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Application Note 1935
ISL85003DEMO1Z, ISL85003ADEMO1Z Evaluation
Board User Guide
Description
The ISL85003 and ISL85003A Demo kits are intended for use
for point-of-load applications sourcing from 4.5V to 18V. The
kits are used to demonstrate the performance of the
ISL85003 and ISL85003A, high efficiency synchronous buck
regulators. The ISL85003 and ISL85003A are offered in a
4x3mm dual flat no lead (DFN) package.
Recommended Equipment
The following materials are recommended to perform testing:
• 0V to 25V power supply with at least 10A source current
capability
• Electronic loads capable of sinking current up to 7A
• Digital Multimeters (DMMs)
• 100MHz quad-trace oscilloscope
Key Features
• Input voltage range 4.5V to 18V
• Current mode control
- DCM/PWM
- Internal or external compensation options
- 500kHz switching frequency option
- External synchronization up to 2MHz on ISL85003
• Adjustable soft-start time on the ISL85003A
• Continuous output current up to 3A
• Minimal external components required
References
ISL85003, ISL85003A
Datasheet
Quick Setup Guide
1. Ensure that the circuit is correctly connected to the supply
and loads prior to applying any power.
2. Connect the bias supply to VIN, the plus terminal to VIN and
the negative return to PGND.
3. Turn on the power supply.
4. Verify the output voltage is 5V for V
OUT.
Evaluating the Other Output Voltage
The ISL85003DEMO1Z kit output is preset to 5V; however,
output voltages are programmed using an external resistor
divider that scales the feedback relative to the internal
reference voltage. Please refer to the application note
AN1930
and the
ISL85003, ISL85003A
datasheet for further information.
Disabling/Enabling Function
The ISL85003DEMO1Z board has EN pin tied to VIN via R
7
.
This keeps the part enabled all the time. To disable the part,
remove R
7
.
MODE/SS Control
The ISL85OO3 evaluation board has a MODE pin that allows
different mode operation. Default board configuration has
R
6
= 200k to V
CC
, which defaults to PWM operation mode. If
this pin is tied to GND the IC will operate in CCM mode.
The ISL85OO3A evaluation board has an SS pin that provides a
programmable soft-start. When the chip is enabled, the
regulated 4
μ
A pull-up current source charges a capacitor C
10
connected from SS to ground. Default board configuration has
R
6
= 200k to V
CC
, which defaults to internal SS.
Ordering Information
PART NUMBER
DESCRIPTION
ISL85003DEMO1Z
Small form factor Demo board for 3A,
4.5V to 18V Switching Regulator, external
synchronization.
ISL85003ADEMO1Z
Small form factor Demo board for 3A,
4.5V to 18V Switching Regulator,
adjustable soft-start time
FIGURE 1. ISL85003ADEMO1Z PICTURES
TOP SIDE
BOTTOM SIDE
May 16, 2014
AN1935.0
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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