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3.5.3 Overload Protection
The evaluation board is configured with hiccup mode overload protection. The restart time can be
programmed by C20 restart capacitor. Figure 4 shows hiccup mode operation in the event of an output
short.
Conditions:
Input Voltage = 24VDC
Output Short
Traces:
Top Trace: SW Voltage Volt/div = 10V
Bottom Trace: Inductor Current, Amp/div = 5A
Horizontal Resolution = 20ms/div
Figure 4. Short Circuit
3.5.4 External Clock Synchronization
A TP3 (SYNC) test point has been provided on the evaluation board in order to synchronize the internal
oscillator to the external clock. Figure 5 shows the synchronized switching operation.
Conditions:
Input Voltage = 24VDC
Load Current = 9A
Traces:
Top Trace: SYNC pulse, 20% duty cycle, Volt/div = 5V
Middle Trace: SW voltage, Volt/div = 20V
Bottom Trace: Inductor Current, Amp/div = 5A
Horizontal Resolution = 2µs/div
Figure 5. Clock Synchronization
4
AN-2112 LM25117 Evaluation Board SNVA469B–May 2011–Revised April 2013
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