TWI497682B - Integrated circuit having circuit damage protection mechanism and method thereof - Google Patents

Description

Integrated circuit with circuit damage protection mechanism and method thereof

The present invention relates to an integrated circuit having a circuit damage protection mechanism and a method thereof.

A DC-to-DC voltage converter, such as a Low Dropout Linear Regulator (LDO) or a Switching Regulator, is used to convert an input voltage to a stable output voltage to provide Load current. In general, conventional DC-to-DC voltage converters include a protection circuit, such as an overcurrent protection circuit, to protect one of the conventional DC-to-DC voltage converter circuits under abnormal operation. Conventional overcurrent protection circuits typically include an overcurrent sensing circuit and an overcurrent control circuit. When the excessive current sensing circuit senses one of the load currents greater than a threshold current, the excessive current control circuit turns off a power transistor connected between the input end and the output end of the voltage converter to protect the electrical system.

However, due to the reverse recovery characteristics of the bulk diode of the power transistor parasitic, a voltage spike occurs on the power transistor during reverse recovery. In addition, some other factors, such as current bouncing, charge injection, or noise interference, may also cause voltage surges. These voltage surges may cause the excessive current protection circuit to malfunction and improperly turn off the power transistor.

It is an object of the present invention to provide an integrated circuit having a circuit damage protection mechanism. According to an embodiment of the invention, the integrated circuit includes a comparator, a first resistor and a high pass filter circuit. One end of the first resistor is coupled to a reference potential, and the other end is coupled to a first input of the comparator to a first node. One end of the high-pass filter circuit is coupled to the first node, and the other end is coupled to a second input end and a voltage signal end of the comparator. Wherein, when an excessive current event occurs at the voltage signal terminal, the comparator is configured to output an excessive current protection signal. In addition, when a surge current event occurs at the voltage signal terminal, the comparator does not output the excessive current protection signal.

Another object of the present invention is to provide a method for protecting a circuit damage, comprising the steps of: (a) inputting a first voltage and a second voltage; and (b) determining whether the second voltage represents a surge voltage; And determining whether the voltage value of the second voltage is higher than a voltage value of the first voltage. The first voltage has a fixed voltage value and the second voltage has a varying voltage value.

The technical features of the present disclosure have been briefly described above, so that a detailed description of the present disclosure will be better understood. Other technical features that form the subject matter of the claims of the present disclosure will be described below. It is to be understood by those of ordinary skill in the art that the present invention disclosed herein may be It should be understood by those having ordinary knowledge in the technical field of the disclosure that such equivalent construction cannot be separated from the attached application. Please understand the spirit and scope of this disclosure as set forth in the patent.

1 is a schematic diagram of an integrated circuit 10 having a circuit damage protection mechanism according to an embodiment of the present invention. In this embodiment, the integrated circuit 10 having the circuit damage protection mechanism includes a comparator 11, a first resistor 12 and a high-pass filter circuit 15. One end of the first resistor 12 is coupled to a reference potential VREF, and the other end is coupled to a first input end of the comparator 11 to a first node A. One end of the high-pass filter circuit 15 is coupled to the first node A, and the other end is coupled to a second input end of the comparator 11 and a voltage signal end 13 to a second node B.

Referring to FIG. 1, in the embodiment, the high-pass filter circuit 15 is composed of a capacitor 153. One end of the capacitor 153 is coupled to the first node A, and the other end is coupled to the second node B. When a voltage signal generated by a large current event occurs at the voltage signal terminal 13, the comparator 11 is configured to output an excessive current protection signal OCP. When a voltage signal generated by a surge current event occurs at the voltage signal terminal 13, the comparator 11 does not output the excessive current protection signal OCP.

2 is a schematic diagram of an integrated circuit 20 having a circuit damage protection mechanism according to another embodiment of the present invention. Compared with FIG. 1, the high-pass filter circuit 15' is composed of a second resistor 151 and a capacitor 155. One end of the second resistor 151 is configured to be in series with the capacitor 155, and the other end is coupled to the first node A of the amplifier 11. One end of the capacitor 155 is coupled to the second resistor 151, and the other end is coupled to the second node B. The components of Figures 1 and 2 are only exemplified There are two possible ways of configuring the high-pass filter circuit. However, the present invention should not be limited thereto.

