Voltage monitoring of switching drivers

Patent metadata

Field	Value
Publication number	US-12500601-B2
Application number	US-202318455313-A
Country	US
Kind code	B2
Filing date	Aug 24, 2023
Priority date	Aug 24, 2023
Publication date	Dec 16, 2025
Grant date	Dec 16, 2025

Abstract

This application relates to methods and apparatus for voltage monitoring of switching drivers. A modulator is configured to receive a modulator input signal and to controlling switching of an output stage of the switching driver to generate a first drive signal. A voltage monitor is configured to receive a first digital signal tapped from the modulator and to generate an indication of output voltage of the first drive signal from the first digital signal by controllably applying an adjustment from the first digital signal to compensate for inaccuracy between the first digital signal and the output voltage. The adjustment is based on monitored operation of the modulator. In some cases the monitored operation may be clipping of the switching driver. In some cases the monitored operation may be a signal generated by the modulator that include a contribution from a feedback signal of output voltage.

First claim

The invention claimed is:

1 . A circuit comprising:
a modulator configured to receive a modulator input signal and to generate at least one control signal based on the modulator input signal for controlling switching of an output stage of a switching driver to generate a first drive signal; and a voltage monitor configured to generate an indication of output voltage of the first drive signal, wherein the voltage monitor is configured to receive a first digital signal tapped from the modulator and to generate said indication of output voltage of the first drive signal from the first digital signal by controllably applying an adjustment from the first digital signal to compensate for inaccuracy between the first digital signal and the output voltage, wherein said adjustment is based on monitored operation of the modulator.

2 . The circuit of claim 1 wherein the first digital signal is the modulator input signal.

3 . The circuit of claim 1 wherein the monitored operation comprises operation of the modulator in a clipping condition and wherein the modulator is configured to output at least one indication of clipping to the voltage monitor.

4 . The circuit of claim 3 wherein operation of the modulator in a clipping condition comprises at least one of: clipping of an analog integrator of the modulator, clipping of a digital filter of the modulator; current limiting of an input current to the output stage being applied; current limiting of an output current from the output stage being applied; and a limit of duty-cycle of the output stage being applied.

5 . The circuit of claim 3 wherein the voltage monitor is configured:
to use the first digital signal to provide the indication of output voltage of the first drive signal when the switching driver is not operating in a clipping condition; and
to generate a synthesised signal to provide the indication of output voltage of the first drive signal when the switching driver is not operating in a clipping condition.

6 . The circuit of claim 5 wherein the voltage monitor is configured to generate the synthesised signal by holding a value of the first digital signal from a time at which the indication of clipping is received.

7 . The circuit of claim 1 wherein the modulator is a closed-loop modulator configured to receive a feedback signal from a first driver output node of the output stage and the indication of output voltage of the first drive signal generated by the voltage monitor is an indication of output voltage at the first driver output node.

8 . The circuit of claim 1 wherein the modulator is a closed-loop modulator configured to receive a feedback signal from a first driver output node of the output stage and wherein the voltage monitor is configured to process the first digital signal according to a defined transfer characteristic for a downstream path from the first driver output node to a load such that the indication of output voltage of the first drive signal generated by the voltage monitor is an indication of output voltage at the load.

9 . The circuit of claim 1 wherein the modulator is a closed-loop modulator configured to receive a feedback signal from a monitoring point of a downstream path from the output stage to a load and the indication of output voltage of the first drive signal generated by the voltage monitor is an indication of output voltage at the monitoring point.

10 . The circuit of claim 9 wherein said monitored operation of the modulator comprises monitoring a second signal generated by the modulator which includes a contribution from the modulator input signal and a contribution from the feedback signal.

11 . The circuit of claim 10 wherein the voltage monitor is configured to receive said second signal and voltage monitor is configured to use the second signal to process the first digital signal to recover the feedback signal.

12 . The circuit of claim 11 wherein the second signal is a digital signal.

13 . The circuit of claim 12 wherein the modulator comprises:
a digital-to-analog converter for receiving the modulator input signal and converting it to analog;
a combiner for combining the analog modulator input signal with the feedback signal; and
a filter arrangement configured to receive the analog output from the combiner, apply filtering and output a filtered digital signal, wherein the filter arrangement comprises a analogue-to-digital converter;
wherein the second signal is tapped from the output of the analogue-to-digital converter.

14 . The circuit of claim 13 wherein the filter arrangement comprises an analogue integrator between the combiner and the analogue-to-digital converter and the voltage monitor is configured to receive and differentiate the second signal and combine the differentiated second signal with the first signal to provide the indication of output voltage of the first drive signal.

15 . The circuit of claim 1 wherein the modulator comprises at least one of: an analogue integrator configured as a wrapping integrator; and a digital integrator configured as a wrapping integrator.

16 . The circuit of claim 1 further comprising digital processing circuitry upstream of the switching driver configured to provide the modulator input signal to the modulator wherein the digital processing circuitry is configured to receive the indication of output voltage of the first drive signal from the voltage monitor for use in at least one control process.

17 . The circuit of claim 16 wherein the digital processing circuitry is configured to receive the indication of output voltage of the first drive signal and to use it, together with an indication of output current from the output stage, for thermal protection of a load driven by the first drive signal.

18 . A driver apparatus for driving a load comprising:
a switching driver comprising an output stage configured to switch a first driver output node between different switching voltages to generate a first drive signal for driving the load at the first driver output node; and a modulator configured to receive a modulator input signal and to control switching of the output stage based on the modulator input signal; and a voltage monitor configured to generate an indication of output voltage of the first drive signal, wherein the voltage monitor is configured to receive a first digital signal indicative of the modulator input signal and a second digital signal indicative of modulator operation and to adjust the first digital signal based on the second digital signal to generate said indication of output voltage of the first drive signal.

19 . A circuit comprising:
a modulator configured to receive a modulator input signal and to generate at least one control signal based on the modulator input signal for controlling switching of an output stage of a switching driver to generate a first drive signal; and a voltage monitor configured to generate an indication of output voltage of the first drive signal, wherein the voltage monitor is configured to receive a first digital signal indicative of the modulator input signal and an indication of clipping of the modulator and:
to use the first digital signal to provide the indication of output voltage of the first drive signal when the switching driver is not clipping; and
to generate a synthesised signal to provide the indication of output voltage of the first drive signal when the switching driver is clipping.

20 . A circuit comprising:
a modulator configured to receive a modulator inpu

Assignees

• Cirrus Logic Int Semiconductor Ltd
• Cirrus Logic Inc

Inventors

• Morgan Ross C
• Robinson Michael

Classifications

• H03M1/46 Primary

  with digital/analogue converter for supplying reference values to converter · CPC title

• H03M1/0626

  by filtering · CPC title

• H03K17/082

  by feedback from the output to the control circuit · CPC title

• H03G7/08

  incorporating negative feedback · CPC title

• H03F3/2175

  using analogue-digital or digital-analogue conversion (H03F3/2173 takes precedence) · CPC title