Method and system for powering down an analog-to-digital converter into a sleep mode

• US 6,642,879 B2
• Filed: 07/16/2001
• Issued: 11/04/2003
• Est. Priority Date: 07/16/2001
• Status: Active Grant

• Current Assignee: Cirrus Logic Incorporated
• Original Assignee: Cirrus Logic Incorporated
• Inventors: Steiner, Philip, Amar, Aryesh
• Primary Examiner(s): Jeanpierre, Peguy
• Application Number:
  US09/906,916
• Publication Number:
  US 20030011499A1
• Time in Patent Office: 841 Days
• Field of Search: 341/155, 341/122, 713/324, 713/323
• US Class Current: 341/155
• CPC Class Codes: H03M 1/002 Provisions or arrangements for saving power, e.g. by allowing a sleep mode, using lower supply voltage for downstream stages, using multiple clock domains or by selectively turning on stages when needed
• CPC Class Codes: H03M 3/32 with special provisions or arrangements for power saving, e.g. by allowing a sleep mode, using lower supply voltage for downstream stages, using multiple clock domains, by selectively turning on stages when needed
• CPC Class Codes: H03M 3/474 using time-division multiplexing

Abstract

A method and system for powering down an analog-to-digital converter (“ADC”) into a sleep mode are disclosed. If the ADC receives a normal set of pulses for a serial clock signal of the ADC, a serial interface controller outputs converted data requested by a user through a serial interface. Also, if the ADC receives a sleep set of pulses for the serial clock signal, a state machine of the ADC powers down the ADC into a sleep mode in which at least parts of the ADC are operated at a reduced power consumption level. Furthermore, if the ADC is in the sleep mode and the ADC receives a wake-up set of pulses for the serial clock signal, the state machine powers back up the ADC from the sleep mode.

Claims

1. A method for powering down an analog-to-digital converter (“

ADC”

) into a sleep mode, comprising the steps of;

in response to an analog-to-digital converter (“

ADC”

) receiving a normal set of serial clock pulses, outputting, by a serial interface controller, converted data requested by a user through a serial interface;

in response to the ADC receiving a sleep set of serial clock pulses powering down, by a state machine of the ADC, the ADC into a sleep mode in which at least parts of the ADC are operated at a reduced power consumption level; and

in response to the ADC being in the sleep mode and the ADC receiving a wake-up set of serial clock pulses, powering up, by the state machine, the ADC from the sleep mode; and

wherein a serial clock signal of the ADC provides either the normal set of serial clock pulses, the sleep set of serial clock pulses or the wake-up set of serial clock pulses and the state machine distinguishes which one of the three sets of serial clock pulses is being provided by the serial clock signal.

2. The method according to claim 1, further comprising the steps of:

determining the ADC receiving the sleep set of serial clock pulses by initializing a state of the state machine to a zero state, incrementing the state by one as each of the pulses is received, determining whether a predetermined state of the state machine has been reached and the serial interface controller has received a high done signal from a digital block of the ADC signifying completion of data conversion; and

in response to the state machine reaching the predetermined state and the serial interface controller receiving the high done signal, changing, by the state machine, a sleep value to a high value, which signifies the ADC to enter the sleep mode.

3. The method according to claim 2, further comprising the steps of:

determining the ADC receiving the wake-up set of serial clock pulses only after the ADC has entered into the sleep mode by further incrementing the state by one as each of other pulses is received and determining whether another predetermined state of the state machine has been reached; and

in response to the state machine reaching the another predetermined state and the sleep value is at the high value, changing, by the state machine, the sleep value from the high value back to the low value, which signifies the ADC to wake up from the sleep mode and resetting the state to the zero state.

4. The method according to claim 2 further comprising the steps of:

determining the ADC receiving the normal set of serial clock pulses by further incrementing the state by one as each of other pulses is received and determining whether the predetermined state of the state machine has been reached and the serial interface controller has not received the high done signal; and

in response to the state machine reaching the predetermined state and the serial interface controller not receiving the high done signal, maintaining, by the state machine, the sleep value to a low value signifying the ADO to operate in a normal mode until a final pulse of the normal set of serial clock pulses has been received.

5. The method according to claim 4, further comprising the step of:

resetting the state to the zero state and restarting execution of the method steps after the ADC operates in the normal mode and finishes outputting the converted data requested by the user and after the state machine receives the final pulse of the normal set of serial clock pulses.

6. The method according to claim 1, further comprising the step of:

idling the ADC, by the state machine, if a signal is not provided as the serial clock signal.

7. The method according to claim 1, wherein a state of the state machine is defined for powering down the ADC Into the sleep mode.

