Multiphase power converter with current balancing
An apparatus includes a voltage control circuit. A first current control circuit has a first current control circuit input coupled to the voltage control circuit's output and has a second current control circuit input. A second current control circuit has a third current control circuit input coupled to the voltage control circuit's output and has a fourth current control circuit input. A current balance circuit has a first current balance circuit output and a second current balance circuit output. The first current balance circuit output couples to the second current control circuit input. The second current balance circuit output couples to the fourth current control circuit input. The current balance circuit generates first and second currents. The first and second currents are based on a difference between a first average current of the first current control circuit and a second average current of the second current control circuit.
1 . A display system, comprising:
a display panel;
a plurality of light emitting diodes (LEDs) arranged with respect to the display panel to illuminate the display panel; and
a voltage control circuit having an output;
a first current control circuit having a first current control circuit input coupled to the output of the voltage control circuit, having a second current control circuit input, and having a first current control circuit output coupled to at least one of the LEDs;
a second current control circuit having a third current control circuit input coupled to the output of the voltage control circuit and having a fourth current control circuit input, and having a second current control circuit output coupled to the least one of the LEDs; and
a current balance circuit having a first current balance circuit output and a second current balance circuit output, the first current balance circuit output coupled to the second current control circuit input, and the second current balance circuit output coupled to the fourth current control circuit input, the current balance circuit configurable to generate a first current at the first current balance circuit output and a second current at the second current balance circuit output, the first and second currents based on a difference between a first average current of the first current control circuit and a second average current of the second current control circuit.
2 . The display system of claim 1 , wherein:
the first current control circuit is configurable to adjust a first reference current based on a current from the output of the voltage control circuit and the first current; and
the second current control circuit is configurable to adjust a second reference current based on the current from the output of the voltage control circuit and the second current.
3 . The display system of claim 2 , wherein:
the first current control circuit is configurable to generate the first reference current by summing the current from the output of the voltage control circuit and the first current; and
the second current control circuit is configurable to generate the second reference current by summing the current from the output of the voltage control circuit and the second current.
4 . The display system of claim 1 , wherein the current balance circuit includes:
a first low-pass filter having a first low-pass filter output and configurable to low-pass filter a first current sense signal to produce a first filtered signal at the first low-pass filter output;
a second low-pass filter having a second low-pass filter output and configurable to low-pass filter a second current sense signal to produce a second filtered signal at the second low-pass filter output; and
a first amplifier having a first amplifier input coupled to the first low-pass filter output and having a second amplifier input coupled to the second low-pass filter output.
5 . The display system of claim 4 , wherein the first current control circuit includes a first transistor, the second current control circuit includes a second transistor, and wherein:
the first low-pass filter is configurable to be disabled during a first blanking period following the first transistor turning on; and
the second low-pass filter is configurable to be disabled during a third blanking period following the second transistor turning on.
6 . The display system of claim 4 , wherein the first current control circuit includes a first transistor, the second current control circuit includes a second transistor, and wherein:
the first low-pass filter is configurable to be disabled during a first blanking period following the first transistor turning on, a second blanking period following the second transistor turning off, and a third blanking period following the second transistor turning on; and
the second low-pass filter is configurable to be disabled during a fourth blanking period following the second transistor turning on, a fifth blanking period following the first transistor turning off, and a sixth blanking period following the first transistor turning on.
7 . The display system of claim 4 , wherein:
the first low-pass filter includes a first resistor coupled to a first capacitor; and
the second low-pass filter includes a second resistor coupled to a second capacitor.
8 . The display system of claim 4 , wherein the first amplifier has a first amplifier output, and the display system further includes:
a switch having a first switch terminal coupled to the first amplifier output and having a second switch terminal;
a second amplifier having a second amplifier input coupled to the second switch terminal and having a third amplifier input;
a reference voltage circuit coupled to the third amplifier input; and
a capacitor having a capacitor terminal coupled to the second switch terminal.
9 . An apparatus, comprising:
a voltage control circuit having an output;
a first current control circuit having a first current control circuit input coupled to the output of the voltage control circuit, having a second current control circuit input;
a second current control circuit having a third current control circuit input coupled to the output of the voltage control circuit and having a fourth current control circuit input; and
a current balance circuit having a first current balance circuit output and a second current balance circuit output, the first current balance circuit output coupled to the second current control circuit input, and the second current balance circuit output coupled to the fourth current control circuit input, the current balance circuit configurable to generate a first current at the first current balance circuit output and a second current at the second current balance circuit output, the first and second currents based on a difference between a first average current of the first current control circuit and a second average current of the second current control circuit.
