US 8,045,348 B2 · Switching mode power supply controller with high voltage startup circuits

Abstract

A controller for a switching mode power supply includes two semiconductor chips. The first semiconductor chip has a high-voltage startup transistor coupled to a high voltage supply input terminal and configured to provide a charging current in a startup phase or protection mode of a switching mode power supply (SMPS) and to provide substantially no current in a normal operation phase of the SMPS. The second semiconductor chip has a control circuit for controlling the switching mode power supply. The second semiconductor chip also has first and second on-chip high-voltage resistors coupled to the high-voltage supply input terminal and the high-voltage startup transistor in the first semiconductor chip. The first and the second on-chip high-voltage resistors are configured to provide a voltage and a current related to a voltage at the high-voltage supply input terminal.

Claims31

Dependent claims

A controller for a switching mode power supply, comprising:

a first semiconductor chip including a high-voltage startup transistor configured for coupling between a high-voltage supply input terminal and a capacitor and configured to provide a charging current to the capacitor in a startup phase or protection mode of a switching mode power supply (SMPS) and to provide substantially no current in a normal operation phase of the SMPS;
and
a second semiconductor chip including a control circuit for controlling the switching mode power supply, the second semiconductor chip also including first and second on-chip high-voltage resistors coupled to the high-voltage supply input terminal and the high-voltage startup transistor in the first semiconductor chip,wherein the control circuit is configured to monitor a high voltage supply at the high-voltage supply input terminalusing a voltage and a current provided by the first and the second on-chip high-voltage resistors.

A switching mode power supply for receiving an input voltage and providing a DC output voltage, the power supply comprising:

a transformer coupled to the input voltage, the transformer including a primary winding, a secondary winding, and one or more auxiliary windings;
a switching mode power supply (SMPS) controller having a feedback terminal for sensing the output voltage and an input power supply terminal for coupling to an auxiliary winding of the transformer, the SMPS controller including:
a first semiconductor chip including a high-voltage startup transistor configured for coupling between a high-voltage supply input terminal and a capacitor and configured to provide a charging current to the capacitor in a startup phase or protection mode of the SMPS and to provide substantially no current in a normal operation phase of the SMPS;
and
a second semiconductor chip having:
a high-voltage terminal for coupling to the input voltage;
a feedback terminal coupled to an auxiliary winding or an opto-coupler for sensing the output voltage;
an input power supply terminal for coupling to an auxiliary winding of the transformer for receiving operating power supply;
a first and a second on-chip high-voltage resistors coupled in series to the input voltage and to the high-voltage startup transistor, and
a control circuit coupled to the feedback terminal and an off-chip power transistor,
wherein a node between the first and the second high-voltage resistors is used for sensing the input voltage.

8 more elements

A switching mode power supply for receiving an input voltage and providing a DC output voltage, the power supply comprising:

a transformer coupled to the input voltage, the transformer including a primary winding, a secondary winding, and one or more auxiliary windings;
a switching mode power supply (SMPS) controller having a feedback terminal for sensing the output voltage and an input power supply terminal for coupling to an auxiliary winding of the transformer, the SMPS controller including:
a first semiconductor chip including Darlington connected high-voltage startup transistors configured for coupling between a high-voltage supply input terminal and a capacitor and configured to provide a charging current to the capacitor in a startup phase or protection mode of the SMPS and to provide substantially no current in a normal operation phase of the SMPS;
and
a second semiconductor chip having:
a high-voltage terminal for coupling to the input voltage;
a feedback terminal coupled to an auxiliary winding or an opto-coupler for sensing the output voltage;
an input power supply terminal for coupling to an auxiliary winding of the transformer for receiving operating power supply;
a first and a second on-chip high-voltage resistors coupled in series to the input voltage and to the Darlington connected high-voltage startup transistors;
a circuit to limit the charging current when the system is in startup phase or protection mode, and
a control circuit coupled to the feedback terminal and an off-chip power transistor,
wherein a node between the first and the second high-voltage resistors is used for sensing the input voltage.

9 more elements

Dependencies are inferred from the claim text.

Switching mode power supply controller with high voltage startup circuits

Life of this patent

Switching mode power supply controller with high voltage startup circuits

Life of this patent

Abstract

Claims31