Output driver circuit

Patent metadata

Field	Value
Publication number	US-10379565-B2
Application number	US-201414521057-A
Country	US
Kind code	B2
Filing date	Oct 22, 2014
Priority date	Apr 27, 2012
Publication date	Aug 13, 2019
Grant date	Aug 13, 2019

Abstract

An output driver circuit provides an overcurrent protection function by a simple circuit configuration. The output driver circuit has a constant-current circuit, a constant-current mirror MOS transistor, and a selector circuit. The constant-current mirror MOS transistor and the output MOS transistor constitute a current mirror circuit. The gate of the output MOS transistor is controlled by a voltage based on a constant current generated by the constant-current mirror MOS transistor, thereby limiting the current flowing between the source and the drain of the output MOS transistor.

First claim

What is claimed is:

1. An output driver circuit with an open-drain output, comprising:
a constant-current circuit which supplies a constant current;
a constant-current mirror MOS transistor which generates a voltage based on the constant current;
a selector circuit which separately receives the voltage based on the constant current that is generated by the constant-current mirror MOS transistor and a voltage of a first supply terminal and outputs one of the received voltages according to a signal supplied to an input terminal of the output driver circuit; and
an output MOS transistor having a gate thereof connected to an output terminal of the selector circuit, an open drain output thereof connected to an output terminal of the output driver circuit, and a source thereof connected to the first supply terminal, the output terminal connected to a second supply terminal through an external pull-up resistor,
wherein the constant-current mirror MOS transistor and the output MOS transistor constitute a current mirror circuit, the selector circuit is between the constant-current mirror MOS transistor and the output MOS transistor, and
a current flowing between the source and the drain of the output MOS transistor is limited by a voltage based on the constant current.

2. The output driver circuit according to claim 1 , wherein the current mirror circuit has a fuse configured to adjust a current mirror ratio to adjust a current limit value of the output MOS transistor.

3. The output driver circuit according to claim 1 , wherein the current mirror circuit has a fuse configured to adjust a current value so as to adjust a current limit value of the output MOS transistor.

Assignees

• Seiko Instr Inc
• Ablic Inc

Inventors

• Mitani Masahiro
• Ariyama Minoru
• Muraoka Daisuke
• Hikichi Tomoki

Classifications

• H03K17/687

  the devices being field-effect transistors · CPC title

• G05F3/262 Primary

  using field-effect transistors only · CPC title

• H03K19/1737

  using multiplexers (H03K19/1738 takes precedence) · CPC title

• H02H9/02

  responsive to excess current {(current limitation for voltage regulators G05F1/573; disconnection after limiting H02H3/025)} · CPC title

• H03K2217/0063

  High side switches, i.e. the higher potential [DC] or life wire [AC] being directly connected to the switch and not via the load · CPC title