lm25117psqx National Semiconductor Corporation, lm25117psqx Datasheet - Page 28

• Manufacturer Part Number: lm25117psqx
• Description: Wide Input Range Synchronous Buck Controller With Analog Current Monitor
• Manufacturer: National Semiconductor Corporation

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Example of Constant Current
Regulator
The LM25117 can be configured as a constant current regu-
lator by using the current monitor feature (CM) as the feed-
back input. A voltage divider at the VCCDIS pin from VOUT
to AGND can be used to protect against output over-voltage.
FIGURE 20. Constant Current Regulator with Hiccup Mode Output OVP
28
When the VCCDIS pin voltage is greater than the VCCDIS
threshold, the controller disables the VCC regulator and the
VCC pin voltage decays. When the VCC pin voltage is less
than the VCC UV threshold, both HO and LO outputs stop
switching. Due to the time delay required for VCC to decay
below the VCC UV threshold, the over-voltage protection op-
erates in hiccup mode. See
Figure
20.
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