TW201319773A - Voltage regulator and operating method thereof - Google Patents

Abstract

A voltage regulator and an operating method of the voltage regulator are provided. The voltage regulator includes a voltage generating unit and a voltage comparing unit. The voltage generating unit outputs an output voltage to a load according to a relationship between a first reference voltage received by a reference input of the voltage generating unit and a voltage level at a feedback input of the voltage generating unit. The voltage comparing unit compares the output voltage of the voltage generating unit and a second reference voltage. When the output voltage of the voltage generating unit is lower the second reference voltage, the voltage comparing unit provides a feedback path between the output and the feedback input of the voltage generating unit. When output voltage of the voltage comparing unit is higher than the second reference voltage, the voltage comparing unit cuts off the feedback path and provides a third reference voltage to the feedback input of the voltage generating unit.

Description

Voltage regulator and its operation method

The invention relates to a voltage regulator and a method of operating the same.

1 is a circuit diagram of a voltage regulator according to a conventional technique, including an error amplifier OP1, an output transistor Pout, and a voltage dividing circuit composed of resistors R11 and R12. Referring to FIG. 1, when the voltage regulator 10 is in normal operation, the voltage VFB received by the positive input terminal of the error amplifier OP1 is close to the reference voltage VREF received by the negative input terminal. When the voltage VFB is less than the reference voltage VREF, the output voltage OPout of the error amplifier OP1 will decrease, so that the gate-source voltage of the output transistor Pout increases and the on resistance decreases, thereby causing the output voltage Vout to increase. Big. On the contrary, when the voltage VFB is greater than the reference voltage VREF, the on-resistance of the output transistor Pout increases, and the output voltage Vout is thus lowered. Since the voltage VFB is a feedback signal divided by the output voltage Vout, the voltage regulator 10 can generate a fixed output voltage Vout using such a feedback relationship.

Since the voltage regulator 10 is just energized, the output of the error amplifier OP1 is in a floating state. In addition to factors such as circuit fabrication and connection, the voltage regulator 10 may generate many unpredictable conditions at startup. For example, the error amplifier OP1 tends to output a pulse with a large amplitude when energized. Such a situation may cause problems with short circuits or damage to transistors or other circuit components. Therefore, how to use the voltage regulator to provide a stable voltage output while ensuring that the voltage regulator does not cause damage due to an unexpected state or output an unexpected result is indeed an important subject in the current field.

The present invention provides a voltage regulator and method of operating the same for protecting circuitry from unwanted damage.

The invention provides a voltage regulator comprising a voltage generating unit and a voltage comparing unit. The voltage generating unit has a reference end, a feedback end and an output end, and the reference end of the voltage generating unit receives the first reference voltage, wherein the voltage generating unit passes the output according to the voltage relationship between the reference end and the feedback end of the voltage generating unit Corresponding to the output voltage to the load. The input end of the voltage comparison unit is coupled to the output end of the voltage generating unit, the output end of the voltage comparison unit is coupled to the feedback end of the voltage generating unit, and the voltage comparing unit compares the voltage of the output end of the voltage generating unit with the second reference voltage Wherein when the voltage at the output of the voltage generating unit is less than the second reference voltage, the voltage comparing unit provides a feedback path between the output end of the voltage generating unit and the feedback terminal, and when the voltage at the output of the voltage generating unit is greater than the second When the voltage is referenced, the voltage comparison unit cuts off the feedback path and provides a third reference voltage to the feedback terminal of the voltage generating unit.

The present invention provides a method of operating a voltage regulator comprising the following steps. First, the voltage generating unit is configured, wherein the voltage generating unit has a reference end, a feedback end and an output end, and the voltage generating unit generates an output voltage corresponding to the load via the output end according to the relationship between the voltage of the reference end and the feedback end. Next, a first reference voltage is provided to the reference terminal of the voltage generating unit. Then, the voltage at the output of the voltage generating unit is compared with the second reference voltage. When the voltage at the output of the voltage generating unit is less than the second reference voltage, a feedback path is provided between the output of the voltage generating unit and the feedback terminal. In addition, when the voltage at the output of the voltage generating unit is greater than the second reference voltage, the feedback path is cut off and a third reference voltage is supplied to the feedback terminal of the voltage generating unit.

