Issue with MC34VR5100A1EP chip

[minalnemade]

Hi,

       We have build custom board with LS1012A and PMIC chip MC34VR5100A1EP. We are facing issue of VSNVS output from PMIC chip. We are providing 3.3V input to PMIC chip but we are not getting VSNVS output inspite of Vin voltage > 3.1V. We have connected VSNVS output to EN pin of PMIC chip. As VSNVS output is missing PMIC chip is not getting enabled and hence it is not generating any output voltages. As per data-sheet of PMIC chip VSNVS output can not be disabled and is generated after Vin voltage > 3.1V (UVDET). Inspite of this condition being met we observed that VSNVS output is not generated by PMIC chip. We are not using coin cell battery input and hence LICELL input of PMIC chip is bypassed to ground through 0.1uf capacitor. All connections of PMIC chip are as per the reference design of LS1012AFRDM. Please let's know what could be the issue.

regards

Minal

[guoweisun]

Hi,

Please note the output current of VSNVS(1mA) and you'd better give us your schematic.

[minalnemade]

Hi Jive,

Please find attached schematics.

Regards

Minal

[guoweisun]

Hi,

Disconnect VSNVS and EN,you can use external signal to control EN then to check this issue.

[minalnemade]

Hi Jive,

We have directly connected 3.3V through 4.7K resistor but we observed

that output voltages randomly comes up and then goes back down.

Please guide.

Thanks & Regards

Minal

[guoweisun]

Hi,

Do you mean that disconnect with EN and VSNVS then supply EN with external 3.3V with 4.7K resistor?

Do you monitor the VSNVS value when you do above operation?

[minalnemade]

Hi,

yes .. we have disconnected EN and VSNVS then supply EN with external

3.3V with 4.7K resistor.

We observed VSNVS to be randomly increasing and going down. It goes max to

2.3V

Thanks & Regards

Minal

[guoweisun · Accepted solution]

Hi，

Can you double check your VSNVS connection in your system except VSNVS connect with EN?

It seems that VSNVS has current limit.