TPS63020EVM-487: BG96 GPRS/NB-IoT power supply

DANIEL TARRAGO

Part Number: TPS63020EVM-487
Other Parts Discussed in Thread: TPS63020, TPS61022, TPS61020

Good morning,

I'm using the evaluation board of the TPS63020 in order to power supply the BG96 modem by Quectel. I have setup the evaluation board (change R1) in order to have 4.2V at the output.

Input voltage for the evaluation board is 3.3V.

TPS63020 is working fine when BG96 is working in Nb-IoT mode (less power consumption) but it is not able to work well when BG96 is set to work at GPRS mode: in GPRS mode, TPS63020 is delivering 4.2V but important 2V down-spikes at this output are noticed when modem is trying to work. I have tested this with 3V3 voltage coming even from a 2A power supply, but result is the same (first, the 3V3 were delivered from my circuit).

Do you have any suggestion to cope with this?

All the best,

Dani

over 4 years ago

0 Minqiu Xie over 4 years ago

TI__Mastermind 21565 points

Hi Daniel:

May I know how much the output current is when GPRS work?

And please measure the Vin, Vout, L1, L2 waveform to help debug.

0 DANIEL TARRAGO over 4 years ago in reply to Minqiu Xie

Prodigy 110 points

Good morning,

According to BG96 datasheet, peak supply current is 2A at maximum.

Please, find attached the following screenshots:

- 'CH1_Vout_CH2_Vin': Vout (CH1-yellow) is set at 4.2V and Vin (blue) is around 3.1V

- 'CH1_Vout_CH2_V_L1': Vout (CH1-yellow) is set at 4.2V and V_L1 (blue) is voltage at pin SW.

I do not know what do you mean with L2??

Furthermore, keep in mind that I'm using the evaluation board of the TPS61022 and the enclosed tests have been performed with an extra output capacitor of about 470uF.

Hope you could give me answers.

All the best,

Dani.

0 Minqiu Xie over 4 years ago in reply to DANIEL TARRAGO

TI__Mastermind 21565 points

Hi Diniel:

May I check what device you are using? TPS61022 or TPS61020 or TPS63020? They are different devices.

0 DANIEL TARRAGO over 4 years ago in reply to Minqiu Xie

Prodigy 110 points

Sorry, I was wrong specifying the reference: I'm using the TPS61022 (now placed on the TPC61022EVM)

Dani.

0 Minqiu Xie over 4 years ago in reply to DANIEL TARRAGO

TI__Mastermind 21565 points

Hi Dani:

Never mind. I will assign this post to my teammate who is the expert of TPS61022.

0 DANIEL TARRAGO over 4 years ago in reply to Minqiu Xie

Prodigy 110 points

OK. Thank you very much.

I would appreaciate to have a workaround ASAP.

All the best,

Dani

0 Zack Liu over 4 years ago in reply to DANIEL TARRAGO

TI__Mastermind 34201 points

Hi Dani,

I would like to confirm the changes of EVM:

1. Vout is set to 4.2V by changing R1.

2. A 470uF extra output capacitor is placed at output.

How long does the 2A current for BG96? I cannot read the time scale of your waveform clearly.

0 DANIEL TARRAGO over 4 years ago in reply to Zack Liu

Prodigy 110 points

Hi,

1.- You are right: R1 is now set to 590K

2.- Correct.

About 25ms: time scale in both figures is 25ms

Best regards.

0 Zack Liu over 4 years ago in reply to DANIEL TARRAGO

TI__Mastermind 34201 points

Hi Dani,

Since the output power during this 25ms is 4.2V*2A=8.4W. Assume TPS61022 efficiency is 93%, so the input average current should be 8.4W/0.93/3.3V=2.73A. That means your upstream 3.3V circuit should have the 2.73A output current capability at least. I would suggest you use a >3A external power supply to do this test again.

0 DANIEL TARRAGO over 4 years ago in reply to Zack Liu

Prodigy 110 points

Hi Zack,

In the normal way of working, equipment is powered by two in-series D-size alkaline batteries.

I already tested it with a 3A power supply, and the result is the same (I can see the power supply limiting)

Regards,

Dani

0 Zack Liu over 4 years ago in reply to DANIEL TARRAGO

TI__Mastermind 34201 points

Hi Dani,

Got it.

I'll do a bench test with the same parameters and let you know the result by end of this Friday. Please be patient.

0 Zack Liu over 4 years ago in reply to DANIEL TARRAGO

TI__Mastermind 34201 points

Hi Dani,

Please see below test waveform with TPS61022EVM.

Modifications: 1. R1 is changed to 600kohm so Vout is set at 4.2V.

2. One 470uF hybrid capacitor is put at output.

As you see, the Vout is stable at 4.2V Vout when load current is increased from 0A to 2A. No voltage drop happens.

Can you do such kind of test and share more clear waveform? I would like to check Vin, Vout, SW waveform. Your previous waveform has too much noise.

CH1: Vout, CH3: VIN, CH4: Iout

0 DANIEL TARRAGO over 4 years ago in reply to Zack Liu

Prodigy 110 points

Good morning,

I will try to have clearer graphs...

Meanwhile: I have the evaluation board connected to my board (where the modem is placed) with 20cm wires. Could the wires be the reason of this behaviour??

Dani.

0 Zack Liu over 4 years ago in reply to DANIEL TARRAGO

TI__Mastermind 34201 points

Hi Dani,

How about the thickness of the 20cm wires? Could you use shorter wires? If you have a concern about it, you can measure the Iout current waveform to check it.