FIG. 3 is a schematic diagram showing the waveform of an integrated circuit with a circuit damage protection mechanism in the event of an excessive current event occurring according to an embodiment of the present invention. FIG. 4 is a schematic diagram showing the waveform of an over-current protection signal triggered by an integrated circuit having a circuit damage protection mechanism according to an embodiment of the present invention.

Referring to Figures 1 through 4, a load current from a voltage converter (not shown) is converted to a voltage signal V _B via a current/voltage converter (not shown). The voltage signal V _{B is} then transmitted via the voltage signal terminal 13 to the second input of the comparator 11. As the load current increases, the voltage signal V _B also increases. At time t, the voltage signal V _B exceeds a threshold voltage signal V _A (its value = VREF) at the first node A, such that the comparator 11 emits an excessive current protection signal OCP, as shown in FIG. The signal OCP subsequently triggers an excessive current protection mechanism to protect the voltage converter from damage.

FIG. 5 is a schematic diagram of a waveform of an integrated circuit with a circuit damage protection mechanism in the event of a surge current event occurring according to an embodiment of the present invention. The voltage value of the threshold voltage signal V _{A '} is equal to VREF before the surge current event occurs. When a surge current event occurs, such as the aforementioned voltage surge due to the reverse recovery characteristic of the body diode, the surge current signal is converted into a surge voltage signal V _S via the current/voltage converter. The surge voltage signal V _{S is} then transmitted via the voltage signal terminal 13 to the second input of the comparator 11. At this time, due to the high frequency characteristic of the high-pass filter circuit 15/15', the alternating component of the surge voltage signal V _S is superimposed with the reference potential VREF to increase the voltage value of the threshold voltage signal V _{A '} . The threshold voltage signal V _{A '} at the first input of the comparator 11 is now higher than the surge voltage signal V _S at the second input of the comparator 11, so the comparator 11 does not The excessive current protection signal OCP is issued. Therefore, the integrated circuit with the circuit damage protection mechanism does not cause the comparator 11 to malfunction during the reverse recovery, and does not properly turn off the power transistor of the voltage converter.

In order to illustrate the selection of the first resistor 12, the second resistor 151, and the capacitor 153/155 in the integrated circuit having the circuit damage protection mechanism according to an embodiment of the present invention, the following description is given, but the present invention should not be limited thereto. .

To avoid the influence of the surge current event with a pulse width of 100 nS (nanoseconds) as shown in FIG. 5, the capacitance C of the capacitor 153/155 and the capacitance C _in the input capacitance of the comparator 11 can be Meet the following conditions: C>>10 C _in

In addition, the selection of the resistance R1 of the first resistor 12 and the resistance R2 of the second resistor 151 can meet the following conditions:

Among them, K1 is preferably selected to be 100 or more, and K2 is a constant between 1 and 20. In the embodiment of Figure 5, K2 is chosen to be 5.

In summary, the circuit damage protection method of the integrated circuit with the circuit damage protection mechanism is as shown in FIG. 6.

6 is a flow chart of a circuit damage protection method according to an embodiment of the present invention. Referring to FIG. 6, in step S501, the comparator of the integrated circuit having the circuit damage protection mechanism receives a first voltage and a second voltage, wherein the first voltage has a predetermined voltage value VREF, and the first The two voltages have a varying voltage value.

In step S503, it is determined whether the second voltage represents a surge voltage. If the second voltage represents a surge voltage, then step S505 is performed. In step S505, the voltage value of the first voltage is raised to be higher than the second voltage, and step S507 is performed to not output an excessive current protection signal. The voltage value of the first voltage is increased by a capacitor to superimpose the alternating current value of the surge voltage and the preset voltage value of the first voltage.

On the other hand, if the first voltage does not represent a surge voltage, step S502 is performed. In step S502, it is determined whether the voltage value of the second voltage is higher than the voltage value of the first voltage. If the voltage value of the second voltage is higher than the voltage value of the first voltage, step S504 is performed to output an excessive current protection signal. Otherwise, step S507 is performed to not output an excessive current protection signal.

