High voltage gate driver current source

Patent metadata

Field	Value
Publication number	US-10659033-B2
Application number	US-201715802787-A
Country	US
Kind code	B2
Filing date	Nov 3, 2017
Priority date	Nov 3, 2017
Publication date	May 19, 2020
Grant date	May 19, 2020

Abstract

A power supply system for USB Power Delivery includes a current source drive circuit to control a power FET to regulate the supply of power along a power path. The current source drive circuit includes a cascode current source and a cascode protection circuit formed by a source follower and a feedback voltage divider. The source follower can be a transistor with its gate connected to a cascode node between upper- and lower-stage transistors of the cascode current source. The divider node of the voltage divider is connected to the gate of the lower-stage transistor. The current source drive circuit can operate within the gate-source voltage specifications of 30-volt DEPMOS devices, and can provide high output impedance to the gate of power FET and a current limit circuit during current limiting operation, without requiring an extra high-voltage mask during fabrication.

First claim

What is claimed is:

1. A circuit comprising:
a power terminal;
a bus terminal;
a power field-effect transistor (FET) having a FET gate and a FET drain and a FET source, in which the FET drain is coupled to the power terminal, and the FET source is coupled to the bus terminal;
a charge pump voltage terminal;
a current mirror including first and second transistors, in which the first transistor has a first gate and a first drain and a first source, the second transistor has a second gate and a second drain and a second source, the first and second sources are coupled to the charge pump voltage terminal, and the second gate is coupled to the first gate and to the second drain;
a biasing current source coupled to the second drain;
a cascode transistor having a third gate and a third drain and a third source, in which the third drain is coupled to the FET gate, and the third source is coupled to the first drain;
a feedback transistor having a fourth gate and a fourth drain and a fourth source, in which the fourth gate is coupled to the first drain, and the fourth drain is coupled to the charge pump voltage terminal;
first and second feedback resistors, in which the first feedback resistor is coupled between the fourth source and the third gate, and the second feedback resistor is coupled between the third gate and the FET drain; and
a current limit circuit including a non-inverting input, an inverting input and an output, in which the output of the current limit circuit is coupled to the FET gate, the non-inverting input is adapted to be coupled to a reference current source, and the inverting input is adapted to be coupled to a power current source.

2. The circuit of claim 1 , wherein the first transistor is a first FET, the cascode transistor is a second FET, and each of the first FET and the second FET has a respective gate-source voltage (VGS) reliability limit of 5 volts or less and a respective drain-source voltage (VDS) reliability limit of 30 volts or less.

3. The circuit of claim 2 , wherein a ratio is greater than 5/9 between: a value of the second feedback resistor; and a sum of a value of the first feedback resistor and the first value of the second feedback resistor.

4. The circuit of claim 3 , further comprising a four-stage charge pump coupled to the charge pump voltage terminal, in which the four-stage charge pump is configured to provide a first voltage potential at the charge pump voltage terminal, and the first voltage potential is at least 10 volts higher than a second voltage potential at the FET drain.

Assignees

• Texas Instruments Inc

Inventors

• Manohar Sujan Kundapur
• Mills Michael James
• Vogt Justin Patrick

Classifications

• G06F13/4282

  on a serial bus, e.g. I2C bus, SPI bus (on daisy chain buses G06F13/4247) · CPC title

• H03K17/063

  in field-effect transistor switches · CPC title

• H03K17/145 Primary

  in field-effect transistor switches · CPC title

• G05F3/245

  producing a voltage or current as a predetermined function of the temperature · CPC title

• H03K2017/307

  circuits simulating a diode, e.g. threshold zero · CPC title