Intersil ISL281X7MSOPEVAL1Z User Manual
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.
J7
J13
C2
4.7µF
R4
DNP
S1AB
FIGURE 1. POWER SUPPLY CIRCUIT
J8
C4
4.7µF
D2D1
S1AB
J10
R16
VREFV+V-
DNP
J9
J11
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.
VCM
IN-
IN+
VREF
IN -
IN +
VREF
GND
RF
100k
Ω
RIN-
10k
Ω
RIN+
10k
Ω
FIGURE 2. BASIC AMPLIFIER CONFIGURATION
IN-
IN+
RREF+
100k
Ω
-
+
VP
V+
V-
VM
ISL281X7
0
Ω
VOUT
RL
DNP
May 25, 2010
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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.
All other trademarks mentioned are the property of their respective owners.
Copyright Intersil Americas Inc. 2010. All Rights Reserved
Application Note 1565Application Note 1565
User-selectable Options
(Figures 3 and 4)
Component pads are included to enable a variety of userselectable 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.
IN- OUTNODEIN+
R10R8
DNP DNP
J1
J2
R1
DNP
R2
DNP
R6
DNP
10k 100k
R7
DNP
R12
10k
R13
DNP
R15
100k
R3
R5
0
DNP
FIGURE 3. INPUT STAGE FIGURE 4. OUTPUT STAGE
R11R9
C3
OPEN
R14
VREF
R14
DNP
To Output
To IN-
To IN+
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.
R18
0
C6
OPEN
R17
DNP
J12
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,
RESISTOR, SMD, 0603, 0.1%, MF, DNP-PLACE HOLDER User selectable resistors - not populated
R14, R16, R17, R19, R20
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
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