TPS923655: CC/CV Charging Mode

Ryu Yamashita

Part Number: TPS923655

Tool/software:

I have looked at the following pages but could not understand them.
https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1282592/tps923655-regarding-the-spec-of-ovp/4881804?tisearch=e2e-sitesearch&keymatch=TPS923655%252520duty#4881804

Could you please tell me about the following?

1.It is stated that in pre-charge mode, a low constant current output value is controlled by a low duty ratio, and in CC mode, a high constant current output value is controlled by a high duty ratio.
What is the reference value that serves as the boundary between low and high?

2.How can Vcc_th be determined for CC/CV Charging Mode?

3.Can you please tell me how the capacity of Cvin should be determined?

4.The recommended values for the loop compensation circuit are listed, but are these values for Vin=12V and Iout=1A in the circuit example?
If so, could you please tell me the formulas for calculating Rcomp and Ccomp?

Best Regards,
Ryu.

over 1 year ago

0 Steven Li over 1 year ago

TI__Mastermind 23190 points

Hi Ryu,

Please refer to my comments below:

For questions 1 and 2, please carefully read the contents in the E2E thread you posted. If there is still something you cannot understand, please let me know. May I understand if you want to use this part to do battery charging, or just LED driving?
For question 3, do you mean the decoupling capacitor for VIN pin? If so, then normally we recommend you place a 100nF as the decoupling capacitor for VIN pin.
For question 4, do you mean the COMP pin parameters listed in Section 9.2 Typical Application from the datasheet? If so, then these are sample parameters for the specific application conditions shown in this section. To design the COMP pin components for your specific application condition, you can refer to this E2E FAQ - [FAQ] How to design the COMP pin components for TPS923655 / TPS923654 / TPS923653 / TPS923652? - Power management forum - Power management - TI E2E support forums

Best Regards,

Steven

0 Ryu Yamashita over 1 year ago in reply to Steven Li

Genius 3705 points

Hi Steven,

Thanks for the reply.
I understand about Q3 and Q4.
I read about Q1 and Q2 but did not understand.
Also, I am planning to use this device only for lighting LEDs.

Best Regards,
Ryu.

0 Steven Li over 1 year ago in reply to Ryu Yamashita

TI__Mastermind 23190 points

Hi Ryu,

So you only need constant-current source to drive the LEDs. Is my understanding correct?

Best Regards,

Steven

0 Ryu Yamashita over 1 year ago in reply to Steven Li

Genius 3705 points

Hi Steven,

That is correct in my understanding, but I don't understand how CC/CV Charging Mode works and would like to know.

Best Regards,
Ryu.

+1 Steven Li over 1 year ago in reply to Ryu Yamashita

TI__Mastermind 23190 points

Hi Ryu,

If you only need to use CC mode, then actually you do not need to care about VCC_TH shown in Figure 8-5 from the datasheet. What you need to care about is to prevent CV mode from affecting the output current when you just need constant-current output. You can refer to this E2E FAQ - [FAQ] How to design the OVP resistor divider for TPS923655 / TPS923654 / TPS923653 / TPS923652? - Power management forum - Power management - TI E2E support forums

VCC_TH is normally cared about by those customers who want to use this device for battery charging. If you want to know more details, I can explain to you through e-mail.

Best Regards,

Steven