Intersil ISL78205EVAL1Z Setup Procedure

ISL78205EVAL1Z Evaluation Board Setup Procedure
The ISL78205EVAL1Z board demonstrates the
synchronous/asynchronous buck operation of the ISL78205. The
board input voltage range is 3V to 40V.
The output voltage is set to 5V and can be changed by altering
the feedback resistors R3 and R4. Note that to increase the
output voltage, the output capacitors' voltage rating needs to be
checked.
The board's output current is 2A typical. The board is set with
default 3.6A OC threshold. The OC threshold can be programmed
by R15 placed at the ILIMIT pin.
The ISL78205EVAL1Z board is configured as a synchronous buck
and can be configured to an asynchronous buck. The board is set
to a default switch frequency of 500kHz. The frequency can be
programmed by R8 at the FS pin.
The board can be synchronized with an external clock. Multiple
ISL78205EVAL1Z boards can be synchronized simply by
connecting their SYNC pins together.
Recommended Equipment
• 0V to 40V power supply with 3A source current
• Load capable of sinking 3A current
• Multimeters
• Oscilloscope
N/A
- Unused Circuits
June 21, 2012
AN1769.0
FIGURE 1. ISL78205EVAL1Z BOARD IMAGE
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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Quick Start-up
Figure 1 shows the board image. Note N/A section shows unused
circuits. The useful buck section is noted inside the block.
1. Connect the power source to inputs J1 (VIN+) and J2 (GND).
Connect the load terminals to buck outputs J3 (VOUT+) and
J4 (GND). Make sure the setup is correct prior to applying any
power or load to the board.
2. Adjust the power source to 12V and turn it on.
3. Verify the output voltage is 5V and use oscilloscope to monitor
the phase node waveforms through J28.
Asynchronous Buck Configuration
To configure the board to asynchronous buck, remove R19 and
change R20 (on bottom of the board) to 0Ω to ensure Q6 is
securely off.
Copyright Intersil Americas Inc. 2012. All Rights Reserved.
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Application Note 1769
Author:Jun Liu
Buck