TL7705B: TL7705B not releasing from Reset

guru sai

Intellectual 550 points

Part Number: TL7705B

Hi Sir,

We are using TL7705B in our design.

While testing we observed the chipset is not releasing from reset.

I am providing exactly 5V at VCC Pin, The voltage at REF (Pin 1) is exactly 2.5V

The voltage at CT pin is also discharged to 0.6V.

I am attaching the schematics please go through it.

I have not provided the pull down resistor of 10K for RESET Pin in schematics. While testing manually i have soldered 10K pull down resistor at RESET pin 6. Even then also i didn't find any improvement. The IC is not releasing from RESET (RESET# pin is always high)

i have even tuned the capacitor C634 to 0.1uF & R4346 to 0 ohm. But still same response.

over 3 years ago

0 guru sai over 3 years ago

Intellectual 550 points

0 Walter Zollinger over 3 years ago in reply to guru sai

TI__Genius 9670 points

Hello Guru,

Have you tried to force a reset by pulling RESIN to ground? Both reset outputs should have pull up/down resistors but as you said it did not change the output. Is the RESET pin constant low with a pull down resistor?

Best,

Walter

0 guru sai over 3 years ago in reply to Walter Zollinger

Intellectual 550 points

Hello Walther,

RESIN pin is constant HIGH @VCC=5V

RESET pin is PULL DOWN with 10K ohm --> observed constant HIGH;

RESET# pin is PULL UP with 10K ohm --> observed constant LOW

RESET=4.3V; RESET#=0V; REF=2.5V; Ct=0.63V

i tried by connecting RESIN pin to LOW @ VCC=5V

Even then i have read same voltages

RESET=4.3V; RESET#=0V; REF=2.5V; Ct=0.63V

0 guru sai over 3 years ago in reply to guru sai

Intellectual 550 points

Hi Walther,

For sense input pin, i have removed resistor divider & replaced with 0 ohm (direct VCC to SENSE pin). Then my chipset starts working.

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TL7705B: TL7705B not releasing from Reset