TPS552872-Q1: CAM_PWR_10V Buck-Boost circuit review

Hi Chonghui,

Thank you for reaching out.

1. What is input voltage range, output voltage and maximum output current?

2.Add 0402 0.1uF ceramic cap in input and output pin to minimize the power loop.

3.Add RC fitler in ISN and ISP pin as below:

4.Change R2506 to 0ohm.

5.You can directly use TDA4_VDD_IO_3V3 signal to control EN pin. Add a pull down resistor.

6.

user5359313 said:

Is there any special reason that we should add the resistors R4507 and R4508 for the BOOT1/2 PINs?

This is not for boot pin, but for SW pin. RC snubber is used to filter SW spike and improve EMI performance. Recommend to change R4507 and R4508 to 1206 package for thermal dissipation.

7.Can you provide output cap P/N for loop calculation.

Regards,

Mulin

Hello Mulin,

Thanks for the quick reply!

The input voltage range is 7 - 16V, VBAT.

Output voltage is 10V.

And the maximum current is 4A.

Best regard,

Chonghui 

Hi Chonghui,

Maximum inductor current will be 10*4/0.95/7=6A. TPS552872 has minimum 3.3A average inductor current limit, so it cannot support this case. Please change to TPS552892-Q1, which is 7A limit and is pin to pin with TPS552872.

For this power level, recommend to change R4505 to 49.9k to set 400kHz switching frequency.

What is the part number of output capacitors?

Regards,

Mulin

Hello Mulin,

We just got the confirmed answer from Camera team that the maximum operating current of each camera is only 178mA. For the worst case scenario, the maximum current is 556mA, then the total current of 4x Cameras is about 2.2A.

Since the output current is only 2.2A in Worst Case, can we still keep the chip to be TPS552872?

Could you please help to review the updated schematic and give us some recommendation?

Best regards,

Chonghui 

baf6858_Buck_Boost_TI review.pdf

Hello Mulin,

Thanks for the recommendation.

We just had a quick call with the Camera Team.

Now we got the updated information that the total current consumption is 715mA@7V.

So we assuming the Maximum current will be up to 1A in Worst Case Scenario. 

It seems TPS552872-Q1 will be suitable for our application.

Could you please help to confirm this point?

Best regards,

Chonghui

Hello Mulin,

Thanks for the confirmation!

Since the output current is only 1A and the switching frequency is 2MHz, we just changed the inductor from 4.7uH to 2.2uH.

Could you please also help to check the inductor is suitable for the application?

For more details, you can check the schematic in the previous reply.

Best regards,

Chonghui

Hi Chonghui,

It is ok to use 2.2uH with 2MHz fsw. You need to do some bench test to evaluate the loop stability.

Regards,

Mulin