Smart Power Stage Rail Bleeding for Fast Shutdown Discharge

The patent applies preliminary action by activating bleed circuits and control transistors immediately upon detecting a power down event, proactively draining the power rails before the system fully shuts off. This prevents the prolonged depletion period that causes boot failures by initiating the draining process as soon as shutdown is detected, rather than waiting for natural depletion.

The patent changes the electrical parameters of the power rails by introducing controlled bleed currents through transistors and resistors. By dynamically adjusting the conductivity of control transistors (Q1, Q2) and activating bleed circuits, the system transforms the slow natural depletion process into a rapid controlled draining process, reducing depletion time from minutes to seconds.

The patent segments the power rail draining process into two distinct phases: first draining the output rail through the low-side transistor, then draining the input rail through the high-side transistor. This segmentation allows each transistor to operate optimally for its specific task, with the low-side transistor fully on for rapid output rail depletion, followed by the high-side transistor handling input rail depletion, thereby managing overall power dissipation efficiently.

The patent employs periodic action by using pulse-width modulation (PWM) to control the high-side transistor after the initial draining phase. Instead of keeping it fully on continuously, the transistor is pulsed periodically, allowing the input rail to drain in controlled intervals. This reduces continuous power dissipation while still achieving complete depletion, balancing speed and energy consumption.

The patent applies preliminary action by first fully turning on the low-side transistor to rapidly deplete the output rail before activating the high-side transistor for input rail draining. This preliminary depletion of the output rail reduces the voltage stress on the high-side transistor during subsequent operation, allowing it to operate in linear or pulsed mode with reduced stress while maintaining fast depletion speed.

The patent maintains continuity of useful action by seamlessly transitioning from low-side transistor operation to high-side transistor operation. The bleed state machine ensures that as one transistor completes its draining task, the other is activated without interruption, maintaining continuous power rail depletion. This continuous action allows the high-side transistor to operate in optimized modes (linear or pulsed) without idle periods, reducing overall stress while maintaining speed.