System and method for multi-channel control system

• US 9,438,452 B2
• Filed: 01/17/2014
• Issued: 09/06/2016
• Est. Priority Date: 04/01/2008
• Status: Active Grant

• Current Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Original Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Inventors: Ploix, Olivier Dominique
• Primary Examiner(s): ORTIZ RODRIGUEZ, CARLOS R
• Application Number:
  US14/158,498
• Publication Number:
  US 20140133545A1
• Time in Patent Office: 963 Days
• Field of Search: 375/238, 700/73
• US Class Current: 1/1
• CPC Class Codes: G05B 19/0423 Input/output
• CPC Class Codes: G05B 2219/21013 Microcontroller and power output switches integrated on same chip
• CPC Class Codes: G08C 19/22 by varying the duration of individual pulses
• CPC Class Codes: H04L 25/4902 Pulse width modulation; Pulse position modulation
• CPC Class Codes: H05B 45/37 Converter circuits
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A system having has a pulse width modulation controller to successively activate each of a plurality of channels each in its own individual channel time slot is described. The system also has a sampling multiplexer configured to successively sample a signal derived from each of the plurality of channels during each individual channel time slot. Each individual time slot has an individual sampling sequence.

Claims

1. A multichannel control system comprising:

a pulse width modulation controller, wherein the pulse width modulation controller is configured to successively activate each of a plurality of channels, each channel of the plurality of channels having a non-overlapping individual channel time slot different from other channels of the plurality of channels, each individual channel time slot being a duration of time in which a corresponding channel is activated; and

a sampling multiplexer configured to successively sample one after another a signal derived from each of the plurality of channels during each individual channel time slot, wherein all of the derived signals are individually sampled within each individual channel time slot, wherein each individual channel time slot comprises an individual sampling sequence having a sampling order, and wherein the sampling order of each individual channel time slot is different from each of the individual sampling sequences of channel time slots associated with the other channels of the plurality of channels.

2. The multichannel control system according to claim 1, wherein each individual sampling sequence samples each of the plurality of channels a fixed delay from a beginning of each individual channel time slot.

3. The multichannel control system according to claim 1, further comprising an Analog to Digital converter coupled to an output of the sampling multiplexer.

4. The multichannel control system according to claim 1, further comprising a bus interface coupled to the pulse width modulation controller and the sampling multiplexer.

5. The multichannel control system according to claim 4, wherein the bus interface comprises a Serial Peripheral Interface (SPI) Bus.

6. The multichannel control system according to claim 4, wherein the bus interface comprises a Local Interconnect (LIN) Bus, a Controller Area Network (CAN) bus.

7. The multichannel control system according to claim 1, wherein each individual sampling sequence comprises a barrel shifted version of a same sequence in which the pulse width modulation controller successively activates each of the plurality of channels.

8. The multichannel control system according to claim 7, wherein the individual sampling sequence is barrel shifted such that a second element of each individual sampling sequence corresponds to a channel currently being activated by the pulse width modulation controller.

9. The multichannel control system according to claim 1, further comprising a lamp driver coupled to at least one of a plurality of output drivers coupled to the pulse width modulation controller.

10. The multichannel control system of claim 9, wherein the lamp driver comprises an LED driver.

11. The multichannel control system of claim 9, wherein the sampling multiplexer is coupled to a current related to a current supplied by at least one of the plurality of output drivers.

12. A method of operating a multichannel control system, the method comprising:

activating an output on a first channel, wherein activating comprises transitioning from one state to another state;

while activating the output on the first channel, sampling a signal derived from a channel other than the first channel and not sampling a signal derived from the first channel;

after sampling the signal derived from the channel other than the first channel, sampling the signal derived from the first channel;

activating an output on a second channel after sampling the signal derived from the first channel;

while activating the output on the second channel, resampling the signal derived from the first channel and not sampling a signal derived from the second channel; and

after resampling the signal derived from the first channel, sampling the signal derived from the second channel.

