TPS922055: Schematic Review

Francesco Niccolini

Prodigy 20 points

Part Number: TPS922055

Tool/software:

Dear TI-,

I 'm writing to request a review of my design. The project specifications are as follows:

The LED driver will be driving 3 LED @0.7A, connected in series (with 3*Vf = 3*12V).
Vcc = 48V
Switching frequency = 100KHz

EN will be connected to a PWM signal and ADIM/HD is pulled up with 10Kohm. FAULT is left floating.
PGND and GND are connected with 0ohm resistor.

Questions:

Does the UVP circuit need any tweaking?
What happens to the internal LDO during a Fault condition?

6 months ago

0 Steven Li 6 months ago

TI__Mastermind 23150 points

Hi NICCOLINI,

Sorry, I am in all-day meeting today. I will reply to you tomorrow. Thanks for your understanding.

Best Regards,

Steven

0 Francesco Niccolini 6 months ago in reply to Steven Li

Prodigy 20 points

Hi Steven Li,

I would be very pleasure if you could reply to my post.

Thank you.

0 Lucia Gao 6 months ago in reply to Francesco Niccolini

TI__Mastermind 30201 points

Dear Niccolini,

Sorry for late. I will take over this case. Pls kindly let me review and I will get back to you before end of tomorrow. Thank you for your understanding!

BRs

Lucia

0 Lucia Gao 6 months ago in reply to Lucia Gao

TI__Mastermind 30201 points

Dear Niccolimi,

First, for your question:

(1) Pls refer to this FAQ with regard to how to design UVP resistor.

[FAQ] How to design the UVP resistor divider for TPS922055 / TPS922054 / TPS922053 / TPS922052?

(2) During fault condition, pls refer to table 7-3 about the behavior. I am not fully sure of what you mean of the LDO behavior. Are you worried about Vcc voltage or Vcc pin status?

Schematic review:

For CSP, CSN design, pls refer below FAQ and update your schematic accordingly:

[FAQ] How to design the CSP and CSN pin components for TPS922055 / TPS922054 / TPS922053 / TPS922052?

If you don't need Fault pin, pls refer to below:

[FAQ] How to deal with the unused FAULT pin of TPS922055 / TPS922054 / TPS922053 / TPS922052?

BTW, would you mind share me what is your application? And where is it is used? Thank you!

BRs

Lucia

0 Francesco Niccolini 6 months ago in reply to Lucia Gao

Prodigy 20 points

Dear Lucia,

Thanks for the reply.

Lucia Gao said:
During fault condition, pls refer to table 7-3 about the behavior. I am not fully sure of what you mean of the LDO behavior. Are you worried about Vcc voltage or Vcc pin status?

As for the behavior of the VCC voltage, I wanted to know if in case of fault the VCC voltage was guaranteed by the Driver or if it's disabled ( in my schematic I connect a "status" LED on VCC).

Lucia Gao said:
For CSP, CSN design, pls refer below FAQ and update your schematic accordingly:

[FAQ] How to design the CSP and CSN pin components for TPS922055 / TPS922054 / TPS922053 / TPS922052?

Ok, I change R6 value to 100ohm and C10 to 1nF.

Lucia Gao said:
BTW, would you mind share me what is your application? And where is it is used? Thank you!

The company where I work is developing boards (with 3 LEDs on board driven by the TPS922055) to be inserted into an industrial machine to illuminate products and carry out quality tests on the processes performed on the product.

0 Lucia Gao 6 months ago in reply to Francesco Niccolini

TI__Mastermind 30201 points

Dear Niccolimi,

If I am understanding correctly, are you wanting to pull up the fault pin to Vcc pin with a pull up resistor, instead of external power supply? So that's the reason you would like to know the status of Vcc voltage?

Thank you for you sharing about project background which is helpful.

Thank you!

BRs

Lucia

0 Francesco Niccolini 6 months ago in reply to Lucia Gao

Prodigy 20 points

No, in my schematic on VCC pin I have connected a LED and 1Kohm resistor to have a visible feedback when the TPS922055 is working. My questions was: if a Fault is detected by the TPS922055, the LED will be turned off ??

Francesco

+1 Lucia Gao 6 months ago in reply to Francesco Niccolini

TI__Mastermind 30201 points

Dear Francesco,

You can connect a "status" LED on VCC to indicate fault. And whether the device will stop switching or not depends on different fault behavior, but internal LDO can still work which means that Vcc is 5.15V typical. But pls be noted of the internal LDO output current limit as shown below.

Thanks!

BRs

Lucia

Power management

Power management forum

TPS922055: Schematic Review