TPS40322EVM-074: EVM EN/SS Start-Up Waveform NOT comply with Figure 20

Eric Lai

Expert 4940 points

Part Number: TPS40322EVM-074

Hi Expert,

The customer see the EN/SS Start-Up Waveform not follow the Figure 20.

Below waveform is measuring from EVM,The yellow is ENx/SSx and the blue is BP6.

We want to know why the ENx/SSx voltage not clamped to 1.3 V.

Best regards,

Eric Lai

Field Application Engineer

Texas Instruments Taiwan Limited

O: +886-2-2175-2582

M: +886-909-262-582

E-Mail:Eric.Lai @ti.com

over 7 years ago

0 Eric Lai over 7 years ago

TI__Expert 4940 points

0 Qian Chen over 7 years ago in reply to Eric Lai

TI__Mastermind 24075 points

Hi Eric,

The EN/SS waveform in datasheet figure is more like Vin startup, not Enable startup.
When VIN is applied and EN/SS pin is low, the VDD and BP6 voltage is already established.
Once EN/SS pin is released, it will stay at 1.3V for a very short time.

In summary, the waveform customer observed is normal, it is not a problem.

Thanks
Qian

Power management

Power management forum

TPS40322EVM-074: EVM EN/SS Start-Up Waveform NOT comply with Figure 20