Precision output control for DC voltage regulators
View Patent ↗A power supply includes an input terminal, an output terminal, a DC voltage regulator coupled between the input terminal and the output terminal to provide a substantially constant DC output voltage at the output terminal, a voltage divider coupled between the output terminal and ground (e.g., earth ground or another suitable reference potential), the voltage divider including at least a first resistance, a second resistance and a first node between the first resistance and the second resistance, the first node coupled to the DC voltage regulator to provide a feedback voltage to the DC voltage regulator for regulating the DC output voltage, and an adjustable shunt regulator coupled between the output terminal and the first node.
1. A power supply comprising:
an input terminal;
an output terminal;
a DC voltage regulator coupled between the input terminal and the output terminal to provide a substantially constant DC output voltage at the output terminal;
a voltage divider coupled between the output terminal and ground, the voltage divider including at least a first resistance, a second resistance and a first node between the first resistance and the second resistance, the first node coupled to the DC voltage regulator to provide a feedback voltage to the DC voltage regulator for regulating the DC output voltage; and
an adjustable shunt regulator coupled between the output terminal and the first node.
2. The power supply of claim 1 further comprising a digital controller having a supply voltage input, wherein the output terminal is coupled to the digital controller's supply voltage input.
3. The power supply of claim 2 wherein the digital controller includes a reference voltage input, and the output terminal is coupled to the digital controller's reference voltage input.
4. The power supply of claim 1 wherein the output terminal and the DC output voltage are a first output terminal and a first DC output voltage, respectively, the power supply further comprising a second output terminal to provide a second DC output voltage different than the first DC output voltage.
5. The power supply of claim 1 wherein said voltage divider is a first voltage divider, the power supply further comprising a second voltage divider coupled between the output terminal and ground, the second voltage divider including at least a third resistance, a fourth resistance and a second node between the third resistance and the fourth resistance, the adjustable shunt regulator including a reference terminal coupled to the second node.
6. The power supply of claim 5 wherein the adjustable shunt regulator includes a cathode terminal, the power supply further comprising a transistor coupled between the cathode terminal of the adjustable shunt regulator and the first node.
7. The power supply of claim 6 wherein the transistor is a field-effect transistor (FET).
8. The power supply of claim 7 wherein the cathode terminal of the adjustable shunt regulator is coupled to the output terminal through a resistance.
9. The power supply of claim 8 wherein the adjustable shunt regulator includes an anode terminal coupled to ground.
10. The power supply of claim 1 wherein the DC voltage regulator comprises a switching regulator.
11. The power supply of claim 10 wherein the switching regulator comprises a buck converter.
12. The power supply of claim 11 wherein the buck converter is a non-isolated buck converter.
13. The power supply of claim 1 wherein the DC voltage regulator comprises a linear regulator.
14. The power supply of claim 1 wherein the DC output voltage has a rated tolerance less than or equal to about one percent (1%).