CONTROL CIRCUIT FOR A HIGH-SIDE SEMICONDUCTOR SWITCH FOR SWITCHING A SUPPLY VOLTAGE

• US 20080303580A1
• Filed: 05/23/2008
• Published: 12/11/2008
• Est. Priority Date: 06/11/2007
• Status: Active Grant

• Current Assignee: Minebea Company Limited (MinebeaMitsumi Inc.)
• Original Assignee: Minebea Company Limited (MinebeaMitsumi Inc.)
• Inventors: Stegmayr, Thomas
• Granted Patent: US 7,692,474 B2
• Time in Patent Office: Days
• US Class Current: 327/390
• CPC Class Codes: H03K 17/063 in field-effect transistor switches
• CPC Class Codes: H03K 17/08142 in field-effect transistor switches
• CPC Class Codes: H03K 17/567 Circuits characterised by the use of more than one type of semiconductor device, e.g. BIMOS, composite devices such as IGBT
• CPC Class Codes: H03K 17/6872 using complementary field-effect transistors
• CPC Class Codes: H03K 2017/066 Maximizing the OFF-resistance instead of minimizing the ON-resistance
• CPC Class Codes: H03K 2217/0036 Means reducing energy consumption

Abstract

A high-side semiconductor switch control circuit for switching a positive supply voltage is provided, having a circuit to provide a drive voltage for the high-side semiconductor switch, a driver circuit for driving the high-side semiconductor switch based on the control circuit, wherein both the circuit for providing the drive voltage as well as the driver circuit operate in relation to a floating switching point, an input circuit portion that receives a control signal related to ground, and a level shift circuit portion that is connected between the input circuit portion and the driver circuit portion and set up so as to transform the control signal related to ground into a floating voltage level for the driver circuit portion.

Claims

1. A control circuit for a high-side semiconductor switch for switching a positive supply voltage, said high-side semiconductor switch being connected between said supply voltage and a floating switching point, said control circuit comprising:

a circuit portion for providing a drive voltage for said high-side semiconductor switch;

a driver circuit portion (48) for driving said high-side semiconductor switch on the basis of said drive voltage, said circuit portion for providing said drive voltage and said driver circuit portion operating in relation to said floating switching point;

an input circuit portion for receiving a control signal related to ground; and

a level shift circuit portion that is connected between said input circuit portion and said driver circuit portion and configured to transform said control signal related to ground into a floating voltage level for said driver circuit portion;

wherein said level shift circuit portion by comprises a degeneratively coupled control semiconductor switch and is coupled to a negative feedback circuit portion, said negative feedback circuit portion has comprising a first negative feedback element and a second negative feedback element that are configured such that, depending on an operating status of said high-side semiconductor switch, only one or both of said negative feedback elements are active as current negative feedback for said control semiconductor switch.

2. The control circuit according to claim 1, wherein said negative feedback circuit portion (60) further comprises:

a holding transistor;

a first negative feedback resistor; and

a second negative feedback resistor;

wherein said negative feedback circuit portion is configured such that during a switch-off operation of said high-side semiconductor switch, said holding transistor blocks conduction and said first and said second negative feedback resistors generate a relatively large current negative feedback and during a stationary OFF state of said high-side semiconductor switch, said holding transistor is switched on and said first and said second negative feedback resistors generate a low current negative feedback.

3. The control circuit according to claim 2, wherein said first negative feedback resistor is connected in parallel to said holding transistor and said second negative feedback resistor is connected in series to said holding transistor.

4. The control circuit according to claim 2, wherein said first and said second negative feedback resistor are connected in series and said holding transistor is connected in parallel to said second negative feedback resistor.

5. The control circuit according to claim 2, wherein said negative feedback circuit portion further comprises an auxiliary transistor that drives said holding transistor.

6. The control circuit according to claim 1, wherein said control semiconductor switch receives said control signal related to ground and, contingent thereon, drives said driver circuit portion, and whereby said control semiconductor switch is connected between said driver circuit portion and said negative feedback circuit portion.

7. The control circuit according to claim 1, wherein said control semiconductor switch is a n-channel MOSFET.

8. The control circuit according to claim 1, wherein said high-side semiconductor switch is an n-channel power transistor, particularly n-channel MOSFET.

9. The control circuit according to claim 2, wherein said holding transistor is an npn-bipolar transistor.

10. The control circuit according to claim 1, said control circuit further comprising:

a low-side semiconductor switch is connected in series between said floating switching point and ground to said high-side semiconductor switch.

11. The control circuit according to claim 1, wherein said driver circuit portion comprises a push-pull circuit having two semiconductor switches.

12. The control circuit according to claim 11, wherein said semiconductor switches of the push-pull circuit comprise two complementary bipolar transistors or two complementary field effect transistors.

13. The control circuit according to claim 1, wherein said circuit portion for providing said supply voltage for said high-side semiconductor switch comprises:

a bootstrap capacitor connected to said floating switching point and to an auxiliary voltage via a diode.

14. The control circuit according to claim 1, wherein said control circuit is configured to be inverting, so that said high-side semiconductor switch switches on when said control signal related to ground is logically low.

15. The control circuit according to claim 1, wherein said supply voltage is a positive DC voltage.