PCA9420/PCA9421 Power Management ICs (PMICs) NXP Semiconductors PCA9420/PCA9421 Power Management ICs (PMICs) are targeted to provide a complete power management solution for low-power microcontrollers or similar applications. These devices integrate two step-down (buck) DC-DC converters with 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 conditions.