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AN1339.0
ISL284xxEVAL1Z Evaluation Board User’s Guide
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-rail 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
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)
External power connections are made through the V
+
, V
-
and GND connections on the evaluation board. For single
supply operation, the V
-
and GND pins are tied together to
the power supply negative terminal. For split supplies +V
and V
-
terminals connect to their respective power supply
terminals. De-coupling capacitors C
1
and C
2
, connect to
GND through R
1
and R
2
, 0Ω resistors. Resistors R
3
and R
4
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
1
and D
2
protect the
circuit in the case of accidental polarity reversal.
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.
2
0
4.7UF
0.1UF
0
00
4.7UF
VM
VP
C4
12
R37
J3
1
C2
12
R44
J2
1
R1 C1
12
C3
12
R48
J1
1
D2
1
D1
21
V- V+
FIGURE 1. POWER SUPPLY CIRCUIT
+
IN-
IN+
RF
VREF
IN(A,B,C,D)-
IN(A,B,C,D)+
GND
100kΩ
RREF(A,B,C,D)+
10kΩ
VOUT(x)
1/4 ISL284xx
VP
V-
10kΩ
0Ω
VM
VCM
IN-
IN+
VREF
V+
RIN-
10kΩ
RIN+
10kΩ
-
+
0Ω
TO OTHER CHANNELS
100kΩ
0Ω
FIGURE 2. BASIC AMPLIFIER CONFIGURATION
Application Note July 23, 2007
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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Copyright Intersil Americas Inc. 2007. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