8. The method according to claim 1, wherein:

the normal set of serial clock pulses determines and indicates operating the ADC in a normal mode;

the sleep set of serial clock pulses determines and indicates powering down the ADC into a sleep mode; and

the wake-up set of serial clock pulses determines and indicates waking up the ADC from the sleep mode and operating the ADC in the normal mode.

9. A serial interface controller for an analog-to-digital converter (“

ADC”

) having a digital system and an analog system wherein the serial interface controller allows a serial device to be coupled to the ADC and the serial interface controller controls the ADC in a normal mode or a sleep mode, comprising;

a state machine having components coupled together in a manner to provide serial interface control operations which include;

in response to the ADC receiving a normal set of serial clock pulses the serial interface controller outputs converted data requested by a user through a serial interface;

in response to the ADC receiving a sleep set of serial clock pulses the state machine powers down the ADC into a sleep mode in which at least parts of the ADC are operated at a reduced power consumption level; and

in response to the ADC being in the sleep mode and the ADC receiving a wake-up set of serial clock pulses, the state machine powers up the ADC from the sleep mode; and

wherein a serial clock signal of the ADC provides either the normal set of serial clock pulses, the sleep set of serial clock pulses, or the wake-up set of serial clock pulses and the state machine distinguishes which one of the three sets of serial clock pulses is being provided by the serial clock signal.

10. The serial interface controller according to claim 9, wherein the components provide the serial interface control operations that further comprise:

the ADC determines receipt of the sleep set of serial clock pulses by initializing a state of the state machine to a zero state, incrementing the state by one as each of the pulses is received, determining whether a predetermined state of the state machine has been reached and the serial interface controller has received a high done signal from a digital block of the ADC signifying completion of data conversion; and

in response to the state machine reaching the predetermined state and the serial interface controller receiving the high done signal, the state machine changes a sleep value to a high value signifying the ADC to enter the sleep mode.

11. The serial interface controller according to claim 10, wherein the components provide the serial interface control operations that further comprise:

the ADC determines receipt of the wake-up set of serial clock purses only after the ADC has entered into the sleep mode by further incrementing the state by one as each of other pulses is received and determining whether another predetermined state of the state machine has been reached; and

in response to the state machine reaching the another predetermined state, the state machine changes the sleep value from the high value back to the low value signifying the ADC to wake up from the sleep mode and the state machine resets the state to the zero state.

12. The serial interface controller according to claim 10 wherein the components provide the serial interface control operations that further comprise:

the ADC determines receipt of the normal set of serial clock pulses by further incrementing the state by one as each of other pulses is received and determining whether the predetermined state of the state machine has been reached and the serial interface controller has not received the high done signal; and

in response to the state machine reaching the predetermined state and the serial interface controller not receiving the high done signal, the state machine maintains the sleep value to a low value signifying the ADC operating in a normal mode until a final pulse of the normal set of serial clock pulses has been received.

13. The serial interface controller according to claim 12, wherein the components provide the serial interface control operations that further comprise:

the ADC resets the state to the zero state and restarts execution after operating in the normal mode and finishes outputting the converted data requested by the user after the state machine receives the final pulse of the normal set of serial clock pulses.

14. The serial interface controller according to claim 9, wherein the components provide the serial interface control operations that further comprise:

the state machine idles the ADC if a signal is not provided as the serial clock signal.

15. The serial interface controller according to claim 9, wherein a state of the state machine is defined for powering down the ADC into the sleep mode.

16. The serial interface controller according to claim 9, wherein:

the normal set of serial clock pulses determines and indicates operating the ADC in a normal mode;

the sleep set of serial clock pulses determines and indicates powering down the ADC into a sleep mode; and

the wake-up set of serial clock pulses determines and indicates waking up the ADC from the sleep mode and operating the ADC in the normal mode.

17. An analog-to-digital converter (“

ADC”

) for converting analog signals to digital signals, comprising;

an analog system having a modulator for processing and converting analog signals to digital signals; and

a digital system coupled to the analog system wherein the digital system processes and outputs the digital signals;

wherein the digital system has a digital logic system, a clock generator, a filter, and a serial port block coupled to each other wherein the serial port block further comprises a serial data interface with a serial interface controller which allows a serial device to be coupled to the ADC and the serial interface controller controls the ADC in a normal mode or a sleep mode, and

wherein the serial interface controller comprises a state machine having components coupled together in a manner to provide serial interface control operations which include;

in response to the ADC receiving a normal set of serial clock pulses, the serial interface controller outputs converted data requested by a user through a serial interface;

in response to the ADC receiving a sleep set of serial clock pulses, the state machine powers down the ADC into a sleep mode in which at least parts of the ADC are operated at a reduced power consumption level; and

in response to the ADC being in the sleep mode and the ADC receiving a wake-up set of serial clock pulses, the state machine powers up the ADC from the sleep mode; and

wherein a serial clock signal of the ADC provides either the normal set of serial clock pulses, the sleep set of serial clock pulses, or the wake-us set of serial clock pulses and the state machine distinguishes which one of the three sets of serial clock pulses is being provided by the serial clock signal.

