Apparatus and method for efficient shutdown of adiabatic charge pumps
An apparatus and method for efficient shutdown of adiabatic charge pumps. A power converter includes a charge pump, a controller, an output load and an inductor. According to one aspect, the power converter includes a switch which is connected across the inductor, where the controller is configured to sense a status of the charge pump and to correspondingly drive the switch element. According to another aspect, the charge pump includes an active discharge circuit and a current-sense circuit, where the current-sense circuit is configured to activate the active discharge circuit. According to yet another aspect, the power converter includes a cascade multiplier having a plurality of high side and low side switches, where a pair of high side and low side switches are enabled simultaneously, such that the pair of high side and low side switches act as an active discharge switch for the charge pump.
1. A power converter, comprising:
a charge pump;
a controller configured to sense a switching status of the charge pump;
an inductor having a first terminal and a second terminal, the first terminal being connected to the charge pump and the second terminal configured to be connected an output load; and
a switch element connected across the inductor, the controller being configured to control the switch element to close and open respectively based on a disable switching and enable switching status of the charge pump.
2. The power converter of claim 1 , further comprising a first capacitor, the first capacitor configured for connection across the output load.
3. The power converter of claim 2 , wherein the controller receives input signals from the charge pump and provides output signals to the charge pump and the switch element.
4. A charge pump comprising:
first and second input terminals configured to receive an input voltage to the charge pump;
third and fourth input terminals configured to output an output voltage of the charge pump based on the input voltage;
a charge pump controller;
an active discharge circuit and a current-sense circuit each connected: a) to the charge pump controller and b) across the third and fourth terminals of the charge pump,
wherein
the charge pump controller is configured to receive a sense status from the current-sense circuit, and to correspondingly drive the current-sense circuit, and
the current-sense circuit is configured to correspondingly activate the active discharge circuit.
5. The charge pump of claim 4 , wherein the active discharge circuit further comprises:
a first logic inverter and a second logic inverter configured to receive a driving signal;
a high-side switch element connected to the first logic inverter;
a low-side switch element connected to the second logic inverter, the high-side switch element and the low-side switch element being connected to each other, and
a clamping switch element for the charge pump having an input connected to the high-side switch element and the low-side switch element, a first output serving as a clamping switch element anode and a second output serving as a clamping switch element cathode.
6. The charge pump of claim 5 , further comprising a diode having its anode connected to the first output of the clamping switch element and its cathode connected to the second output of the clamping switch element.
7. The charge pump of claim 4 , wherein the current-sense circuit further comprises:
a first logic inverter configured to receive a driving signal;
a logic latch having its set terminal connected to the to the first logic inverter;
a current-sense comparator configured to receive the driving signal, and configured to provide an output signal to a logic OR gate,
wherein the logic latch provides an output signal in response to the driving signal and the output of the logic OR gate.
8. A circuital arrangement, comprising:
a charge pump having a controller;
a cascade multiplier having a plurality of high side and low side switches,
wherein
the controller is configured to receive a pair of external signals, and to correspondingly drive the plurality of high side and low side switches in the cascade multiplier,
a first pair of high side and low side switches from the plurality of high side and low side switches are enabled simultaneously, such that the first pair of high side and low side switches act as an active discharge switch for the charge pump, and
the first pair of high side and low side switches are coupled to a first phase node of the cascade multiplier.
9. The circuital arrangement of claim 8 , wherein
a second pair of high side and low side switches from the plurality of high side and low side switches are enabled simultaneously, such that the first and second pair of high side and low side switches act as an active discharge switch for the charge pump, and
the second pair of high side and low side switches are coupled to a second phase node of the cascade multiplier that is different from the first phase node.
10. The circuital arrangement of claim 8 , further comprising a first electro-static discharge element.
11. The circuital arrangement of claim 10 , further comprising a second electro-static discharge element.
12. The circuital arrangement of claim 10 , wherein the first electro-static discharge element comprises a diode.
13. The circuital arrangement of claim 10 , wherein the first electro-static discharge element comprises a MOSFET.
14. The circuital arrangement of claim 11 , wherein the second electro-static discharge element comprises a diode.
15. The circuital arrangement of claim 11 , wherein the second electro-static discharge element comprises a MOSFET.
16. The circuital arrangement of claim 9 , further comprising a first electro-static discharge element.
17. The circuital arrangement of claim 16 , further comprising a second electro-static discharge element.
18. A power converter, comprising:
a charge pump;
a controller;
an adiabatic element;
an output load comprising a programmable current sink circuit that is configured to draw a current through the output load based on a control signal from the controller, wherein the output load is connected to the adiabatic element, and
wherein
during a shut down phase of the power converter, the controller first controls the programmable current sink to reduce the current drawn through the output load and then controls the charge pump to disable switching.
19. The power converter of claim 18 , wherein the output load comprises a plurality of light emitting diodes.
20. The power converter of claim 18 , wherein the output load comprises a plurality of light emitting diodes connected in series.