13. The method of claim 12, further comprising:

converting the sampled signal from the first channel from an analog domain to a digital domain representation; and

writing the digital domain representation to a first channel A/D register.

14. The method of claim 13, further comprising:

writing a command on an interface bus to activate the first channel before activating the output on the first channel;

writing a command on the interface bus to read the first channel A/D register; and

reading the first channel A/D register on the interface bus.

15. The method of claim 14, further comprising reading the first channel A/D register for a last sample before the first channel is deactivated.

16. The method of claim 15, wherein:

activating the output on the first channel comprises illuminating a light;

writing a command on the interface bus to activate the first channel comprises writing a frequency and a pulse width;

the sampled signal from the first channel is a signal derived from a performance parameter of the light; and

the method further comprising adjusting the frequency and pulse width based on contents of the first channel A/D register.

17. The method of claim 14, wherein writing a command on the interface bus to activate the first channel comprises writing a pulse width.

18. The method of claim 12, wherein activating the output on the first channel comprises illuminating a light.

19. The method of claim 12, further comprising sampling a signal derived from the second channel after sampling the signal derived from the first channel.

20. The method of claim 19, further comprising:

successively activating outputs on additional channels;

sampling a signal derived from each additional channel a fixed period of time after each channel is activated;

converting the signal derived from each additional channel a fixed period of time after each channel is activated to a digital domain; and

writing the converted signal from each additional channel to a channel designated A/D register, wherein the channel designated A/D register is overwritten;

deactivating an output on a particular channel; and

holding a value of a A/D register of the particular channel after deactivating the output of the particular channel.

21. A semiconductor circuit for controlling a plurality of lights, the semiconductor circuit comprising:

a pulse width modulator, the pulse width modulator configured to

provide a signal comprising a duty cycle and a frequency to a plurality of output channels, and

stagger a timing of each signal on the plurality of output channels so that none of the plurality of outputs transition simultaneously;

feedback paths coupled to ones of the plurality of output channels;

an analog to digital converter configured to successively sample each of the feedback paths; and

a bus interface coupled to the pulse width modulator and the analog to digital converter, wherein each output channel is activated in a first repeating sequence of designated output channel time slots; and

the analog to digital converter successively samples each of the feedback paths in a second repeating sequence, wherein the second repeating sequence depends on which one of the designated output time slots is active.

22. The semiconductor circuit of claim 21, wherein the second repeating sequence comprises a shift of the first repeating sequence, wherein a magnitude of the shift depends on which one of the designated output time slots is active.

23. The semiconductor circuit of claim 22, wherein the shift is configured to cause a feedback channel coupled to a present channel to be sampled at a fixed number of second repeating sequence intervals from a beginning of a present channel time period.

24. The semiconductor circuit of claim 22, wherein the pulse width modulator is configured to output a plurality of output frequencies and a plurality of pulse widths.

25. The semiconductor circuit of claim 21, further comprising light sources coupled to ones of the plurality of output channels.

26. The semiconductor circuit of claim 21, wherein the pulse width modulator comprises a counter and a plurality of delay circuits coupled to an output of the counter, wherein the plurality of output channels are coupled to corresponding outputs of the plurality of delay circuits.

27. The semiconductor circuit of claim 26, further comprising a plurality of output circuits coupled between corresponding outputs of the plurality of delay circuits and the plurality of output channels.

28. The semiconductor circuit of claim 26, wherein an output of a first of the plurality of delay circuits is coupled to an input of a second of the plurality of delay circuits.

29. The semiconductor circuit according to claim 21, further comprising:

a first gate control circuit having an input coupled to a first output channel of the plurality of output channels, the first gate control circuit having an output configured to be coupled to a gate of a first transistor; and

a first current sense circuit having an input configured to be coupled to a sensing terminal of the first transistor and an output coupled to a first feedback path of the feedback paths corresponding to the first output channel.

