TWI445160B - Esd protection and display driver circuit thereof - Google Patents

Description

Electrostatic protection circuit and display drive circuit

The present invention is a technology related to electrostatic discharge (ESD) protection in the semiconductor industry, and is particularly suitable for an electrostatic discharge protection circuit between an open drain output and a power supply voltage VDD.

In general, electrostatic voltages present in the environment or on the human body can be as high as several thousand volts. In the manufacturing process of active array devices (such as liquid crystal displays, organic light-emitting diode displays, electronic paper displays), if thousands of volts of static electricity flow into the active array device on the operator, the static electricity will damage the active array device. The thin film transistor and its internal circuitry. In the semiconductor industry, from the manufacture, packaging, and assembly of integrated circuits (ICs), even after the product is completed, integrated circuits are inevitably exposed to the electrostatic discharge threat environment, including human use (human Body model (HBM), machine model (MM), charge-device model (CDM), and field-induced model (FIM) all produce operating voltage than the integrated circuit itself. It should be several hundred thousand times higher than the static voltage. Such a high static voltage will generate a large electrostatic current at the moment of discharge to burn the internal circuit.

In order to avoid electrostatic damage to the electronic components of the active array device, an electrostatic discharge protection (ESD protection) component is usually provided between the external internal circuits of the main internal circuit to ensure that the electrostatic discharge current does not occur when an electrostatic discharge event (ESD event) occurs. It will be damaged by the main internal circuit. If there is no electrostatic discharge protection when an electrostatic discharge event occurs, the electrostatic discharge current will flow through the internal circuit, causing the internal circuit to burn out. The so-called electrostatic discharge protection is to make a short circuit between the external circuit and the low voltage terminal VSS (usually the ground terminal), so that the short circuit is not turned on under the normal operation voltage. It maintains normal operation, and a short circuit occurs when an electrostatic discharge occurs to quickly turn on the electrostatic discharge current.

Figure 1 is a circuit diagram showing a conventional type of electrostatic protection circuit. As shown in FIG. 1 , the resistor R and the capacitor C are connected in series to form a low-pass filter. The inverter 101 is coupled between the power terminal and the ground. The inverter 101 includes a P-type transistor 105 and N. The transistor 107, the driving transistor 103 for conducting static electricity, is connected between the power supply terminal VDDA, the ground terminal GNDA, and the inverter 101. When static electricity is present on the power supply terminal VDDA, the voltage on the power supply terminal VDDA is instantaneously increased. At this time, the potential at the terminal end X does not catch up with the potential on the power supply terminal VDDA, and the voltage on the gate of the P-type transistor 105 in the inverter 101. It will be smaller than the voltage on the power supply terminal VDDA, so that the P-type transistor 105 is turned on, and the connection will also cause the driving transistor 103 to be turned on, thereby eliminating the static electricity on the power supply terminal VDDA.

However, under a high voltage process, for example, under a voltage process of 12V to 18V, since the holding voltage of the driving transistor 103 is lower than the voltage of the power supply terminal VDDA, the driving transistor 103 is easily turned to the power supply terminal. VDDA draws a large current, causing the driving transistor 103 or other components to burn out, which not only makes the driving transistor 103 unable to continue to remove static electricity, but is also likely to cause other circuits to be damaged due to high temperature.

Therefore, a new electrostatic protection circuit is needed, which can effectively eliminate static electricity, and can avoid being burned by a large current, and also avoid damage to the circuit in the display.

Therefore, an aspect of the present invention provides an electrostatic protection circuit capable of preventing a large current from being burned by itself and effectively eliminating static electricity.

According to an embodiment of the invention, an electrostatic protection circuit protects a system from electrostatic damage. The electrostatic protection circuit includes a dual carrier junction transistor, a capacitor, and a resistor. The double-carrier junction transistor has a base, an emitter, and a collector. The emitter is electrically connected to a power terminal or a ground terminal, and the collector is electrically connected to a ground terminal or a power terminal; the capacitor One of the first ends is electrically connected to the base of the bipolar junction transistor, and the other end of the capacitor is electrically connected to the ground. One end of the resistor is electrically connected to the base of the bipolar junction transistor, and the other end of the resistor is electrically connected to the power terminal.

Another aspect of the present invention provides an electrostatic protection circuit capable of preventing self-extraction of a large current and burning, and enhancing the efficiency of eliminating static electricity.

