US 2008/0258696 A1Published application

Series regulator circuit

AssigneeFreescale Semiconductor, Inc.

InventorHiroyuki Kimura

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Abstract

A series regulator circuit for reducing current consumption, enabling switching between different current consumption modes, and suppressing output voltage fluctuations. A constant current source 20, connected to an input voltage line, is connected to a ground voltage line via a resistor element 21 and transistor B1. Gate terminals of transistors M2, M4 are connected between the constant current source 20 and transistor B1. The transistor M2 is connected to the input voltage line via a transistor M1 activated in a high current mode. The source terminals of the transistors M2, M4 function as the series regulator circuit output terminal, which is connected to the ground voltage line via a resistor element 23 and transistor M3, activated in a high current mode, or via resistor elements 24, 25. A connection node between the resistor elements 24, 25 is connected to a base voltage of the transistor B1.

Claims5

Dependent claims

A series regulator circuit comprising:

a first transistor connected to a constant current source, which is connected to an input voltage line, and a reference voltage line;
a second transistor connected to the input voltage line and an output terminal;
a first switch element connected to the input voltage line;
a third transistor connected to the first switch element and the output terminal;
a first resistor and a second resistor connected in series between the output terminal and the reference voltage line;
a third resistor connected to the output terminal;
and
a second switch element connected to the third resistor and the reference voltage line;
wherein the first transistor includes a control terminal connected between the first resistor and the second resistor;
the second transistor and the third transistor each include a control terminal connected between the constant current source and the first transistor;
and
when in a high current mode in which current consumption at the output terminal is high, the first switch element is activated to supply current via the third transistor, and the second switch element is activated so that current flows through the third resistor.

9 more elements

Dependencies are inferred from the claim text.