10 . The apparatus of claim 9 , wherein:
the first current control circuit is configurable to adjust a first reference current based on a current from the output of the voltage control circuit and the first current; and
the second current control circuit is configurable to adjust a second reference current based on the current from the output of the voltage control circuit and the second current.
11 . The apparatus of claim 10 , wherein:
the first current control circuit is configurable to generate the first reference current by summing the current from the output of the voltage control circuit and the first current; and
the second current control circuit is configurable to generate the second reference current by summing the current from the output of the voltage control circuit and the second current.
12 . The apparatus of claim 9 , wherein the current balance circuit includes:
a first low-pass filter having a first low-pass filter output and configurable to low-pass filter a first current sense signal to produce a first filtered signal at the first low-pass filter output;
a second low-pass filter having a second low-pass filter output and configurable to low-pass filter a second current sense signal to produce a second filtered signal at the second low-pass filter output; and
a first amplifier having a first amplifier input coupled to the first low-pass filter output and having a second amplifier input coupled to the second low-pass filter output.
13 . The apparatus of claim 12 , wherein the first current control circuit includes a first transistor, the second current control circuit includes a second transistor, and wherein:
the first low-pass filter is configurable to be disabled during a first blanking period following the first transistor turning on; and
the second low-pass filter is configurable to be disabled during a third blanking period following the second transistor turning on.
14 . The apparatus of claim 12 , wherein the first current control circuit includes a first transistor, the second current control circuit includes a second transistor, and wherein:
the first low-pass filter is configurable to be disabled during a first blanking period following the first transistor turning on, a second blanking period following the second transistor turning off, and a third blanking period following the second transistor turning on; and
the second low-pass filter is configurable to be disabled during a fourth blanking period following the second transistor turning on, a fifth blanking period following the first transistor turning off, and a sixth blanking period following the first transistor turning on.
15 . The apparatus of claim 12 , wherein:
the first low-pass filter includes a first resistor coupled to a first capacitor; and
the second low-pass filter includes a second resistor coupled to a second capacitor.
16 . The apparatus of claim 12 , wherein the first amplifier has a first amplifier output, and the apparatus further includes:
a switch having a first switch terminal coupled to the first amplifier output and having a second switch terminal;
a second amplifier having a second amplifier input coupled to the second switch terminal and having a third amplifier input;
a reference voltage circuit coupled to the third amplifier input; and
a capacitor having a capacitor terminal coupled to the second switch terminal.
17 . An apparatus, comprising:
a first current control circuit having a first transistor, the first current control circuit having a first clock input, a first error current input, a first current balance input, and a first output, the first current control circuit configurable to combine a first error current from the first error current input with a first balance current from the first current balance input to produce a first reference current, and to change a state of the first transistor in response to a first current through the first transistor reaching the first reference current;
a second current control circuit having a second transistor, the second current control circuit having a second clock input, a second error current input, a second current balance input, and a second output, the second current control circuit configurable to combine a second error current from the second error current input with a second balance current from the second current balance input to produce a second reference current, and to change a state of the second transistor in response to a second current through the second transistor reaching the second reference current; and
a current balance circuit having a first input, a second input, a first current output, and a second current output, the first input coupled to the first output, the second input coupled to the second output, the first current output coupled to the first current balance input, and the second current output coupled to the second current balance input, the current balance circuit configurable to produce the first balance current at the first current output and the second balance current at the second current output in response to a difference between the first current and the second current.
18 . The apparatus of claim 17 , wherein the current balance circuit is configurable to produce the first balance current and the second balance current in response to the difference between an average of the first current and an average of the second current.
19 . The apparatus of claim 17 , wherein:
the first current control circuit configurable to combine the first error current with the first balance current by summing the first error current with the first balance current; and
the second current control circuit configurable to combine the second error current with the second balance current by summing the second error current with the second balance current.
20 . The apparatus of claim 17 , wherein the current balance circuit includes a first amplifier configurable to produce a first signal at an output of the first amplifier, the first signal indicative of the difference between the first current and the second current, the first current control circuit also including a first capacitor coupled to the output of the first amplifier through a first switch, the first capacitor configurable to retain a voltage from the output of the first amplifier in response to the first switch being closed.