TPS61322: TI data sheet does not show input capacitor

AB Singh

Part Number: TPS61322
Other Parts Discussed in Thread: TPS61299

Tool/software:

Hello TI experts!

I am trying to select a switching Regulator for my company's design where PCB is very small. I have evaluated many regulators, and read many articles on Internet. All regulators have an input capacitor C1. This includes many TI regulators. But the TPS61322 does not have C1. No explanation is given in the datasheet. I am tempted to use this regulator, but reluctant due to lack of explanation. Can TI experts explain this please. Thanks.

3 months ago

0 Stefan Schauer 3 months ago

TI__Guru 58521 points

Hi Singh,

The engineer is out of office. Please expect a reply till Tuesday.

Best Regards,

Stefan

0 Nini Zhong 3 months ago in reply to Stefan Schauer

TI__Genius 13205 points

you could use 10uF 0603 capacitor for reference. Similar to the recommendation of TPS61299 data sheet.

0 AB Singh 3 months ago in reply to Nini Zhong

Prodigy 120 points

It is safe to use an input capacitor. But why does it not show in the datasheet? There must be a reason...?

0 Mulin Yuan 3 months ago in reply to AB Singh

TI__Genius 14870 points

Hi AB,

Sorry for confusing you.In Detail Design Schematics in datasheet and EVM user guide shematic, the input capacitors is included. The input capacitor is a must for the converter.

Regards,

Mulin

+1 AB Singh 3 months ago in reply to Mulin Yuan

Prodigy 120 points

Hello Mulin,

I had studied the entire datasheet (DS). The two circuits shown in Sections 8.3.1 are not applicable in my design.

I have one Ni-MH battery cell 1.25V - 1.2V. I need to boost it to 3.3V to supply power to the entire device including the MCU (BLE CC2340). The current as per the DSs of all components in the device is 65mA max. (Let's say less than 100mA.) Therefore, I selected TPS613221A.In this case, the circuit shown in section 8.2.1 is applicable. And that circuit does not have any input capacitor. The extrapolated efficiency (Fig. 8-8) still shows about 80% at 100mA current. The device should typically consume about 50-55mA.

Well. I will use an input capacitor as per ur recommendation. But my question remains - why the DS does not show any C1, whereas all other regulators do. Thanks.

+1 Mulin Yuan 3 months ago in reply to AB Singh

TI__Genius 14870 points

Hi AB,

We will update the datasheet in next version. Thanks.

Regards,

Mulin

0 AB Singh 2 months ago in reply to Mulin Yuan

Prodigy 120 points

Thanks. This issue is resolved.

Power management

Power management forum

TPS61322: TI data sheet does not show input capacitor