TPS25985: Question about the operation sequence of the SWEN and EN/UVLO pins on the TPS259850.

KYUNGJAE LEE

Part Number: TPS25985

Tool/software:

Hi TI experts,

The text in the datasheet states that the pull-up power for the SWEN pin should be powered up before the TPS259850 device is enabled.

However, in Figure 8-8 of the datasheet, the EN/UVLO pin appears to operate before the SWEN pin.

Could you clarify which pin, SWEN or EN/UVLO, should operate first?

Thanks

2 months ago

0 Kunal Goel 2 months ago

TI__Guru 65345 points

Hi KJ,

Sequencing is not important. We just need to ensure that SWEN pull-up is derived from VIN supply.

Regards

Kunal Goel

0 KYUNGJAE LEE 2 months ago in reply to Kunal Goel

Prodigy 10 points

Hi Kunal Goel,

In my application, the SWEN pull-up voltage is not derived from VIN but is supplied from a separate, isolated power source.

In this circuit, is it safe as long as the Enable signal remains in a disabled state, regardless of whether VIN or the SWEN pull-up voltage is applied first?

The circuit is currently designed so that both the VIN and SWEN pull-up voltages must be applied, in any order, for it to enable.

Thanks

0 Kunal Goel 2 months ago in reply to KYUNGJAE LEE

TI__Guru 65345 points

Hi KJ,

Please pull-up swen from Vin. This is important to ensure startup.

Regards

Kunal Goel

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TPS25985: Question about the operation sequence of the SWEN and EN/UVLO pins on the TPS259850.