer twice this signal current to the inverting input of the op amp A1. Amplifier A1 and External Resistor R2 form a current-to-voltage converter to produce a rail-to-rail output voltage at V

OUT

.

Op amp A1 is a high precision auto-zero amplifier. This amplifier preserves the performance of the autocorrecting, current-mode amplifier topology while offering the user a true voltage-in, voltage-out instrumentation amplifier. Offset errors are corrected internally.

An external reference voltage is applied to the noninverting input of A1 to set the output reference level. External Capacitor C2 is used to filter out correction noise.

CC

V

INN

M5

M3 M4

I – I

R1

II

V

INP

2I

M1

R1

– V

INP

)

INN

R1

M2

2I

(V

I

=

R1

HIGH PSR AND CMR

Common-mode rejection and power supply rejection indicate the amount that the offset voltage of an amplifier changes when its common-mode input voltage or power supply voltage changes. The autocorrection architecture of the AD8293G80/AD8293G160 continuously corrects for offset errors, including those induced by changes in input or supply voltage, resulting in exceptional rejection performance. The continuous autocorrection provides great CMR and PSR performances over the entire operating temperature range (−40°C to +85°C).

The parasitic resistance in series with R2 does not degrade CMR, but causes a small gain error and a very small offset error. Therefore, an external buffer amplifier is not required to drive V

to maintain excellent CMR performance. This helps reduce

REF

system costs over conventional instrumentation amplifiers.

1/f NOISE CORRECTION

Flicker noise, also known as 1/f noise, is noise inherent in the physics of semiconductor devices and decreases 10 dB per decade. The 1/f corner frequency of an amplifier is the frequency at which the flicker noise is equal to the broadband noise of the amplifier. At lower frequencies, flicker noise dominates, causing large errors in low frequency or dc applications.

Flicker noise is seen effectively as a slowly varying offset error, which is reduced by the autocorrection topology of the AD8293G80/AD8293G160. This allows the AD8293G80/ AD8293G160 to have lower noise near dc than standard low noise instrumentation amplifiers.

C2

M6

I – I

I + I

R2

V

= V

R1

2I

R1

V

BIAS

V

REF

OUT

R3

A1

2R2

V

– V

INP

+

REF

R1

C3

INN

07451-020

EXTERNAL

Figure 18. Simplified Schematic

Rev. 0 | Page 10 of 16

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APPLICATIONS INFORMATION

OVERVIEW

The AD8293G80/AD8293G160 reduce board area by integrating filter components, such as Resistors R1, R2, and R3, as shown in Figure 19. Two outputs are available to the user: OUT (Pin 6) and ADC OUT (Pin 4). The difference between the two is the inclusion of a series 5 k resistor at ADC OUT. With the addition of an external capacitor, C3, ADC OUT forms a second filter, comprising of the 5 k resistor and C3, which can be used as an ADC antialiasing filter. In contrast, OUT is the direct output of the instrumentation amplifier. When using the antialiasing filter, there is slightly less switching ripple at ADC OUT than when obtaining the signal directly from OUT.

+5

0.1µF

S

+IN

8

R1

4kΩ

–IN

1

Figure 19. AD8293G160 with Antialiasing Filter and Level-Shifted Output

(Using the Resistor Divider at the REF Pin, the Output Is Biased at 2.5 V)

REFERENCE CONNECTION

Unlike traditional 3-op-amp instrumentation amplifiers, parasitic resistance in series with REF (Pin 3) does not degrade CMR performance. The AD8293G80/AD8293G160 can attain extremely high CMR performance without the use of an external buffer amplifier to drive the REF pin, which is required by industrystandard instrumentation amplifiers. Reducing the need for buffer amplifiers to drive the REF pin helps to save valuable printed circuit board (PCB) space and minimizes system costs.

For optimal performance in single-supply applications, REF should be set with a low noise precision voltage reference, such as the ADR44x (see Figure 20). However, for a lower system cost, the reference voltage can be set with a simple resistor voltage divider between the supply and GND (see Figure 19). This configuration results in degraded output offset performance if the resistors deviate from their ideal values. In dual-supply applications, V

The REF pin current is approximately 10 pA, and as a result, an external buffer is not required.

REF

C2

680pF

7 5 6

IN-AMP

REFGND

32

FILT+V

R2

320kΩ

AD8293G160

100kΩ

OUT

5kΩ

R3

0.1µF

ADC OUT

100kΩ

OUTPUT TO ADC WITH ANTI ALIASING FILTER

4

C3 39nF

+5V

can simply be connected to GND.

