TWI420770B - Driver circuit with electrostatic discharge protection - Google Patents

Description

Driver circuit with electrostatic discharge protection

The present invention relates to a circuit, and more particularly to an electrostatic discharge protection circuit.

In recent years, with the rapid development of science and technology, the wide application of microelectronic technology and the increasingly complex electromagnetic environment, more and more attention has been paid to the electromagnetic field effects of electrostatic discharge such as electromagnetic interference (EMI) and electromagnetic compatibility (EMC). Due to the increased functionality of the chip and circuit integration, the integrated circuit design is more sensitive to electrostatic discharge. Designers must make the integrated circuit provide the most effective ESD protection possible, while leaving additional protection components without taking up too much board space and cost.

Figure 1A is a conventional driver circuit with electrostatic discharge protection. The driver circuit 100 includes a light emitting diode driver 110, an inductor Ls, a diode Ds, and capacitors C _Q and C1. The inductor Ls and the diode Ds are connected to the junction LX of the LED driver 110 to form a boost circuit. Capacitor C _{Q is} used to conduct static electricity at node N1, and C1 is used to conduct static electricity at node N2. Since the contact Ch1 of the LED driver 110 outputs a switching signal similar to the pulse width modulation signal, the capacitor C1 affects the signal switching speed. In addition, in principle, static electricity will be directed to the power supply terminal, and negative static electricity will be directed to the ground terminal. The design of the contact Ch1 can guide the negative static electricity to the ground by the internal diode D ₀ inside the LED driver 110. However, there is no way to get static electricity to a power supply.

Figure 1B is another conventional driver circuit with electrostatic discharge protection. The driver circuit 100 includes a light emitting diode driver 110, an inductor Ls, a diode Ds, a capacitor C _Q, and diodes D1 and D2. The inductor Ls and the diode Ds are connected to the junction LX of the LED driver 110 to form a boost circuit. Capacitor C _{Q is} used to conduct static electricity at node N1, and diodes D1 and D2 are used to conduct static electricity at node N2. However, the other end of the diode D1 is connected to the operating voltage Vin of the LED driver. If the positive static electricity is applied to the operating voltage Vin of the LED driver, the stability and quality of the operating voltage Vin will be affected.

Therefore, it is necessary to provide a driver circuit that can properly guide static electricity.

The present disclosure provides a driver circuit with electrostatic discharge protection, comprising: a driver having a dimming unit for generating a dimming signal at a first output node according to a pulse width modulation signal; a boosting circuit, Coupling the driver, generating an output voltage at a second output node according to an input voltage and a boosting signal from a boosting unit of the driver; and an electrostatic discharge protection circuit for reducing the first output node and The static electricity of the second output node includes: a capacitor coupled between the second output node and the ground to guide the static electricity of the second node; and a first guiding component coupled to the first An positive static electricity is transmitted between the output node and the second output node, wherein the positive static electricity of the first output node is transmitted to the first output node through the first guiding component, and The positive static electricity from the first output node is reduced by the capacitor.

The above described drive circuit can guide a larger electrostatic voltage and maintain the circuit operation quality than the conventional circuit.

The above described objects, features, and advantages of the present invention will become more apparent from the description of the preferred embodiments of the invention. . The driver circuit 200 includes a driver 210, a first guiding element 220, a second guiding element 230, an inductor Ls, a diode Ds, and a capacitor C _Q .

The driver 210 has a dimming unit 212. The dimming unit 212 generates a periodically switched dimming signal on the output pin Ch1 according to the input pulse width modulation signal. In this embodiment, the output pin Ch1 is directly connected to the first output node N1, and therefore has a dimming signal at the first output node N1. Generally, the circuit structure of the dimming unit 212 has an MOS transistor connected to the output pin Ch1, such as the MOS transistor Q ₀ shown in FIG. In this embodiment, the MOS transistor Q ₀ has an intrinsic diode D ₀ (body diode) that can direct negative static electricity at the first output node N1 to ground.

In the present embodiment, the boosting circuit composed of the inductor Ls and the diode Ds is coupled to the driver 210, and according to the input voltage Vin and the boosting signal from the boosting unit (not shown) of the driver 210 (by the driver 210) The pin LX output) produces an output voltage Vo at the second output node N2. With the booster circuit, the output voltage Vo is greater than the input voltage Vin.

An electrostatic discharge (ESD) protection circuit is used to reduce the static electricity of the first output node and the second output node. In one embodiment, the ESD protection circuit is disposed outside the driver and is composed of a capacitor C _Q and a first guiding component 220. The first guiding element 220 may be a one-way conducting element or a resistor, but is not limited thereto. The one-way conducting component may be a diode, a metal oxide semiconductor device (MOS), a field-oxide device, a bipolar junction transistor, or a controlled rectifier (SCR). One, but not limited to.