The invention also provides a voltage regulator comprising an error amplifier, an output transistor and a voltage comparison unit. The error amplifier has a first input end, a second input end and an output end, wherein the second input end of the error amplifier is coupled to the first reference voltage. The output transistor has a first end, a second end and a control end, wherein the control end of the output transistor is coupled to the output end of the error amplifier, the first end of the output transistor is coupled to the power supply voltage, and the output transistor is The two ends correspond to the output voltage to the load. The input end of the voltage comparison unit is coupled to the second end of the output transistor, the output end of the voltage comparison unit is coupled to the first input end of the error amplifier, and the voltage comparison unit provides a feedback path to the second end of the output transistor Between the first input terminals of the error amplifier, and the voltage comparison unit compares the voltage of the second end of the output transistor with the second reference voltage, wherein when the voltage of the second end of the output transistor is greater than the second reference voltage, the voltage comparison unit provides The third reference voltage is to the control terminal of the output transistor.

Based on the above, the present invention provides a voltage regulator and an operation method thereof. When the output voltage is greater than the second reference voltage, the output of the voltage generation unit is limited, so that the voltage regulator does not generate an unexpected wave or a large voltage. The input even caused damage to the transistor.

The above described features and advantages of the present invention will be more apparent from the following description.

2 is a functional block diagram of a voltage regulator according to a first embodiment of the present invention. Referring to FIG. 2 , the voltage regulator 20 includes a voltage generating unit 110 and a voltage comparing unit 120 . The voltage generating unit 110 has a reference terminal RIN, a feedback terminal FIN, and an output terminal OUT. The reference terminal RIN receives the first reference voltage REF1. The voltage generating unit 110 then generates an output voltage Vout to the load 150 via the output terminal OUT according to the relationship between the voltages of the first reference voltage REF1 and the feedback terminal FIN.

The input terminal CIN of the voltage comparison unit 120 is coupled to the output terminal OUT of the voltage generating unit 110 and receives the output voltage Vout of the voltage generating unit 110. The output terminal COUT of the voltage comparison unit 120 is coupled to the feedback terminal FIN of the voltage generating unit 110 and provides a feedback voltage FB. The voltage comparison unit 120 compares the output voltage Vout of the voltage generating unit 110 with the second reference voltage REF2. When the output voltage Vout is less than the second reference voltage REF2, the voltage comparison unit 120 provides a feedback path between the output terminal OUT of the voltage generating unit 110 and the feedback terminal FIN. On the other hand, when the output voltage Vout of the voltage generating unit 110 is greater than the second reference voltage REF2, the voltage comparing unit 120 cuts off the feedback path and supplies the third reference voltage REF3 to the feedback terminal FIN of the voltage generating unit 110.

In different embodiments, the voltage levels of the first reference voltage REF1, the second reference voltage REF2, and the third reference voltage REF3 may be the same as each other, or may be different from each other. The voltage levels of the first reference voltage REF1, the second reference voltage REF2, and the third reference voltage REF3 may be determined according to the design specifications of the actual product. For example, in this embodiment, the third reference voltage REF3 may be a ground voltage or other low level voltage (fixed voltage), which may be adjusted according to the actual application, and the present invention is not limited to the above.

3 is a functional block diagram of a voltage regulator according to a second embodiment of the present invention. The embodiment shown in FIG. 3 can refer to the related description of FIG. 2. Compared with FIG. 2, the second embodiment illustrated in FIG. 3 provides a more detailed operation of the voltage comparison unit 120. Referring to FIG. 3 , the voltage comparison unit 120 includes a voltage dividing circuit 121 , a first comparator 122 , a first switching unit 123 , and a second switching unit 124 . The voltage dividing circuit 121 is coupled between the output terminal OUT of the voltage generating unit 110 and the third reference voltage REF3. The voltage dividing circuit 121 divides the output voltage Vout of the voltage generating unit 110 to generate a first feedback voltage FB1 and a second feedback voltage FB2. The voltage levels of the first feedback voltage FB1 and the second feedback voltage FB2 may be the same as each other or may be different from each other depending on the design specifications of the actual product.

The first comparator 122 has a first input terminal CIN11, a second input terminal CIN12 and an output terminal, wherein the first input terminal CIN11 receives the second reference voltage REF2, and the second input terminal CIN12 receives the first voltage from the voltage dividing circuit 121. The voltage FB1 is feedback. The first switch unit 123 has a first end S11, a second end S12 and a control end S13, and the second switch unit 124 has a first end S21, a second end S22 and a control end S23. The first end S11 of the first switch unit 123 and the first end S21 of the second switch unit 124 are coupled to the feedback end FIN of the voltage generating unit 110, and the control end S13 of the first switch unit 123 and the second switch unit 124 And S23 is coupled to the output of the first comparator 122. The second end S12 of the first switching unit 123 is coupled to the third reference voltage REF3, and the second end S22 of the second switching unit 124 receives the second feedback voltage FB2.