07451-021

Rev. 0 | Page 11 of 16

+5

7

IN-AMP

REFGND

C2

5 6

FILT+V

R2

32

VOLTAGE

REFERENCE

0.1µF

OUTPUT

OUT

R3

5kΩ

ADC OUT

AD8293Gxx

4

1µF0.1µF

07451-022

0.1µF

S

+IN

8

R1

4kΩ

–IN

1

Figure 20. Operating on a Single Supply Using an External Voltage Reference

(The Output Can Be Used Without an Antialiasing Filter if the Signal

Bandwidth Is <10 Hz)

OUTPUT FILTERING

The output of the AD8293G80/AD8293G160 can be filtered to reduce switching ripple. Two filters can be used in conjunction to set the filter frequency. In the example that follows, two 700 Hz filters are used in conjunction to form a 500 Hz (recommended) bandwidth. Because the filter resistors are integrated in the AD8293G80/AD8293G160, only external capacitors are needed to set the filter frequencies.

The primary filter is needed to limit the amount of switching noise at the output. Regardless of the output that is being used, OUT or ADC OUT, the primary filter comprising R2 and C2 must be implemented. The R2 value depends on the model; Tabl e 7 shows the R2 value for each model.

Table 7. Internal R2 Values

Model R2 (kΩ)

AD8293G80 160 AD8293G160 320

The following equation results in the C2 value needed to set a 700 Hz primary filter. For a gain of 160, substitute R2 with 320 k; for a gain of 80, substitute R2 with 160 k.

C2 = 1/(700 × 2 × π × R2)

Adding an external capacitor, C3, and measuring the output from ADC OUT further reduces the correction ripple. The internal 5 kΩ resistor, labeled R3 in Figure 18, forms a low-pass filter with C3. This low-pass filter is the secondary filter. Set to 700 Hz, the secondary filter equation for C3 is as follows:

C3 = 1/(700 × 2 × π × 5 k)

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he addition of another single pole of 700 Hz on the output

T (from the secondary filter in Figure 18) is required for bandwidt

hs greater than 10 Hz. These two filters, together, produce an overall bandwidth of 500 Hz. The internal resistors, R2 and R3, have an absolute tolerance of 20%. Ta b le 8 lists the standard capacitors needed to create a filter with an overall bandwidth of 500 Hz.

Table 8. Standard Capacitors Used to Form a Filter with an Overall Bandwidth of 500 Hz

Model C2 (pF)

C3 (nF)

AD8293G80 1300 39 AD8293G160 680 39

For applications with low bandwi ths (<10 Hz), only the primary

d filter is required. In such an event, the high frequency noise from the auto-zero amplifier (output amplifier) is not filtered before the following stage.

CLOCK FEEDTHROUG

The AD8293G80/AD8293G160

H

use two synchronized clocks to perform the autocorrection. The input voltage-to-current amplifiers are corrected at 60 kHz.

Trace amounts of these clock freque

ncies can be observed at the OUT pin. The amount of visible correction feedthrough is dependent on the values of the filters set by R2/C2. Use ADC OUT to create a filter using R3/C3 to further reduce correction feedthrough as described in the Output Filtering section.

POWER SUPPLY BYPASSING

The AD8293G80/AD8293G160 use internally generated clock signals to perform autocorrection. As a result, proper bypassing is necessary to achieve optimum performance. Inadequate or improper bypassing of the supply lines can lead to excessive noise and offset voltage.

A 0.1 µF surface-mount capacitor should be connected between the supply lines. This capacitor is necessary to minimize ripple from the correction clocks inside the IC. For dual-supply operation, a 0.1 µF (ceramic) surface-mount capacitor should be connected from each supply pin to GND.

For single-supply operation, a 0.1 µF surface-mount capacitor should be connected from the supply line to GND.

All bypass capacitors should be positioned as close to the DUT supply pins as possible, especially the bypass capacitor between the supplies. Placement of the bypass capacitor on the back of the board directly under the DUT is preferred.

