TPS7A6650H-Q1: work status is not normal

user6116926

Part Number: TPS7A6650H-Q1

Hi TI,

I used the part TPS7A6650H-Q1 in my design now, when the power is on, I test the Vout is 5V in the beginning ,it is normal. but a few seconds later i found the input current get larger to 50mA rapidly, and the TPS7A6650 get heater, and Vin have some sparks. it seems the part is not stable. how could i debug, thanks

Briefly describe the circuit as below:

Vin :12V

input capacitor: 1uF

output capacitor: 3uF

PG: connect 10K resistor with Vout

CT: connect 1nF to GND

EN: connect with Vin directly.

over 4 years ago

0 user6116926 over 4 years ago

Prodigy 100 points

no load

0 Stephen Ziel over 4 years ago in reply to user6116926

TI__Mastermind 32875 points

Hello,

Can you please provide a schematic with component manufacturing part numbers?
I am particularly interested in the manufacturing number or numbers of Cout.

Thanks,

- Stephen

0 user6116926 over 4 years ago in reply to Stephen Ziel

Prodigy 100 points

Hi Stephen,

Thanks for your support, sorry, i don't know how to insert picture in the dialog, the schematic i used is similar to the circuit which you recommend in the Page 13 of the datasheet, except the diode in the input. the part number of Cout is CGA4J3X8R1C105K125AE of TDK, connect there 1uF capacitor together in parallel in the output.

because the output current is just 50mA, so i used 3 ways circuit (12V to 5V) in my design.today i found that it work normally when i test 1 way DC/DC circuit only, but if i power on 3 ways circuit at the same time, i found the PIN1 of each part sparks and I-in increase rapidly accordingly, it seems like the input of the TPS7A6650 can't connect together directly?

0 Stephen Ziel over 4 years ago in reply to user6116926

TI__Mastermind 32875 points

Hello,

I believe you are using 3 parallel output capacitors, with manufacturing part number (CGA4J3X8R1C105K125AE) in parallel on the output.
When you say "3 ways circuit", are you describing 3, TPS7A6650's in parallel?
This can be completed but we recommend using ballast resistors to help each LDO share the current.
Please see the following app note for guidance in parallel LDO designing:

http://www.ti.com/lit/an/slva250/slva250.pdf

Thanks,

- Stephen

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TPS7A6650H-Q1: work status is not normal