Other Parts Discussed in Thread: TPS2663, TPS2660
How to recover fast during supply line interruptions ?
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During supply line interruptions, the TPS2640 eFuse turns-OFF and restarts in dVdT mode which takes significant amount of time to recover the output voltage. Till that time, the load has to be supported by the buffer capacitor to meet class-A system performance.
Let’s take an example with specifications:
Vin = 24V
Cout = 440 µF
Cdvdt = 680 nF
Rilim = 22.4 kΩ sets Current limit at 530 mA
Load = 200 mA
Power fail interval = 5 ms
As you see in the below test waveform, the output voltage drops as low as 6-V due to slow restart in dVdT mode. That means the Cout has to be increased dramatically and it is just case of load current as low as 200 mA.
Solutions:
As seen in the below test waveform, the device starts in current limit mode and quickly recovers the output voltage.