The first comparator 122 compares the first feedback voltage FB1 with the second reference voltage REF2. When the first feedback voltage FB1 is smaller than the second reference voltage REF2, the first comparator 122 turns the first switching unit 123 off, and turns the second switching unit 124 on, so as to be turned back. The second feedback voltage FB2 of the voltage FB is transmitted to the feedback terminal FIN of the voltage generating unit 110. When the second switching unit 124 is turned on, it can be seen that there is a feedback path in the voltage comparison unit 120 between the output terminal OUT of the voltage generating unit 110 and the feedback terminal FIN. Conversely, when the first feedback voltage FB1 is greater than the second reference voltage REF2, the first comparator 122 disables the second switching unit 124, and the first switching unit 123 is turned on. When the first switching unit 123 is turned on, the voltage comparison unit 120 supplies the third reference voltage REF3 as the feedback voltage FB to the feedback terminal FIN of the voltage generating unit 110. When the second switching unit 124 is not turned on, it can be considered that the feedback path existing in the voltage comparison unit 120 is cut off.

4 is a flow chart showing a method of operating the voltage regulator 11 in accordance with an embodiment of the present invention, and FIG. 5 is a flow chart showing a method of operating the voltage regulator 11 according to an embodiment of the invention. Referring to FIG. 4 and FIG. 5 simultaneously, the voltage generating unit 110 is disposed in the voltage regulator 11 in step S501. In the present embodiment, the voltage generating unit 110 includes an error amplifier OP1 and an output transistor Pout. The error amplifier OP1 has a first input OPIN1, a second input OPIN2 and an output OPO. In this embodiment, as shown in FIG. 4, the first input terminal OPIN1 is a positive input terminal (non-inverting input terminal), and the second input terminal OPIN2 is a negative input terminal (inverting input terminal). In other embodiments, the first input OPIN1 can be a negative input and the second input OPIN2 can be a positive input. The second input terminal OPIN2 and the first input terminal OPIN1 of the error amplifier OP1 are respectively connected to the reference terminal RIN and the feedback terminal FIN of the voltage generating unit 110. That is, the first input terminal OPIN1 of the error amplifier OP1 is coupled to the output terminal of the voltage comparison unit 120. At step S502, the first reference voltage REF1 is supplied to the reference terminal RIN of the voltage generating unit 110. Therefore, the second input terminal OPIN2 of the error amplifier OP1 is capable of receiving the first reference voltage REF1.

The output transistor Pout has a first end, a second end, and a control end. In this embodiment, the output transistor Pout is a P-channel metal oxide semiconductor (PMOS) transistor. In other embodiments, the output transistor Pout can be other types of transistors. A control terminal (eg, a gate) of the transistor Pout is coupled to an output terminal OPO of the error amplifier OP1. The first end (eg, the source) of the transistor Pout is coupled to the power supply voltage VCC, and the second end (eg, the drain) of the transistor Pout is coupled to the output terminal OUT of the voltage generating unit 110 to generate an output voltage Vout correspondingly. To load 150.

Please continue to refer to Figures 4 and 5. In the present embodiment, the voltage dividing circuit 121 is formed by connecting the resistors R1, R2, and R3 in series. However, the present invention is not limited thereto, and can be changed according to the actual application. The first switching unit 123 includes a N-channel metal oxide semiconductor (NMOS) transistor SW1, and the second switching unit 124 includes a PMOS transistor SW2.

In this embodiment, the first input terminal (eg, the positive input terminal) of the first comparator 122 receives the second reference voltage REF2, and the second input terminal (eg, the negative input terminal) of the first comparator 122 is received from the resistor R1. The first feedback voltage FB1 is received at a common junction with the resistor R2. At step S503, conceptually, the first comparator 122 compares the second reference voltage REF2 with the output voltage Vout of the voltage generating unit 110. In fact, the first comparator 122 can compare the second reference voltage REF2 with the first feedback voltage FB1 representing the output voltage Vout.

If it is determined in step S503 that the first feedback voltage FB1 is smaller than the second reference voltage REF2, step S504 is performed. At step S504, the first comparator 122 outputs a low level voltage such that the transistor SW1 is in a cut-off state and the transistor SW2 is in an on state. When the transistor SW2 is turned on and the transistor SW1 is turned off, the voltage comparison unit 120 supplies the second feedback voltage FB2 as the feedback voltage FB to the feedback terminal FIN of the voltage generating unit 110.

