The TPS65263-1Q1 is a monolithic, triple-synchronous step-down (buck) converter with 3-A/2-A/2-A output currents. A wide 4- to 18-V input supply voltage range encompasses most intermediate bus voltages operating off 5-, 9-, 12-, 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 TPS65263-1Q1 is equipped with an I²C compatible bus for communication with SoC to control buck converters. Through the I²C interface, SoC can enable or disable the buck converters, set output voltage (BUCK2 only), and read status registers. External feedback divider resistors can set the initial start-up voltage of the buck2. After the voltage identification VID DAC is updated through the I²C, output voltage of the buck2 can be independently programmed with 7 bits VID from 0.68 to 1.95 V in 10-mV voltage step resolution. Output voltage of the buck2 transition begins after the I²C interface receives the command for the GO bit in the command register.

If SDA and SCL pins are floated or are connected to GND, the I²C communication is rejected and the TPS65263-1Q1 operates as a traditional triple buck. Each buck on or off is separately controlled by the relevant enable pin. The buck2 output voltage is set with the external feedback divider resistors.

In the light load condition, the converter operates at continuous current mode (CCM) with a fixed frequency for optimized output ripple. PSM can be enabled through I2C so that the converter automatically operates in pulse skipping mode (PSM) to save power.

The TPS65263-1Q1 implements a constant frequency, peak current mode control that simplifies external loop compensation. The wide switching frequency of 200 kHz to 2.3 MHz allows for optimizing system efficiency, filtering size, and bandwidth. The switching frequency can be adjusted with an external resistor connecting between the ROSC pin and ground. The TPS65263-1Q1 also has an internal phase locked loop (PLL) controlled by the ROSC pin that can be used to synchronize the switching cycle to the falling edge of an external system clock. The switching clock of buck1 is 180° out-of-phase operation from the clocks of buck2 and buck3 channels to reduce input current ripple, input capacitor size, and power-supply-induced noise.

The TPS65263-1Q1 is designed for safe monotonic start-up into prebiased loads. The default start-up is when VIN is typically 3.8 V. The ENx pin can also be used to adjust the input voltage undervoltage lockout (UVLO) with an external resistor divider. In addition, the ENx pin has an internal 3.9-µA current source, so the EN pin can be floating for automatically powering up the converters.

The TPS65263-1Q1 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 V_BST-V_LX in each buck. When V_BST-V_LX voltage drops to the threshold, LX pin is pulled low to recharge the bootstrap capacitor. The TPS65263-1Q1 can operate at 100% duty cycle as long as the bootstrap capacitor voltage is higher than the BOOT-LX UVLO threshold, which is typically 2.1 V.

The TPS65263-1Q1 has power-good comparators with hysteresis, which monitor the output voltages through internal feedback voltages. I²C can read the power-good status with the command register. The device also features the PGOOD pin to supervise output voltages of the buck converter. When all bucks are in regulation range and power sequence is done, PGOOD is asserted high.

The SS (soft-start/tracking) pin is used to minimize inrush currents or provide power-supply sequencing during power up. A small value capacitor or resistor divider is connected to the pin for soft start or voltage tracking.

The TPS65263-1Q1 is protected from overload and overtemperature 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 0.6-V reference voltage. The TPS65263-1Q1 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 shuts down and restarts after the hiccup time (8192 clock cycles). The TPS65263-1Q1 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 TPS65263-1Q1 is restarted under control of the soft-start circuit automatically.