an1344

ISL2828xEVAL1Z Evaluation Board User’s Guide
Application Note
August 2, 2007
Introduction
AN1344.0
R49 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,
C10 and C18, are connected close to the part to filter out
high frequency noise. Anti-reverse diodes D1, D2 and zener
diode D3 protect the circuit in the case of accidental polarity
reversal.
1
Reference Documents
R40
C10
C10
• ISL28286 Data Sheet, FN6312
J2
C12
C12
R46
R46
+
4.7UF
4.7μF
D2
D2
00
1
1 A
A
2
NC
NC
RF
+
IN(A, B)IN-
IN-
0
C18
C18
0.1UF
0.1μF
C16
C16
+
DNP
VP
1/2 ISL2828x
VP
0Ω
V+
IN+
VOUT(x)
V-
+
VM
10kΩ
10kΩ
RREF(A,B)+
0Ω
R49
CC 3 3
100kΩ
10kΩ
VREF
D3
The schematic of each of the 2 op amps 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 2.4VDC to +5VDC
supply, or from dual supplies from ±1.2VDC to ±2.5VDC.
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.
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+
and V- terminals connect to their respective power supply
terminals. De-coupling capacitors C12, C17, connect to
ground through R1, R46, 0Ω resistors. Resistors R40 and
VCM
1
Amplifier Configuration (Figure 2)
Power Supplies (Figure 1)
IN(A, B)+
+
FIGURE 1. POWER SUPPLY CIRCUIT
The ISL2828xEVAL1Z is designed to enable the IC to
operate from a single supply (+2.4VDC to +5VDC), or from
split supplies (±1.2VDC to ±2.5V). The board is configured
for 2 independent op amps 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 is included).
IN+
C17
C17
V+
V+
4.7UF
D1 4.7μF
D1
MMBZ52xxB
Evaluation Board Key Features
RIN+
2
D3
0
VM
RIN-
R1
R1
00
0.1μF
• ISL28288 Data Sheet, FN6339
J1
1
J3
V-
R49
The ISL2828x amplifiers feature low noise, low distortion,
and rail-to-rail output drive capability. They are designed to
operate with single and dual supplies from +5VDC
(±2.5VDC) down to +2.4VDC (±1.2VDC).
1
The ISL2828xEVAL1Z evaluation board is a design platform
containing all the circuitry needed to characterize critical
performance parameters of the ISL28286 and ISL28288
dual operational amplifiers, using a variety of user defined
test circuits.
R40
®
100kΩ
0Ω
TO OTHER CHANNEL
VREF
GND
10kΩ
FIGURE 2. BASIC AMPLIFIER CONFIGURATION
1
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. 2007. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
Application Note 1344
User-Selectable Options (Figures 3 to 5)
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.
The outputs (Figure 3) have additional resistor and capacitor
placements for loading.
A voltage divider and filter option (Figure 4) 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.
ROUT A
R55
R55
0
DNP
R44
R39
IN+ A DNP
ENA 6
3
R57
V- 7
ENB 11
IN+ B
R37
DNP
RFA1, R45, 100k
R36
DNP
INA+ 5
J15 OUT A
12
5
2 34
DNP
R57
10K
IN- A
2
OUT
10K
R53
OPEN
1
R51
DNP
R51 DNP
1
R53
C19 OPEN
2
In the standard configuration (Figure 5), R41 and R45 are RF
feedback resistors for the two independent amplifiers, set for
AV = 10. Resistors R47 and R48 connect the DUT output to
the output circuit (Figure 3). The additional unpopulated
components, R34 to R39, R42 to R44, C10, C11, C13 to C15
and C18 allow the user to configure the board for a variety of
other applications such as cascaded gain stages, active
feedback loops, etc.
