TPS65218: Unused DCDC regulators

Daniel Brown

Part Number: TPS65218
Other Parts Discussed in Thread: TPS65217

Hello,

For the TPS65218, if I do not need some of the DCDC regulators can I leave them open? For example, for the BU system, if I am not using DCDC5, can
I leave it with not filter inductor and cap and feedback? Similar for the other block of regulators, if not using DCDC2, can I do the same here?

We discovered that, at least with the TPS65217, a similar PMIC, that if not filter and feedback are provided then the failure of this output would prevent
the startup of the other regulators.

Thanks.
Dan

over 7 years ago

0 Kevin LaRosa over 7 years ago

TI__Genius 17380 points

Hi Daniel,

The same behavior should be true for TPS65218, though with strict = 0 it looks like you can potentially tie the feedback to a higher voltage: e2e.ti.com/.../554657

0 Daniel Brown over 7 years ago in reply to Kevin LaRosa

Intellectual 870 points

Hi Kevin,

What about DCDC5? Will leaving this open influence DCDC6 or any other rails LDO1 and DCDC1-4?

Thanks.

0 Daniel Brown over 7 years ago in reply to Kevin LaRosa

Intellectual 870 points

Can I tie FB5 to FB6 or any other rail and thus leave L5 open?

0 Kevin LaRosa over 7 years ago in reply to Daniel Brown

TI__Genius 17380 points

Hi Daniel,

Based on the TPS65218 User's Guide, DCDC6 is enabled before DCDC5 and DCDC6 voltage > DCDC5 voltage, so I would expect that as long as STRICT = 0, tying FB5 to FB6 and leaving L5 unconnected should be fine. I would recommend checking your workaround on a demo board, like the TPS65218EVM. I'd also recommend leaving unpopulated pads for the proper connections in case they are desired later.

Power management

Power management forum

TPS65218: Unused DCDC regulators