TPS62442-Q1: output voltage abnormal

xiaodong.2.zhu

Part Number: TPS62442-Q1

before the device start, the output shart like RC curve, and when shut down EN pin, the output is still on about 300mV. could you explain why? and detail reason

6 months ago

0 Excel Regidor 6 months ago

TI__Mastermind 26966 points

Hi Xiaodong,

Apologies for the late response.

Can you share the circuit diagram and waveforms as indicated below to better understand the issue? What is system load of 1V8 rail?

1. VIN and EN pin voltage, 1V8 voltage (Ch1), Inductor current (of Ch1)

Best regards,

Excel

0 xiaodong.2.zhu 6 months ago in reply to Excel Regidor

Prodigy 10 points

hello Excel:

schematic as below:

waveform:

The power application is used head unit product and supply for serializer IC. input voltage is 3V3, EN pin is 3V3 from MCU.

+1 Excel Regidor 6 months ago in reply to xiaodong.2.zhu

TI__Mastermind 26966 points

Hi Xiaodong,

Thanks for the quick response.

There might be another source current (Isource = 300mV / 50ohm = 6mA) on 1V8 rail causing it not to fall ~0V when EN = Low. Can you isolate the 1V8 rail to any other connect and check the output voltage waveform again? Do you observe the same case in 1V0V rail?

Best regards,

Excel

0 xiaodong.2.zhu 6 months ago in reply to Excel Regidor

Prodigy 10 points

Hi Excel,

you are right. after disconnect, the output is OK, this abnormal voltage is from load side.

thank you for your support!

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TPS62442-Q1: output voltage abnormal