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Application Note 1565
ISL281X7MSOPEVAL1Z Evaluation Board User’s Guide
Introduction
The ISL281X7MSOPEVAL1Z evaluation board is a design
platform containing all the circuitry needed to
characterize critical performance parameters of the
ISL281X7 operational amplifiers in MSOP-8 package,
using a variety of user defined test circuits.
The ISL281X7 operational amplifiers feature low bias
current, low noise, and low offset and temperature drift.
Reference Documents
• ISL28107 Data Sheet, FN6631
• ISL28117 Data Sheet, FN6632
• ISL28127 Data Sheet, FN6633
Evaluation Board Key Features
The ISL281X7MSOPEVAL1Z is designed to enable the IC
to operate from a single supply, +4.5VDC to +40VDC or
from split supplies, ±2.25VDC to ±20V. The board is
configured for a single op amp 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 are included.
Power Supplies (Figure 1)
External power connections are made through the +V, -V,
VREF and Ground connections on the evaluation board.
For single supply operation, the -V and Ground 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 C2 and C4 connect close to their respective
supplies, while two additional capacitors, C1 and C5, are
connected close to the part to filter out high frequency
noise. Anti-reverse diodes D1 and D2 protect the circuit
in the case of accidental polarity reversal.
Amplifier Configuration (Figure 2)
The schematic of 1/2 of the op amp 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 supply or from dual
supplies. The VREF pin must be connected to ground to
establish a ground referenced input for dual supply
operation, or can be externally set to any reference level for
single supply operation. VREF should not be left floating.
C2
4.7µF
DNP
D2D1
R16
R4
C4
J8
J11
J9
J10
J7
J13
S1AB
4.7µF
S1AB
DNP
VREFV+V-
FIGURE 1. POWER SUPPLY CIRCUIT
IN-
IN+
RF
VREF
IN -
IN +
GND
100k
Ω
RREF+
VOUT
ISL281X7
VP
V-
0
Ω
VM
VCM
IN-
IN+
VREF
V+
RIN-
10k
Ω
RIN+
10k
Ω
-
+
100k
Ω
RL
DNP
FIGURE 2. BASIC AMPLIFIER CONFIGURATION
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 |Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright Intersil Americas Inc. 2010. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
May 25, 2010
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User-selectable Options
(Figures 3 and 4)
Component pads are included to enable a variety of user-
selectable circuits to be added to the amplifier VREF,
inputs, outputs, and the amplifier feedback loops. The
Inputs (Figure 3) have additional resistor and capacitor,
and jumper placements for loading and/or measurement
of frequency sensitive parameters.
The outputs (Figure 4) have additional resistor and
capacitor placements for filtering and loading.
NOTE: Operational amplifiers are sensitive to output
capacitance and may oscillate. In the event of oscillation,
reduce output capacitance by using shorter cables, or
add a resistor in series with the output.
FIGURE 3. INPUT STAGE FIGURE 4. OUTPUT STAGE
IN- OUTNODEIN+
C3
R7
R5
J2
J1
R1
R6
R14
R2
R14
R3
R15
R10R8
R11R9
DNP DNP
DNP
DNP
DNP
DNP
DNP
OPEN
DNP
DNP
10k 100k
100k
10k
0
VREF
To Output
To IN+
To IN-
R13
R12
R18
J12
C6
R17
DNP
0
OPEN
TABLE 1. ISL281X7MSOPEVAL1Z COMPONENTS PARTS LIST
DEVICE # DESCRIPTION COMMENTS
C2, C4 CAP, SMD, 0805, 4.7µF, 50V, 10%, X7R, ROHS Power Supply Decoupling
C1, C5 CAP, SMD, 0603, 0.01µF, 50V, 10%, X7R, ROHS Power Supply Decoupling
C3, C6 CAP, SMD, 0603, DNP-PLACE HOLDER, ROHS User selectable capacitors - not populated
D1, D2 DIODE-RECTIFIER, 40V, 0.5A, ROHS Reverse Power Protection
U1 (ISL28107FUZ) OP AMP, MSOP, ROHS
U1 (ISL28117FUZ) OP AMP, MSOP, ROHS
U1 (ISL28127FUZ) OP AMP, MSOP, ROHS
R1-R4, R6-R8, R10, R13,
R14, R16, R17, R19, R20
RESISTOR, SMD, 0603, 0.1%, MF, DNP-PLACE HOLDER User selectable resistors - not populated
R5, R18 RES, SMD, 0603, 0Ω, 1/10W, TF, ROHS Zero ohm user selectable resistors
R9, R12 RES, SMD, 0603, 10k, 1/10W, 1%, TF, ROHS Gain resistors
R11, R15 RES, SMD, 0603, 100k, 1/10W, 1%, TF, ROHS Gain resistors
Application Note 1565Application Note 1565
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Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the
reader is cautioned to verify that the Application Note or Technical Brief is current before proceeding.
For information regarding Intersil Corporation and its products, see www.intersil.com
AN1565.0
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Application Note 1565
FIGURE 5. ISL281X7MSOPEVAL1Z TOP VIEW
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IN +
IN+
OUTPUT
IN-
OUT
NODE
IN -
2
R14
C3
OPEN
1
OPEN
DNP 100K
0.01UF
4.7UF
DNP
S1AB
DNP
DNP
0
10K
100K
DNP DNP
DNP
DNP
DNP
DNP
0
DNP
DNP
DNP
10K
R9
1
2
R11
2
R8
1
22
R13
1
2
R15
1
2
R3
1
2
R12
1
2
R17
1
2
R2
1
R6
1
2
R1
C6
1
2
J13
1
J7
1
2
3
J10
1
1
J11
1
J8
1
2
3
J1
1
2
3
4
5
J2
1
2
3
4
5
J12
1
2
3
4
5
C5
C1
C4C2
R5
1
2
R7
1
2
1
2
J3
1
2
1
2
1
J4
1
2
R4
R16
R18
D1
2
D2
2
R19
R20
0.01UF
DNP
1
R10
2
J6
S1AB
1
J9
4.7UF
1
J5
MSOP8
8
7
6
54
3
2
1
U1
1
3
4
8
6
7
5
Pack.
Generic
2
V-
V+
VREF
VREF
FIGURE 6. ISL281X7MSOPEVAL1Z SCHEMATIC DIAGRAM
Application Note 1565
