ANALOG DEVICES AD8270 Service Manual

Precision Dual-Channel,

–

+

B

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FEATURES

With no external resistors

Difference amplifier: gains of 0.5, 1, or 2 Single ended amplifiers: over 40 different gains Set reference voltage at midsupply

Excellent ac specifications

15 MHz bandwidth 30 V/μs slew rate

High accuracy dc performance

0.08% maximum gain error 10 ppm/°C maximum gain drift

80 dB minimum CMRR (G = 2) Two channels in small 4 mm × 4 mm LFCSP Supply current: 2.5 mA per channel Supply range: ±2.5 V to ±18 V

APPLICATIONS

Instrumentation amplifier building blocks Level translators Automatic test equipment High performance audio Sine/Cosine encoders

GENERAL DESCRIPTION

The AD8270 is a low distortion, dual-channel amplifier with internal gain setting resistors. With no external components, it can be configured as a high performance difference amplifier with gains of 0.5, 1, or 2. It can also be configured in over 40 singleended configurations, with gains ranging from −2 to +3.

The AD8270 is the first dual-difference amplifier in the small 4 mm × 4 mm single-difference amplifier. The smaller package allows a 2× increase in channel density and a lower cost per channel, all with no compromise in performance.

The AD8270 operates on both single and dual supplies and

equires only 2.5 mA maximum supply current for each ampli-

r fier. It is specified over the industrial temperature range of

−40°C to +85°C and is fully RoHS compliant.

LFCSP. It requires the same board area as a typical

Difference Amplifier

AD8270

FUNCTIONAL BLOCK DIAGRAM

S

OUTA

+V

15

16

10kΩ 10kΩ 10kΩ 10kΩ

1–IN1A

10kΩ

_

+

AD8270

20kΩ 20kΩ20kΩ20kΩ

5

6

REF1A

REF2A

Figure 1.

IN2A

IN1A

2

3

4

Table 1. Difference Amplifiers by Category

High Speed

High V

oltage

Single-Supply Unidirectional

AD8270 AD628 AD8202 AD8205 AD8273 AD629 AD8203 AD8206 AMP03 AD8216

S

OUT

–V

14

13

12 –IN1B

10kΩ

_

+

8

7

REF2B

REF1B

10kΩ

11 –IN 2B

10 +IN2B

9+IN1B

Single-Supply Bidirectional

6979-001

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her 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.

AD8270

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REVISION HISTORY

1/08—Revision 0: Initial Version

Rev. 0 | Page 2 of 20

AD8270

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SPECIFICATIONS

DIFFERENCE AMPLIFIER CONFIGURATIONS

VS = ±15 V, V

Table 2.

G = 0.5 G = 1 G = 2 Parameter Conditions Min Typ Max Min Typ Max Min Typ Max Unit

DYNAMIC PERFORMANCE

Bandwidth 20 15 10 MHz Slew Rate 30 30 30 V/μs Settling Time to 0.01% 10 V step on output 700 800 700 800 700 800 ns Settling Time to 0.001% 10 V step on output 750 900 750 900 750 900 ns

NOISE/DISTORTION

Harmonic Distortion

Voltage Noise1 f = 0.1 Hz to 10 Hz 2 1.5 1 μV p-p f = 1 kHz 52 38 26 nV/√Hz GAIN

Gain Error 0.08 0.08 0.08 %

Gain Drift TA = −40°C to +85°C 1 10 1 10 1 10 ppm/°C INPUT CHARACTERISTICS

OUTPUT CHARACTERISTICS

Sinking 60 60 60 mA POWER SUPPLY

T

1

2

3

4

2

Offset

Average Temperature Drift TA = −40°C to +85°C 3 2 1.5 μV/°C

Common-Mode Rejection

Ratio Power Supply Rejection Ratio 2 10 2 10 2 10 μV/V Input Voltage Range Common-Mode Resistance4 7.5 10 7.5 kΩ Bias Current 500 500 500 nA

Output Swing −13.8 +13.8 −13.8 +13.8 −13.8 +13.8 V T Short-Circuit Current Limit Sourcing 100 100 100 mA

Supply Current

(per Amplifier)

Includes amplifier voltage and current noise, as well as noise of internal resistors. Includes input bias and offset errors. At voltages beyond the rails, internal ESD diodes begin to turn on. In some configurations, the input voltage range may be limited by the internal op amp (see the

Input Voltage Range section for details).

