The TPS65265 is a monolithic triple synchronous step-down (buck) converter with 5-A/3-A/2-A output currents. A wide 4.5-V to 17-V input supply voltage range encompasses most intermediate bus voltages operating off 5-V, 9-V, 12-V, or 15-V power bus. The feedback voltage reference for each buck is 0.6 V. Each buck is independent with dedicated enable, soft-start and loop compensation pins.

The TPS65265 implements a constant frequency, peak current mode control that simplifies external loop compensation. The wide switching frequency of 250 kHz to 2.3 MHz allows optimizing system efficiency, filtering size and bandwidth. The switching frequency can be adjusted with an external resistor connecting between ROSC pin and ground. The switching clock is 120° out-of-phase operation from the clocks of buck1, buck2, and buck3 channels to reduce input current ripple, input capacitor size and power supply induced noise.

The TPS65265 has been designed for safe monotonic startup into pre-biased loads. The default start up is when VIN is typically 3.8 V. The ENx pin also can be used to adjust the input voltage undervoltage lockout (UVLO) with an external resistor divider. In addition, the ENx pin has an internal 2.9µA current source, so the EN pin can be floating for automatically powering up the converters.

The TPS65265 reduces the external component count by integrating the bootstrap circuit. The bias voltage for the integrated high-side MOSFET is supplied by a capacitor between the BST and LX pins. A UVLO circuit monitors the bootstrap capacitor voltage VBST-VLX in each buck. When V_BST-V_LX voltage drops to the threshold, LX pin is pulled low to recharge the bootstrap capacitor. The TPS65265 can operate at 100% duty cycle as long as the bootstrap capacitor voltage is higher than the BOOT-LX UVLO threshold which is typically 2.2 V.

The TPS65265 features PGOOD pin to supervise each output voltage of buck converters. The TPS65265 has power good comparators with hysteresis, which monitor the output voltages through feedback voltages. When all bucks are in regulation range and power sequence is done, PGOOD is asserted to high after the adjustable delay time.

The TPS65265 operates in PSM with connecting PSM pin to high or leaving float and operates in force continuous current mode (FCC) with driving PSM pin to GND.

The TPS65265 is protected from overload and over temperature fault conditions. The converter minimizes excessive output overvoltage transients by taking advantage of the power good comparator. When the output is over, the high-side MOSFET is turned off until the internal feedback voltage is lower than 105% of the 0.6V reference voltage. The TPS65265 implements both high-side MOSFET overload protection and bidirectional low-side MOSFET overload protections to avoid inductor current runaway. If the overcurrent condition has lasted for more than the OC wait time (256 clock cycle), the converter will shut down and restart after the hiccup time (8192 clock cycles). The TPS65265 shuts down if the junction temperature is higher than thermal shutdown trip point. When the junction temperature drops 20°C typically below the thermal shutdown trip point, the TPS65265 will be restarted under control of the soft start circuit automatically.