ZHCSJW0D June 2019 – March 2020 TPS62840
In PWM mode, the duty-cycle of a buck converter is given as D = VOUT/VIN. The duty-cycle increases as the input voltage comes closer to the output voltage. Once the input voltage decreases to near 100% duty cycle, the output voltage set point is increased by +30 mV. As the input voltage decreases further, the device enters 100% duty-cycle mode and keeps the high-side MOSFET on continuously. The output (VOUT) is connected to the input (VIN) through the inductor and the internal high-side MOSFET. The minimum input voltage to maintain a given output voltage depends on the load current and is calculated as:
The TPS6284x contains special circuitry to keep an ultra-low IQ of 120 nA during 100% mode operation.