In another embodiment, to enhance the efficiency of the electrostatic discharge protection, an electrostatic discharge (ESD) protection circuit additionally adds a second guiding component 230 between the first output terminal N1 and the ground to guide the first output terminal. Negative static of N1 to ground. The second guiding component 230 may be a diode, a kinetic diode, a capacitor, a Transient Voltage Suppressor, a varistor or a 矽 controlled rectifier, but is not limited thereto.

In another embodiment, the first guiding element 210 and the third guiding element (not shown) can be connected in series, and the positive static electricity can be guided more effectively. The third guiding element may also be a unidirectional conduction element or a resistor, but is not limited thereto.

The capacitor C _{Q is} coupled between the second output node N2 and the ground, and is mainly for guiding the static electricity of the second output node N2. The first guiding component 220 is coupled between the first output node N1 and the second output node N2 for guiding positive static electricity of the first output node N2. In detail, the positive static electricity of the first output node N1 is transmitted to the second output node N2 through the first guiding element 220, and then the positive static electricity from the first output node N1 is lowered by the capacitor C _Q , and the first output is at the first output. The negative static electricity of the node N1 can be guided to the ground by the internal diode D _{0 of the} driver 210. Therefore, the first guiding element 220 forms an ESD protection cell with the inscribed diode D ₀ of the MOS transistor Q ₀ inside the driver 210.

In one embodiment, when the first guiding element 220 is, for example, a diode, the electrostatic discharge protection capability is increased from 6 KV to 25 KV in an actual ESD test. In another embodiment, when the second guiding component 230 is externally connected between the first output node N1 and the ground, the second guiding component 230 forms a set of ESD protection cells with the first guiding component 220. The electrostatic discharge protection capability can exceed 25KV.

In the end, it is obvious to those skilled in the art that they can easily use the disclosed concept and the specific embodiments to change and design other structures that can perform the same purpose without departing from the invention and the scope of the claims.

100, 150, 200. . . Driver circuit

110, 160, 210. . . driver

Ls. . . inductance

Ds, D ₁ , D ₂ , D ₀ . . . Dipole

C _Q , C1. . . capacitance

Q ₀ . . . MOS transistor

220. . . First guiding element

230. . . Second guiding element

Figure 1A is a conventional driver circuit with electrostatic discharge protection;

Figure 1B is another conventional driver circuit with electrostatic discharge protection;

Figure 2 is a driver circuit with electrostatic discharge protection of the present invention.

200. . . Driver circuit

210. . . driver

L _S . . . inductance

D ₀ . . . Dipole

C _Q . . . capacitance

Q ₀ . . . MOS transistor

220. . . First guiding element

230. . . Second guiding element

Claims (9)

A driver circuit with electrostatic discharge protection, comprising: a driver having a dimming unit for generating a dimming signal at a first output node according to a pulse width modulation signal; a boosting circuit coupled to the The driver generates an output voltage at a second output node according to an input voltage and a boost signal from a boost unit of the driver; and an electrostatic discharge protection circuit for reducing the first output node and the second The static electricity of the output node includes: a capacitor coupled between the second output node and the ground to guide the static electricity of the second node; and a first guiding component coupled to the first output node Positive static electricity for guiding the first output node with the second output node; wherein positive static electricity of the first output node is transmitted to the second output node through the first guiding element, and The capacitor reduces positive static electricity from the first output node. The driver circuit with electrostatic discharge protection according to claim 1, wherein the first guiding element is a one-way conducting element or a resistor. The driver circuit with electrostatic discharge protection according to claim 2, wherein the unidirectional conduction device is a diode, a metal oxide semiconductor device (MOS), a field-oxide device, and a bipolar Bipolar junction transistor or controlled rectifier (SCR). The driver circuit with electrostatic discharge protection according to claim 1, wherein the driver further comprises a transistor device having an internal diode, the inscribed diode guiding the first output The node's negative static to ground. The driver circuit with electrostatic discharge protection according to claim 1, further comprising a second guiding component coupled between the first output terminal and the ground for guiding the first output end The negative static electricity of the point to the ground. The driver circuit with electrostatic discharge protection according to claim 5, wherein the second guiding element is a diode, a kinetic diode, a capacitor, a transient voltage suppressor, and a varistor. Or manually control the rectifier. The driver circuit with electrostatic discharge protection according to claim 1 further includes a third guiding element connected in series with the first guiding element for improving the efficiency of guiding static electricity. The driver circuit with electrostatic discharge protection according to claim 1, wherein the electrostatic discharge protection circuit is disposed outside the driver. The driver circuit with electrostatic discharge protection according to claim 1, wherein the output voltage is greater than the input voltage.