UCD90160: UCD90160 and TPS65273V are not responding on PMBUS

Hi

Before answering your question, it is good to keep one post for device so that different group can better support and help. 

Have you probed the V33A/V33D/BPCAP/RESET/SCL/SDA pin from both UCD90160 to ensure that the device is power up?

Regards

Yihe

Hi yihe,

Thanks for reply. I will open another thread for TPS65273V.

I have probed V33A/V33D/RESET/SCL/SDA and they all on 3.3V, pin15 receiving I2C CLK, pin 16 receiving I2C data

but BPCAP pin is stay on GND.

Hi Alex,

Using the UCD9XXX Device GUI (should be downloaded already if you installed Fusion Digital Designer GUI), can you look for DEVICE_ID and also try Scan in ROM Mode? See picture below:
 

Also I wanted to clarify, the V33A resistor (R192 and R302) that ties V33A to V33D, in your schematic you have 1 ohm resistors, datasheet specifies 4.99 ohm. Is there a reason you went with 1 ohm instead of the datasheet recommendation?

Regards,

Samuel Gradinaru

1/ Yes, I try all options but it only find other ICs on the bus, no UCD ACK

2/ because I copy the design from PMP9444 so using 1ohm to separate them. 

Beside UCD eval board even use FB to connect V33A and V33D for fliting.

As now BPCAP voltage on GND level, is it mean the internal 1.8 LDO not functioning?

is there any method reset the LDO? 

Hi

if BPCAP is at 0V, the device won't function. it can explain why GUI can not detect the device.

Could you put the board under magnifier to double check the soldering to see whether there is any short between BPCAP and GND.

Regards

Yihe

Hi TI team,

I fixed my board by replacing new IC, TI tools now can communicate to all devices.

somehow I got some bad IC at first place...

Anyway, thanks for supporting.