an1426

ISL28196EVAL1Z, ISL28197EVAL1Z
Evaluation Board User’s Guide
®
Application Note
September 25, 2008
Introduction
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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 D1 and
D2 protect the circuit in the case of accidental polarity
reversal.
The ISL2819xEVAL1Z evaluation board is a design platform
containing all the circuitry needed to characterize critical
performance parameters of the ISL28196 and ISL28197
comparators, using a variety of user defined test circuits.
The ISL28196 and ISL28197 are CMOS comparators
featuring low supply currents (2.5uA and 0.8uA
respectively), low input bias currents (15pA), rail-to-rail input
and output drive capability, and are designed to operate with
two 1.5V Alkaline batteries.
Comparator Configuration (Figure 2)
C4
J1
V-
The ISL2819xEVAL1Z is designed to enable the IC to
operate from a single supply, +1.8VDC to +5.5VDC or from
split supplies, ±0.9VDC to ±2.75V. The board is configured
for a single comparator. An external reference voltage
(VREF) pin provides the capability to adjust comparator
threshold level.
C2
R21
R1
C1
4.7µF
0
0
4.7µF
D2
D1
V+
0
Evaluation Board Key Features
R24
• ISL28196, ISL28197 Data Sheet, FN6152
J3
Reference Documents
0
• ISL28197EVAL1Z
R20
• ISL28196EVAL1Z
J2
The schematic of the comparator with the components
supplied is shown in Figure 2. Resistors R12 and R15 form a
high resistance voltage divider with a current draw of only
250nA at VREF = 5V. At this level, the low bias current
(15pA) adds only 75µV of error to the comparator threshold
level of 2.5V. Resistors R5 and R6 form high impedance
inputs to prevent loading of the input signal.
Ordering Information
C3
0.1µF
0.1µF
Power Supplies (Figure 1)
VM
External power connections are made through the +V, -V,
VREF 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, +V and -V terminals connect to their respective
VP
FIGURE 1. POWER SUPPLY CIRCUIT
V+
VREF
R15
10M
R5 10M
-
R22
+
IN-
0
ISL28196
or
ISL28197
R7 1M
IN+1
R6 10M
IN+2
R12
10M
V-
FIGURE 2. EQUIVALENT CIRCUIT SCHEMATIC
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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Application Note 1426
User-selectable Options (Figures 3, 4)
Comparator with Hysteresis (Figure 5)
Component pads are included to enable a variety of
user-selectable circuits to be added to the comparator
inputs, the VREF input, and comparator output.
A positive feedback hysteresis loop can be created by a
connection between the output and one of the non-inverting
inputs (IN1+ or IN2+). The other non-inverting input can be
used to set the comparator’s threshold level. The ratio of R6
and R7 can be used to select the desired hysteresis level.
Since IN-, in this case, becomes the comparator’s signal
input, R12 and R15 will have to be removed.
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.
J4
The output (Figure 5) has additional resistor and capacitor
placements for loading.
RREF
FIGURE 3. INPUT STAGE
J5
R27
OUT
DNP
DNP
R25
DNP
0
TO IN +
OPEN
FIGURE 4. OUTPUT STAGE
V+
VREF
DNP = DO NOT POPULATE
VIN
(COMPARATOR
INPUT)
0
OPEN
TO IN C10
R13
10M
0
R26
R23
R6
R9
R3
DNP
J8
DNP
R11
DNP
OPEN
C8
1M
C7
IN2+
R14
R7
DNP
J7
R22
IN-
R5 10M
IN1+
R7 1M
IN2+
R6 10M
R15
DNP
-
IN1+
OPEN
TO OUT
C9
C5
4.7µF
0
DNP
10M
R17
R15
OPEN
10M
0
C6
R12
R5
10M
R8
R2
J6
DNP
IN-
DNP
R10
R18
REF1
R22
VOUT
0
+
VTH
(COMPARATOR
THRESHOLD
LEVEL)
ISL28196
OR
ISL28197
R12
DNP
EXTERNAL CONNECTION
V-
FIGURE 5. COMPARATOR WITH HYSTERESIS
2
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Application Note 1426
ISL2819xEVAL1Z Components Parts List
DEVICE #
DESCRIPTION
COMMENTS
C1,C2, C5
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 (ISL28196EVAL1Z)
ISL28196FHZ-T7, IC-RAIL-TO-RAIL COMPARATOR, SOT-23, ROHS
U1 (ISL28197EVAL1Z)
ISL28197FHZ-T7, IC-RAIL-TO-RAIL COMPARATOR, SOT-23, ROHS
R2, R3, R8, R9, R13, R14,
RESISTOR, SMD, 0603, 0.1%, MF, DNP-PLACE HOLDER
R16, R18, R19, R23, R25, R27
User-selectable resistors - not
populated
R1, R10, R11, R17, R20, R21, RES, SMD, 0603, 0Ω, 1/10W, TF, ROHS
R22, R24, R26
0Ω user-selectable resistors
R4
RES, SMD, 0603, 10k, 1/10W, 1%, TF, ROHS
Gain and other user-selectable
resistors
R7
RES, SMD, 0603, 1M, 1/10W, 1%, TF, ROHS
Input resistors
R5, R6, R12, R15
RES, SMD, 0603, 10M, 1/10W, 1%, TF, ROHS
Input resistors
3
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Application Note 1426
FIGURE 6. ISL2819xEVAL1Z TOP VIEW
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
4
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J4
4.7µF
0
0
C1
0
R20
4.7µF
4.7µF
D1
D2
DNP
C5
10M
OPEN
C4
C3
0.1µF
R19
OPEN
DNP
10k
2
S1 3 ENABLE
VP
1
VM
DNP
4
ISL28196/7
DISABLE
FIGURE 7. ISL2819xEVAL1Z SCHEMATIC DIAGRAM
J5
DNP
R27
5
+-
DNP
2
3
VP
6
R25
1
DNP
R4
0
R23
R16
DNP
0
C9
U1
J9
R26
OUT
VM
EN
R22
RGA+
OPEN
R9
C10
DNP
R3
10M
RINA2+
0
VP
C8
OPEN
R6
J8
VM
DNP
RINA+
R11
DNP
1M
R13
C7
RREFA+
R14
Application Note 1426
IN2+
RINA1+
R7
J7
DNP
IN1+
DNP
0.1µF
OPEN
R8
RINA2-
DNP
R2
5
DNP
10M
R18
C6
10M
J6
R1
RREFAR15
R12
IN-
R5
R21
RREF
R24
0
C2
V+
0
R17
0
RINAR10
J1
V-
J2
J3
REF1
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