If it is determined in step S503 that the first feedback voltage FB1 is greater than the second reference voltage REF2, then step S505 is performed. At step S505, the first comparator 122 outputs a high level voltage such that the transistor SW1 is in an on state, and the transistor SW2 is in a truncated state. When the transistor SW2 is turned off and the transistor SW1 is turned on, the voltage comparison unit 120 supplies the third reference voltage REF3 as the feedback voltage FB to the feedback terminal FIN of the voltage generating unit 110. It should be noted that the embodiments of the switch units 123 and 124 are not limited thereto, and may be combined with an appropriate embodiment according to the actual application to achieve the same purpose.

Referring to FIG. 2, the implementation of the voltage comparison unit 120 is not limited to the modes shown in FIG. 3 and FIG. In other embodiments of the present invention, the feedback path provided between the output terminal OUT and the feedback terminal FIN of the voltage generating unit 110 shown by the voltage comparing unit 120 shown in FIG. 2 is not cut off due to the voltage comparison result. Instead, when the voltage Vout at the output of the voltage generating unit 110 is greater than the second reference voltage REF2, the voltage comparing unit 120 supplies the third reference voltage REF3 to the control terminal of the output transistor Pout. Therefore, when the output voltage Vout is excessively large, the voltage regulator 11 can quickly and immediately turn off the output transistor Pout, avoiding the possibility that the output transistor Pout and/or the load 150 is damaged.

FIG. 6 is an embodiment of a voltage regulator according to a third embodiment of the present invention. The embodiment shown in FIG. 6 can be referred to the related description of FIG. 2, FIG. 3 and FIG. Referring to FIG. 6, the coupling relationship between the error amplifier OP1, the output transistor Pout, and the load 150 is the same as that of the above embodiment, and details are not described herein. The difference from the embodiment shown in FIG. 4 lies in the implementation of the voltage comparison unit 120. The voltage comparison unit 120 in FIG. 6 includes a voltage dividing circuit 121, a first comparator 122, and a switching unit 125. The voltage dividing circuit 121 is composed of resistors R1, R2, and R3. The resistors R1, R2 and R3 are connected in series between the second end of the output transistor Pout and the third reference voltage REF3 to provide a feedback voltage FB to the feedback terminal FIN of the error amplifier OP1. The first input (eg, the negative input) of the first comparator 122 receives the second reference voltage REF2, and the second input (eg, the positive input) receives the feedback voltage FB1 from the voltage divider circuit 121. In the embodiment, the switch unit 125 includes an NMOS transistor SW3. A first end (eg, a drain) of the transistor SW3 is coupled to a control terminal of the output transistor Pout, and a second terminal (eg, a source) of the transistor SW3 is coupled to the third reference voltage REF3, and a control terminal of the transistor SW3 (eg, The gate is coupled to the output of the first comparator 122.

When the divided voltage of the output voltage Vout (the feedback voltage FB1) is greater than the second reference voltage REF2, the first comparator 122 outputs a high level voltage such that the transistor SW3 is turned on, and the voltage comparison unit 120 thus provides the third reference voltage REF3. (for example, the ground voltage) to the control terminal of the output transistor Pout, causing the output transistor Pout to be turned off. On the contrary, when the divided voltage of the output voltage Vout (the feedback voltage FB1) is smaller than the second reference voltage, the first comparator 122 outputs a low-level voltage so that the transistor SW3 is turned off, so the operation of the output transistor Pout is not affected. . The embodiment of the switch unit 125 is not limited thereto, and may be combined with an appropriate embodiment according to the actual application to achieve the same object.

FIG. 7 is a schematic diagram of a function of a voltage regulator 11 according to a fourth embodiment of the present invention. The embodiment shown in FIG. 7 can refer to the related description of FIG. 2, FIG. 3, FIG. 4 and FIG. In this embodiment, in addition to the architecture described in the foregoing embodiments, the current sensing unit 130 and the current limiting unit 140 are added. The current sensing unit 130 senses the output current at the output of the voltage generating unit 110 and transmits the sensed current sensing result to the current limiting unit 140. The current limiting unit 140 compares the first reference current with the current sensing result, and limits the output current of the output end of the voltage generating unit 110 according to the comparison result. When the output current of the voltage generating unit 110 is greater than a preset value, the current limiting unit 140 controls the voltage generating unit 110 to limit the output current of the voltage generating unit 110. Therefore, in addition to the function of limiting the output voltage, the voltage regulator 11 further increases the protection effect of limiting the maximum current.

