TPS55287: TPS55287 query

Hi Dilip,

Did you try to use 75H address? Can you provide schematic for me to check? What is input voltage, output voltage and output current? Did you check the VCC voltage?

Regards,

Mulin

Hi Dilip,

Did you try to use 75H address? Can you provide schematic for me to check? What is input voltage, output voltage and output current? Did you check the VCC voltage?

Regards,

Mulin

Hello Mr. Yuan

We tried with 0x75 address but still getting NACK, please see the below screenshot

Mahabir Verma 

Hi Mahabir,

Can you check the VCC waveform? Is it stable at 5.2V?

Can you help provide the input voltage, output voltage and output current information? What is part number of output caps? I have seen some design problem in the schematic, I will give you more comments with your feedback.

Regards,

Mulin

Hi Yuan 

VCC is stable at 5.2V. Output we have set at 10.8V we are using this device in CV configuration Vout goes to Linear LED driver. Below are the output capacitor part no.

UCM1H220MCL1GS

C1206C475K5RACAUTO 

Mahabir Verma 

OUTPUT_BCM_J202_2W 1.pdf

Dear sir

please find attached schematic pdf for reference.

let me know if any change is required,

Hi Yuan 

Any Update on the schematic?

Mahabir Verma 

Yuan,

It's very Urgent !! , Can we have call today .

Hi Dilip,

I am looking into this and I need some time to find some possibility. I will reply to you in an hour.

Hi Dilip,

Below is my feedback about the schematic:

1.Change R129 to 0ohm. You can try this first.

2.Recommend to add more input cap to stabilize input voltage. What is input voltage range?

3.Add a pull down resistor in EN pin.

4.Change R91 to 0ohm.

5. Change R121 to 0ohm and let it NC if dithering is used.

6.Change inductor to 4.7uH.

7. The 22uF cap is too small with large ESR. Recommend to change to larger capacitance with smaller ESR. What is the maximum output current?

8. Compensation parameters is not suitable. Change C72 to 10nF first. I can help evaluate compensation parameters with Vin, Iout, and the new PN of output caps information.

Regards,

Mulin

Hi Yuan

Please refer below Block diagram for LED current details mentioned on the each output.

Input voltage range will be 9V to 16V

Mahabir Verma 

Hi Verma,

Did you get the ACK by changing mode resistor?

Recommend to change the output caps. For current design, recommended compensation parameters: R110=2k, C74=15nF, C73=2.2nF.

Regards,

Mulin

Hi Yuan

We are writing the register data as shown in image. But not able to see any change in FB/INT pin. Switching is not happening, can you help to get it diagnosed.

Mahabir Verma 

Hi Mahabir,

I recommend to change the mode pin resistor to 0ohm, did you try this?

Yes tried it’s not working, one more thing resistor at DITH is required or not

HI Yuan 

Inductor switching is not happening. Refer the below image for register setting, Please review and give your valuable feedback.

Yuan 

VCC we are getting around 6V.

Hi Mahabir,

To read 74H, SDA should write 11101000, but from the waveform, it writes 11101001. Also ,there is a slow ramp in the first SCL clock, is there any issue from master device?

Regards,

Mulin

Hi Yuan

 I2C is working fine, Now we are struggling with VCC around 6V and Inductor Switching not started.

Mahabir Verma 

Hi Mahabir,

Sorry for confusing, the address is right, but normally the first byte should be write,  so it should be 11101000 74h write. Can you ask customer to check again?

Hi Mulin 

Same we are following in SW. we are sending first write with 74H.

Mahabir Verma 

Hi Mahabir,

I will wait for your update as communicated in  the meeting.

Regards,

Mulin