Internal resistors are trimmed to be ratio matched but have ±20% absolute accuracy. Common-mode resistance was calculated with both inputs in parallel. Common-

mode impedance at only one input is 2× the resistance listed.

= 0 V, TA = 25°C, R

REF

3

= 2 kΩ, specifications referred to input, unless otherwise noted.

LOAD

f = 1 kHz, V

= 600 Ω

R

LOAD

450 1500 300 1000 225 750 μV

DC to 1 kHz 70 86 76 92 80 98 dB

−15.4 +15.4 −15.4 +15.4 −15.4 +15.4 V

= −40°C to +85°C −13.7 +13.7 −13.7 +13.7 −13.7 +13.7 V

A

2.3 2.5 2.3 2.5 2.3 2.5 mA

= −40°C to +85°C 3 3 3 mA

A

= 10 V p-p,

OUT

84 145 95 dB

Rev. 0 | Page 3 of 20

AD8270

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VS = ±5 V, V

Table 3.

G = 0.5 G = 1 G = 2 Parameter Conditions Min Typ Max Min Typ Max Min Typ Max Unit

DYNAMIC PERFORMANCE

Bandwidth 20 15 10 MHz Slew Rate 30 30 30 V/μs Settling Time to 0.01% 5 V step on output 550 650 550 650 550 650 ns Settling Time to 0.001% 5 V step on output 600 750 600 750 600 750 ns

NOISE/DISTORTION

Harmonic Distortion

Voltage Noise1 f = 0.1 Hz to 10 Hz 2 1.5 1 μV p-p f = 1 kHz 52 38 26 nV/√Hz GAIN

Gain Error 0.08 0.08 0.08 %

Gain Drift TA = −40°C to +85°C 1 10 1 10 1 10 ppm/°C INPUT CHARACTERISTICS

Offset

Average Temperature Drift TA = −40°C to +85°C 3 2 1.5 μV/°C

Common-Mode Rejection Ratio DC to 1 kHz 70 86 76 92 80 98 dB

= 0 V, TA = 25°C, R

REF

2

= 2 kΩ, specifications referred to input, unless otherwise noted.

LOAD

f = 1 kHz, V

= 600 Ω

R

LOAD

= 5 V p-p,

OUT

101 141 112 dB

450 1500 300 1000 225 750 μV

Power Supply Rejection Ratio 2 10 2 10 2 10 dB

Input Voltage Range

Common-Mode Resistance

3

4

−5.4 +5.4 −5.4 +5.4 −5.4 +5.4 V

7.5 10 7.5 kΩ

Bias Current 500 500 500 nA OUTPUT CHARACTERISTICS

Output Swing −4 +4 −4 +4 −4 +4 V T

= −40°C to +85°C −3.9 +3.9 −3.9 +3.9 −3.9 +3.9 V

A

Short-Circuit Current Limit Sourcing 100 100 100 mA

Sinking 60 60 60 mA POWER SUPPLY

Supply Current (per Amplifier) 2.3 2.5 2.3 2.5 2.3 2.5 mA T

1

Includes amplifier voltage and current noise, as well as noise of internal resistors.

2

Includes input bias and offset errors.

3

At voltages beyond the rails, internal ESD diodes begin to turn on. In some configurations, the input voltage range may be limited by the internal op amp (see the

Input Voltage Range section for details).

4

Internal resistors are trimmed to be ratio matched but have ±20% absolute accuracy. Common-mode resistance was calculated with both inputs in parallel. Common-

mode impedance at only one input is 2× the resistance listed.

= −40°C to +85°C 3 3 3 mA

A

Rev. 0 | Page 4 of 20

AD8270

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ABSOLUTE MAXIMUM RATINGS

Table 4.

Parameter Rating

Supply Voltage ±18 V Output Short-Circuit Current

Input Voltage Range ±V

See derating

ve in Figure 2

cur

S

Storage Temperature Range −65°C to +130°C Specified Temperature Range −40°C to +85°C Package Glass Transition Temperature (TG) 130°C ESD (Human Body Model) 1 kV ESD (Charge Device Model) 1 kV ESD (Machine Model) 0.1 kV

Stresses above those listed under Absolute Maximum Ratings

y cause permanent damage to the device. This is a stress

ma 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

Table 5. Thermal Resistance

Thermal Pad θ

16-Lead LFCSP with Thermal Pad

JA

57 °C/W

Soldered to Board 16-Lead LFCSP with Thermal Pad

96 °C/W

Not Soldered to Board

The θJA values in Tabl e 5 assume a 4-layer JEDEC standard board with zero airflow. If the thermal pad is soldered to the board, it is also assumed it is connected to a plane. θ exposed pad is 9.7°C/W.

