LOW DROPOUT REGULATOR WITH WIDE INPUT SUPPLY VOLTAGE

• US 20190324484A1
• Filed: 04/24/2019
• Published: 10/24/2019
• Est. Priority Date: 04/24/2018
• Status: Active Grant

• Current Assignee: Etron Technology Inc
• Original Assignee: Etron Technology Inc
• Inventors: Cheng, Wei-Chuan, Wu, Keng-Yi
• Granted Patent: US 10,591,941 B2
• Time in Patent Office: Days
• CPC Class Codes: G05F 1/461 using an operational amplifier as final control device
• CPC Class Codes: G05F 1/565 sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor G05F1/563 takes precedence
• CPC Class Codes: G05F 1/575 characterised by the feedback circuit
• CPC Class Codes: H02M 1/0032 Control circuits allowing low power mode operation, e.g. in standby mode
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators
• CPC Class Codes: H03K 5/24 the characteristic being amplitude
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A low dropout regulator with wide input supply voltage includes a controller, an comparing circuit, a feedback circuit, an adjustable source follower, and an adjustable driving circuit. The controller is used for detecting a supply voltage. The feedback circuit, the comparing circuit, the adjustable source follower, and the adjustable driving circuit are used for regulating an output voltage according to a reference voltage. When the adjustable source follower and the adjustable driving circuit operate in the low-voltage mode, the controller further activates a first parallel metal-oxide-semiconductor transistor in the adjustable source follower and a second parallel metal-oxide-semiconductor transistor in the adjustable driving circuit.

Claims

1. A low dropout regulator with wide input supply voltage, comprising:

a controller detecting a supply voltage;

an comparing circuit;

a feedback circuit;

an adjustable source follower; and

an adjustable driving circuit;

wherein the feedback circuit, the comparing circuit, the adjustable source follower, and the adjustable driving circuit are used for regulating an output voltage according to a reference voltage;

wherein when the adjustable source follower and the adjustable driving circuit operate in a low-voltage mode, the controller further activates a first parallel metal-oxide-semiconductor transistor in the adjustable source follower and a second parallel metal-oxide-semiconductor transistor in the adjustable driving circuit.

2. The low dropout regulator of claim 1, further comprising:

a stabilization capacitor stabilizing the output voltage.

3. The low dropout regulator of claim 1, wherein the feedback circuit, the comparing circuit, the adjustable source follower, and the adjustable driving circuit form a negative feedback loop to regulate the output voltage according to the reference voltage.

4. The low dropout regulator of claim 3, wherein the adjustable source follower has high sinking capability and fixed sourcing capability, and provides a low impedance path to the adjustable driving circuit to increase stability and operating bandwidth of the negative feedback loop.

5. The low dropout regulator of claim 1, wherein when the supply voltage is greater than a first reference voltage, the adjustable source follower and the adjustable driving circuit operate in a high-voltage mode, when the supply voltage is between the first reference voltage and a second reference voltage, the adjustable source follower and the adjustable driving circuit operate in the low-voltage mode, and when the supply voltage is less than the second reference voltage, the adjustable source follower is turned off and the adjustable driving circuit operates in a bypass mode.

6. The low dropout regulator of claim 5, wherein when the adjustable driving circuit operates in the bypass mode, gates of metal-oxide-semiconductor transistors in the adjustable driving circuit receive a predetermined voltage, and the predetermined voltage makes the metal-oxide-semiconductor transistors be substantially completely turned on.

7. The low dropout regulator of claim 1, wherein when the supply voltage is greater than a first reference voltage or the supply voltage is between the first reference voltage and a second reference voltage, the comparing circuit is turned on, and when the supply voltage is less than the second reference voltage, the comparing circuit is turned off.

8. The low dropout regulator of claim 1, wherein the comparing circuit is coupled to the controller;

the feedback circuit is coupled to the comparing circuit;

the adjustable source follower is coupled to the controller and the comparing circuit; and

the adjustable driving circuit is coupled to the controller, the adjustable source follower, and the feedback circuit.

9. The low dropout regulator of claim 1, wherein the reference voltage is a bandgap reference voltage, and not changed with temperature, process, and the supply voltage.

10. The low dropout regulator of claim 1, wherein the controller, the comparing circuit, the feedback circuit, the adjustable source follower, and the adjustable driving circuit are integrated in a monolithic chip.

11. The low dropout regulator of claim 1, wherein when the adjustable driving circuit operates in a bypass mode, the controller further activates the second parallel metal-oxide-semiconductor transistor in the adjustable driving circuit.

12. A low dropout regulator with wide input supply voltage, the low dropout regulator regulating an output voltage according to a reference voltage and comprising:

an adjustable driving circuit comprising a first transmission transistor and a second transmission transistor connected to the first transmission transistor in parallel; and

a controller detecting a supply voltage;

wherein when the supply voltage is lower than a first reference voltage, the controller activates the second transmission transistor to increase the output voltage.

13. The low dropout regulator of claim 12, further comprising:

an comparing circuit;

a feedback circuit; and

an adjustable source follower comprising a first and a second transistor circuits, wherein the controller optionally activates transistors connected in parallel in the first transistor circuits and transistors connected in parallel in the second transistor circuits;

wherein the feedback circuit, the comparing circuit, the adjustable source follower, and the adjustable driving circuit regulates the output voltage according to the reference voltage.

14. The low dropout regulator of claim 13, wherein when the supply voltage is between the first reference voltage and a second reference voltage, the controller activates parallel metal-oxide-semiconductor transistors in the first and the second transistor circuits.

15. The low dropout regulator of claim 13, wherein when the supply voltage is greater than the first reference voltage, the adjustable source follower and the adjustable driving circuit operate in a high-voltage mode, when the supply voltage is between the first reference voltage and a second reference voltage, the adjustable source follower and the adjustable driving circuit operate in the low-voltage mode, and when the supply voltage is less than the second reference voltage, the adjustable source follower is turned off and the adjustable driving circuit operates in a bypass mode.

16. The low dropout regulator of claim 12, wherein when the supply voltage is between the first reference voltage and a second reference voltage, or is lower than the second reference voltage, the controller activates the second transmission transistor, and the second reference voltage is less than the first reference voltage.