INPUT OVERVOLTAGE PROTECTION

All terminals of the AD8293G80/AD8293G160 are protected against ESD. In the case of a dc overload voltage beyond either supply, a large current would flow directly through the ESD protection diodes. If such a condition can occur, an external resistor should be used in series with the inputs to limit current for voltages beyond the supply rails. The AD8293G80/AD8293G160 can safely handle 5 mA of continuous current, resulting in an external resistor selection of

R

= (VIN − VS)/5 mA

EXT

+5

C2

0.1µF

S

LOAD

I

R

1.8V

DC-DC

Figure 21. Measuring Current Through a Shunt Resistor (Filter Is Set to 500 Hz)

SHUNT

+IN

8

R1

4kΩ

–IN

1

1.3nF

7 5 6

FILT+V

R2

160kΩ

IN-AMP

REFGND

32

OUT

R3

5kΩ

ADC OUT

AD8293G80

4

C3 39nF

+3.3V

ADC

REF

0.1µF

10µF

07451-023

Rev. 0 | Page 12 of 16

AD8293G80/AD8293G160

C

www.BDTIC.com/ADI

OUTLINE DIMENSIONS

2.90 BS

1.95 BSC

56

0.65 BSC

2.80 BSC

1.45 MAX

SEATING PLANE

0.22

0.08

8° 4° 0°

0.60

0.45

0.30

1.60 BSC

PIN 1

INDICATOR

1.30

1.15

0.90

0.15 MAX

847

13

2

0.38

0.22

COMPLIANT TO JEDEC STANDARDS MO-178-BA

Figure 22. 8-Lead Small Outline Transistor Package [SOT-23]

(RJ-8)

Dimensions shown in millimeters

ORDERING GUIDE

Model Gain Temperature Range Package Description Package Option Branding

AD8293G80ARJZ-R21 80 −40°C to +85°C 8-Lead SOT-23 RJ-8 Y1H AD8293G80ARJZ-R7 AD8293G80ARJZ-RL AD8293G80BRJZ-R2 AD8293G80BRJZ-R7 AD8293G80BRJZ-RL AD8293G160ARJZ-R2 AD8293G160ARJZ-R7 AD8293G160ARJZ-RL AD8293G160BRJZ-R2 AD8293G160BRJZ-R7 AD8293G160BRJZ-RL

1

Z = RoHS Compliant Part.

1

80 −40°C to +85°C 8-Lead SOT-23 RJ-8 Y1H

1

80 −40°C to +85°C 8-Lead SOT-23 RJ-8 Y1H

1

80 −40°C to +85°C 8-Lead SOT-23 RJ-8 Y1N

1

80 −40°C to +85°C 8-Lead SOT-23 RJ-8 Y1N

1

80 −40°C to +85°C 8-Lead SOT-23 RJ-8 Y1N

1

160 −40°C to +85°C 8-Lead SOT-23 RJ-8 Y11

1

160 −40°C to +85°C 8-Lead SOT-23 RJ-8 Y11

1

160 −40°C to +85°C 8-Lead SOT-23 RJ-8 Y11

1

160 −40°C to +85°C 8-Lead SOT-23 RJ-8 Y1K

1

160 −40°C to +85°C 8-Lead SOT-23 RJ-8 Y1K

1

160 −40°C to +85°C 8-Lead SOT-23 RJ-8 Y1K

Rev. 0 | Page 13 of 16

AD8293G80/AD8293G160

www.BDTIC.com/ADI

NOTES

Rev. 0 | Page 14 of 16

AD8293G80/AD8293G160

www.BDTIC.com/ADI

NOTES

Rev. 0 | Page 15 of 16

AD8293G80/AD8293G160

www.BDTIC.com/ADI

NOTES

Rev. 0 | Page 16 of 16

Datasheet AD8293G80 Datasheet (ANALOG DEVICES)

Specifications and Main Features

Frequently Asked Questions

User Manual

FEATURES

APPLICATIONS

FUNCTIONAL BLOCK DIAGRAM

GENERAL DESCRIPTION

TABLE OF CONTENTS

REVISION HISTORY

SPECIFICATIONS

ELECTRICAL CHARACTERISTICS

ABSOLUTE MAXIMUM RATINGS

THERMAL RESISTANCE

ESD CAUTION

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

TYPICAL PERFORMANCE CHARACTERISTICS

THEORY OF OPERATION

HIGH PSR AND CMR

1/f NOISE CORRECTION

APPLICATIONS INFORMATION

OVERVIEW

REFERENCE CONNECTION

OUTPUT FILTERING

POWER SUPPLY BYPASSING

INPUT OVERVOLTAGE PROTECTION

OUTLINE DIMENSIONS

ORDERING GUIDE