| US 7,612,549 B1 | ||
| Low drop-out regulator with fast current limit | ||
| Shun-Hau Kao, Taipei County (Taiwan); and Mao-Chuan Chien, Taipei County (Taiwan) | ||
| Assigned to Advanced Analog Technology, Inc., Hsinchu (Taiwan) | ||
| Filed on Nov. 13, 2008, as Appl. No. 12/270,843. | ||
| Claims priority of application No. 97136826 A (TW), filed on Sep. 25, 2008. | ||
| Int. Cl. G05F 1/00 (2006.01) | ||
| U.S. Cl. 323—281 [323/274] | 13 Claims |
| 1. A Low Drop-Out (LDO) regulator with fast current limit, comprising:
a first transistor, comprising:
a first end, coupled to an input voltage source;
a second end for outputting an output voltage source; and
a control end for receiving a current control signal to control current of the output voltage source outputted from the second
end of the first transistor;
an error amplifier, comprising:
a negative input end for receiving a reference voltage;
a positive input end for receiving a voltage divided from the output voltage source; and
an output end, the error amplifier generating the current control signal through the output end of the error amplifier according
to the reference voltage and the voltage divided from the output voltage source;
an adjustable reference voltage circuit for generating an adjustable reference voltage; and
a second transistor, comprising:
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, coupled to the adjustable reference voltage circuit for receiving the adjustable reference voltage;
wherein when the second transistor is turned on, voltage of the current control signal is clamped by the adjustable reference
voltage.
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