High voltage switch pre-driver circuit
View Patent ↗Switch pre-driver systems and methods are described. The present switch pre-driver systems and methods facilitate switch driver breakdown protection, reduction of leakage current, and avoidance of false switching. In one embodiment, a switch system includes a switch driver, a switch pre-driver, and a mode detection circuit. The switch driver drives a voltage. The switch pre-driver controls the switch driver. The mode detection circuit notifies the switch pre-driver of a mode condition.
1. A switch system comprising:
a switch driver to drive a voltage;
a switch pre-driver to control the switch driver, wherein the pre-driver sets a driver control signal based upon a voltage input; and
a detection circuit to activate the switch pre-driver in response to a high voltage mode signal, to maintain a level of the driver control signal output by the switch pre-driver such that a difference between the voltage input and the driver control signal is less than a breakdown limit of components of the switch driver.
2. A switch system of claim 1 wherein the switch driver is a single MOS transistor.
3. A switch system of claim 1 wherein the switch pre-driver sets the driver control signal equal to a base power voltage level disabling the switch driver when the voltage input is at or below the base power voltage level.
4. A switch system of claim 1 wherein the switch pre-driver outputs the driver control signal to follow the voltage input keeping the switch driver turned off when the voltage input is between a base power voltage level and a trip voltage.
5. A switch system of claim 1 wherein the switch pre-driver outputs the driver control signal to turn on the switch driver when the voltage input is above a trip voltage.
6. A switch system of claim 1 wherein the voltage input includes a point to point voltage input.
7. A switch system of claim 2 further comprising a well bias device to apply at least one bias voltage to the switch pre-driver.
8. A switch system of claim 7 wherein the bias level is adjustable.
9. A switch system of claim 7 wherein an output of the switch pre-driver is a function of one gate threshold voltage.
10. A switch system comprising:
a switch driver to drive a voltage;
a switch pre-driver to control the switch driver based upon a voltage input (Vpp_in); wherein the switch pre-driver includes:
a first component for setting to set an output of the switch pre-driver equal to a base power voltage level (vpwr);
a second component to set the output of the switch pre-driver equal to a transition voltage level;
a third component to set the output of the switch pre-driver equal to a pre-determined voltage level (vppgate) during a high voltage mode, a difference between Vpp_in and vppgate is less than a breakdown limit of components of the switch driver; and
a detection circuit to activate the switch pre-driver in response to a high voltage mode input signal, to couple vppgate to turn on the switch driver.
11. A switch system of claim 10 wherein the second component includes a PMOS transistor, and the first component is disabled when Vpp_in is greater than the base power voltage level plus a threshold voltage of the PMOS transistor (vpwr+Vtp).
12. A switch system of claim 10 wherein the second component includes a PMOS transistor that turns on when Vpp_in is raised above vpwr making vppgate follow Vpp_in.
13. A switch system of claim 10 wherein the third component includes a stack of NMOS transistors that draw a small keep-alive current during the high voltage mode.
14. A switch system of claim 10 wherein the third component includes an NMOS transistor that controls vppgate output from the switch pre-driver.
15. A switch pre-driver comprising:
a fist component to set an output of the switch pre-driver equal to a base power voltage level (vpwr);
a second component to set the output of the switch pre-driver equal to a transition voltage level; and
a third component to set the output of the switch pre-driver equal to a pre-determined voltage level during a high voltage mode, a difference between a voltage input of the switch pre-driver and the output of the switch pre-driver is less than a breakdown limit of components of a switch driver coupled to the switch pre-driver; and
a detection circuit to activate the switch pre-driver in response to a high voltage mode input signal and to couple the output of the switch pre-driver to turn on the switch driver.
16. A switch pre-driver of claim 15 wherein the first component is disabled when a voltage input (Vpp_in) of the switch pre-driver is greater than the base power voltage level (vpwr) plus a threshold voltage (Vtp) of the first component.
17. A switch pre-driver of claim 15 wherein the second component includes a weak PMOS that turns on when a voltage input (Vpp_in) of the switch pre-driver is raised above the base power voltage level (vpwr) making the output of the switch pre-driver (vppgate) follow the voltage input (Vpp_in).
18. A switch pre-driver of claim 15 wherein the third component is activated when a high voltage is detected and a circuit coupled to the switch pre-driver enters a high voltage mode.
19. A switch pre-driver of claim 15 wherein the third component includes a stack of NMOS transistors that draw a small keep-alive current.
20. A switch pre-driver of claim 15 wherein the third component includes a strong NMOS transistor that controls the output of the switch pre-driver (vppgate).