SLDS222C October 2019 – October 2023 TPS65313-Q1
PRODUCTION DATA
The BOOST converter is a synchronous converter with a fixed frequency and current-mode PWM control for exceptional line and load regulation. The PWM switching frequency is 2.2 MHz. The BOOST converter has its own enable bit (the BOOST_EN control bit in the PWR_CTRL control register). By default, this bit is enabled at power-up, and can be disabled after power-up by the MCU.
The output voltage of the BOOST converter is fixed at 5 V. At low loads, the boost converter stays in the fixed-frequency mode.
The BOOST converter integrates circuitry to provide a closed-loop soft-start operation. The BOOST output voltage initially starts to ramp with wide-vin BUCK1 ramp rate. Once wide-vin BUCK1 output voltage completes its ramp-up, the BOOST starts its soft-start. The soft-start circuit uses a linear increase of the internal reference voltage from 0 V to its nominal value. This linear increase occurs in 2 ms while the internal control loop drives the VBOOST voltage from 0 V to 5 V, limits the inrush current drawn by the external load, and prevents the soft-start from being affected by the size of the output capacitor or the output regulation voltage. The soft-start interval is reset by a shutdown event (the WAKE pin driven low or global transition the OFF state condition).
When the BOOST converter is disabled while the BUCK1 regulator stays enabled, the BOOST output voltage is not 0 V, because it is connected to the input supply (essentially, the BUCK1 output) through the body diode of the HS power MOSFET.