30. The semiconductor circuit according to claim 29, further comprising the first transistor, wherein the first transistor comprises a current sensing cell coupled to the sensing terminal.

31. The semiconductor circuit according to claim 29, further comprising:

a second gate control circuit having an input coupled to a second output channel of the plurality of output channels, the second gate control circuit having an output configured to be coupled to a gate of a second transistor; and

a second current sense circuit having an input configured to be coupled to a sensing terminal of the second transistor and an output coupled to a second feedback path of the feedback paths corresponding to the second output channel.

32. A system for controlling a pulse width modulated peripheral device, the system comprising:

a pulse width modulator configured to provide a signal comprising a duty cycle and a frequency to a plurality of output channels, and stagger a timing of each signal on the plurality of output channels so that none of the plurality of output channels turn on simultaneously;

peripheral devices coupled to ones of the plurality of output channels;

feedback paths coupled to ones of the plurality of output channels;

an analog to digital converter configured to successively sample each of the feedback paths and write a digital domain representation of sampled signal on each of the feedback paths to a corresponding A/D register;

a bus interface coupled to the pulse width modulator and the analog to digital converter; and

a controller coupled to the bus interface, the controller configured to issue commands to the pulse width modulator, wherein the bus interface is configured to receive a command to activate a selected channel of the plurality of output channels, receive a command to read an A/D register corresponding to the selected channel, and provide contents of the A/D register corresponding to the selected channel.

33. A multichannel control system comprising:

a controller configured to perform the step of activating an output on a first channel; and

a sampling multiplexer configured to sample a signal derived from a channel other than the first channel and to not sample a signal derived from the first channel while the controller activates the output on the first channel, and sample the signal derived from the first channel after sampling the signal derived from the channel other than the first channel, wherein

the controller is further configured to perform the step of activating an output on a second channel after the sampling multiplexer samples the signal derived from the first channel; and

the sampling multiplexer is further configured to resample the signal derived from the first channel and to not sample a signal derived from the second channel while the controller activates the output on the second channel.

34. The multichannel control system of claim 33, further comprising an analog to digital converter configured to:

convert the sampled signal from the first channel from an analog domain to a digital domain representation; and

write the digital domain representation to a first channel A/D register.

35. The multichannel control system of claim 34, wherein:

the controller is further configured to perform the step of successively activating outputs on additional channels;

the sampling multiplexer is further configured to sample a signal derived from each additional channel a fixed period of time after each channel is activated;

the analog to digital converter is further configured to

convert the signal derived from each additional channel a fixed period of time after each channel is activated to a digital domain, and

write the converted signal from each additional channel to a channel designated A/D register, wherein the channel designated A/D register is overwritten; and

the controller is further configured to perform the steps of

deactivating an output on a particular channel, and

holding a value of a A/D register of the particular channel after deactivating the output of the particular channel.

36. The multichannel control system of claim 34, wherein the controller is further configured to perform the steps of:

writing a command on an interface bus to activate the first channel before activating the output on the first channel;

writing a command on the interface bus to read the first channel A/D register; and

reading the first channel A/D register on the interface bus.

37. The multichannel control system of claim 36, wherein the controller is further configured to perform the step of reading the first channel A/D register for a last sample before the first channel is deactivated.

38. The multichannel control system of claim 37, wherein:

the step of activating the output on the first channel comprises illuminating a light;

the step of writing the command on the interface bus to activate the first channel comprises writing a frequency and a pulse width;

the sampled signal from the first channel is a signal derived from a performance parameter of the light; and

the controller is further configured to perform the step of adjusting the frequency and pulse width based on contents of the first channel A/D register.

39. The multichannel control system of claim 36, wherein the step of writing the command on the interface bus to activate the first channel comprises writing a pulse width.

40. The multichannel control system of claim 33, wherein the step of activating the output on the first channel comprises illuminating a light.

41. The multichannel control system of claim 33, wherein the controller is further configured to perform the step of sampling a signal derived from the second channel after sampling the signal derived from the first channel.