Circuit for generating precision soft-start frequency for either value of address bit applied to external reset pin

1. A multi-function circuit comprising:

a programmable off-chip control input-coupling section comprising a single input pin adapted to receive a selected one of a plurality of different control inputs for programming respectively different parameters of said multi-function circuit; and

an on-chip signal generation section comprising an oscillator stage which is operative to generate the same periodic signal, in response to either of two different control inputs being applied to said single input pin for programming either of two different parameters of said multi-function circuit, and which is operative to produce a further output signal in response to a third control input being applied to said single input pin, wherein the on-chip signal generation section has a given function/property that is selectively programmable by the value of the control input applied to said single input pin.

2. The multi-function circuit according to claim 1 , wherein said oscillator stage is operative to generate said periodic signal as a prescribed soft-staff frequency signal for controlling switching times of output switching devices of a synchronous rectified buck mode DC-DC converter, in response to either of two control inputs, respectively representative of different logical values, being coupled to said single input pin.

3. The multi-function circuit according to claim 1 , wherein said oscillator stage is operative to generate the value of a selected bit of a multi-bit address of a driver device with which said multi-function circuit is associated, in accordance with the value of a control voltage coupled to said single pin.

4. The multi-function circuit according to claim 1 , wherein said oscillator stage is operative to produce said flirt her output signal as a reset output signal, in response to application of an external reset-representative control input to said single input pin.

5. The multi-function circuit according to claim 1 , wherein said respectively different parameters of said multi-function circuit include a first, decoded address bit-representative output, that corresponds to the logical value of the control input, a second, soft-staff oscillator signal for establishing switching times of output devices of an associated DC-DC converter power supply system, in response to the application of either of two logical values of an address bit-defining control input, and a third, reset output, that is selectively produced in response to the coupling of a prescribed external reset-representative control input to the single input pin.

6. The multi-function circuit according to claim 1 , wherein said oscillator stage is operative to generate an address output representative of a bit of a multi-bit address of a device containing said multi-function circuit, and trigger the generation of a soft-start frequency signal in response to either of two address bit-defining voltages being applied to an input resistor coupled to said single input pin of said off-chip programming section, and wherein said input pin is adapted to selectively receive an external register reset signal via a signal-coupling path that by-passes said input resistor.

7. The multi-function circuit according to claim 1 , wherein said on chip signal generation section is operative, in response to the application of said external register reset signal to said single input pin by way of said signal-coupling path, to generate a reset output for application to a reset terminal of a downstream register.

8. The multi-function circuit according to claim 1 , wherein said on chip signal generation section includes a relatively small valued resistor that couples said single input pin of said off chip programming section to input transistor circuit, which is operative to produce an output current mirrored by a first current mirror stage to control the generation of said periodic signal by said oscillator stage.

9. The multi-function circuit according to claim 8 , wherein said input transistor circuit is operative to produce a second output current that is mirrored by a second current mirror stage to control the generation of said periodic signal by said oscillator stage, for a second of said two different parameters of said multi-function circuit.

10. A multi-function circuit comprising:

a programming section having a single control pin that is adapted to receive a plurality of different control inputs that program respectively different parameters of said multi-function circuit; and

a signal generation section, which is operative to generate a periodic output signal, in response to the application of either of two different control inputs to said single input pin that program respectively different parameters of said multi-function circuit, and which is operative to produce a farther output signal in response to a third control input being applied to said single input pin;

wherein said signal generation section includes a relatively small valued resistor that couples said single input pin of said programming section to input transistor circuit of said signal generation section, which is operative to produce a first output current mirrored by a first current mirror stage of said signal generation section, to control generation of a soft-staff oscillator signal.

11. The multi-function circuit according to claim 10 wherein said signal generation section includes an oscillator stage that is operative to generate said periodic output signal as a prescribed soft-staff frequency signal for controlling switching operations of output switching devices of a DC-DC converter, in response to either of two control inputs, respectively representative of different logical values, being coupled to said single input pin.

12. The multi-function circuit according to claim 11 , wherein said signal generation section is operative, in accordance with the value of a control voltage coupled to said single pin, to generate the value of a selected bit of a multi-bit address of a driver device that controls switching operations of said output switching devices of said DC-DC converter.

13. The multi-function circuit according to claim 11 , wherein said respectively different parameters of said signal generation section circuit include a first, decoded address bit-representative output representative of the logical value of said control input, a second signal, comprising the soft-start oscillator signal for controlling switching operations of switching devices of an associated DC-DC converter power supply system, in response to the application of either of two logical values of an address bit-defining control input, and a third, reset output, that is selectively produced in response to the coupling of a prescribed external reset-representative control input to the single input pin.

14. The multi-function circuit according to claim 13 , wherein said input transistor circuitry is operative to produce a second output current that is mirrored by a second current mirror stage to control the generation of said periodic output signal by said oscillator stage.

15. The multi-function circuit according to claim 10 , wherein said signal generation section is operative to produce said further output signal as a reset output signal, in response to application of an external reset-representative control input to said single input pin.

16. A method of controllably generating a plurality of respectively different functional outputs in accordance with respectively different values of a control input, said method comprising the steps of:

(a) coupling said respectively different values of said control input to a single control pin that is off chip;

(b) generating a periodic output signal on-chip, in response to the application of either of two different control inputs to said single control pin; and

(c) generating a farther output signal in response to application of a third control input to said single control pin.

17. The method according to claim 16 , wherein step (b) comprises generating a prescribed soft-staff frequency signal for controlling switching operations of output switching devices of a DC-DC converter, in response to either of two control inputs, respectively representative of different logical values, being coupled to said single control pin.

18. The method according to claim 17 , wherein step (b) comprises generating the value of a selected bit of a multi-bit address of a driver device that controls switching operations of said output switching devices of said DC-DC converter, in accordance with the value of said control input coupled to said single control pin, and wherein step (c) comprises generating said further her output signal in response to application of an external reset-representative control input to said single control pin.