C13
CFA DNP
- 4 INA+
3 OUTA R42
15 V+ RGDIFF
DNP
+14 OUTB
INB+ 12
R38
DNP
13 INB-
R47
RSA
OUT A
C14
DNP CLA
C15
CLB
DNP
OUT B
RSB
R48, 0
R43, DNP
IN- B
FIGURE 3. 1/2 OUTPUT STAGE
RFB1, R41,100k
C11
CFB DNP
1
OPEN
2
100k
RREF
1
RREFAR31
R31
C9
C9
1
2
+
4.7µF
DNP
3
R2
R2
RINA2RINA2-
DNP
R8
R8
DNP
DNP
1
R17
R17
J6
4
INA2-
RINAR21
R21
10k
C6
C6
2
1
0
00
R32
R32
2
OPEN
OPEN
R33
R33
1
FIGURE 5. OPTIONAL COMPONENTS
VREF
10k
C2
C2
2
DNP
DNP
3
1
5
R25
R25
J5
4
INA1-
J4
J4
REF1
REF1
RINA1R13
R13
+
C3
C3
2
1
OPEN
OPEN
R9
R9
1
OPEN
DNP
DNP RINA2+
RINA2+ R18 DNP
100k
1
ININ+
R26
100k
RGA+
1
R3
R3
2
R18
2
RINA+
R22
R22
10k
C7 210K
C7
00
DNP
3
1
4
INA2+
J8
2
RREFA+
R30
R30
R26
3
1
4
INA1+
RINA1+
R14
R14
1
2
DNP
J7
J7
FIGURE 4. 1/2 INPUT STAGE
ISL2828xEVAL1Z Components Parts List
DEVICE NUMBER
DESCRIPTION
C9, C12, C17
CAP-TANTALUM, SMD, D, 4.7µF, 50V, 10%, LOW ESR, ROHS
COMMENTS
Power supply decoupling
C10,C18
CAP, SMD, 0603, 0.1µF, 25V, 10%, X7R, ROHS
Power supply decoupling
C6-C25
CAP, SMD, 0603, DNP-PLACE HOLDER, ROHS
User selectable capacitors not populated
DIODE-RECTIFIER, SMD, SOD-123, 2P, 40V, 0.5A, ROHS
Reverse power protection
DIODE-ZENER, SMD, SOD-123, 2P, 5.1V, 350mV, ROHS
Reverse power protection
D1,D2
D3
U1 (ISL28286EVAL1Z)
ISL28286FAZ, IC-RAIL-TO-RAIL PRECISION OP AMP, 16P, QSOP, ROHS
U1 (ISL28288EVAL1Z)
ISL28288FAZ, IC-RAIL-TO-RAIL PRECISION OP AMP, 16P, QSOP, ROHS
RESISTOR,SMD, 0603, 0.1%, MF, DNP-PLACE HOLDER
User selectable resistors - not
populated
RES, SMD, 0603, 0W, 1/10W, TF, ROHS
0Ω user selectable resistors
R6, R7, R20-R23, R33, R53, R54
RES, SMD, 0603, 10k, 1/10W, 1%, TF, ROHS
RG gain resistors
R28, R30, R41, R45
RES, SMD, 0603, 100k, 1/10W, 1%, TF, ROHS
RF gain resistors
R2-R5, R8-R10, R12, R16-R19,
R24-R27, R29, R31, R34-R39,
R42-R44, R50-R52, R57, R58
R1, R11, R13-R15, R24, R25, R32,
R40, R46-R49, R55, R56
2
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August 2, 2007
Application Note 1344
ISL2828xEVAL1Z Top View
3
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August 2, 2007
4
INB2-
INB1-
INB2+
INB1+
ENB
ENA
INA2+
INA1+
INA2-
INA1-
(C6)
DNP
DNP
(R5)
DNP
(R12)
RINB2- DNP
(C1)
(C8)
DNP
(C5)
(10 k)
(R20)
RINB-
(R24)
DNP
RGB-
RREFB-(R29) DNP
RGB+
(R27)
DNP
RINB+ (R23) (10 k)
(R16)
DNP
RINB1- (R11) (0)
(R4)
DNP
(R10)
RINB2+ DNP
V+
RGA+
(R26)
DNP
RREFB+ (R28) (100 k)
(R19)
DNP
RINB1+ (R15) (0)
(C4) DNP
(C7)
(R18)
DNP
(R7) (10 k)
(R6) (10 k)
(R3)
DNP
DNP
RINA+ (R22) (10 k)
RINA2+ DNP
(R9)
RREFA+(R30) (100 k)
(C3) DNP
RGA(R25)
DNP
RREFA- (R31) DNP
RINA- (R21) (10 k)
(R17)
DNP
RINA1+ (R14) (0)
(R2)
DNP
(R8)
RINA2- DNP
(C2) DNP
RINA1- (R13) (0)
(C10)
V-
(R32)
RREF
(R37)
DNP
4
3
2
(0)
4.7uF
(C9)
(10 k)
(R33)
(R38)
DNP
INB+ 5
ENB
V-
ENA
INA+ 1
(R36)
DNP
VREF
(R35) DNP
(R34) DNP
(R39)
DNP
-
-
(0)
4.7uF
(R43) DNP
(C18)
V-
(0)
(R40)
(D2)
GND
5.1V
(C16)
(D3)
DNP
+
CFB DNP
(C11)
V+
4.7uF
(C17)
(C15)
CLB
DNP
DNP
(C14)
CLA
V+
(0)
(R49)
(D1)
(R42)
RGDIFF
DNP
RFB1 (R41) (100 k)
V-
OUTB
V+
6 INB-
7
8
9 OUTA
10 INA-
(R46) (C12)
+
+
CFA DNP
(C13)
RFA1 (R45) (100 k)
(R44)
DNP
DNP
(0)
(R1)
RSB
(R48) (0)
ROUTAB
(R47) (0)
RSA
(C20)
DNP
(R52)
DNP
(R50)
DNP
(C19)
DNP
(R51)
DNP
(R54)
(10 k)
(R56) (0)
ROUTB
(R53)
(10 k)
(R55) (0)
ROUTA
(R58)
DNP
(R57)
DNP
OUTB
OUTA
Application Note 1344
ISL2828xEVAL1Z Schematic Diagram
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
AN1344.0
August 2, 2007
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