Current-fed multiple-output power converter
View Patent ↗A power converter is disclosed. According to one embodiment, the power converter includes a first stage comprising a current source and a second stage comprising n output circuits for converting the current signal into n corresponding output voltages. Each of the n output circuits includes an output switch responsive to a corresponding n th control signal for regulating the corresponding n th output voltage. The second stage further comprises a controller for generating the n control signals. The controller includes, for each of the n output circuits, an error amplifier, a waveform generator, and a summing circuit. Each error amplifier is configured to generate an output signal based upon a comparison of the output voltage of the n th output circuit and a corresponding n th reference voltage. Each waveform generator generates a waveform signal. The waveform signals for the n output circuits are characterized by a common amplitude and period, and the phases of the waveforms signals are spaced at predetermined intervals. For each of the n outputs, the corresponding summing circuit sums the output of the error amplifier and the waveform signal to generate an amplitude-shifted waveform signal. The controller further includes a comparator for outputting the n control signals to the output switches based upon a comparison of the relative amplitudes of the amplitude-shifted waveform signals.
1. A power converter comprising:
a first stage comprising a current source for generating a current signal; and
a second stage comprising:
n output circuits coupled to the current source for converting the current signal into n corresponding output voltages, wherein each of the n output circuits comprises an output switch responsive to a corresponding n th control signal for regulating the corresponding n th output voltage; and
a controller for generating the n control signals comprising:
for each of the n output circuits:
an error amplifier configured to generate a duration control signal based upon a comparison of the output voltage of the n th output circuit and a corresponding n th reference voltage; and
a pulse generator coupled to the error amplifier and configured to output the control signal to the switch of the corresponding n th output circuit, wherein the control signal is output responsive to a falling edge of a trigger input received by the pulse generator, and wherein a duration of the control signal is determined based upon a pre-determined output duration of the pulse generator and a value of the duration control signal;
wherein the pulse generators are interconnected in a wrap-around configuration such that the falling edge of the control signal output by each pulse generator operates as the trigger input for a subsequent pulse generator.
2. The power converter of claim 1 , wherein the current source comprises a single magnetic device.
3. The power converter of claim 2 , wherein the current source comprises a buck converter.
4. The power converter of claim 2 , wherein the current source comprises a boost converter.
5. The power converter of claim 2 , wherein current source is isolated from the second stage and comprises a flyback converter.
6. The power converter of claim 1 , wherein n is a number greater than 1.
7. The power converter of claim 1 , wherein the control signals generated by the controller for controlling the output switches of the n output circuits are characterized by switching cycles having a dynamic frequency.
8. The power converter of claim 2 , wherein the current source is a controlled switch-mode current source.
9. The power converter of claim 8 , wherein the current source comprises a controller and at least two switches for controlling a magnitude of the current signal, wherein the switches are responsive to corresponding control signals generated by the controller.
10. The power converter of claim 9 , wherein the controller of the first stage generates the control signals based at least on part upon a sum of the durations of the control signals output by the pulse generators.
11. The power converter of claim 1 , wherein at least one of the output switches is a switch selected from the group consisting of: a 3-terminal MOSFET switch, a 4-terminal MOSFET switch, a J-FET switch, and a CMOS switch.
12. The power converter of claim 1 , wherein at least one output switch comprises an N-Channel Power MOSFET having a gate terminal, a source terminal, a drain terminal, and a body terminal, wherein the body terminal is coupled to a voltage that is no greater than the lowest of the n output voltages.
13. The power converter of claim 12 , wherein the MOSFET comprises a short circuit metallization layer, and wherein the short circuit metallization layer comprises the source terminal and the base terminal.