Advanced Analog Technology, Inc.

Shun-Hau Kao

Mao-Chuan Chien

Chih-Liang Huang

A low dropout regulator includes an error amplifier, an N-type depletion MOSFET, a first switch, a second switch, a low-pass filter resistor, and a low-pass filter capacitor. By switching on both the first switch and the second switch, a voltage level of an output node at a negative input terminal of the error amplifier may be rapidly raised to be close to and lower than a voltage level of an input node at a gate of the N-type depletion MOSFET. Both the first switch and the second switch are then switched off immediately so that the voltage level of the output node is gradually raised to be equal to the voltage level of the input node through the low-pass filter resistor.

Quick-start low dropout regulator

A soft-start voltage circuit includes an operational amplifier, a first and a second capacitors, a first and a second switches, and a voltage level shifter. The operational amplifier includes a positive end, a negative end, and an output end coupled to the negative end of the operational amplifier for outputting the soft-start voltage. The voltage level shifter is coupled between the first capacitor and the positive end of the operational amplifier for shifting a level of the voltage on the first capacitor. The first switch is coupled between the first and the second capacitors for coupling the first and the second capacitors according to the clock. The second switch is coupled between the second capacitor and the negative end of the operational amplifier for coupling the second capacitor and the negative end of the operational amplifier according to the inverted clock.

Soft-start voltage circuit

An LDO with over-current protection includes a first and a second P-type transistor, a sensing resistor, a comparator, and an error amplifier. The channel aspect ratio of the first P-type transistor is much higher than that of the second P-type transistor. The first P-type transistor generates output voltage source according to input voltage source and current control signal. The sensing resistor is coupled among the input voltage source, the second P-type transistor, and the comparator, providing a sensing voltage. The comparator generates a current limiting signal according to first reference voltage and the sensing voltage. When the current limiting signal enables the error amplifier, the error amplifier adjusts voltage of the current control signal according to second reference voltage and voltage divided from the output voltage source; when the current limiting signal disables the error amplifier, voltage of the current control signal is not adjusted.

Low drop out regulator with over-current protection

An LDO with fast current limit includes P-type transistor, an error amplifier, an adjustable reference voltage circuit for generating an adjustable reference voltage, and an N-type transistor. The P-type transistor includes a first end coupled to the input voltage source, a second end for outputting an output voltage source, and a control end for receiving a current control signal in order to control the current of the output voltage source. The error amplifier generates the current control signal according to the reference voltage and a voltage divided from the output voltage source. N-type transistor includes a first end coupled to the output end of the error amplifier, a second end coupled to the input voltage source, and a control end for receiving the adjustable reference voltage. When the N-type transistor is turned on, the voltage of the current control signal is clamped by the adjustable reference voltage.

Growing community of inventors

Taipei County, Taiwan

Shun-Hau Kao