Intersil ISL2827xINEVAL1Z User Manual
®
ISL2827xINEVAL1Z Evaluation Board
User’s Guide
Application Note June 15, 2009
AN1290.2
Introduction
The ISL2827xINEVAL1Z evaluation board is a design
platform containing all the circuitry needed to characterize
critical performance parameters of the ISL28270, ISL28271,
ISL28272 or ISL28273 Dual Instrumentation Amplifiers using
a variety of user defined test circuits.
The ISL2827x series of amplifiers are dual channel
instrumentation amplifiers optimized for 2.4V to 5V single
supplies. These devices feature an Input Range
Enhancement Circuit (IREC) which enables the inputs to
swing to the rails. The ISL28270 and ISL28273 maintain
CMRR performance from the positive rail down to within
50mV of the negative rail. The ISL28271 and ISL28272 can
swing 100mV beyond the rails. The output operation of all
devices is rail-to-rail. The ISL28270 and ISL28272 are
compensated for a minimum gain of 100 and the ISL28271
and ISL28273 are compensated for a minimum gain of 10.
Reference Documents
• ISL28270, ISL28273 Data Sheet, FN6260
• ISL28271, ISL28272 Data Sheet, FN6390
Evaluation Board Key Features
The ISL2827xINEVAL1Z is designed to be operated from a
single supply (+2.4VDC to +5VDC), or from split supplies
(±1.2VDC to ±2/5V). The board is configured for 2
independent instrumentation amplifiers connected for a
closed loop gain of 101 (ISL28270, ISL28272) or a gain of
10 (ISL28271, ISL28273) with inverting and non-inverting
high impedance terminated with 100k resistors to ground.
Each amplifier contains it’s own VREF input to establish an
input common mode reference. An ENABLE
provided for each amplifier to be used to save power by
powering the device down.
select switch is
GND VSP
D
1
2
12
D
1
A
2
NC
1
C
10µF
1
R
0
33
4
1
VP
2
0.1µF
C
5
1
D
1
2
3
3
C
2
2
0.1µF
VSM
1
R
0
32
C
3
1
VM
FIGURE 1. POWER SUPPLY CIRCUIT
Power Supplies (Refer to Figure 1)
External power connections are made through the VSP (+V),
VSM (-V) and GND connections on the evaluation board.
For single supply operation, the VSM (-V) and GND pins are
tied together to the power supply negative terminal. For split
supplies, VSP (+V) and VSM (-V) terminals connect to their
respective power supply terminals. Resistors R
and R33
32
are 0Ω but can be changed by the user to provide power
supply filtering, or to reduce the voltage rate-of-rise to less
than ±1V/µs. Anti-reverse diodes D
and D2 protect the
1
circuit in the case of accidental polarity reversal.
Amplifier Configuration (Refer to Figure 2)
The schematic of each of the two op amps with the
components supplied is shown in Figure 2. The circuit
implements a differential input instrumentation amp with a
closed loop gain of 101 for the ISL28270 and ISL28272, and
10 for the ISL28271, ISL28273. The circuit can operate from
a single 2.4VDC to +5VDC supply, or from dual supplies
from ±1.2VDC to ±2.5VDC.The output common mode
reference is applied to the VREF pin, and has a range from
ground (VM) to VP.
IN+(x)
IN+
IN-
VCM
VREF
IN-(x)
VREF(x)
GND
1
VP
ENABLE
IN+
+
IN-
-
100kΩ
100kΩ
FIGURE 2. BASIC AMPLIFIER CONFIGURATION
FB+
+
FB-
-
R
G
1kΩ
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774
-V
VM
R
F
100kΩ (ISL28270, ISL28272)
9.09kΩ (ISL28271, ISL28273)
| Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright Intersil Americas Inc. 2007, 2009. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
1/2 ISL28270, ISL28271, ISL28272, ISL28273
0Ω
10kΩ
VOUT(x)
Application Note 1290
User-selectable Options (Refer to Figure 3)
Component pads are included to enable a variety of user
selectable circuits to be added to the amplifier differential
inputs, the VREF input, and the amplifier feedback loop. A
voltage divider and filter option can be added to establish a
power supply tracking common mode reference at the VREF
input, or a coaxial connection to the amplifier FB+ pin can be
made at the FB+ BNC connector. The differential inputs have
additional resistor placements for adding input attenuation,
or to establish input DC offsets through the VREF pin.
ISL2827xINEVAL1Z Components Parts List
VREFA
J
4
1
FB+A
-INA
+INA
R
J
R
8
13
DNP
J
R
9
18
0
R
19
DNP
J
R
10
21
0
R
22
DNP
R
6
C
R
0
3
14
VREFA
R
20
100k
DNPDNP
OPEN
100k
5
VREFA
R
23
V+V-
R
15
DNP
R
17
1k
R
16
DNP
FIGURE 3. COMPONENT-SELECTABLE OPTIONS
DEVICE # DESCRIPTION COMMENTS
C3, C
5
C
, CFB, CLA, C
FA
LB
CAP, SMD, 0805, 0.1µF, 25V, 10%, X7R, ROHS Power Supply Decoupling
CAP, SMD, 0805, DNP-PLACE HOLDER, ROHS Optional Amplifier Feedback Caps
Not Populated
C
, C
1
2
C
4
D
, D
1
2
U
1
CAP, SMD, 1206, 1µF, 25V, 10%, X7R, ROHS Power Supply Decoupling
CAP-TANTALUM, SMD, D, 10µF, 35V, 10%, LOW ESR,
ROHS
DIODE-RECTIFIER, SMD, MELF, 2 Ld, 50V, 1A, GPP,
Optional VREF Filter
Not Populated
Reverse Power Protection
ROHS
ISL28270FAZ or ISL28271FAZ or ISL28272FAZ or
ISL28273FAZ INSTRUMENTATION AMP,16P, QSOP,
ROHS
R
, R33, R
32
, RIB. RES, SMD, 0805, 1k, 1/8W, 1%,TF, ROHS RI Gain Resistors
R
IA
R
, R
1
2
R
to R
15
, R12, R20, R22, R27, R
R
9
R
, RFB (ISL28271, ISL28273) RES, SMD, 0805, 9.09k, 1/8W, 1%, TF, ROHS RF Gain Resistors - ISL28271,
FA
R
, RFB (ISL28270, ISL28272) RES, SMD, 0805, 100k, 1/8W, 1%, TF, ROHS RF Gain Resistors - ISL28270
FA
R
, R6, R10, R11, R13, R14, R19, R21, R23, R25,
3
R
, R30, RLA, RLB, RX.
28
S
, S
1
2
18
IN+A
, R
IN+B
, R
IN-A
29
, R
, RSA, RSBRES, SMD, 0805, 0Ω, 1/8W, TF, ROHS 0Ω User Selectable Resistors
IN-B
RES, SMD, 0805, 10k, 1/8W, 1%,TF, ROHS ENABLE Pull-up Resistors
RES, SMD, 0805, 100k, 1/10W, 1%, TF, ROHS
CAP, SMD, 0805, DNP-PLACE HOLDER, ROHS User Selectable Resistors
Not Populated
ISL28272
RES, SMD, 0805, DNP-PLACE HOLDER, ROHS User Selectable Resistors
Not Populated
SWITCH-SEALED MINI TOGGLE, TH, 3P, SP,
Enable/Disable Select Switches
ON/NONE/ON, GOLD
2
AN1290.2
June 15, 2009
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