TPS65912: need Forbid vcc output when poweron

zhanbo Wang

Part Number: TPS65912

shown as the picture above , when my MCU power on, I do the GPIO init firstly, then I set the registers to enable ENx pins 、AVS voltage、OP voltage etc.

the TPS65912 will output default voltage immediately , this will destroy other device which powered by TPS65912

so what should I do to avoid the default voltage output ? whether the only solution is using Customized OTP ?

I use three channel DCDC1 DCDC3 DCDC4,the flow of init code are shown as below:

gpio_set_pin(G_PMU_CONFIG2, GPIO_PV_HIGH);

gpio_set_pin(G_PMU_CONFIG1, GPIO_PV_LOW);

gpio_set_pin(G_PMU_PWRHOLD, GPIO_PV_HIGH);

gpio_set_pin(G_PMU_nPWRON, GPIO_PV_LOW);

gpio_set_pin(G_PMU_SLEEP, GPIO_PV_LOW);

gpiohs_set_pin(HG_PMU_EN1, GPIO_PV_LOW);

gpiohs_set_pin(HG_PMU_EN3, GPIO_PV_LOW);

gpiohs_set_pin(HG_PMU_EN4, GPIO_PV_LOW);

usleep(30 * 1000); //during the 30ms , default voltage output shown as the oscilloscope ， this is unexpected

tps_set_reg(TPS65912_EN1_SET2, 0x04);

tps_set_reg(TPS65912_EN3_SET2, 0x10);

tps_set_reg(TPS65912_EN4_SET2, 0x20);

tps_set_reg(TPS65912_DCDC1_CTRL, 0x1C);

tps_set_reg(TPS65912_DCDC3_CTRL, 0x1C);

tps_set_reg(TPS65912_DCDC4_CTRL, 0x1C);

tps_set_reg(TPS65912_DCDC1_OP, 0x0);

tps_set_reg(TPS65912_DCDC3_OP, 0x0);

tps_set_reg(TPS65912_DCDC4_OP, 0x0);

tps_set_reg(TPS65912_DCDC1_AVS, 0x80);

tps_set_reg(TPS65912_DCDC3_AVS, 0x80);

tps_set_reg(TPS65912_DCDC4_AVS, 0x80);

over 3 years ago

0 Daniel W over 3 years ago

TI__Genius 13216 points

Hi,

What TPS65912 OPN are you using?

Thanks,

Daniel W

0 zhanbo Wang over 3 years ago in reply to Daniel W

Prodigy 10 points

Hi， TPS659122

0 Daniel W over 3 years ago in reply to zhanbo Wang

TI__Genius 13216 points

Hi Zhanbo,

Are any of the ENx pins high during power up? If so, please hold them low until the device has been reprogrammed as necessary

Thanks,

Daniel W

0 zhanbo Wang over 3 years ago in reply to Daniel W

Prodigy 10 points

I am sure of that, but the output voltage was set to 0 until registers setted , I searched TI , so we have to use customize OTP ,which may connect En1 to DCDC1, En3 to DCDC3 ,EN4 to DCDC4 when power on read OTP?

0 Daniel W over 3 years ago in reply to zhanbo Wang

TI__Genius 13216 points

Hi Zhanbo,

Can you rewrite the registers before PWRON is set low? This will prevent the main power sequence from starting and allow you to set the resources as needed.

Thanks,

Daniel W

0 zhanbo Wang over 3 years ago in reply to Daniel W

Prodigy 10 points

Hi,Daniel

It seem to make no difference to set PWRON low after write register,

gpio_set_pin(G_PMU_CONFIG2, GPIO_PV_HIGH);

gpio_set_pin(G_PMU_CONFIG1, GPIO_PV_LOW);

gpio_set_pin(G_PMU_PWRHOLD, GPIO_PV_HIGH);

gpio_set_pin(G_PMU_nPWRON, GPIO_PV_HIGH);

gpio_set_pin(G_PMU_SLEEP, GPIO_PV_LOW);

gpiohs_set_pin(HG_PMU_EN1, GPIO_PV_LOW);

gpiohs_set_pin(HG_PMU_EN3, GPIO_PV_LOW);

gpiohs_set_pin(HG_PMU_EN4, GPIO_PV_LOW);

write registers ...

gpio_set_pin(G_PMU_nPWRON, GPIO_PV_LOW);

0 Daniel W over 3 years ago in reply to zhanbo Wang

TI__Genius 13216 points

Hi Zhanbo,

PWRHOLD high will also start the power sequence. Please keep nPWRON high and PWRHOLD low before writing the registers

Thanks,

Daniel W

0 zhanbo Wang over 3 years ago in reply to Daniel W

Prodigy 10 points

As the spec shown. we have to set PWRON pulled low OR PWRHOLD = HIGH to leave OFF status, I2C is in reset before Start-up Sequencing , and I have tried what you said , the phenomenon that I2C is in reset conforms the spec,

0 Daniel W over 3 years ago in reply to zhanbo Wang

TI__Genius 13216 points

Hi Zhanbo,

Yes I agree the I2C will be in reset before starting the power up sequence. It appears that an OTP with no default outputs would be necessary to make this strategy work.

Thanks,

Daniel W

0 zhanbo Wang over 3 years ago in reply to Daniel W

Prodigy 10 points

Hi Daniel,
Thanks for your help , and I will find other OPN to compare with my needs.
B&R.

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TPS65912: need Forbid vcc output when poweron