Integrated current mode PWM drive system supply voltage scaleable while retaining a high precision
AssigneeSTMicroelectronics S.r.l.
InventorsAlberto Salina, Donatella Brambilla
Life of this patent
Estimating the term…
Abstract
In a current mode pulse width modulation (PWM) integrated drive system having an external load, a switched-capacitor amplifier and a sample & hold stage connected in cascade form a current sensing amplifier for a control loop. The current sensing amplifier overcomes resistive mismatchings, thus permitting a scaling down of the supply voltage with high precision for the integrated drive system.
Claims28
An integrated current mode switching drive system for an external load, comprising:
- a differential error amplifier having a first input connected to a first control voltage and a second input connected to a reference voltage;
- a first resistor connected to the first input of said differential error amplifier and receiving a second control signal;
- a second resistor connected to the first input of said differential error amplifier and receiving a third control signal;
- a third resistor connected in series with the external load;
- a current sense amplifier circuit having an input connected across the third resistor and an output generating the third control signal, said current sense amplifier circuit comprising
- a switched capacitor stage comprising an operational amplifier, a plurality of switches and capacitors connected to said operational amplifier so that said operational amplifier is configured alternately as a buffer and charge transfer circuit responsive to a pair of complementary control signals applied to said switches, and
- a sample and hold circuit having an input connected to an output of the switched capacitor stage and having an output generating the third control signal.
An integrated current mode switching drive system for an external load, comprising:
- a differential error amplifier having a first input and a second input connected to a reference voltage;
- a sensing resistor connected in series with the external load;
- and
- a current sense amplifier circuit having an input connected across the sensing resistor and an output coupled to the first input of said differential error amplifier, said current sense amplifier circuit comprising a switched capacitor stage comprising an operational amplifier, a plurality of switches and capacitors connected to said operational amplifier so that said operational amplifier is configured alternately as a buffer and charge transfer circuit responsive to a pair of complementary control signals applied to said switches.
A method of providing current for an external load using a current sense amplifier circuit configured as a switched capacitor stage, the method comprising the steps of:
- applying a first control voltage and a reference voltage to respective first and second inputs of a differential error amplifier;
- receiving a second control signal via a first resistor connected to the first input of the differential error amplifier;
- receiving a third control signal via a second resistor connected to the first input of the differential error amplifier;
- connecting a third resistor in series with the external load;
- generating the third control signal from the current sense amplifier circuit having an input connected across the third resistor, the current sense amplifier comprising an operational amplifier having a plurality of switches and capacitors connected to the operational amplifier so that the operational amplifier is configured alternately as a buffer and charge transfer circuit responsive to a pair of complementary control signals applied to the switches, and connecting a sample and hold circuit having an input connected to an output of the switched capacitor stage and having an output generating the third control signal.
Dependencies are inferred from the claim text.