TPS61022: TPS61022 in parallel with a ultra low Power StepUp

Answering your Questions:

(2)100mA for ?s (it is fine for TPS61022 at all conditions)

à 8s

What is your power source?

à Battery with min. 1,8V for get please the 0,7V – it was a type form my side. (we have already TPS61022 today in use)

If you needs longer battery life time, then using TPS61022 for high power and TPS61099 for low power to save current consumption is ok

• Yeah, that’s my question:so, can we combine the TPS61022 with the TPS61099 like in my attached drawing? What is need to be done, when for example TPS61022 is enabled (by enabled pin) and TPS61099 is also working:
  • Does TPS61022 influence TPS61099,when TPS61022 is NOT enabled. Do we have to add something that the combination is possible?
  • For the case both are enaböled (TPS61022+TPS61099..when modem is running), do we have to take care on something?
  • As remember: we want to combine the 2 blocks, because We want to make quiescent current as low as possible. TPS61099 has low quiescent current and TPS61022 is only responsible for the current peak of the Modem.

Hi Andreas,

I think it is possible to parallel TPS61022 to TPS61099. When they are paralleled together, the one with lower impedance contributes higher current in heavy load. The frequency interface between each other can also generate beat frequency on VOUT. 

Let me test this case and feedback to you later. Thanks!

-Wenhao

okay, perfect, waiting for your test

thanks

Hi Wenhao,

thas really great . thanks for the evaluation- we will take this product!

Hi Wenhao,

just one question to get the summary:

in this situation: TPS61022 is not enbaled and only TPS61099 is maintaining the VOut, what did you measured as quiesient current? How many uA?

Hi Andreas,

If you need quiescent current test, please tell me your desired feedback resistors value for TPS61022 and your most concern use case (VIN, VOUT), i can tell test engineer to test this value for us. Thanks!

-Wenhao

Hi Wenhou,

see attached the TPS61022. In parallel there should be now TPS61099

The worst case: VIN=1,2VDC  VOUT 3,8VDC

Hi Andreas,

So I would let them to test the quiescent current for below case:

(1)TPS61022 disabled, TPS61099 enabled;

(2)TPS61022 same schematic as above;

It suddenly reminds me of TPS61099's schematic on your side. Would you please also share it? Please note the tested value iwill be larger than what listed in datasheet because we measure the shut down current and assume VOUT=0V, but in your parallel operation VOUT is never 0V. Also the FB resistors are different from test.

-Wenhao

Hi Andreas,

Could you please comment above questions? It is meaningful to test IQ for both TPS61099 and TPS61022 because your system will use both of them.

-Wenhao

Answer:
Sory for being late, but i was on a short business trip. Okay. the topic is. we have not TPS61099 inserted yet (only TPS61022), because
we want to know exactly this, how to put it in parallel. So pls recommend the best setting (around TPS61099) you can do, we will do
this as first setUp.

Hi Wenhao,
i do not fully understand your feedback:
1) you already have your setUp with your evaluation kits. so you can measure the quiscient current in this setUp right?
2) why: today we have only TPS61022 and NO TPS61099 conntec. so i have no circuit diagram and i suppose you give us a recommandation for this to achieve minimal quiecient current when mainting the VOUt
by TPS61022 disabled and TPS61099 enabled

Hi Andreas,

OK. Let me check this and give your the recommendation next week. Thanks!

-Wenhao

Hi Andreas,

I found TPS61022 with your configuration is unstable. It is mainly because of insufficient output capacitor. I see you have only use 2*10uF/10V. Considering DC bias effect this would derate 80% capacitance. This would make only about 4uF capacitance on output. I do not recommend the schematic like this. 

For TPS61022, we should use more capacitor on VOUT to help increase PM and GM for your 2A in 3s. The performance of TPS61022 should be taken more care of because it is shut down in normal state;

For TPS61099, use EVM configuration is recommended.

Let me configure TPS61022 board with right COUT setting. Thanks!

-Wenhao

Hi Wenhao, thnaks for first evaluation. So, only to be clear:

1) On TPS61022 you will now configure correct COUT

2) on TPS61099 you recommend setting according EVK

you will configure 1)+2) and you will measure then quiescient current? to have final result.

correct?

Hi Andreas,

1) On TPS61022 you will now configure correct COUT

Yes, the FB setting will be same as yours.

2) on TPS61099 you recommend setting according EVK

Yes, that is correct.

you will configure 1)+2) and you will measure then quiescient current? to have final result.

I will measure below cases:

Case 1: TPS61022 enabled+TPS61099 enabled;

Case 2: TPS61022 disabled+TPS61099 enabled;

Case 3: TPS61022 enabled+TPS61099 disabled;

Note in all of three cases above, TPS61099 and TPS61022 has been paralleled.

-Wenhao

Hi Andreas,

The test resource is very limited. I want to make sure the test would be do for several times.  Could you please confirm if you are ok with below configuration? Thanks!

TPS61099: CIN: 10uF/25V/X5R/0603*1, COUT: 10uF/25V/X5R/0603*2; RFB_H is 1Meg, RFB_L is 390k, there is a 27pF cap parallel with RFB_H as loop compensator;

TPS61022: CIN: 10uF/25V/X5R/0603*1, COUT: 10uF/25V/X5R/0603*3; RFB_H is 820k, RFB_L is 150k;

-Wenhao

Hi Wenhou, 

we doublechecked, yes this configuration would be absolut ok to check the quiescient current.

thanks very much

Hi Andreas,

Thanks for confirmation. Will give your results by this week.

-Wenhao

Thnaks