LMR36520: Customer Questions

Katsu Matsunaga

Part Number: LMR36520

Hello,

I have been receiving question about LMR36520.

1. Input capacitor: Could you tell me recommended capacitor value of electrolytic capacitor which is used with ceramic capacitor in series?

2. Is it correct that dummy resistor is not required for correct operation at no load?

3. What is VIN voltage at VCC =3.8V(VCC_UVLO_Rising)? I would like to know a relation between VCC voltage and VIN.

4. About equation 1 in datasheet p13, Ilimit is LS_Limit or max current for the application?

Best regards,

Katsu

over 3 years ago

0 Iven Su over 3 years ago

TI__Expert 8245 points

Hi,

Please see my inputs below:

1. Ceramic capacitors for input are good enough, no need to add e-cap in series. If you want to add e-caps, please ensure you also use ceramic capacitors which have low ESR so that the input ripple can be lower.

2. Yes, dummy resistor is not required for a normal designed work.

3. VCC is output of an internal LDO which has its input from VIN.

4. Ilimit is LS_Limit.

0 Katsu Matsunaga over 3 years ago in reply to Iven Su

TI__Expert 7730 points

Hi,

Thank you for your support.

Regarding Q3, I would like to know the Vin when VCC out is 3.8V.

Can I have the Vin voltage?

Best regards,

Katsu

0 Katsu Matsunaga over 3 years ago in reply to Katsu Matsunaga

TI__Expert 7730 points

Iven-san

I mistook about Q1.

Customer is planning to place the e-cap in parallel with ceramic cap. In this case, there is no e-cap for input capacitor too?

Best regards,

Katsu

0 Iven Su over 3 years ago in reply to Katsu Matsunaga

TI__Expert 8245 points

Hi,

There is no such data but when Vin = 4.2V, VCC should be higher than 3.8V.

For Q1, if ceramic is sufficient, there is no need to add an e-cap.

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LMR36520: Customer Questions