an1420

ISL282x6EVAL1Z Evaluation Board User’s Guide
®
Application Note
August 28, 2008
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Introduction
J11
J6
V-
R31
C2
C4
4.7µF
C3
4.7µF
C5
0.01µF
• ISL28256 Data Sheet
• ISL28266 Data Sheet
Evaluation Board Key Features
The ISL282x6EVAL1Z 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 dual 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.
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
Power Supplies (Figure 1)
External power connections are made through the +V, -V,
VREF and Ground connections on the evaluation board.
RF
VP
RIN-
IN-
IN-
V+
10kΩ
RIN+
VREF
ISL282x6 (1/2)
100kΩ
IN -
VREF
0.01µF
User selectable SMA edge connectors are also provided for
+V and -V. 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 to their respective supplies through R16
and R31 0Ω resistors. These resistors 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 C5 are connected
close to the part to filter out high frequency noise.
Anti-reverse diode D1 protects the circuit in the case of
accidental polarity reversal.
• ISL28246 Data Sheet
VCM
J14
FIGURE 1. POWER SUPPLY CIRCUIT
• ISL28236 Data Sheet
IN +
J13
D1
Reference Documents
IN+
J12
0
R16
The ISL28236 and ISL28246 high-speed operational
amplifiers feature low power consumption, while ISL28256
and ISL28266 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.
VREF
V+
J8
0
The ISL282x6EVAL1Z evaluation board is a design platform
containing all the circuitry needed to characterize critical
performance parameters of the ISL282x6 operational
amplifiers in both MSOP-8 and SOIC-8 packages, using a
variety of user defined test circuits.
IN+
0Ω
VOUT
V-
+
VM
10kΩ
RREF+
RL
100kΩ
10kΩ
GND
FIGURE 2. BASIC AMPLIFIER CONFIGURATION
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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Application Note 1420
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.
The outputs (see Figure 4) have a 10kΩ load resistor to
ground and have additional resistor and capacitor
placements for loading.
User-selectable Options (Figures 3 and 4)
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.
Component pads are included to enable a variety of
user-selectable 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.
OUT
R13
10k
100k
C1
OPEN
R14
R2
10k
DNP
R15
R18
DNP
100k
C6
OPEN
R26
TO OUTPUT
TO INTO IN+
0
VREF
FIGURE 3. INPUT STAGE (1/2)
2
FROM OUTPUT
10k
R11
OPEN
R28
R12
DNP
R17
R10
DNP
DNP
NODE
C8
DNP
R6
J2
R3
DNP
0
R5
R1
DNP
J1
R4
DNP
IN+
IN-
FIGURE 4. OUTPUT STAGE (1/2)
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Application Note 1420
ISL282x6EVAL1Z Components Parts List
DEVICE #
DESCRIPTION
COMMENTS
C2, C4
CAP-TANTALUM, SMD, D, 4.7µF, 50V, 10%, LOW ESR, ROHS
Power supply decoupling
C3, C5
CAP, SMD, 0603, 0.1µF, 25V, 10%, X7R, ROHS
Power supply decoupling
C1, C6 thru C10
CAP, SMD, 0603, DNP-PLACE HOLDER, ROHS
User-selectable capacitors - not
populated
D1
DIODE-SCHOTTKY BARRIER, SMD, SOT-23, 3P, 40V, ROHS
Reverse power protection
U1 (ISL28236FUZ)
IC-5 MHz RRIO OP AMP, 8P, MSOP, ROHS
U1 (ISL28236FBZ)
IC-5 MHz RRIO OP AMP, 8P, SOIC, ROHS
U1 (ISL28246FUZ)
IC-5 MHz RRIO OP AMP, 8P, MSOP, ROHS
U1 (ISL28246FBZ)
IC-5 MHz RRIO OP AMP, 8P, SOIC, ROHS
U1 (ISL28256FUZ)
IC-39µA RRIO OP AMP, 8P, MSOP, ROHS
U1 (ISL28256FBZ)
IC-39µA RRIO OP AMP, 8P, SOIC, ROHS
U1 (ISL28266FUZ)
IC-39µA RRIO OP AMP, 8P, MSOP, ROHS
U1 (ISL28266FBZ)
IC-39µA RRIO OP AMP, 8P, SOIC, ROHS
R30, R32, R34 thru R36
RESISTOR, SMD, 0603, 0.1%, MF, DNP-PLACE HOLDER
User selectable resistors - not
populated
R4, R16, R25 thru R27, R31
RES, SMD, 0603, 0Ω, 1/10W,TF, ROHS
0Ω user selectable resistors
R11, R14, R21, R24, R28, R29 RES, SMD, 0603, 10k, 1/10W, 1%, TF, ROHS
Gain and other user selectable
resistors
R13, R18, R19, R23
Gain resistors
RES, SMD, 0603, 100k, 1/10W, 1%, TF, ROHS
3
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Application Note 1420
FIGURE 5. ISL282x6EVAL1Z TOP VIEW (SOIC SHOWN)
4
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Application Note 1420
J16
J15
ISL282x6EVAL1Z Schematic Diagram
10k
C7
0
OPEN
R27
0
C8
C9
OPEN
R26
OPEN
R28
OPEN
R29
C6
10k
DNP
DNP
R22
DNP
R19
R18
100k
R15
R13
100K
C1 1
OPEN 2
R14 3
10K 4
R11
10k
R4
0
VREF
1
8
U1
2
7
SOIC8
6
3
MSOP8
5
4
DNP
100k
8
7 OPEN
6
5 R21
10k
R24
10K
R23
100k
C10
R34
DNP
OUTB NODEB IN+B IN-B
0.01µF
C4
4.7µF
C5
V+
R32
DNP
R12
R10
DNP
0.01µF
DNP
R6
R5
IN-A IN+A NODEA OUTA
DNP
DNP
C2
D1
R17
4.7µF
C3
2
1
DNP
0
R16
V-
R30
J6
DNP
0
R31
J8
R35
3
DNP
J11
R25
J12
0
R20
J13
DNP
R36
VREF
J14
DNP
R8
J4
R7
DNP
J3
DNP
DNP
R2
J2
J1
R1
R3
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
5
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