Intersil ISL284xxEVAL1Z Series User Manual

®

ISL284xxEVAL1Z Evaluation Board User’s Guide

Application Note July 23, 2007

Introduction

The ISL284xxEVAL1Z evaluation board is a design platform
containing all the circuitry needed to characterize critical
performance parameters of the ISL28470 quad
instrumentation amplifier using a variety of user defined test
circuits.

The ISL284xx are quad operational amplifiers featuring low
noise, low distortion, and rail-to-rai l output drive capability.
They are designed to operate with single and dual supplies
from +5VDC (±2.5VDC) down to +2.4VDC (±1.2VDC).

Reference Documents

• ISL28476 Data Sheet, FN6301

• ISL28478 Data Sheet, FN6339

• ISL28486 Data Sheet, FN6312

• ISL28488 Data Sheet, FN6339

Evaluation Board Key Features

AN1339.0

supply operation, the V
the power supply negative terminal. For split supplies +V
and V

terminals connect to their respective power supply

-

terminals. De-coupling capacitors C
GND through R

1

are 0Ω but can be changed by the user to provide additional
power supply filtering, or to reduce the voltage rate-of-rise to
less than ±1V/µs. Anti-reverse diodes D
circuit in the case of accidental polarity reversal.

V- V+

1

R37

C4

12

FIGURE 1. POWER SUPPLY CIRCUIT

and GND pins are tied together to

-

and C2, connect to

1

and R2, 0Ω resistors. Resistors R3 and R4

and D2 protect the

1

J3

VM

C2

4.7UF

0

J2

R44

12

D2

2

1

R1 C1

1

00

D1

21

4.7UF

C3

12

0.1UF

J1

1

12

0

R48

VP

The ISL284xxEVAL1Z is designed to enable the IC to
operate from a single supply (+2.4VDC to +5VDC), or from
split supplies (±1.2VDC to ±2/5V). The board is configured
for 4 independent op amps connected for differential input
with a closed loop gain of 10. A single external reference
voltage (VREF) pin and provisions for a user-selectable
voltage divider (filter is included).

Power Supplies (Figure 1)

RIN-

10kΩ

RIN+

10kΩ

+

, V-

External power connections are made through the V
and GND connections on the evaluation board. For single

IN(A,B,C,D)-

IN-

IN+

IN(A,B,C,D)+

VCM

VREF

VREF

GND

0Ω

+

IN-

-

IN+

+

RREF(A,B,C,D)+
100kΩ

10kΩ

0Ω

Amplifier Configuration (Figure 2)

The schematic of each of the 4 op amps with the
components supplied is shown in Figure 2. The circuit
implements a differential input-amp with a closed loop gain
of 10. The circuit can operate from a single 2.4VDC to
+5VDC supply, or from dual supplies from ±1.2VDC to
±2.5VDC. The VREF pin can be connected to ground to
establish a ground referenced input for split supply
operation, or can be externally set to any reference level for
single supply operation.

RF

100kΩ

VP

V+
V-

VM

TO OTHER CHANNELS

1/4 ISL284xx

0Ω

VOUT(x)

10kΩ

1

FIGURE 2. BASIC AMPLIFIER CONFIGURATION

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

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All other trademarks mentioned are the property of their respective owners.

Copyright Intersil Americas Inc. 2007. All Rights Reserved

Application Note 1339

User-selectable Options (Figure 3)

Component pads are included to enable a variety of
user-selectable circuits to be added to the amplifier inputs,
the VREF input, and the amplifier feedback loops. A voltage
divider and filter option can be added to establish a power
supply-tracking common mode reference at the VREF input.
The inverting and non-inverting inputs have additional
resistor placements for adding input attenuation, or to
establish input DC offsets through the VREF pin.

.

J4

REF1

1

RREF

0

R32

12

10K

R33

C5

4.7UF

RINA-

R14

IN(A,B,C,D)-

J5

5

3

4

IN(A,B,C,D)+

J6

5

3

4

1
2

0

RINA2-

R2

DNP

RINA1+

R5

1
2

10K

C7

12

OPEN

10K

C6R6

12

OPEN

DNP

R11

RINA+

R15

0

R20

R21

RREFA-

R28

DNP

DNP

RREFA+

R24

100K

RGA+

DNP

FIGURE 3. COMPONENT-SELECTABLE OPTIONS

IN-A

IN+A

ISL284xxEVAL1Z Components Parts List

DEVICE NUMBER DESCRIPTION COMMENTS

C1, C2, C5 CAP-TANTALUM, SMD, D, 4.7µF, 50V, 10% LOW ESR, ROHS Power Supply Decoupling

C3, C4 CAP, SMD, 0603, 0.1µF, 25V, 10%, X7R, ROHS Power Supply Decoupling

C6-C25 CAP, SMD, 0603, DNP-PLACE HOLDER, ROHS User selectable capacitors - not

populated

D1, D2 DIODE-RECTIFIER, SMD, SOD-123, 2P, 40V, 0.5A, ROHS Reverse Power Protection
U1 (ISL28476EVAL1Z) ISL28476FAZ, IC-RAIL-TO-RAIL PRECISION OP AMP, 16P, QSOP, ROHS
U1 (ISL28478EVAL1Z) ISL28478FAZ, IC-RAIL-TO-RAIL PRECISION OP AMP, 16P, QSOP, ROHS
U1 (ISL28486EVAL1Z) ISL28486FAZ, IC-RAIL-TO-RAIL PRECISION OP AMP, 16P, QSOP, ROHS
U1 (ISL28488EVAL1Z) ISL28488FAZ, IC-RAIL-TO-RAIL PRECISION OP AMP, 16P, QSOP, ROHS

R2-R4, R11-R13, R20-R23, R25,

R26, R28, R30, R31, R34, R38,

R42, R43, R46, R55-R58,

R59-R62

R6, R8, R10, R15, R17, R19, R36,

R41, R51-R54, R63-R66

R5, R7, R9, R14, R16, R18, R33,

R35, R40, R67-R70

R24, R27, R29, R39, R45, R47,

R49, R50

R1, R32, R37, R44, R48 RES, SMD, 0805, 0Ω, 1/8W, TF, ROHS 0Ω user selectable resistors

RESISTOR, SMD, 0603, 0.1%, MF, DNP-PLACE HOLDER User selectable resistors - not

populated

RES, SMD, 0603, 0Ω, 1/16W,TF, ROHS 0Ω user selectable resistors

RES, SMD, 0603, 10k, 1/10W, 1%, TF, ROHS RG gain resistors

RES, SMD, 0603, 100k, 1/10W, 1%, TF, ROHS RF gain resistors

2

AN1339.0

July 23, 2007