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Application Note 1531
ISL28005 Evaluation Board User’s Guide
Introduction
The ISL28005 evaluation board is a design platform
containing all the circuitry needed to characterize critical
performance parameters of the ISL28005 in either a high
side or low-side current sense application. The ISL28005
is available in fixed 100V/V, 50V/V, 20V/V gains.
Reference Documents
• ISL28005 Data Sheet, FN6973
Evaluation Board Schematic
The ISL2800XEVAL1Z evaluation board is configured
with either the ISL28005-100, ISL28005-50 or
ISL28005-20 device.
Figure 1 shows the basic application circuit and optional
protection components for the fixed gain parts. Figure 2
shows the complete schematic for the ISL2800XEVAL1Z
evaluation board.
Components shown in red in Figure 1 are optional
transient protection and not required for clean
environments. Note: The evaluation board comes
equipped with the transient protection devices.
Optional Transient Protection
For applications where the load and the power source are
permanently connected, transient protection is not
required and only an external current sense resistor (R3)
is needed.
For applications where fast transients can generate
voltage spikes that can overdrive the amplifier input and
drive the output of the amplifier into the rails, resulting in
a long overload recovery time. Common mode capacitors
C7, C9 and differential capacitor C8 are used to filter the
common mode and differential voltage spikes.
For switching applications or where fast transients are
caused by hot plugging the source or load, external
protection components may be needed. The external
current limiting resistor (R6) in Figure 1 will limit the
peak current through the internal ESD diodes to <20mA.
This condition can occur in applications that experience
high levels of in-rush current causing high peak voltages
that can damage the internal ESD diodes of the
ISL28005. If the current limiting resistor is required, it
needs to be placed on the RS- input (R6). Placing it on
the RS+ input side (R7) will result in a much larger error
voltage due to the ISL28005 taking its supply current
from the sense current in high-side applications.
For example:
Current limiting resistor R6 with a value of 100Ω will
provide protection for a 2V transient with the maximum
of 20mA flowing through the input while adding only an
additional 13µV (worst case over-temperature) of VOS as
shown in Equation 1. Note: Worst case over-temperature
input bias current on the RS- input is 130nA.
Current limiting resistor R7 with value of 100Ω will
provide the same transient protection, but with an error
voltage of 800µV. Note: Worst case over-temperature
input bias current on the RS+ input is 8µA as shown in
Equation 2.
R7 is a carry-over from our characterization board and
was used to measure input bias current. The evaluation
board is populated with a zero ohm resistor for R7.
Power Supplies
External power connections are made through the VS+
and Ground connections on the evaluation board.
Capacitors C2 and C4 perform two duties, de-coupling
the supplies and with R15, filtering of the power supply
noise. Anti-reverse diodes D1 and D3 protect the circuit
in the case of accidental polarity reversal of the supply.
Resistor R12 is used to connect ground to the fixed gain
parts.
ISL2800XEVAL1Z and BOM
Figure 3 shows the top view of the ISL2800XEVAL1Z
evaluation board. The evaluation board Bill Of Materials
is given in Table 1.
R6IRS-
×100Ω130nA×13μV== (EQ. 1)
R7IRS+
×100Ω8μA×800μV== (EQ. 2)
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. 2010. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
February 18, 2010
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FIGURE 1. SIMPLIFIED ISL2800XEVAL1Z SCHEMATIC DIAGRAM
GND VS+
V-REF
I-SENSE
I-SENSE+
OUT
I-SENSE-
0.10
0
1000pF
J5
R26
R18 R23
R12
D3
D1
J1
R15
R13
C10
R3
C4
C2
C9
C7
5
4
3
2
1
U1
J6
J2
R9
J3
R6
R7
C8
J4
OPEN
0
SOT23_5
0
1µF
0.01µF
S1AB
0
S1AB
0
0
0.01µF
100
1000pF
0
DNP
ISL28005
OPTIONAL TRANSIENT PROTECTION
D2
J13
DNP
Application Note 1531
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February 18, 2010
Application Note 1531
FIGURE 2. ISL2800XEVAL1Z SCHEMATIC DIAGRAM
I-SENSE-
ARE FOR KELVIN CONNECTIONS
R16-R20 AND R21-R25
I-SENSE+
GND VS+
V-REF
I-SENSE
OUT
1000pF
J4 1
R16
DNP
DNP
R17
R18
0
DNP
R19
R20
DNP
DNP
R5
DNP
R4
DNP
R25
DNP
R24
0.10
DNP
R1
R2
R23
0
DNP
R22
12 D3
S1AB
J5
1
R13
DNP
R14
R11
DNP
DNP
C2
0
R12
DNP
0
OPEN
100
S1AB
0.01µF
1µF
SOT23_5
0
OPEN
J3
R9
R8
J2 1
J6
1
2
3
4
U1
1
2
3
5
C4
C10
R15
C20
J1 1
D1
21
R10
R26
4
DNP
5
C9
1000pF
R7
0
R6
100
C8
0.01µF
C7
DNP
R21
DNP
R3
ISL28005
D2
J13
DNP
4
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
AN1531.0
February 18, 2010
Application Note 1531
FIGURE 3. ISL2800XEVAL1Z TOP VIEW
TABLE 1. ISL2800XEVAL1Z COMPONENTS PARTS LIST
DEVICE # DESCRIPTION COMMENTS
C2 CAP, SMD, 0805, 1µF, 50V, 20%, X7R, ROHS Power Supply Decoupling and Input Filter
C4, C8 CAP, SMD, 0603, 0.01µF, 50V, 10%, X7R, ROHS Power Supply Decoupling/Input Filter and
Differential Current Sense Filter
C7, C9 CAP, SMD, 0603, 1000pF, 50V, 10%, X7R, ROHS Common Mode Current Sense Filter
C10, C20 CAP, SMD, 0603, DNP - Place Holder, ROHS User Selectable Capacitors - Not Populated
D1, D3 Diode-Rectifier, SMD, S1AB, 50V, ROHS Reverse Power Protection
U1 (ISL28005-100EVAL1Z) ISL28005FH100Z-T7, SOT-23, ROHS
U1 (ISL28005-50EVAL1Z) ISL28005FH50Z-T7, SOT-23, ROHS
U1 (ISL28005-20EVAL1Z) ISL28005FH20Z-T7, SOT-23, ROHS
R16, R17, R19 -R22,
R24, R25
Resistor, SMD, 0603, MF, DNP - Place Holder User Selectable Kelvin Connection - Not Populated
R26 Resistor, SMD, 0603, MF, DNP - Place Holder User Selectable Output Load Resistor - Not Populated
R3 Resistor, SMD, 2512, 0.1Ω, 1W, 1%, TF, ROHS Sense Resistor
R1, R2, R4, R5 Resistor, SMD, 2512, DNP - Place Holder User Selectable Sense Resistors - Not Populated
R6, R7, R13, R18, R23 Resistor, SMD, 0603, 0Ω, 1/10W, TF, ROHS Zero Ohm User Selectable Resistors
R15 Resistor, SMD, 0603, 100Ω, 1/10W, TF, ROHS Current Limiting Resistors
