The TPS55289 is a 8-A buck-boost DC-to-DC converter with the four integrated MOSFETs. The TPS55289 can operate over a wide range of 3.0-V to 30-V input voltage and 0.8-V to 22-V output voltage. The device can smoothly transition amongst buck mode, buck-boost mode, and boost mode according to the input voltage and the set output voltage. The TPS55289 operates in buck mode when the input voltage is greater than the output voltage and in boost mode when the input voltage is less than the output voltage. When the input voltage is close to the output voltage, the TPS55289 alternates between one-cycle buck mode and one-cycle boost mode.

The TPS55289 uses an average current mode control scheme. Current mode control provides simplified loop compensation, rapid response to the load transients, and inherent line voltage rejection. An error amplifier compares the feedback voltage with the internal reference voltage. The output of the error amplifier determines the average inductor current.

An internal oscillator can be configured to operate over a wide range of frequency from 200 kHz to 2.2 MHz. The internal oscillator can also synchronize to an external clock applied to the DITH/SYNC pin. To minimize EMI, the TPS55289 can dither the switching frequency at ±7% of the set frequency.

The TPS55289 works in fixed-frequency PWM mode at moderate to heavy load currents. In light load condition, the TPS55289 can be configured to automatically transition to PFM mode or be forced in PWM mode by setting the corresponding bit in an internal register.

The output voltage of the TPS55289 is adjustable by setting the internal register through I²C interface. An internal 11-bit DAC adjusts the reference voltage related to the value written into the REF register. The device can also limit the output current by placing a current sense resistor in the output path. These two functions support the programmable power supply (PPS) feature of the USB PD.

The TPS55289 provides average inductor current limit of 8 A typically. In addition, the device provides cycle-by-cycle peak inductor current limit during transient to protect the device against overcurrent condition beyond the capability of the device.

A precision voltage threshold of 1.23 V with 5-μA sourcing current at the EN/UVLO pin supports programmable input undervoltage lockout (UVLO) with hysteresis. The output overvoltage protection (OVP) feature turns off the high-side FETs to prevent damage to the devices powered by the TPS55289.

The device provides a hiccup mode option to reduce the heating in the power components when the output short circuit happens. When the hiccup mode is enabled, the TPS55289 turns off for 76 ms and restarts at soft-start–up.