an1565

Application Note 1565
ISL281X7MSOPEVAL1Z Evaluation Board User’s Guide
Introduction
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.
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.
VREF
J11
J10
V+
J9
V-
J13
Reference Documents
J8
J7
The ISL281X7 operational amplifiers feature low bias
current, low noise, and low offset and temperature drift.
Evaluation Board Key Features
DNP
R4
• ISL28127 Data Sheet, FN6633
C2
C4
4.7µF
D1
4.7µF
D2
S1AB
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.
DNP
• ISL28117 Data Sheet, FN6632
R16
• ISL28107 Data Sheet, FN6631
S1AB
FIGURE 1. POWER SUPPLY CIRCUIT
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.
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
RF
ISL281X7
100kΩ
IN RININ-
VP
IN-
V+
10kΩ
RIN+
IN+
IN +
VCM
VREF
VREF
IN+
10kΩ
0Ω
VOUT
V+
VM
RREF+
RL
100kΩ
DNP
GND
FIGURE 2. BASIC AMPLIFIER CONFIGURATION
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.
Copyright Intersil Americas Inc. 2010. All Rights Reserved
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Application Note 1565
User-selectable Options
(Figures 3 and 4)
The outputs (Figure 4) have additional resistor and
capacitor placements for filtering and loading.
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.
R9
R11
10k
100k
C3
R2
OPEN
R14
VREF
R13
R15
DNP
100k
To Output
To INTo IN+
FIGURE 3. INPUT STAGE
R18
J12
0
DNP
DNP
DNP
R10
DNP
R14
R6
R8
R12
10k
DNP
OUT
C6
J2
NODE
OPEN
R17
R3
DNP
DNP
0
R7
R5
R1
DNP
J1
IN+
DNP
IN-
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 4. OUTPUT STAGE
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
2
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Application Note 1565
FIGURE 5. ISL281X7MSOPEVAL1Z TOP VIEW
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
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J8
2
4.7UF
D1
1
2
S1AB
4.7UF
D2
1
1
1
1
C4
1
1
C2
DNP
R4
DNP
1
2
VREF
J11
3
2
J10
3
J9
J13
V+
R16
J7
V-
S1AB
4
NODE
4
3
0
2 1
R9
2 1
10K
2
R5
1
R1
J6
2
2
5
0
C5
0.01UF
C1
DNP
5
R18
VREF
1
R13
DNP
2
1
R15
2
100K
FIGURE 6. ISL281X7MSOPEVAL1Z SCHEMATIC DIAGRAM
1
2
J12
5
3
4
4
6
2
4
7
6
DNP
3
8
7
1
3
8
1
10K
2
U1
MSOP8
Generic
Pack.
OPEN
R17
R2
R12
1
2
C6
1
1
1
2
2
DNP
0.01UF
DNP
R20
1
R7
2
DNP
DNP
R3
+
1
R19
4
3
IN
1
2
OPEN
R11
100K
DNP
J25
C3
1
2
DNP
2
1
R6
1
2
J15
2
DNP
DNP
J4
J3
DNP
R10
OUTPUT
Application Note 1565
-
2 1
2
2
2
2
IN
1
1
1
1
R8
1
OUT
R14
IN+
J5
IN-
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