FIG. 8 is an embodiment of a voltage regulator 11 according to a fifth embodiment of the present invention. The embodiment shown in FIG. 8 can refer to the related description of FIG. 7. Referring to FIG. 8 , the voltage regulator 11 includes a voltage generating unit 110 , a voltage comparing unit 120 , a current sensing unit 130 , a current limiting unit 140 , and a temperature sensing unit 160 . The voltage generating unit 110 and the voltage comparing unit 120 can be implemented by referring to the related descriptions of the foregoing embodiments, and thus are not described herein again. The current sensing unit 130 includes a first P-type transistor P1, the gate of which is coupled to the output terminal OPO of the error amplifier OP1, the first end of the transistor P1 (eg, the source) is coupled to the power supply voltage VCC, and the transistor P1 The second end (eg, the drain) outputs a current sensed result to the current limiting unit 140. The current sensing unit 130 generates a sensing current Is according to the output current Iout. The proportional relationship between the sense current Is and the output current Iout depends on the ratio of the size of the transistor P1 to the size of the output transistor Pout, for example, Iout: Is=K1: 1, where K1 is The first ratio value is positively correlated with the size ratio relationship between the transistor P1 and the output transistor Pout.

The current limiting unit 160 includes a first current source IS1, a first current mirroring unit 141, a second current mirroring unit 142, and a pull-up unit 143. The first current source IS1 generates a first reference current ir1. The first current mirroring unit 141 is coupled to the current sensing unit 130 to receive the current sensing result and mirrored to generate the first mirror current im1. The second current mirroring unit 142 is coupled to the first current mirror unit 141 and the first current source IS1. The second current mirroring unit 142 receives the first reference current ir1 and mirrors the second mirror current im2. The pull-up unit 143 is coupled to the first current mirror unit 141 and the first current mirror unit 142. Whether to pull up the gate voltage of the output transistor Pout is determined according to the first mirror current im1 and the second mirror current im2.

The first current mirror unit 141 includes a first N-type transistor N1 and a second N-type transistor N2. The first end of the transistor N1 (eg, the drain) receives the current sensing result, that is, the sensing current Is, the second end of the transistor N1 (eg, the source) is coupled to the third reference voltage REF3, and the transistor N1 The gate is coupled to the drain of the transistor N1 itself. The first end of the transistor N2 (eg, the drain) outputs a first mirror current im1, the second end of the transistor N2 (eg, the source) is coupled to the third reference voltage REF3, and the gate of the transistor N2 is coupled. To the gate of transistor N1. According to the size ratio between the transistors N1 and N2, the first mirror current im1 has a fixed proportional relationship with the sensing current Is, for example, Is: im1=K2: 1, where K2 is the second ratio value, and the transistor N1 Positively related to the size ratio between N2. Therefore, the relationship between the first mirror current im1 and the output current Iout is im1=Iout/(K1*K2).

The second current mirror unit 142 includes a second P-type transistor P2 and a third P-type transistor P3. The first end of the transistor P2 (eg, the drain) is coupled to the first current source IS1 to receive the first reference current ir1, the second end of the transistor P2 (eg, the source) is coupled to the power supply voltage VCC, and the transistor P2 The gate is coupled to the drain of the transistor P2 itself. The first end of the transistor P3 (eg, the drain) outputs a second mirror current im2, the second end of the transistor P3 (eg, the source) is coupled to the power supply voltage VCC, and the gate of the transistor P3 is coupled to the transistor The gate of P2. According to the size ratio between the transistors P2 and P3, the second mirror current im2 has a fixed proportional relationship with the first reference current ir1, for example, im2: ir1=K3: 1, where K3 is the third ratio value, and the transistor The size ratio between P2 and P3 is positively correlated. Therefore, the relationship between the second mirror current im2 and the first reference current ir1 is im2=K3*Iout. The fixed current ir1 generated by the first current source IS1 is a current limit set to prevent the output current Iout from being excessively changed. For example, when the voltage regulator is activated, there may be a case where the output current Iout is excessive; or when the short circuit occurs inside the voltage regulator 11, there may be an excessive or too small output current Iout.

