TPS65070's VSYS seems abnormal on my custom OMAP-L138 board.

Seyoung Park

Other Parts Discussed in Thread: OMAP-L138

Hello,

I made my OMAP-L138 application board based on Logic EVM.

It is supplied only AC-5V but made up like "Logic OMAP-L138 EVM".

Seeing below the capure is VSYS from SYS pin.

Why is SYS voltage pulsating?

TS --- open

#PB_IN -- open

THRESHOLD--<300k>--VSYS

AVDD6--<10uF ceramic>--GND

Thank you for your concern.

0 Daniel Acevedo over 14 years ago

Please provide a screen shot of the voltage at L4, VIN and inductor current. Also, please provide your schematic and layout.

0 Seyoung Park over 14 years ago in reply to Daniel Acevedo

Thank you Mr. Acebedo.

Now "0.02R" resister between L1/2/3 and OMAP-L138 is opened not to supply power.

L4 is grounded(to the GND) and is checkted stable 0V on oscilloscope.

"5V -> AC(in)" current is checked to 1.4mA by multimeter.

Seeing below caputure is the voltage of BATT(pin 5,6).

BATT is not connected any battery but connected just 10uF and 01uF ceramic capacitors.

USB(pin 12) is 0V.

I'm sorry that I can't provide schematics and pcb layout.

My best regards.

0 Daniel Acevedo over 14 years ago in reply to Seyoung Park

Are you loading Vsys during startup? If you would like to email me the schematics and layouts I will provide my email address.

Power management forum