Resonant capacitor stabilizer in resonant converters
According to an implementation, a resonant converter for resonant capacitance stabilization during start-up includes an oscillator configured to generate a first clock signal to drive a first driver for a first power switch, and a second clock signal to drive a second driver for a second power switch during switching operations, and a resonant capacitor stabilizer configured to control the second driver to periodically activate the second power switch to discharge a resonant capacitor of a resonant network during initialization of the switching operations of the resonant converter.
1. A resonant converter for resonant capacitance stabilization during start-up, the resonant converter comprising:
an oscillator configured to generate a first clock signal to drive a first driver for a first power switch, and a second clock signal to drive a second driver for a second power switch during switching operations; and
a resonant capacitor stabilizer configured to control the second driver to periodically activate the second power switch to discharge a resonant capacitor of a resonant network during initialization of the switching operations of the resonant converter,
the resonant capacitor stabilizer configured to activate the second power switch for a first duration and activate the second power switch for a second duration such that the second power switch is deactivated during a period of time between the first duration and the second duration.
2. The resonant converter of claim 1 , wherein the second duration is longer than the first duration.
3. The resonant converter of claim 1 , wherein, after the second power switch is activated during an activation instance, the resonant capacitor stabilizer is configured to deactivate the second power switch in response to a voltage of an integrated current sense signal being equal to or below a voltage threshold.
4. The resonant converter of claim 3 , further including:
an integrated current sense circuit connected to the resonant capacitor, the integrated current sense circuit configured to sense the integrated current sense signal on a primary side of a transformer of the resonant network,
the resonant capacitor stabilizer being configured to receive the voltage of the integrated current sense signal, and compare the voltage of the integrated current sense signal to the voltage threshold.
5. The resonant converter of claim 1 , wherein the resonant capacitor stabilizer is configured to trigger a soft start circuit to start soft start operations in response to the second power switch being activated longer than a threshold.
6. The resonant converter of claim 1 , wherein the resonant capacitor stabilizer includes:
a latch having a set terminal, a reset terminal, and an output terminal, the output terminal of the latch being connected to the second driver;
a timer connected to the set terminal of the latch;
a voltage comparator having a first input terminal connected to a voltage of an integrated current sense signal, a second input terminal connected to a reference voltage,
and an output terminal connected to the reset terminal of the latch; and
an on-time counter connected to the timer and the output terminal of the latch.
7. The resonant converter of claim 6 , wherein the timer is configured to periodically activate the set terminal of the latch such that the output terminal of the latch periodically sends a high state of a capacitor stabilization signal to the second driver to turn-on the second power switch to discharge the resonant capacitor.
8. The resonant converter of claim 6 , wherein the on-time counter is configured to count an activation time of the second power switch, and, in response to the activation time exceeding a threshold, the on-time counter is configured to send a stabilization end signal to the timer to end the discharging of the resonant capacitor.
9. The resonant converter of claim 6 , wherein the voltage comparator is configured to compare the voltage of the integrated current sense signal and the reference voltage, and, in response to the reference voltage being larger than the voltage of the integrated current sense signal, the voltage comparator is configured to reset the latch causing the second power switch to deactivate.
10. A resonant converter for resonant capacitance stabilization during start-up, the resonant converter comprising:
an oscillator configured to generate a first clock signal to drive a first driver for a first power switch, and a second clock signal to drive a second driver for a second power switch during switching operations; and
a resonant capacitor stabilizer configured to control the second driver to activate the second power switch to discharge a resonant capacitor of a resonant network during a capacitor stabilization period that occurs during initialization of the switching operations of the resonant converter,
the resonant capacitor stabilizer configured to control the second driver to deactivate the second power switch in response to a voltage of an integrated current sense signal being equal to or less than a threshold voltage.
11. The resonant converter of claim 10 , wherein the resonant capacitor stabilizer is configured to control the second driver to activate and deactivate multiple times during the capacitor stabilization period.
12. The resonant converter of claim 10 , wherein the resonant capacitor stabilizer is configured to activate the second power switch at a first time and then deactivate the second power switch when the voltage of the integrated current sense signal is equal to or less than the threshold voltage such that the second power switch is activated for a first duration, wherein the resonant capacitor stabilizer is configured to activate the second power switch at a second time and then deactivate the second power switch when the voltage of the integrated current sense signal is equal to or less than the threshold voltage such that the second power switch is activated for a second duration.
13. The resonant converter of claim 12 , wherein the second duration is longer than the first duration.
14. The resonant converter of claim 10 , wherein the resonant capacitor stabilizer is configured to receive the integrated current sense signal sensed on a primary side of a transformer of the resonant network.
15. The resonant converter of claim 14 , further comprising:
an integrated current sense circuit connected to the resonant capacitor, the integrated current sense circuit configured to sense the integrated current sense signal on the primary side of the transformer of the resonant network, the integrated current sense circuit including a capacitor divider.
16. The resonant converter of claim 10 , wherein the resonant capacitor stabilizer is configured to trigger a soft start circuit to start soft start operations in response to an activation period of the second power switch being longer than a threshold.
17. A resonant converter for resonant capacitance stabilization during start-up, the resonant converter comprising:
an oscillator configured to generate a first clock signal to drive a first driver for a first power switch, and a second clock signal to drive a second driver for a second power switch during switching operations; and
a resonant capacitor stabilizer configured to control the second driver to activate the second power switch to discharge a resonant capacitor of a resonant network during initialization of the switching operations of the resonant converter, the resonant capacitor stabilizer including:
a timer configured to periodically activate the second power switch; and
an on-time counter is configured to count an activation time of the second power switch,
the resonant capacitor stabilizer configured to trigger a soft start circuit to start soft start operations in response to the activation time of the second power switch exceeding a threshold.
18. The resonant converter of claim 17 , wherein the resonant capacitor stabilizer is configured to deactivate the second power switch at each activation instance in response to a voltage of an integrated current sense signal being equal to or below a voltage threshold.
19. The resonant converter of claim 17 , wherein the second power switch is a low-side metal oxide semiconductor field effect transistor (MOSFET).