TPS61088: Issue with TPS61088

Srinivas Beera

Part Number: TPS61088

Dear Sir/Madam,

We have designed 5V/6A boost converter with TPS61088. Attaching schematic for reference. It is giving bad efficiency. For 1.5A load and 1.8A load , the efficiencies are 77% and 69% respectively. If i increase load , the results are very bad. I am giving 4.2V at input.

Please suggest if anything has missed in the schematic.

over 7 years ago

0 Helen chen over 7 years ago

TI__Mastermind 40080 points

The efficiency depend on the pcb layout and the inductor you used. Could you please share the pcb layout and the indcutor ds with us so that we check in detail.?

0 Srinivas Beera over 7 years ago in reply to Helen chen

Prodigy 220 points

We have used inductor which has generated in webench TI simulation , that is SRP6540-1R5M. I will send you layout soon .

0 Helen chen over 7 years ago in reply to Srinivas Beera

TI__Mastermind 40080 points

OK, pLease attached the pcb of each layer, highliht the GND. Thanks

0 Srinivas Beera over 7 years ago in reply to Helen chen

Prodigy 220 points

TPS61088.xlsx

Attached excel with images which shows tps61088 section , SYS_GND and analog gnd. Let me know is this OK or you need more info.

0 Helen chen over 7 years ago in reply to Srinivas Beera

TI__Mastermind 40080 points

your output power is big, so if the pcb board is small you need to use at least 4-layer board to handle the thermal. even if the pcb board is very big, you need to pour a whole ground at the bottom layer. like the TPS61088 UG does.

0 Helen chen over 7 years ago in reply to Srinivas Beera

TI__Mastermind 40080 points

The efficiency is related with the test method, what is the location of the Vin, Vo you tested? make sure the Vin, Vo is tested at the input and output caps.

0 Srinivas Beera over 7 years ago in reply to Helen chen

Prodigy 220 points

Hello Helen,

Tested 5V/6A for full load and taken reading at input and output points of PCBs. Now the efficiency looks OK. I am herewith attaching output and input voltage waveforms (AC mode) , I can see low peak to peak ripples, but there is switching noise also. How this can eliminate. These noise increase if my input voltage decreases. Please suggest.

Another issue is length of cable effect on output and input voltages.

We have designed 5V/6A Power supply PCB which is little distance from another PCB which has battery. Also 5V output from PCB will go to another PCB. Because this there will drop in voltage.

What is your suggestion? Any changes in schematic which i have shared yesterday.

0 Helen chen over 7 years ago in reply to Srinivas Beera

TI__Mastermind 40080 points

What is the bandwidth and test method you used when test the output ripple?
For the issue of cable effect, please use short and thick cable, no other solution. Because your currenr is big.

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TPS61088: Issue with TPS61088