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1. (WO2018100389) RÉGULATEURS DE TENSION
Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

Claims

1. An electronic device comprising a voltage regulation circuit portion arranged to receive an input voltage and provide a regulated output voltage, the voltage regulation circuit portion comprising:

a first voltage regulator arranged to receive the input voltage at a first regulation input and a first reference voltage at a first reference input, said first voltage regulator being arranged, in a first mode of operation, to vary the regulated output voltage in response to a difference between the regulated output voltage and the first reference voltage;

a first reference voltage source arranged to provide said first reference voltage;

a second voltage regulator arranged to receive the input voltage at a second regulation input and a second reference voltage at a second reference input, said second voltage regulator being arranged, in a second mode of operation, to vary the regulated output voltage in response to a difference between the regulated output voltage and the second reference voltage, said second voltage regulator being arranged to provide a greater maximum output current than said first voltage regulator;

a second reference voltage source arranged to provide said second reference voltage;

a switch portion arranged to connect the first reference voltage to the second reference input in a third mode of operation in which the first voltage regulator provides the regulated output voltage and the second voltage regulator provides additional output current.

2. The electronic device as claimed in claim 1 , wherein the first reference voltage source comprises a bandgap reference circuit.

3. The electronic device as claimed in claim 1 or 2, wherein the second reference voltage source comprises a bandgap reference circuit.

4. The electronic device as claimed in any preceding claim, wherein the third mode of operation comprises a transitory mode that is activated in response to a transition in the output current to a value greater than the maximum output current of the first voltage regulator.

5. The electronic device as claimed in any preceding claim, arranged to generate a signal indicative of the second reference voltage source being initialised and to switch from the third mode of operation to the second mode of operation upon said signal being generated.

6. The electronic device as claimed in claim 5, further comprising a reference voltage monitor circuit arranged to generate said signal indicative of the second reference voltage source being initialised.

7. The electronic device as claimed in any preceding claim, wherein the second reference voltage source comprises:

a bandgap circuit portion comprising first and second reference transistors and a current source arranged to drive the first reference transistor at a first current density and to drive the second reference transistor at a second, different current density, wherein the first reference transistor is connected to a first node and the second reference transistor is connected to a second node;

an operational transconductance amplifier arranged to produce an output current that is proportional to a difference between a voltage at the first node and a voltage at the second node; and

an output current mirror circuit portion arranged to generate a mirror current that is a scaled version of the output current and drive said mirror current through a load so as to produce the second reference voltage;

wherein the reference voltage monitor circuit portion is arranged to monitor the operational transconductance amplifier and generate a flag if a current flowing through the operational transconductance amplifier exceeds a threshold.

8. The electronic device as claimed in claim 7, wherein the operational transconductance amplifier comprises first and second differential pair field-effect-transistors arranged such that a gate terminal of the first differential pair field-effect-transistor is connected to the first node and a gate terminal of the second differential pair field-effect-transistor is connected to the second node.

9. The electronic device as claimed in claim 8, wherein the operational transconductance amplifier comprises first and second current mirror load field-effect-transistors, arranged such that:

a drain terminal of the first current mirror load field-effect-transistor is connected to a drain terminal of the first differential pair field-effect-transistor;

a drain terminal of the second current mirror load field-effect-transistor is connected to a drain terminal of the second differential pair field-effect-transistor; and

respective gate terminals of the first and second current mirror load field-effect-transistors are connected to the drain terminal of the first current mirror load field-effect-transistor.

10. The electronic device as claimed in claim 9, wherein the first current mirror load field-effect-transistor is matched to the first replica current mirror field-effect-transistor.

11. The electronic device as claimed in any preceding claim, further comprising a second current mirror and a replica field-effect-transistor having a gate terminal thereof connected to the first node, and wherein the second current mirror is arranged to generate a replica current that is a scaled version of the output current and drive said replica current through a first reference resistor so as to generate a voltage at a monitor node between the second current mirror and the first reference resistor.

12. The electronic device as claimed in claim 1 1 , wherein the second current mirror comprises first and second replica current mirror field-effect-transistors, arranged such that: respective gate terminals of the first and second replica current mirror field-effect-transistors are connected to a drain terminal of the first replica current mirror field-effect-transistor and to a drain terminal of the replica field-effect-transistor; and a drain terminal of the second replica current mirror field-effect-transistor is connected to the monitor node.

13. The electronic device as claimed in claim 1 1 or 12, wherein the reference voltage monitor circuit comprises a single-input logic gate having an input terminal thereof connected to the monitor node, wherein the logic gate is arranged to

produce a first logic value at an output thereof if the voltage at the monitor node is above a first threshold and to produce a second logic value at the output if the voltage at the monitor node is below a second threshold.

14. The electronic device as claimed in claim 13, wherein the logic gate comprises a Boolean inverter, wherein the first logic value is logic low and the second logic value is logic high.

15. The electronic device as claimed in claim 14, comprising a hysteresis arrangement connected between the input and the output of the inverter and is arranged such that the first threshold is different to the second threshold.

16. The electronic device as claimed in claim 15, wherein the hysteresis arrangement comprises a second reference resistor and a switching arrangement, and wherein said switching arrangement selectively couples the first and second reference resistors.

17. The electronic device as claimed in any preceding claim, arranged to operate in the third mode of operation upon powering up said device if the required output current exceeds the maximum output current of the first voltage regulator.

18. The electronic device as claimed in claim 17, arranged to switch to the second mode of operation once the second voltage regulator is ready for use.

19. The electronic device as claimed in any preceding claim, wherein the first reference voltage source is arranged to receive the input voltage and to generate the first reference voltage therefrom.

20. The electronic device as claimed in any preceding claim, wherein the second reference voltage source is arranged to receive the output voltage and to generate the second reference voltage therefrom.

21. The electronic device as claimed in any preceding claim, wherein the switch portion is arranged to mirror a replica current from the first voltage regulator to the second voltage regulator when operating in the third mode of operation.

22. The electronic device as claimed in any preceding claim, further comprising a load current monitor circuit portion arranged to monitor the output current and selectively enable the first mode of operation if the output current is less than a first threshold value.

23. The electronic device as claimed in any of claims 1 to 21 , further comprising a load current monitor circuit portion arranged to monitor the output current and selectively enable the second mode of operation if the output current is greater than a second threshold value.

24. The electronic device as claimed in claim 22, wherein the load current monitor circuit portion is further arranged to monitor the output current and selectively enable the second mode of operation if the output current is greater than a second threshold value.

25. The electronic device as claimed in claim 24, wherein the first and second threshold values are the same.

26. The electronic device as claimed in claim 24, wherein the first and second threshold values are different.