TPS61093EVM-519: Vout error

Toshihiro Watanabe

Genius 10235 points

Part Number: TPS61093EVM-519
Other Parts Discussed in Thread: TPS61093

Hello,

We tried to make Vout = 12V but the result was Vout=9.1V, VFB=0.3794V. What is the possible reason?

1) Is there any setting we should care about?

2) Why is VFB voltage not be 0.5V but 0.3794V? I think enough current is flowing in feedback resisters.

The below is the configuration.

R1: 220k

R2: 10k

R3: Open

R4: 10k

R5: 75k

L1: 4.7u

C5: 47n

C6: Open

Best regards,

Toshihiro Watanabe

over 5 years ago

0 Jasper Li over 5 years ago

TI__Mastermind 46905 points

Hi Toshihiro-san,

The resistance of the R5 should be still 200Kohm.

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

TI__Genius 10235 points

Hello Jasper-san,
Thank you for the support. I think SS pin voltage doesn't reach 0.5V but only 5uA x 75kohm = 0.375V. Let us try this.
Best regards,
Toshihiro Watanabe

0 Toshihiro Watanabe over 5 years ago in reply to Toshihiro Watanabe

TI__Genius 10235 points

Hello Jasper-san,
Must R5 value is 200kohm?
Is there any issue if R5=75kohm and feedback resister is calculated assuming Vref=0.375V?
Best regards,
Toshihiro Watanabe

0 Toshihiro Watanabe over 5 years ago in reply to Toshihiro Watanabe

TI__Genius 10235 points

Hello,
The background is we want faster discharge time like less than 0.5sec for example.
Best regards,
Toshihiro Watanabe

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

TI__Mastermind 46905 points

Hi Hi Toshihiro-san,

we can only reduce the capacitor. this resistor can't be too low.

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

TI__Genius 10235 points

Hello Jasper-san,
Smaller capacitor will be startup time will be reduced. Does this mean TPS61093 has a limitation between soft start and discharge time?
Best regards,
Toshihiro Watanabe

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

TI__Mastermind 46905 points

Hi Toshihiro-san,

does the discharge time refer to the output voltage discharge time after the device is disabled? if yes, the discharge time should be NOT related to the SS pin behavior.

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TPS61093EVM-519: Vout error