Protection Circuit with a FET Device Coupled from a Protected Bus to Ground
A semiconductor device includes a voltage input circuit node and a ground voltage node. A first transistor is coupled between the voltage input circuit node and the ground voltage node. A triggering circuit is coupled between the voltage input circuit node and the ground voltage node in parallel with the first transistor. The triggering circuit includes a trigger diode. An output of the triggering circuit is coupled to a control terminal of the first transistor. A load is powered by coupling the load between the voltage input circuit node and the ground voltage node.
1 . A semiconductor device, comprising:
a first circuit node;
a second circuit node;
a first transistor coupled between the first circuit node and second circuit node;
a second transistor coupled between the first circuit node and a control terminal of the first transistor;
a triggering circuit coupled between the first circuit node, the second circuit node, and a control terminal of the second transistor; and
a voltage limiting circuit coupled between the second transistor and the control terminal of the first transistor, wherein the voltage limiting circuit includes a third transistor comprising a first conduction terminal of the third transistor coupled to a first conduction terminal of the second transistor and a second conduction terminal of the third transistor coupled to the control terminal of the first transistor, and wherein the second transistor is configured as a driver for the first transistor.
2 . The semiconductor device of claim 1 , wherein the triggering circuit includes a Zener diode.
3 . The semiconductor device of claim 2 , wherein the triggering circuit further includes a fourth transistor comprising a control terminal of the fourth transistor coupled to the Zener diode.
4 . The semiconductor device of claim 1 , wherein the voltage limiting circuit includes a Zener diode coupled to a control terminal of the third transistor.
5 . The semiconductor device of claim 4 , wherein the Zener diode is coupled between the second circuit node and the control terminal of the third transistor.
6 . The semiconductor device of claim 1 , further including a resistance coupled between the first circuit node and second circuit node in series with the first transistor.
7 . A semiconductor device, comprising:
a first circuit node;
a second circuit node;
a first transistor coupled between the first circuit node and second circuit node;
a second transistor coupled between the first circuit node and a control terminal of the first transistor;
a triggering circuit coupled between the first circuit node, the second circuit node, and a control terminal of the second transistor; and
a voltage limiting circuit coupled between the second transistor and the control terminal of the first transistor, wherein the voltage limiting circuit includes a Zener diode.
8 . The semiconductor device of claim 7 , wherein the second transistor is configured as a driver for the first transistor through the voltage limiting circuit.
9 . The semiconductor device of claim 7 , wherein the voltage limiting circuit includes a third transistor comprising a first conduction terminal of the third transistor coupled to a first conduction terminal of the second transistor, a second conduction terminal of the third transistor coupled to the control terminal of the first transistor, and a control terminal of the third transistor coupled to the Zener diode.
10 . The semiconductor device of claim 7 , further including a resistance coupled between the first circuit node and second circuit node in series with the first transistor.
11 . The semiconductor device of claim 7 , further including a load including a first terminal of the load coupled directly to the first circuit node and a second terminal of the load coupled directly to the second circuit node.
12 . The semiconductor device of claim 7 , wherein the triggering circuit includes a second Zener diode.
13 . The semiconductor device of claim 12 , wherein the triggering circuit further includes a fourth transistor comprising a control terminal of the fourth transistor coupled to the second Zener diode.
14 . A method of electrical-overstress protection, comprising:
coupling a first transistor between a first circuit node and second circuit node;
coupling a second transistor between the first circuit node and a control terminal of the first transistor;
coupling a triggering circuit between the first circuit node, the second circuit node, and a control terminal of the second transistor; and
coupling a voltage limiting circuit between the second transistor and the control terminal of the first transistor, wherein the voltage limiting circuit includes a Zener diode.
15 . The method of claim 14 , further including configuring the second transistor to drive the first transistor through the voltage limiting circuit.
16 . The method of claim 14 , wherein the voltage limiting circuit includes a third transistor comprising a first conduction terminal of the third transistor coupled to a first conduction terminal of the second transistor, a second conduction terminal of the third transistor coupled to the control terminal of the first transistor, and a control terminal of the third transistor coupled to the Zener diode.
17 . The method of claim 14 , further including coupling a resistance between the first circuit node and second circuit node in series with the first transistor.
18 . The method of claim 14 , further including disposing a load with a first terminal of the load coupled directly to the first circuit node and a second terminal of the load coupled directly to the second circuit node.
19 . The method of claim 14 , further including providing the triggering circuit to include a second Zener diode.
20 . The method of claim 19 , further including providing the triggering circuit to include a fourth transistor comprising a control terminal of the fourth transistor coupled to the second Zener diode.