1 General description
The PCA9421 is a highly integrated Power Management IC (PMIC), targeted to provide a full power
management solution for low-power microcontroller applications or other similar applications.
The device also integrates two step-down (buck) DC-DC converters which have I2C programmable output voltage. Both buck regulators have integrated high-side and low-side switches and related control circuitry, to minimize the external component counts; a Pulse-Frequency Modulation (PFM) approach is utilized to achieve better efficiency under light load condition. Other protection features such as overcurrent protection, undervoltage lockout (UVLO), etc., are also provided. By default, the input for these regulators is powered by either VIN or VIN_AUX, whichever is greater.
In addition, two on-chip LDO regulators are provided to power up various voltage rails in the system. Other features such as Fm+ I2C-bus interface, chip enable, interrupt signal, etc. are also provided. The chip is offered in 2.09 mm x 2.09 mm, 5 x 5 bump, 0.4 mm pitch WLCSP package; and 3 mm x 3 mm, 24-pin QFN package.

2 Features and benefits
• Two step-down DC-DC converters
– Very low quiescent current
– Programmable output voltage
– SW1: core buck converter, 0.5 V to 1.5 V output, 25 mV/step, and a fixed 1.8 V, up to 250 mA
– SW2: system buck converter, 1.5 V to 2.1 V/2.7 V to 3.3 V output, 25 mV/step, up to 500 mA
– Low-power mode for extra power saving
• Two LDOs
– Programmable output voltage regulation
– LDO1: always-on LDO, 1.70 V to 1.90 V output, 25 mV/step, up to 1 mA
– LDO2: system LDO, 1.5 V to 2.1 V/2.7 V to 3.3 V output, 25 mV/step, up to 250 mA
• 1 MHz I2C-bus target interface
• -40 °C to +85 °C ambient temperature range
• Offered in 5 x 5 bump-array WLCSP and 24-pin QFN package

3 Applications
• Low power microcontroller application
• Direct powered IoT and consumer