According to another embodiment of the present invention, an electrostatic protection circuit provides electrostatic protection. The electrostatic protection circuit includes a dual carrier junction transistor, a capacitor, a resistor, and a diode. The bipolar junction transistor has a base, an emitter, and a collector. The emitter is electrically connected to a power terminal or a ground terminal, and the collector is electrically connected to a ground terminal or a power terminal. One of the first ends of the capacitor is electrically connected to the base of the bipolar junction transistor, and the other end of the capacitor is electrically connected to the ground. One end of the resistor is electrically connected to the base of the bipolar junction transistor, and the other end of the resistor is electrically connected to the power terminal. The diode has a positive electrode and a negative electrode. The positive electrode of the diode is electrically connected to the ground terminal, and the negative electrode of the diode is electrically connected to the power terminal.

The electrostatic protection circuit of the above embodiment can effectively remove static electricity inside and outside the display in a stable state, protect the display from electrostatic damage, and does not cause components of the electrostatic protection circuit to burn out.

The electrostatic protection circuit of the above embodiment is applied to the driving integrated circuit of the display, and can effectively remove static electricity inside and outside the display in a stable state, protect the display from electrostatic damage, and not burn the components of the electrostatic protection circuit itself. It does not increase the temperature of the display and affect the performance of the display.

Please refer to FIG. 2 , which is a schematic diagram of a display driving circuit and an electrostatic protection circuit thereof according to an embodiment of the present invention. The display driving circuit 200 mainly includes a diode 203, an internal circuit 207, and an electrostatic protection circuit 209. The diode 203 has a positive electrode and a negative electrode, the positive electrode of the diode 203 is electrically connected to the ground GNDA, and the negative electrode of the diode 203 is electrically connected to the power supply terminal VDDA.

In order to maintain the non-conduction at normal operating voltage and the high-static voltage to be turned on, the reverse bias characteristic of the diode 203 is usually used to exclude static electricity, that is, only the static electricity makes the diode 203 When the reverse bias is greater than its punch through voltage, it will penetrate through to shunt the electrostatic discharge current. More specifically, it is assumed that there is a positive static electricity on the power supply terminal VDDA, so that the voltage on the power supply terminal VDDA is suddenly increased, and the two ends of the diode 203 are reversely biased, and the diode 203 is penetrated and collapsed. Discharge static electricity on the power supply terminal VDDA to the ground terminal GNDA to avoid electrostatic damage and internal circuit 207.

However, if the diode 203 is used alone to exclude static electricity, the elimination of static electricity is not very efficient, and static electricity may still damage the internal components of the display driving circuit. Therefore, it is necessary to simultaneously use the electrostatic protection circuit 209 to remove static electricity.

Please refer to FIG. 3, which is a circuit diagram of an electrostatic protection circuit according to an embodiment of the present invention. The electrostatic protection circuit 209 can be used alone in the display driving circuit to exclude static electricity, or can be used together with the diode to exclude static electricity.

The electrostatic protection circuit 209 protects the system from electrostatic damage. For example, the electrostatic protection circuit 209 can be placed on a display (not shown) to provide electrostatic protection for the drive circuitry of the display. The electrostatic protection circuit 209 mainly includes a bipolar junction transistor 301, a capacitor 305, and a resistor 303. The bipolar junction transistor 301 has a base Ba, an emitter Em, and a collector Co. The bipolar junction transistor is a PNP type bipolar junction transistor, and the emitter Em is electrically Connect the power supply terminal VDDA or the ground terminal GNDA. The collector Co is electrically connected to the ground terminal GNDA or the power terminal VDDA. The first end of the capacitor 305 is electrically connected to the base Ba of the bipolar junction transistor 301, and the other end of the capacitor 305 is electrically connected to the ground GNDA. One end of the resistor 303 is electrically connected to the base Ba of the bipolar junction transistor 301, and the other end of the resistor 303 is electrically connected to the power supply terminal VDDA.

In the electrostatic protection circuit 209 of FIG. 3, the transistor 301 is a PNP bipolar junction transistor, and the emitter of the PNP bipolar junction transistor is electrically connected to the power supply terminal VDDA, PNP double carrier. The collector Co of the junction transistor is electrically connected to the ground GNDA.

Capacitor 305 and resistor 303 form a low pass filter. In this embodiment, the RC time constant of the low pass filter is between milliseconds and microseconds to maintain the normal operation of the display driver circuit. In detail, under normal operating conditions in which it is not necessary to exclude static electricity, the potential at the terminal X is slightly lower than the potential at the power supply terminal VDDA, while still turning off the transistor 301. When there is a positively charged static electricity at the power supply terminal VDDA, the voltage at VDDA on the power supply terminal changes rapidly. When the voltage change period is between the millisecond and microsecond, the voltage at the terminal X does not catch up with the voltage on VDDA. The base junction of transistor 301 is forward biased such that transistor 301 conducts to reject positively charged static electricity.

