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ISL281x6EVAL1Z Evaluation Board User’s Guide
Application Note
August 17, 2007
Introduction
• ISL28136 Data Sheet, FN6153
C4
• ISL28146 Data Sheet, FN6321
R20
Reference Documents
• ISL28166 Data Sheet, FN6155
J1
C3
0.1µF
VM
VP
FIGURE 1. POWER SUPPLY CIRCUIT
Evaluation Board Key Features
The ISL281x6EVAL1Z is designed to enable the IC to
operate from a single supply, +2.4VDC to +5.5VDC or from
split supplies, ±1.2VDC to ±2.75V. The board is configured
for a single op amp connected for differential input with a
closed loop gain of 10. It also contains a single external
reference voltage (VREF) pin and provisions for a
user-selectable voltage divider (filter are included).
Amplifier Configuration (Figure 2)
The schematic 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 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.
Power Supplies (Figure 1)
External power connections are made through the V+, Vand 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+
RF
ISL281x6
100kΩ
IN -
VP
RIN-
IN-
IN-
V+
10kΩ
RIN+
IN+
IN+
VCM
0Ω
0Ω
VOUT
V-
+
VM
10kΩ
IN+
GND
0
C1
+
D1 4.7µF
0.1µF
• ISL28156 Data Sheet, FN6154
VREF
R1
R24
R21
C2
+
4.7µF D2 0
V+
0
V-
J2
The ISL28136 and ISL28146 high-speed operational
amplifiers feature low power consumption, while ISL28156
and ISL28166 operational amplifiers feature ultra-low power
consumption. All op amps have rail-to-rail output drive
capability and are designed to operate with a single lithium
cell or two Ni_Cd batteries.
J3
and V- terminals connect to their respective power supply
terminals. De-coupling capacitors C1 and C2 connect to
ground through R1 and R21 0Ω resistors. Resistors R20 and
R24 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. Two additional capacitors,
C3 and C4 are connected close to the part to filter out high
frequency noise. Anti-reverse diodes D1and D2 protect the
circuit in the case of accidental polarity reversal.
The ISL281x6EVAL1Z evaluation board is a design platform
containing all the circuitry needed to characterize critical
performance parameters of the ISL281x6 operational
amplifiers, using a variety of user defined test circuits.
VREF
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0
®
RREF+
RL
100kΩ
10kΩ
10kΩ
FIGURE 2. BASIC AMPLIFIER CONFIGURATION
1
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
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Application Note 1351
User-selectable Options (Figures 3 and 4)
The output (Figure 4) has a 10kΩ load resistor to ground,
and has additional resistor and capacitor placements for
loading.
Component pads are included to enable a variety of
user-selectable circuits to be added to the amplifier inputs,
the VREF input, outputs and the amplifier feedback loops.
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.
J4
A voltage divider and filter option (Figure 3) 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.
DNP
RINA2+
TO INC10
TO IN+
OPEN
J5 OUT
DNP
R25
10k
R23
DNP
C9
OPEN
100k
R27
R26
0
0
C8
C5
+
4.7µF
0
R22
TO OUT
OPEN
0
R6
R9
R3
DNP
IN2+ J8
DNP
OPEN
RINA+
R11
DNP
10k
C7
RREF
RREFA+
R14
R13
R2
DNP
RINA1+
R7
IN1+ J7
R17
DNP
DNP
OPEN
R12
10k
RINA2-
IN- J6
R8
RREFAR15
DNP
R5
0
C6
10k
RINAR10
R18
REF1
RGA+
FIGURE 4. 1/2 OUTPUT STAGE
FIGURE 3. 1/2 INPUT STAGE
ISL281x6EVAL1Z Components Parts List
DEVICE NUMBER
C1, C2, C5
DESCRIPTION
COMMENTS
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-C10
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 (ISL28136EVAL1Z)
ISL28136FHZ-T7, IC-RAIL-TO-RAIL OP AMP, SOT-23,ROHS
U1 (ISL28146EVAL1Z)
ISL28146FHZ-T7, IC-RAIL-TO-RAIL OP AMP, SOT-23, ROHS
U1 (ISL28156EVAL1Z)
ISL28156FHZ-T7, IC-RAIL-TO-RAIL OP AMP, SOT-23, ROHS
U1 (ISL28166EVAL1Z)
ISL28166FHZ-T7, IC-RAIL-TO-RAIL OP AMP, SOT-23, ROHS
R2, R3, R6, R8, R9, R12, R13, RESISTOR, SMD, 0603, 0.1%, MF, DNP-PLACE HOLDER
R15, R16, R23, R25, R27
User-selectable resistors - not
populated
R1, R10, R11, R17, R20, R21, RES, SMD, 0603, 0Ω, 1/10W, TF, ROHS
R24, R26, R22
0Ω user-selectable resistors
R4, R5, R7, R18
RES, SMD, 0603, 10k, 1/10W, 1%, TF, ROHS
Gain and other user selectable
resistors
R14, R19
RES, SMD, 0603, 100k, 1/10W, 1%, TF, ROHS
Gain resistors
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Application Note 1351
ISL281x6EVAL1Z Top View
3
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Application Note 1351
TO
J5
PART
OUT
ISL281x6EVAL1Z Schematic Diagram
CLOSE
DNP
0
VP
V+
10k
R25
C3
0.1µF
R26
R27
0
J1
4.7µF
0
0
4.7µF
J2
R22
0
D1
C1
R1
R23
C9
R21
DNP
OPEN
C2
R24
D2
OPEN
VM
C8
0
J3
4
SOT23_6
4
GENERIC
PACK 5
3
2
2
3
6
1
1
U1
100k
CLOSE
R19
6
5
VP
0.1µF
C4
TO
PART
V-
R20
4.7µF
0
10k
R17
R18
VP
DISABLE
S1
10k
2
EN
DNP
J8
IN2+
J9
R4
DNP
RINA2+
OPEN
R6
10K
C7
RINA1+
R7
J7
IN1+
3 ENABLE
0
RINA+
R11
OPEN
R2
R3
R5
10K
RINA2DNP
DNP
J6
R8
R9
IN-
DNP
DNP
C6
R12
0
R16
DNP
RGA+
C10
DNP
RINAR10
OPEN
100k
RREFA+
R14
DNP
R13
RREFAR15
DNP
1
J4
REF1
VM
RREF
C5
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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August 17, 2007
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