npm1300 problem

[sunnyyang]

hi professor,

    The npm1300 is used for power management  on my borad.When VBAT and VBUS are connected simultaneously, the bulk 2 output power supply varies between 1V and 3.3V.When only VBUS is connected, the bulk 2 output voltage is fixed at 3.3V, which meets my expectations.

    The chip version i am using is CAAACA 2335A1.Does this version of the chip have such characteristics that VBAT must be connected?

Here are the DTS fragments:

&arduino_i2c {
npm1300_ek_pmic: pmic@6b {
compatible = "nordic,npm1300";
reg = <0x6b>;

npm1300_ek_gpio: gpio-controller {
compatible = "nordic,npm1300-gpio";
gpio-controller;
#gpio-cells = <2>;
ngpios = <5>;
};

npm1300_ek_regulators: regulators {
compatible = "nordic,npm1300-regulator";
/* limits are set to min/max allowed values */
npm1300_ek_buck1: BUCK1 {
regulator-min-microvolt = <1800000>;
regulator-max-microvolt = <3300000>;
/delete-property/ regulator-init-microvolt;
};
npm1300_ek_buck2: BUCK2 {
regulator-min-microvolt = <1000000>;
regulator-max-microvolt = <3300000>;
regulator-init-microvolt = <3300000>;
regulator-always-on;
regulator-boot-on;
/delete-property/ retention-microvolt;
/delete-property/ enable-gpios;
/delete-property/ retention-gpios;
/delete-property/ pwm-gpios;
};

npm1300_ek_ldo1: LDO1 {
/delete-property/ regulator-min-microvolt;
/delete-property/ regulator-max-microvolt;
/delete-property/ regulator-initial-mode;
/delete-property/ enable-gpios;
};

npm1300_ek_ldo2: LDO2 {
regulator-min-microvolt = <1800000>;
regulator-max-microvolt = <3300000>;
regulator-init-microvolt = <1800000>;
regulator-initial-mode = <NPM1300_LDSW_MODE_LDO>;
regulator-always-on;
regulator-boot-on;
/delete-property/ enable-gpios;
};
};
npm1300_ek_charger: charger {
compatible = "nordic,npm1300-charger";
term-microvolt = <4200000>;
term-warm-microvolt = <4000000>;
current-microamp = <400000>;
dischg-limit-microamp = <1000000>;
vbus-limit-microamp = <500000>;
thermistor-ohms = <10000>;
thermistor-beta = <3380>;
charging-enable;
vbatlow-charge-enable;
};
npm1300_ek_buttons: buttons {
compatible = "gpio-keys";
pmic_button0: pmic_button_0 {
gpios = < &npm1300_ek_gpio 0 GPIO_ACTIVE_HIGH>;
label = "Pmic button switch 0";
zephyr,code = <INPUT_KEY_0>;
};
};
npm1300_ek_leds: leds {
compatible = "nordic,npm1300-led";
nordic,led0-mode = "host";
nordic,led1-mode = "charging";
nordic,led2-mode = "error";
};
};
};

[helsing]

Hi sun yang,

Just letting you know we have started looking into this.

[helsing]

Hi sun yang,

When VBAT and VBUS are connected simultaneously, the bulk 2 output power supply varies between 1V and 3.3V

Do you have any plot from an oscilloscope showing this?

The npm1300 is used for power management  on my borad.

Would you be able to share the schematic of your design? Has anyone at Nordic reviewed your design? We offer a review of the Nordic related part of the design as a free service. If you would like us to do this, we could make the ticket private so that you can add upload the files.

[helsing]

When VBAT and VBUS are connected simultaneously, the bulk 2 output power supply varies between 1V and 3.3V.

What are the voltages on VBAT and VBUS when this occur?

[sunnyyang]

I'm sorry, there's an issue with my description.When VBAT is connected, the bulk 2 voltage is fixed and outputs 3.3v, regardless of whether VBUS is connected or not. When only VBUS is connected,the bulk 2 output power supply varies between 1V and 3.3V. The schematic is detailed in the following image.

[helsing]

Thank you for the update.

The issue you're experiencing could be because the device is drawing more current than what the USB host can provide. The current limit for VBUS is set at 500mA. If the device draws more than this, the system's voltage (VSYS) will drop.

Vsys can also drop if the USB host can only deliver, for example, 100mA, and the device draws more than this. Even if the VBUS current limit is set to 500mA.

The overlay looks OK and works as expected when we are testing it.