18. The ADC according to claim 17, wherein the components provide the serial interface control operations that further comprise:

the ADC determines receipt of the sleep set of serial clock pulses by initializing a state of the state machine to a zero state, incrementing the state by one as each of the pulses is received, determining whether a predetermined state of the state machine has been reached and the serial interface controller has received a high done signal from a digital block of the ADO signifying completion of data conversion; and

in response to the state machine reaching the predetermined state and the serial interface controller receiving the high done signal, the state machine changes a sleep value to a high value signifying the ADC to enter the sleep mode.

19. The ADC according to claim 18, wherein the components provide the serial interface control operations that further comprise:

the ADC determines receipt of the wake-up set of serial clock pulses only after the ADC has entered into the sleep mode by further incrementing the state by one as each of other pulses is received and determining whether another predetermined state of the state machine has been reached; and

in response to the state machine reaching the another predetermined state, the state machine changes the sleep value from the high value back to the low value signifying the ADC to wake up from the sleep mode and the state machine resets the state to the zero state.

20. The ADC according to claim 18 wherein the components provide the serial Interface control operations that further comprise:

the ADC determines receipt of the normal set of serial clock pulses by further incrementing the state by one as each of other pulses is received and determining whether the predetermined state of the state machine has been reached and the serial interface controller has not received the high done signal; and

in response to the state machine reaching the predetermined state and the serial interface controller not receiving the high done signal, the state machine maintains the sleep value to a low value signifying the ADC operating in a normal mode until a final pulse of the normal set of serial clock pulses has been received.

21. The ADC according to claim 20, wherein the components provide the serial interface control operations that further comprise:

the ADC resets the state to the zero state and restarts execution after operating in the normal mode and finishes outputting the converted data requested by the user after the state machine receives the final pulse of the normal set of serial clock pulses.

22. The ADC according to claim 17, wherein the components provide the serial interface control operations that further comprise:

the state machine idles the ADC if a signal is not provided as the serial clock signal.

23. The ADC according to claim 17, wherein a state of the state machine is defined for powering down the ADC into the sleep mode.

24. The ADC according to claim 17, wherein:

the normal set of serial clock pulses determines and indicates operating the ADC in a normal mode;

the sleep set of serial dock pulses determines and indicates powering down the ADC into a sleep mode; and

the wake-up set of serial clock pulses determines and indicates waking up the ADC from the sleep mode and operating the ADC in the normal mode.

25. A method of utilizing a serial clock signal for controlling an analog-to-digital converter between a normal operational mode and a sleep mode, comprising the steps of:

sending a sleep clock signal to indicate an analog-to-digital converter (“

ADC”

) to power down into a sleep mode;

when the ADC is in the sleep mode, sending a wake up signal to indicate the ADC to power up from the sleep mode; and

sending a normal clock signal to indicate the ADC to convert and output data in a normal operational mode; and

wherein a serial clock signal provides either the sleep clock signal, the wake up signal, or the normal clock signal.

26. The method according to claim 25, further comprising the steps of:

intializing a sleep value to a low value wherein the sleep value set to a high value signifies the ADC to enter the sleep mode and the sleep value set to a low value signifies the ADC to operate in a normal mode;

initializing a state of a state machine of the ADC to a zero state;

incrementing the state by one as each pulse of the serial clock signal is received;

determining the serial clock signal has sent the sleep clock signal by determining whether the state machine has reached a predetermined state and a serial interface of the ADC has received a high done signal from a digital block of the ADC;

when the ADC is in the sleep mode, determining the serial clock signal has sent the wake up signal by determining whether the state machine has reached another predetermined state and the sleep value is equal to a high value; and

determining the serial clock signal has sent the normal clock signal by determining whether the state machine has reached the predetermined state and the high done signal has not been received from the digital block by the serial interface.

27. The method according to claim 25, further comprising:

distinguishing, by a state machine, which one of the sleep clock signal, the wake up signal, or the normal clock signal is being provided by the serial clock signal.

28. The method according to claim 26, wherein:

the normal clock signal is a normal set of serial clock pulses which determines and indicates operating the ADC in the normal operational mode;

the sleep clock signal is a sleep set of serial clock pulses which determines and indicates powering down the ADC into a sleep mode; and

the wake up signal is a wake-up set of pulses which determines and indicates waking up the ADC from the sleep mode and operating the ADC in the normal operational mode.