Datasheet

8.3 Test Results
PASS IN OUT
V V V= -
2420TPS PASS OUT
P V I= ´
Getting Started (example) www.ti.com
Observe waveforms similar to Figure 6 .
• The current to the load is not constant but increases after the initial inrush. Current is low initially
because the voltage across the internal MOSFET is initially at its highest level and the controller is
power limiting the MOSFET.
• Although the current limit, I
FLT
, is set to 4 A, the start up current never goes above 2.2 A because of
the power limiting. However, 4 A is available to the steady state load when the MOSFET is fully
enhanced.
• At the end of the capacitor charge time, the current drops to the dc level powering the resistive part of
the load, about 0.8 A.
• Power Good ( PG) is true when the output voltage is within 0.3 V of the input voltage.
Figure 6. Example Scope Trace
10 TPS2420 Hot Swap Controller System Test Board SLUU343 – January 2009
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