an1348

Application Note 1348
Author: Bob Pospisil
1µF
D2
S1AB
S1AB
J10
J11
VREF
0.1µF
1µF
D1
C5
C4
0.01µF
C8
C2
J9
J13
V+
DNP
DNP
C7
0.1µF
R4
C1
The ISL28190 and ISL28191 amplifiers feature ultra-low
noise, ultra-low distortion, and rail-to-rail output drive
capability. They are designed to operate with single and dual
supplies from +5.5VDC (±2.75VDC) down to +3VDC (±1.5VDC).
0.01µF
V-
R16
J7
The ISL2819xEVAL1Z evaluation board is a design platform
containing all the circuitry needed to characterize critical
performance parameters of the ISL28190 and ISL28191
single operational amplifiers, using a variety of user-defined
test circuits.
J8
ISL2819xEVAL1Z Evaluation Board User Guide
Reference Documents
• ISL28190 Datasheet
• ISL28191 Datasheet
FIGURE 1. POWER SUPPLY CIRCUIT
Key Features
D1 and D2, protect the circuit in case of accidental polarity
reversal.
The ISL2819xEVAL1Z is designed to enable the IC to operate
from a single supply (+3VDC to +5.5VDC) or from split supplies
(±1.5VDC to ±2.75VDC). 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 is provided,
as well as a user-selectable voltage divider (filter 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 +3VDC to +5.5VDC supply, or from dual supplies
from ±1.5VDC to ±2.75VDC. The VREF pin can be connected to
ground to establish a ground-referenced input for split-supply
operation, or it can be externally set to any reference level for
single-supply operation.
Power Supplies (Figure 1)
External power connections are made through the V+, V- 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, the V+ and
V- terminals connect to their respective power supply
terminals. De-coupling capacitors C2 and C4 are connected
close to the power supply terminals. To filter out
high-frequency noise, four additional capacitors (C1, C5, C7
and C8) are connected close to the part. Anti-reverse diodes,
RF
+
IN-
RIN-
V+
499Ω
IN+
IN+
VCM
4.99kΩ
VP
IN-
INRIN+
ISL2819x
IN+
50Ω
VOUT
V+
VM
499Ω
RREF+
VREF
VREF
4.99kΩ
GND
FIGURE 2. BASIC AMPLIFIER CONFIGURATION
May 19, 2011
AN1348.1
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
Copyright Intersil Americas Inc. 2007, 2011. All Rights Reserved.
1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries.
All other trademarks mentioned are the property of their respective owners.
Application Note 1348
User-selectable Options
(Figures 3 and 4)
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.
Component pads are included to enable a variety of
user-selectable circuits to be added to the amplifier inputs, the
VREF input, the outputs, and the amplifier feedback loops.
The output (Figure 4) has a series 50Ω back-termination resistor
to drive 50Ω cables, and additional resistor and capacitor
placements for loading.
A voltage divider and filter option (Figure 3) can be added to
establish a power-supply-tracking common mode reference at
C3
TO IN TO DUT
OUTPUT
IN +
J2
R12
R2
J12
TO IN +
499
DNP
OUTPUT
R18
TO DUT
OUTPUT 49.9
DNP
4.99k
DNP
DNP
OPEN
R17
499
C6
R9
0
DNP
R5
R1
R7
IN J1
OPEN
R11
R13
R15
DNP
4.99k
VREF
FIGURE 3. INPUT STAGE
FIGURE 4. OUTPUT STAGE
ISL2819xEVAL1Z Components Parts List
DEVICE NUMBER
DESCRIPTION
COMMENTS
C2, C4
CAP, SMD, 1206, 1µF, 100V, 10%, X7R, ROHS
Power supply decoupling
C1, C5
CAP, SMD, 0603, 0.01µF, 50V, 10%, X7R, ROHS
Power supply decoupling
C7, C8
CAP, SMD, 0603, 0.1µF, 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, SMD, 4.5X3.9mm,
50V, 1A, ROHS
Reverse power protection
U1 (ISL28190EVAL1Z)
ISL28190FHZ-T7, IC-RAIL-TO-RAIL OP AMP,
SOT-23, ROHS
U1 (ISL28191EVAL1Z)
ISL28191FHZ-T7, IC-RAIL-TO-RAIL OP AMP,
SOT-23, ROHS
R1-R4, R6-R8, R10, R13, R14, R16, R17, R20
RESISTOR, SMD, 0603, 0.1%, MF,
DNP-PLACEHOLDER
User-selectable resistors; not populated
RES, SMD, 0603, 0Ω, 1/10W, TF, ROHS
0Ω user-selectable resistors
R18
RES, SMD, 0603, 49.9Ω, 1/10W, 1%, TF, ROHS
User-selectable output resistors
R9, R12
RES, SMD, 0603, 499Ω, 1/10W, 1%, TF, ROHS
Gain resistors
R11, R15
RES, SMD, 0603, 4.99k, 1/10W, 1%, TF, ROHS
Gain resistors
RES, SMD, 0603, 10k, 1/10W, 1%, TF, ROHS
User-selectable resistors
R5, R21
R19
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May 19, 2011
Application Note 1348
ISL2819xEVAL1Z Top View
3
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Application Note 1348
J12 OUTPUT
ISL2819xEVAL1Z Schematic Diagram
DNP
R17
OPEN
J11
49.9
R18
C6
0.1µF
VREF
C8
0.01µF
C5
J10
R6
R7
4.99k
DNP
VREF
R15
499
R12
4.99k
R9
499
0.1µF
R3
C7
R20
DNP
DNP
R21
0
C3
OPEN
R11
R10
DNP
R8
DNP
0
J3
DNP
R5
R4
IN-
DNP
J4
R14
DNP
OUT
J5
IN+
J7
J6
NODE
S1AB
C2
V-
J13
1µF
D1
DNP
R13
U1
S1AB
C4
1µF
D2
V+
J8
SOT23_6
R16
J9
1
6
2 GENERIC 5
PACK.
3
4
DNP
0.01µF
10K
ENABLEJ14
DNP
DNP
R2
IN + J2
IN - J1
R1
R19
2
S1
3
1
C1
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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