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 configured to operate according to an enabled switching state and a disabled switching state;
an inductor having a first terminal and a second terminal, the first terminal connected to the charge pump and the second terminal configured to be connected to an output load; and
a switch element connected across the inductor, the switch element configured to:
close during the disabled switching state of the charge pump, and
open during the enabled switching state of the charge pump.
2. The power converter of claim 1 , further comprising a first capacitor, the first capacitor configured to provide an output voltage to the output load.
3. The power converter of claim 1 , wherein
the switch element is configured to be closed prior to disabling a switching of the charge pump.
4. The power converter of claim 1 , wherein
the switch element is configured to be closed concurrently with disabling a switching of the charge pump.
5. The power converter of claim 1 , wherein the switch element comprises a GaAs transistor.
6. The power converter of claim 1 , wherein the switch element comprises a GaN transistor.
7. 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;
an active discharge circuit connected across the third and fourth terminals of the charge pump; and
a current-sense circuit connected across the third and fourth terminals of the charge pump, the current-sense circuit configured to be driven by a controller based on a sense status signal generated by the current-sense circuit, the current-sense circuit further configured to correspondingly activate the active discharge circuit.
8. The charge pump of claim 7 , wherein the active discharge circuit further comprises:
a first inverter and a second inverter configured to receive a driving signal;
a high-side switch element connected to the first inverter;
a low-side switch element connected to the second inverter, the high-side switch element connected to the low-side switch element; 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.
9. The charge pump of claim 8 , 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.
10. The charge pump of claim 7 , wherein the current-sense circuit further comprises:
a first inverter configured to receive a control signal;
a latch having its set terminal connected to the to the first inverter; and
a current-sense comparator configured to receive the control signal, the current-sense comparator further configured to provide an output signal to an OR gate,
wherein the latch provides an output signal in response to the control signal and the output of the OR gate.
11. The charge pump of claim 8 , wherein the high-side switch element and the low-side switch element comprise GaAs transistors.
12. The charge pump of claim 8 , wherein the high-side switch element and the low-side switch element comprise GaN transistors.
13. A charge pump, comprising:
a controller; and
a cascade multiplier having a plurality of high side and low side switches,
wherein
the controller is configured to receive an external signal and to correspondingly drive the plurality of high side and low side switches in the cascade multiplier,
a first high side switch and a first low side switch from the plurality of high side and low side switches are enabled simultaneously, such that the first high side switch and the first low side switch act as an active discharge switch for the charge pump, and
the first high side switch and the first low side switch are coupled to a first phase node of the cascade multiplier.
14. The charge pump of claim 13 , wherein
a second high side switch and a second low side switch from the plurality of high side and low side switches are enabled simultaneously, such that the first high side and low side switches and the second high side and low side switches act as an active discharge switch for the charge pump, and
the second 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.
15. The charge pump of claim 13 , further comprising a first electro-static discharge element.
16. The charge pump of claim 15 , further comprising a second electro-static discharge element.
17. The charge pump of claim 15 , wherein the first electro-static discharge element comprises a diode.
18. The charge pump of claim 15 , wherein the first electro-static discharge element comprises a MOSFET.
19. The charge pump of claim 16 , wherein the second electro-static discharge element comprises a diode.
20. The charge pump of claim 16 , wherein the second electro-static discharge element comprises a MOSFET.
21. The charge pump of claim 14 , further comprising a first electro-static discharge element.
22. The charge pump of claim 21 , further comprising a second electro-static discharge element.
23. The charge pump of 13 , wherein the plurality of high side and low side switches in the cascade multiplier comprises GaAs transistors.
24. The charge pump of 13 , wherein the plurality of high side and low side switches in the cascade multiplier comprises GaN transistors.
25. A method to shut down a charge pump, the method comprising:
providing a charge pump;
coupling an adiabatic element to the charge pump;
coupling an output load the adiabatic element, the output load comprising a programmable current sink circuit; and
shutting down the charge pump by:
i) controlling the programmable current sink circuit to reduce a current drawn through the output load; and
ii) based on the controlling, controlling the charge pump to disable switching.
26. The method according to claim 25 , wherein the output load comprises a plurality of light emitting diodes.
27. The method according to claim 25 , wherein the output load comprises a plurality of light emitting diodes connected in series.