TPS61202: circuit review

Chong Yu

Part Number: TPS61202

Hi,

My customer need assistance.

I`ve facing a problem with my power management circuit based on TPS61202 IC. When supplied by single cell Li-ion the IC and inductor burn and do not work (no 5V in Vout).
I ask expert team to help me reviewing the design and suggesting ways for fixing this issue.

• Circuit Detail:

Vin = 2.5V ~ 3.7V
Expected Vout = 5V
Iout = 0.3A

• Bill of material:

Designator	Quantity	Manuf_part_1	Manuf_1
C3	1	CC0402KRX7R7BB104	YAGEO
C4	1	DNP
C28	1	TAJA475K016R	AVX
C29	1	TAJA106K016R	AVX
C37	1	TAJA106K016R	AVX
C41	1	CC0402KRX7R7BB104	YAGEO
C99	1	TAJA475K016R	AVX
C100	1	TAJA475K016R	AVX
C102	1	LMK107B7105MAHT	Taiyo Yuden
C103	1	TAJA106K016R	AVX
CN14	1
CN15	1	505567-0281	MOLEX
D6	1	RSX071VYM30FHTR	Rohm Semiconductor
D7	1	ESDZL5-1F4	ST
L6	1	LQH3NPN2R2MJRL	Murata
Q1	1	NVR1P02T1G	ON Semiconductor
R1	1	DNP
R2	1	RC0603FR-07510RL	YAGEO
R3	1	RC0603FR-07680RL	YAGEO
R4	1	RC0603FR-07680RL	YAGEO
R5	1	RC0603FR-07680RL	YAGEO
R6	1	RC0603FR-07100KL	YAGEO
R7	1	RC0603FR-07820RL	YAGEO
R8	1	DNP
R9	1	RC0603FR-0710KL	YAGEO
R10	1	RC0603FR-07100RL	YAGEO
R11	1	RC0603FR-0710KL	YAGEO
R12	1	DNP
R13	1	DNP
R18	1	RC0603FR-07330RL	YAGEO
R19	1	RC0603FR-07220KL	YAGEO
R44	1	RC0603JR-070RL	YAGEO
R45	1	RC0603FR-0710KL	YAGEO
R50	1	RC0603FR-0710KL	YAGEO
R51	1	CRCW06032M00FKEAC	Vishay
R52	1	RC0603FR-07180RL	YAGEO
SB1	1	DNP
SB8	1	DNP
SB22	1	DNP
U7	1	LD1117S33TR	ST
U15	1	MCP73831T-2ATI/OT	Integrated Circuits
U17	1	TPS61202DRC	Texas Instruments

Please help. Thanks.

over 3 years ago

0 Zack Liu over 3 years ago

TI__Mastermind 34201 points

Hi Chong,

I cannot see the schematic very clearly. Can you share me a high-resolution picture or send the schematic and layout together via email?

Could this failure be replicated on multiple PCBs or it only happened on one PCB?

0 Chong Yu over 3 years ago in reply to Zack Liu

TI__Intellectual 1435 points

Hi, Zack.

I have attached the inquiry file. Please check and help.

TPS61202 issue - IC and L burning.docx

0 Wenhao Wu over 3 years ago in reply to Chong Yu

TI__Genius 9046 points

Hi Chong,

Sorry I just return from holiday yesterday. I go through the schematic and below is some questions I have, could you please help check with your customer and give your comments below? Thank you very much!

Could you please help check with customer is this failure replicated on multiply PCBs or it only happened on single PCB?

Could you please help send me layout to check? Most of cases the burn issue happens with inappropriate layout.

Why customer use D6 here?

-Wenhao

0 Wenhao Wu over 3 years ago in reply to Wenhao Wu

TI__Genius 9046 points

Hi Chong,

Any feedbacks?

-Wenhao

0 Chong Yu over 3 years ago in reply to Wenhao Wu

TI__Intellectual 1435 points

Hi Wu,

I got no respond from my customer.

Regards.

0 Chong Yu over 3 years ago in reply to Wenhao Wu

TI__Intellectual 1435 points

Hi Wu,

Here is the layout:

D6 is from na auxiliary 5V circuit (external power supply).

Regards.

0 Wenhao Wu over 3 years ago in reply to Chong Yu

TI__Genius 9046 points

Hi Chong,

I checked the layout and schematic. Here is my comments:

Layout

1.The GND connect is breaking the GND into patch. This is not good and could cause introduce parasitic parameters inside critical loop (VOUT->GND->SW);

2.Other parts look ok.

Schematic.

1.Since there will be an auxiliary supply at VOUT. PS should not connect to VIN. The reason is, to support pre-biased start-up, there should be no negative current flowing in synchronous FET. When PS is set to high and external power supply exists, the sync FET may be on for quite a time and cause large negative current into inductor.

My suggestions:

1.Remove D6;

2.Make GND layers a solid polygon and implement multiply GND layers;

3.Tie PS to GND.

-Wenhao

0 Chong Yu over 3 years ago in reply to Wenhao Wu

TI__Intellectual 1435 points

Hi Wu,

My customer replied:

I notice the issue was not fixed even with PS tied to GND.

Regards.

0 Wenhao Wu over 3 years ago in reply to Chong Yu

TI__Genius 9046 points

Hi Chong,

Did they remove D6?

-Wenhao

0 Wenhao Wu over 3 years ago in reply to Wenhao Wu

TI__Genius 9046 points

Hi Chong,

To follow up with you, could you please help check with customer what is their latest updates? Did they recover Vout after D6 is removed?

-Wenhao

0 Chong Yu over 3 years ago in reply to Wenhao Wu

TI__Intellectual 1435 points

Hi Wu,

I got no response from my customer.

Regards.

Because of the Thanksgiving holiday in the U.S., TI E2E™ design support forum responses may be delayed from November 25 through December 2. Thank you for your patience.

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TPS61202: circuit review