TLV61220: Vout can't reach 3.3V for Vin from 1.5V to 3V

Siva Rajan

Part Number: TLV61220

Hi,

Good day. I am using this Boost IC for Vout 3.3V, 40mA for the input voltage range from 1.5V to 3V. But it is not working as per the Webench simulation report. The Schematic circuit, BOM and waveform for various nodes are given for your reference. Kindly provide the solution to solve this issue.

C1, C2	10µF ±10% 16V Ceramic Capacitor X5R 0603 (1608 Metric)	Murata Electronics	GRM188R61C106KAALJ
L1	FIXED IND 4.7UH 1.1A 160 MOHM	TDK	MLP2016H4R7MT0S1
U1	Boost Switching Regulator IC Positive Adjustable 1.8V 1 Output 220mA (Switch) SOT-23-6	Texas Instruments	TLV61220DBVR
R1	1 MOhms ±1% 0.063W, 1/16W Chip Resistor 0402 (1005 Metric) Thick Film	Vishay Dale	CRCW04021M00FKEDC
R2	178 kOhms ±1% 0.063W, 1/16W Chip Resistor 0402 (1005 Metric) Automotive AEC-Q200 Thick Film	Vishay Dale	CRCW0402178KFKED

1. Output voltage graph at 3V input (Vout 2.4V instead of 3.3V)

2. Feedback voltage graph

Thanks,

Siva

over 5 years ago

0 Jasper Li over 5 years ago

TI__Mastermind 46905 points

hi Siva,

from the measurement, the FB voltage is 1V when output voltage is 2.4V. so the IC is not solder correctly or the feedback resistor is wrong.

0 Siva Rajan over 5 years ago in reply to Jasper Li

Prodigy 40 points

Hi Jasper,

Thanks for the prompt reply. As per your comments, I re-soldered and checked the PCB. The R1 and R2 value is correct as per BOM. But, still the Vfb and Vout is 0.425 and 2.35V respectively. Please see the below graphs,

1. Vout is 2.35V

2. Vfb is 0.425V

Thanks,

Siva

0 Jasper Li over 5 years ago in reply to Siva Rajan

TI__Mastermind 46905 points

Hi Siva,

what is the loading during the measurement? did you observe similar behavior in several boards?

could you share the layout?

0 Siva Rajan over 5 years ago in reply to Jasper Li

Prodigy 40 points

Hi Jasper,

The load is 165ohm resistor. And also we observed the similar result in other boards also. As you requested, the board layout is given below,

Thanks,

Siva

0 Jasper Li over 5 years ago in reply to Siva Rajan

TI__Mastermind 46905 points

Hi Siva,

the layout is the high risk leading to such issue. the routing of the output capacitor is too long. please place a 0.1uF capacitor above the IC and connect the capacitor with IC VOUT and GND pin directly.

0 Siva Rajan over 5 years ago in reply to Jasper Li

Prodigy 40 points

Hi Jasper,

I tried the 0.1uF capacitor. But still no improvement.

Thanks,

Siva

0 Jasper Li over 5 years ago in reply to Siva Rajan

TI__Mastermind 46905 points

Hi Siva,

what is the part number of the inductor? did you see the behavior in several board after adding the 0.1uF capacitor?

0 Jasper Li over 5 years ago in reply to Jasper Li

TI__Mastermind 46905 points

Hi Siva,

any update in this case?

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TLV61220: Vout can't reach 3.3V for Vin from 1.5V to 3V