TPS2065C: TPS2065C Ron resistance

MIKHAIL SALOV

Expert 6890 points

Part Number: TPS2065C
Other Parts Discussed in Thread: TPS2553, TPS2069C

Good day Colleagues,

My customer uses the TPS2065CDGNR but claims the Ron resistance is 2 times higher than a datasheet described.

He measured voltage drop with a resistive load (1A@5V) and says values are 0.243V and 0.271V.

Looks like the Ron is around 300mOhm. But the datasheet says in worst case it's 120mOhm.

Power pad soldered to Ground.

Could you comment what can be wrong here and what customer has to check?

Thank you, Mike

over 7 years ago

0 Feifei Shen over 7 years ago

TI__Expert 3275 points

Hi Mike,
How did customer measure the voltage drop on IC?
Monitor the voltage difference between Vin and Vout on tps2065c pins?

Best regards,
Feifei

0 MIKHAIL SALOV over 7 years ago in reply to Feifei Shen

TI__Expert 6890 points

Good day Feifei,

Correct, customer measured the voltage Vin and Vout.
The input is 4.998V at 1A load, so the input voltage is very stable. the output voltage drops around 300mV.

Thank you, Mike

0 Michael Tan over 7 years ago in reply to MIKHAIL SALOV

TI__Expert 8420 points

Hi mike,

As the Rds(on) is very samll , so the test point should set at Vin and Vout pin of the device.
Also the loading current is big , it will create the heat for internal mosfet and then the Rds(on) will increase accordingly .

Correct test process:
Power on the device (5V), use of DC source to change the Vds between Vin and Vout ( Dc source should trun up slowly ) , record the Iout of DC source. Rds(on)= Vds/I.

Michael .Tan

0 MIKHAIL SALOV over 7 years ago in reply to Michael Tan

TI__Expert 6890 points

Good day Michael,

Thank you for answer!

Customer made the measurement between Vin and Vout. He did not measure the input and output voltages.

The datasheet says the maximum operation current for the TPS2065C is 1A and he wants to get this current @5V for USB.

What you can recommend to support 1Amp for a long period of time?

Thank you, Mikhail

0 MIKHAIL SALOV over 7 years ago in reply to MIKHAIL SALOV

TI__Expert 6890 points

Michael,

Could you tell me if the TPS2553 can supply 1A for a long period of time. What will be voltage drop for this part @1A of the output current?

Thank you, Mike

0 Michael Tan over 7 years ago in reply to MIKHAIL SALOV

TI__Expert 8420 points

Good day Mike,

TPS2065C is designed for continuous 1A output , So this part is suitable for your application at 1A current output .

Michael .Tan

0 MIKHAIL SALOV over 7 years ago in reply to Michael Tan

TI__Expert 6890 points

Thank you, Michael,

I worry about the voltage drop on the output. Probably devices rated for 1.5A will have smaller drop (smaller Ron resistance)?
It's important to have the output voltage close to 5V.
What Ron do you think will have the TPS2553 at 1A?

Thank you, Mike

0 Michael Tan over 7 years ago in reply to MIKHAIL SALOV

TI__Expert 8420 points

Hi Mike,

Both tps2069C and tps2553 rds(on) you can read in the datasheet . vdrop=Iout*Rds(on)
Both of them are popular in the USB port , you needn't to warry the vout drop.

Michael.Tan

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TPS2065C: TPS2065C Ron resistance