TPS62840: tps62840 transient load

Sammi Shang

Part Number: TPS62840

Dear team,

Customer has a question about tps62840. The topology is VBAT(2V~6V)-->TPS62840-->3.3V NB-IOT module.

Customer found when battery in low capacity state, the voltage will change to 2V, then NB-IOT module will restart. And customer measured the input and output waveform when battery voltage drop, and the output voltage of TPS62840 will drop to 2V in 5ms. And the minimum working voltage for NB-IOT is 3.0V. I have attached the schematic and waveform, hope you could give some suggestion.

The NB-IOT could also work in 3.6V, but we may recommend TPS62842, so this is also one option for us.

Thanks.

Best regards,

Sammi

over 5 years ago

0 Febin over 5 years ago

TI__Mastermind 25430 points

Hi Sammi,

TPS62840 is configured to get an output voltage of 3.3V to power NB-IOT module. So, it is very clear that VCC_BAT should be above this voltage. I see that the input of TPS62840 is reaching 3V when the battery voltage drops. Hence, we have a lower output voltage because the efficiency of this device is around 80-90% (depending on the load as well). Therefore, it is required to have slightly higher input voltage to get an output of at least 3V.

I am afraid, I do not understand the purpose of replacing it with TPS62842. If you need to output 3.6V, it will be required to have higher input voltage, which in this case, worsens the situation. I hope, I understand your problem correctly.

Regards,

Febin

0 Febin over 5 years ago in reply to Febin

TI__Mastermind 25430 points

Hi Sammi,

Do you have some updates?

Regards,

Febin

0 Sammi Shang over 5 years ago in reply to Febin

TI__Expert 4450 points

Hi Febin，

Thanks for your remind. I have conclusion with customer, this could be closed.

Best regards,

Sammi

0 Febin over 5 years ago in reply to Sammi Shang

TI__Mastermind 25430 points

Hi Sammi,

Thank you for the quick response.

Regards,

Febin

Power management

Power management forum

TPS62840: tps62840 transient load