Unit

at the

JC

MAXIMUM POWER DISSIPATION

The maximum safe power dissipation for the AD8270 is limited by the associated rise in junction temperature (T approximately 130°C, which is the glass transition temperature, the plastic changes its properties. Even temporarily exceeding this temperature limit may change the stresses that the package exerts on the die, permanently shifting the parametric performance of the amplifiers. Exceeding a temperature of 130°C for an extended period of time can result in a loss of functionality.

The AD8270 has built-in, short-circuit p output current to approximately 100 mA (see Figure 19 for

ore information). While the short-circuit condition itself does

m not damage the part, the heat generated by the condition can cause the part to exceed its maximum junction temperature, with corresponding negative effects on reliability.

3.2

2.8

2.4

2.0

1.6

1.2 PAD NOT SOLDERED

0.8

MAXIMUM POWER DISSIPATION (W)

0.4

0

–50 –25 0 25 50 75 100 1 25

Figure 2. Maximum Power Dissipation vs. Ambient Temperature

ESD CAUTION

PAD SOLDERED

= 57°C/W

θ

JA

= 96°C/W

θ

JA

AMBIENT TEMPERATURE (°C)

) on the die. At

J

rotection that limits the

TJ MAXIMUM = 130°C

06979-003

Rev. 0 | Page 5 of 20

AD8270

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PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

S

–V

OUTA

+V

OUT

14

13

15

16

PIN 1

1–IN1A

2–IN2A

3+IN2A

4+IN1A

INDICATOR

AD8270

TOP VIEW

(Not to Scale)

5

6

12 –IN1B

11 –I N2B

10 +IN2B

9+IN1B

8

7

REF1A

REF2A

REF2B

REF1B

Figure 3. Pin Configuration

06979-002

Table 6. Pin Function Descriptions

Pin No. Mnemonic Description

1 −IN1A 10 kΩ Resistor Connected to Negative Terminal of Op Amp A. 2 −IN2A 10 kΩ Resistor Connected to Negative Terminal of Op Amp A. 3 +IN2A 10 kΩ Resistor Connected to Positive Terminal of Op Amp A. 4 +IN1A 10 kΩ Resistor Connected to Positive Terminal of Op Amp A. 5 REF1A

6 REF2A

7 REF2B

8 REF1B

20 kΩ Resistor Connected to Positive Terminal of Op Amp A. Most configurations use this pin as a reference

oltage input.

v 20 kΩ Resistor Connected to Positive Terminal of Op Amp A. Most configurations use this pin as a reference

oltage input.

v 20 kΩ Resistor Connected to Positive Terminal of Op Amp B. Most configurations use this pin as a reference

oltage input.

v 20 kΩ Resistor Connected to Positive Terminal of Op Amp B. Most configurations use this pin as a reference

oltage input.

v 9 +IN1B 10 kΩ Resistor Connected to Positive Terminal of Op Amp B. 10 +IN2B 10 kΩ Resistor Connected to Positive Terminal of Op Amp B. 11 −IN2B 10 kΩ Resistor Connected to Negative Terminal of Op Amp B. 12 −IN1B 10 kΩ Resistor Connected to Negative Terminal of Op Amp B. 13 −V

S

Negative Supply. 14 OUTB Op Amp B Output. 15 OUTA Op Amp A Output. 16 +V

S

Positive Supply.

Rev. 0 | Page 6 of 20

ANALOG DEVICES AD8270 Service Manual

FEATURES

APPLICATIONS

GENERAL DESCRIPTION

FUNCTIONAL BLOCK DIAGRAM

TABLE OF CONTENTS

REVISION HISTORY

SPECIFICATIONS

DIFFERENCE AMPLIFIER CONFIGURATIONS

ABSOLUTE MAXIMUM RATINGS

THERMAL RESISTANCE

MAXIMUM POWER DISSIPATION

ESD CAUTION

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS