LP87524B-Q1: LP87524J-Q1Rrad

Hello,

Thanks for your response.

 I would like to know that without I2C how can I enable all the four buck?

The EN1 pin controls the Buck 0 correct? but when I am applying voltage on EN1 pin I am getting 0V n Buck 0

Can you please help me in this?

Hello Aaquib,

The EN1 pin controls all the bucks, including BUCK0. So when ever you have HIGH on EN1 , the device should power up all the regulators in sequence defined in the OTP . 

 1. Check the voltage on EN1 pin. It should be higher than 1.2 V and typically close to 3.3 since in the schematic is provided by 3.3 VIO. 

2. And what do you mean that BUCK0 has not voltage ? do other bucks 1, 2 and 3 have output voltages ? 

Regards,

Ishtiaque 

We are currently giving 5V to EN1 pin and getting 0V on Buck 0,1,2 and 3. 

Hi,

Okay so the 5V is applied at the same time when VANA voltage is available to the PMIC ? 

And what is the status of NRST signal? It is HIGH or LOW? It should remain HIGH.

Regards,

Ishtiaque 

The VANA is 5V at the same time and the NRST is high 

Hi,

I do not see any other reason to not power up with EN1 except following schematic discrepancies. 

1. VANA filtering cap is too high. Recommended one is the 100nF. 

2. Snubber series resistor is 3.9 ohm recommended in the datasheet. 

3. Highlighted below is not the typical use in case of radar SoC.  You did not mention what is the application or use case here.

Regards,

Ishtiaque 

Hi, 

1. We tried removing the filter capacitor at VANA pins with that we also removed the 22uF filter capacitor and set the EN1 pin high 3.3V. We are observing voltage on all the four bucks but the voltage we observe are Buck0 - 1.9V Buck1 - 2V, Buck2 - 1.2V and Buck3 - 1V. But when we are reapplying the capacitors we are getting 0V on all four bucks. 

3 . The application is for building the circuit for AWR Radar .

Hi,

You removed the 22uF capacitor at the VANA pin but did you replace with 100nF one?

Now it seems that you have are getting voltage at the BUCKs. Also observe that you have stable 5V input supply to the PMIC.

Is this one board that has issue? Have you checked with another good board by doing ABA swap test?

Also have soldered the PMIC with hand ? Is this prototype ? If yes then have you checked whether the PMIC is perfectly soldered down?

Regards,

Ishtiaque 

Hi,

Thanks for your response.

Yess I replaced it with 100mF when as I said we not getting the correct voltage values on the bucks. 

We tried by enabling all four bucks using I2C without using EN pin.

So now we tried by setting EN1 pin low and rest same voltages.

We sent the following values to each bucks as follows:

• 0x84 to Buck0 register (0x02) we are getting voltage as 3.3V
• 0x84 to Buck1 register (0x04) we are getting voltage as 1.2V
• 0xA2 to Buck2 register (0x06) we are getting voltage as 1.0V
• 0xA2 to Buck3 register (0x08) we are getting voltage as 1.8V

But the issue here is that we are not able to enable all four bucks at a time. When we are enabling all 4 bucks at the same time we are not observing voltage at buck2. we tried individually enaballing all the four bucks it is working as expected. We also tried enabling 3 bucks at a time with different combinations it is working. But when we are enabling all 4 bucks at a time it is not working correctly.

We have done the swap test with another good board as well.

Yes this is a prototype we have hand soldered the PMIC but we check it is perfectly soldered.

Hi Aaquib,

Thanks for your the feedback. 

But as I explained since now you have implemented all the measures that were required. 

Aaquib Niyama said:

We have done the swap test with another good board as well

So what is the result of swap test ? 

To my understanding now issue seems to be with soldering. Often it happens when you try to hand solder and if the device is not properly soldered then you get different voltages than expected. So may be you should try soldering new device and make sure that it is properly soldered. 

Regards,

Ishtiaque 

Hi,

As I mentioned we checked the device is properly solder we verified on the board.

As we are getting correct output while doing it via I2C. 

Hi Aaquib,

Ishtiaque Panhwar said:

So what is the result of swap test ?