Power supply rail controller

• US 20030218386A1
• Filed: 01/24/2003
• Published: 11/27/2003
• Est. Priority Date: 01/25/2002
• Status: Active Grant

• Current Assignee: Masimo Corporation
• Original Assignee: Masimo Corporation
• Inventors: Smith, Robert, Al-Ali, Ammar, Diab, Mohamed K., Dalke, David, Coverston, Ronald
• Granted Patent: US 7,015,451 B2
• Time in Patent Office: Days
• US Class Current: 307/80
• CPC Class Codes: A61B 2560/0209 adapted for power saving
• CPC Class Codes: A61B 2560/0214 of power generation or supply
• CPC Class Codes: A61B 5/14551 for measuring blood gases

Abstract

A power supply rail controller operates on an analog component having a signal input, a power input and a signal output. A voltage controller provides a control output responsive to the signal output. A power supply generates a voltage for the power input, where the voltage is responsive to the control output. The voltage is reduced in magnitude to reduce power dissipation and increased in magnitude to avoid signal distortion.

Claims

1. A power supply rail controller comprising:

a preamplifier having a signal input, a power input and a signal output, said signal input adapted to receive a detector response to optical radiation;

a first power supply generating a first voltage;

a second power supply generating a second voltage, the magnitude of said second voltage being greater than the magnitude of said first voltage; and

a voltage selector providing an enable output responsive to said signal output,

wherein said power input is adapted to receive power from one of said first power supply and said second power supply as selected by said enable output.

2. The power supply rail controller according to claim 1 wherein said voltage selector comprises:

a comparator having a first input, a second input and a trigger output,

said first input set to a predetermined first threshold voltage,

said second input in communications with said signal output so that said trigger output is responsive to said signal output compared to said first threshold voltage,

said second power supply selected by said enable output in response to said trigger output.

3. The power supply rail controller according to claim 1 wherein said voltage selector comprises:

a digital signal processor (DSP) generating said enable output;

a voltage selection algorithm configured to execute on said DSP in response to said trigger output; and

a second threshold voltage embedded within said selection algorithm,

said DSP in communications with said signal output, and

said second power supply being disabled by said enable output in response to the magnitude of said signal output being less than the magnitude of said second threshold voltage.

4. The power supply rail controller according to claim 1 further comprising:

a supply isolation having a first input from said first power supply and a second input from said second power supply and a power output in communications with said power input,

said first power supply being always enabled,

said second power supply being selectively enabled, and

said supply isolation allowing said power input to be pulled to said second voltage when said second power supply is enabled.

5. The power supply rail controller according to claim 1 wherein said preamplifier comprises:

a first RC network providing feedback from said signal output to an inverting input; and

a second RC network providing a load to a non-inverting input,

said first RC network identical to said second RC network so that said signal input is a balanced, differential input.

6. A power supply rail controller method comprising the steps of:

preamplifying a detector signal input utilizing a power input so as to generate a signal output;

generating a low voltage for said power input so as to lower power consumption;

generating a high voltage for said power input so as to reduce distortion on said signal output;

setting a threshold voltage;

monitoring said signal output in relation to said threshold voltage; and

selecting one of said low voltage and said high voltage for said power input in response to said monitoring step.

7. The power supply rail controller method according to claim 6 wherein said preamplifying step comprises the substep of providing a balanced input to said detector input signal configured to amplify differential voltage and reject common mode voltage.

8. The power supply rail controller method according to claim 6 wherein said setting step comprises the substeps of:

calculating a maximum signal output before saturation with said low voltage on said power input; and

predetermining a percentage of said maximum signal output as said threshold voltage.

9. The power supply rail controller method according to claim 8 wherein said predetermining step comprises the substeps of:

calculating a first percentage for a first threshold voltage to use when selecting said high voltage so as to allow sufficient time to avoid signal distortion; and

calculating a second percentage for a second threshold voltage to use when selecting said low voltage, said second percentage sufficiently less than said first percentage so as to reduce sensitivity to said signal output.

10. The power supply rail controller method according to claim 6 wherein said monitoring step comprises the substeps of:

comparing said signal output to said threshold voltage; and

triggering a processor interrupt when said signal output exceeds said threshold voltage.

11. The power supply rail controller method according to claim 10 wherein said monitoring step comprises the further substep of indicating when said signal output returns below a lower second threshold voltage.

12. The power supply rail controller method according to claim 10 wherein said selecting step comprises the substep of selecting said high voltage in response to said triggering substep.

13. The power supply rail controller method according to claim 11 wherein said selecting step comprises the substep of selecting said low voltage in response to said indicating substep.

14. The power supply rail controller method according to claim 6 wherein said selecting step comprises the substeps of:

enabling said low voltage for said power input;

isolating said low voltage from said high voltage; and

selectively enabling said high voltage for said power input so as to pull said power input from said low voltage to said high voltage.

15. A power supply rail controller comprising:

a preamplifier means for inputting a detector signal and providing gain to generate an output signal;

a first supply means for generating a low supply voltage to said preamplifier means;

a second supply means for generating a high supply voltage to said preamplifier means; and

a voltage selection means for enabling one of said first and second supply means in response to said output signal.

16. The power supply rail controller according to claim 15 further comprising a isolation means for routing said low supply voltage and said high supply voltage to said preamplifier means.

17. The power supply rail controller according to claim 15 wherein said voltage selection means comprises a comparator means for indicating when said output signal exceeds a predetermined threshold so as to enable said second supply means.

18. The power supply rail controller according to claim 15 wherein said voltage selection means comprises a processor means for monitoring said output signal and deciding when to re-enable said first supply means.

19. The power supply rail controller according to claim 15 wherein said preamplifier means comprises a differential input means for rejecting common mode noise.

20. A power supply rail controller comprising:

an analog component having a signal input, a power input and a signal output;

a voltage controller providing a control output responsive to said signal output; and

a power supply generating a voltage for said power input, wherein said voltage is responsive to said control output so that said voltage is reduced in magnitude to reduce power dissipation and increased in magnitude to avoid signal distortion.