The technical and technical features of the present invention have been disclosed as above, and those skilled in the art can still make various substitutions and modifications without departing from the spirit and scope of the invention. Therefore, the scope of the present invention should be construed as being limited by the scope of the appended claims

10‧‧‧Integral circuit with circuit damage protection mechanism

20‧‧‧Integral circuit with circuit damage protection mechanism

11‧‧‧ Comparator

12‧‧‧First resistance

13‧‧‧voltage signal terminal

15,15'‧‧‧High-pass filter circuit

151‧‧‧second resistance

153‧‧‧ Capacitance

155‧‧‧ Capacitance

A‧‧‧first node

B‧‧‧second node

S501~S507‧‧‧Steps

1 is a schematic diagram of an integrated circuit having a circuit damage protection mechanism according to an embodiment of the present invention; FIG. 2 is a schematic diagram of an integrated circuit having a circuit damage protection mechanism according to another embodiment of the present invention; FIG. 3 is an embodiment of the present invention; FIG. 4 is a schematic diagram of a waveform of an integrated circuit with a circuit damage protection mechanism triggering an excessive current protection signal according to an embodiment of the present invention; FIG. 5 is a schematic diagram of a waveform of an integrated circuit having a circuit damage protection mechanism according to an embodiment of the present invention when a surge current event occurs; and FIG. 6 is a flowchart of a circuit damage protection method according to an embodiment of the present invention.

10‧‧‧Integral circuit with circuit damage protection mechanism

11‧‧‧ Comparator

12‧‧‧First resistance

13‧‧‧current signal terminal

15‧‧‧High-pass filter circuit

153‧‧‧ Capacitance

A‧‧‧first node

B‧‧‧second node

Claims (10)

An integrated circuit having a circuit damage protection mechanism includes: a comparator; a first resistor having one end coupled to a reference potential and the other end coupled to a first input of the comparator to a first node And a high-pass filter circuit having one end coupled to the first node, and the other end coupled to a second input end of the comparator and a voltage signal end coupled to a second node; wherein, when an excessive current event occurs The voltage signal terminal is configured to output an excessive current protection signal; and wherein the comparator does not output the excessive current protection signal when a surge current event occurs at the voltage signal terminal. The integrated circuit of claim 1, wherein the high-pass filter circuit comprises: a capacitor, one end of which is coupled to the first node, and the other end of which is coupled to the second node. The integrated circuit of claim 1, wherein the high-pass filter circuit comprises: a second resistor coupled to the first node at one end thereof; and a capacitor coupled to the second resistor at one end The other end is coupled to the second node. For example, the integrated circuit described in claim 2 or 3, wherein the capacitance of the capacitor is calculated by the following formula: C>10*Cin, where C represents the capacitance of the capacitor, and Cin represents the comparator. The capacitance of the input capacitor. The integrated circuit of claim 2, wherein the resistance of the second resistor is calculated by the following formula: R = (K1 * T) / (2 * π * C), wherein R Representing the resistance of the second resistor, K1 represents a constant value between 1 and 10, T represents the pulse width of the surge current event, and C represents the capacitance of the capacitor. The integrated circuit of claim 2, wherein the resistance of the first resistor is calculated by using the following formula: R>(100*T)/(2*π*C), wherein R Representing the resistance of the first resistor, T represents the pulse width of the surge current event, and C represents the capacitance of the capacitor. A method for circuit damage protection mechanism, the method comprising: (a) inputting a load current; (b) inputting a first voltage and a second voltage related to the load current; and (c) determining whether the second voltage represents a surge voltage; and (d) determining whether the voltage value of the second voltage is higher than a voltage value of the first voltage; wherein the first voltage has a fixed voltage value that does not vary with the load current, and the second The voltage has a voltage value that varies with the load current. The method of claim 7, wherein the step (b) further comprises: when the second voltage represents the surge voltage, increasing a voltage value of the first voltage to be higher than a voltage value of the second voltage; Does not output a large current protection signal. The method of claim 8, wherein the voltage value of the first voltage is increased by a capacitor to superimpose an alternating current value of the surge voltage and a fixed voltage value of the first voltage. The method of claim 7, wherein the step (b) further comprises When the second voltage does not represent the surge voltage, step (c) is performed, and in step (c), when the voltage value of the second voltage is higher than the voltage value of the first voltage, an excessive current is output. The signal is protected, and when the voltage value of the second voltage is lower than the voltage value of the first voltage, the excessive current protection signal is not output.