POWER-DOWN DISCHARGER

摘要

Active post-power loss discharging of capacitors is provided. In an integrated circuit having a startup behavior depending on a capacitor voltage, a discharge transistor is provided to discharge the capacitor. A power-down discharger actively drives the discharge transistor after a power supply voltage drops below a threshold. The power-down discharger may include, or be coupled to, an internal capacitance that is charged when the power supply voltage is above the threshold, thereby storing sufficient energy for later driving of the discharge transistor. A diode is employed to ensure that the loss of power does not drain away the needed energy until after the discharge has been completed. One illustrative discharging method includes: sensing a condition indicative of power supply voltage loss for an integrated circuit; and actively driving the discharge transistor into a conducting state. The sensing may include driving the discharge transistor inversely to a signal from a pin.

主权项

1. An integrated circuit having a startup behavior that depends at least in part on a voltage of an internal or external capacitor, the circuit comprising:
a discharge transistor that discharges the capacitor when driven to a conducting state; and a power-down discharger that actively drives the discharge transistor to the conducting state after a power supply voltage provided to the integrated circuit drops below a threshold.