The electrostatic protection circuit of the above embodiment is applied to the driving integrated circuit of the display, and can effectively remove static electricity inside and outside the display in a stable state, protect the display from electrostatic damage, and not burn the components of the electrostatic protection circuit itself. It does not increase the temperature of the display and affect the performance of the display.

The present invention has been disclosed in the above embodiments, and is not intended to limit the present invention. Any one of ordinary skill in the art to which the present invention pertains may make various changes and modifications without departing from the spirit and scope of the invention. The scope of protection of the present invention is therefore defined by the scope of the appended claims.

101. . . inverter

103. . . Drive transistor

105. . . P-type transistor

107. . . N type transistor

200. . . Display driver circuit

203. . . Dipole

207. . . Internal circuit

209. . . Electrostatic protection circuit

301. . . Transistor

303. . . resistance

305. . . Capacitor

Ba. . . Base

C. . . capacitance

Co. . . Collector

Em. . . Emitter

GNDA. . . Ground terminal

R. . . resistance

VDDA. . . Power terminal

X. . . End point

The above and other objects, features, advantages and embodiments of the present invention will become more apparent and understood.

Figure 1 is a circuit diagram showing a conventional type of electrostatic protection circuit.

2 is a schematic diagram of a display driving circuit and an electrostatic protection circuit thereof according to an embodiment of the present invention.

Fig. 3 is a circuit diagram showing an electrostatic protection circuit according to an embodiment of the present invention.

209. . . Electrostatic protection circuit

301. . . Transistor

303. . . resistance

305. . . Capacitor

Ba. . . Base

Co. . . Collector

Em. . . Emitter

GNDA. . . Ground terminal

VDDA. . . Power terminal

X. . . End point

Claims (10)

An electrostatic protection circuit for protecting a system from electrostatic damage, the electrostatic protection circuit comprising: a double carrier junction transistor having a base, an emitter, and a collector, the emitter being electrically connected a power supply terminal or a ground terminal, the collector is electrically connected to a ground terminal or a power terminal; a capacitor, a first end of the capacitor is electrically connected to the base of the bipolar junction transistor, The other end of the resistor is electrically connected to the ground end; and a resistor is electrically connected to the base of the bipolar junction transistor, and the other end of the resistor is electrically connected to the power terminal. The electrostatic protection circuit of claim 1, wherein the electro-crystal system is a PNP bipolar junction transistor, and the emitter of the PNP bipolar junction transistor is electrically connected to the power terminal, the PNP The collector of the bipolar junction transistor is electrically connected to the ground. The electrostatic protection circuit of claim 2, wherein when a positively charged static electricity is present at the power supply terminal, the PNP dual carrier junction transistor is turned on to exclude positively charged static electricity. The electrostatic protection circuit of claim 1, wherein the capacitor and the resistor form a low pass filter having a RC time constant between a millisecond and a microsecond. The electrostatic protection circuit of claim 1, wherein the electrostatic protection circuit is disposed on a display to provide electrostatic protection for a driving circuit of a display. A display driving circuit for providing electrostatic protection, the display driving circuit comprising: a double carrier junction transistor having a base, an emitter, and a collector, the emitter being electrically connected to a power terminal or a a grounding end, the collector is electrically connected to a ground or a power terminal; a capacitor, a first end of the capacitor is electrically connected to the base of the bipolar junction transistor, and the other end of the capacitor is electrically Connected to the ground terminal; a resistor, one end of the resistor is electrically connected to the base of the bipolar junction transistor, the other end of the resistor is electrically connected to the power terminal; and a diode, The anode and the cathode are electrically connected to the ground, and the cathode of the diode is electrically connected to the power terminal. The display driving circuit of claim 6, wherein the electro-crystal system is a PNP dual-carrier junction transistor, and the emitter of the PNP bipolar junction transistor is electrically connected to the power terminal, the PNP The collector of the bipolar junction transistor is electrically connected to the ground. The display driving circuit of claim 7, wherein when a positively charged static electricity is present at the power supply terminal, the PNP dual carrier junction transistor is turned on to exclude positively charged static electricity. The display driving circuit of claim 6, wherein the capacitor and the resistor form a low pass filter having a RC time constant between a millisecond and a microsecond. The display driving circuit of claim 6, wherein the electrostatic protection circuit is disposed on a display to provide electrostatic protection for a driving circuit of a display.