Performance Characteristics
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4.5
Shutdown
Figure 6
shows the shutdown procedure by powering off the source power. When UVLO pin voltage is
less than 1.26V, the switching stops and soft-start capacitors are discharged by internal switches.
Conditions:
Input Voltage = 12VDC
0.5
Ω
Load on 3.3v output
Traces:
Top Trace: Input Voltage, Volt/div = 10V
Middle Trace1: 3.3V Output, Volt/div = 2V
Middle Trace2: VCC, Volt/div = 5V
Bottom Trace: SS voltage, Volt/div = 5V
Horizontal Resolution = 20 ms/div
Figure 6. Shutdown
5
Performance Characteristics
Figure 7
shows the efficiency curves. The efficiency of the power converter is 90% at 12V with full load
current. Monitor the current into and out of the evaluation board. Monitor the voltage directly at the input
and output terminals of the evaluation board.
Figure 7. Typical Efficiency vs Load Current
6
AN-2066 LM25119 Evaluation Board
SNVA445B – August 2010 – Revised April 2013
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