Texas Instruments Corporation

Gabriel A Rincon

Marco Corsi

Nicolas Salamina

Michael R Kay

Robert B Borden

A voltage regulator circuit includes: a first MOS transistor 12 coupled between a voltage supply line and an output node 44, the first MOS transistor 12 providing a stable voltage on the output node 44; a source follower 24 coupled to a gate of the first MOS transistor 12; an amplifier 38 coupled to a gate of the source follower 24 for controlling the response of the first MOS transistor 12; negative feedback circuitry coupled between the output node 44 and the amplifier 38, the feedback circuitry providing feedback to the amplifier 38; a current conveyer 46 coupled to the first MOS transistor 12; and positive feedback circuitry 26 coupled between the current conveyer 46 and the source follower 24.

Low drop-out voltage regulator with PMOS pass element

A circuit and method for sensing and limiting current. An output driving transistor (M1) is coupled between a circuit output terminal and a power supply terminal. A replicator circuit is formed in a cross-coupled quad configuration from bipolar transistors (Q11, Q12, Q13 and Q14) and is coupled to a second transistor (M2) which generals a voltage proportional to the current flowing in the output driving transistor (M1). The current sensing circuit generates an output current which is proportional to the current flowing in the output driving transistor multiplied by a ratio of the sizes of the second transistor and the output driving transistor. In a current limiting configuration, the output of the cross-coupled quad is used to reset a flip-flop (FF1) that drives the gate terminal of the output transistor (M1), thus shutting down the output transistor before it is damaged due to excess current. The circuitry of the invention may be applied to a high side driver or a low side driver output circuit. Other embodiments are also described.

Current sensing circuit and method

A circuit and method for sensing and limiting current. A resistor (R1) is used to generate a voltage (V1) proportional to the current flowing in an output transistor (M1). A comparator is formed in a cross coupled quad configuration from bipolar transistors (Q11, Q12, Q13 and Q14) and is coupled to the resistor (R1). When the current in the resistor (R1) generates a voltage in excess of a threshold voltage for the cross coupled quad circuit, the cross coupled quad generates an output indicating the threshold has been reached. In a current limiting configuration, the output of the cross coupled quad is used to reset a flip-flop (FF1) that drives the gate terminal of the output transistor (M1), thus shutting down the output transistor before it is damaged due to excess current. The threshold voltage that triggers the cross coupled quad is proportional-to-absolute-temperature. This property allows the comparator to be combined with an aluminum resistor (R1) to form a current sensing circuit that has a threshold current that is independent of temperature, since the temperature coefficient of the resistor will cancel the temperature coefficient of the comparator. The threshold voltage of the comparator may be adjusted by adjusting the emitter areas of the bipolar transistors (Q11, Q12, Q13 and Q14) which make up the cross coupled quad circuit. The circuitry of the invention may be applied to a high side driver or a low side driver output circuit. Other embodiments are also described.

Cross coupled quad comparator for current sensing independent of

An amplifier circuit (10) is provided. The amplifier (10) includes an amplifier stage (14) coupled to an output stage (18). Output stage (18) comprises a sourcing circuit (20) and a sinking circuit (22). The current in sinking circuit (22) is approximately mirrored at low current in mirror circuit (34). At higher currents, resistor (36) maintains the current in mirror circuit (34) below the current in sinking circuit (22). A diode (38) diverts current to mirror circuit (34) to aid sinking circuit (22) in sinking current from a load (12). A current source (29) supplies current to sourcing circuit (20) and mirror circuit (34). A control signal output by amplifier stage (14) causes mirror circuit (34) to draw or not draw current from current source (29). If mirror circuit (34) draws current from current source (29), output stage (18) sinks current in sinking circuit (22). If mirror circuit (34) does not draw current from current source (29), output stage (18) sources current through sourcing circuit (20).

Controlled current output stage amplifier circuit and method

An amplifier circuit (10) is provided. Amplifier (10) has an amplifier stage (14) that is coupled to control an output stage (18). Output stage (18) includes a sourcing circuit (20) and a sinking circuit (22). Output stage (18) also includes a mirror circuit (42) that is coupled to an output of amplifier stage (14). Output stage (18) also includes a current balancing circuit (30) coupled to mirroring circuit (42) and sourcing circuit (20). Mirroring circuit (42) draws current from balancing circuit (30) in response to a first predetermined output from amplifier stage (14) such that balancing circuit (30) causes an insignificant current to flow in sourcing circuit (20). Thus amplifier (10) operates to sink current from an external load (12). Alternatively, mirroring circuit (42) may draw an insignificant current from balancing circuit (30) in response to a second predetermined output of the amplifier stage (14). This causes a significant current flow in sourcing circuit (20).

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Margate, FL, United States of America

Gabriel A Rincon