The pull-up unit 143 includes a fourth P-type transistor P4. The gate of the transistor P4 is coupled to the first mirror current im1 and the second mirror current im2, the first end (eg, the source) of the transistor P4 is coupled to the power supply voltage VCC, and the second end of the transistor P4 (eg The bungee is coupled to the gate of the output transistor Pout. The pull-up unit 143 determines whether or not to be activated based on the magnitudes of the first mirror current im1 and the second mirror current im2. For example, when the first mirror current im1 is smaller than the second mirror current im2, the gate voltage of the transistor P4 rises, so that the pull-up unit 143 is not activated. On the contrary, when the first mirror current im1 is larger than the second mirror current im2, the gate voltage of the transistor P4 is lowered, so that the pull-up unit 143 is activated. The activated pull-up unit 143 pulls up the gate voltage of the output transistor Pout to be close to the power supply voltage VCC to turn off the output transistor Pout.

In addition, the first mirror current im1 is proportional to the output current Iout, and the second mirror current im2 is proportional to the first reference current ir1. Therefore, with proper design, when the output current Iout does not reach the upper limit, that is, the first mirror current im1 is smaller than the second mirror current im2, and the pull-up unit 143 is not activated. On the contrary, when the output current Iout is higher than the upper limit, the first mirror current im1 is made larger than the second mirror current im2. Therefore, the pull-up unit 143 is activated, that is, the transistor P4 pulls up the gate voltage of the output transistor Pout to be close to the power supply voltage VCC, so that the output transistor Pout is turned off. The current limiting unit 160 can use this mechanism to limit the current and thereby protect the circuit.

The temperature sensing unit 160 includes a comparator COM2 and a switching unit 161. The positive input terminal of the comparator COM2 is coupled to the temperature reference voltage TREF, and the negative input terminal of the comparator COM2 is coupled to the temperature voltage TV of the load. For example, the load includes a battery and the temperature voltage TV is a corresponding voltage of the battery temperature. The switch unit 161 includes a PMOS transistor SW4. The first end (eg, the source) is coupled to the power supply voltage VCC, and the second end (eg, the drain) is coupled to the output terminal OPO of the error amplifier OP1, and the control end thereof is coupled. The output of the comparator COM2. The temperature reference voltage TREF is an upper limit of the battery temperature voltage TV. When the temperature voltage TV is greater than the temperature reference voltage TREF, the comparator COM2 will output a low level voltage so that the fourth switching unit 161 is turned on. When the fourth switching unit 161 is turned on, the voltage of the output terminal OPO of the error amplifier OP1 is pulled up to be close to the power supply voltage VCC, so that the output transistor Pout is cut off. In other words, when the battery temperature in the load 150 is too high, the temperature sensing unit 160 cuts off the output of the voltage generating unit 110 output voltage Vout and current Iout so that the temperature of the battery in the load does not continuously rise. In the present embodiment, the temperature sensing unit 160 is a selectively implemented unit. In the case where the temperature sensing unit 160 is not implemented (removed), other units in the voltage regulator 11 and their functions are not affected.

FIG. 9 is an embodiment of a voltage regulator according to a sixth embodiment of the present invention. The embodiment shown in FIG. 9 can refer to the related description of FIG. 7 and FIG. 8. The coupling relationship and implementation manner of each unit are the same as the foregoing embodiment of FIG. 7 and FIG. 8 except that the amplification current source module 145 is added next to the first current source IS1.

Referring to FIG. 9 , the amplification current source module 145 includes a comparator COM3 , a second current source IS2 , and a switching unit 1451 . Comparator COM3. The positive input terminal of the comparator COM3 is coupled to the fourth reference voltage REF4, and the negative input terminal is coupled to the output terminal of the voltage generating unit 110. For example, in this embodiment, the negative input terminal of the comparator COM3 is coupled to the output terminal of the voltage generating unit 110 via the resistor R41. Resistors R41, R42, R43 and R44 form a voltage divider circuit. This voltage dividing circuit receives the output voltage Vout of the voltage generating unit 110. The negative input terminal of the comparator COM3 receives the divided voltage VOS output by the voltage dividing circuit. The second current source IS2 is used to generate the reference current ir2. The switch unit 1451 includes an NMOS transistor SW5, the first end of which is coupled in parallel with the first current source IS1 to the second current mirror unit 142, and the second end of which is coupled to the second current source IS2. The control terminal of the switch unit 1451 is coupled to the output of the comparator COM3.

When the output divided voltage VOS is smaller than the fourth reference voltage REF4, the comparator COM3 outputs a high level voltage at the output terminal, so that the switching unit 1451 is turned on. After the switching unit 1451 is turned on, the current received by the drain of the second P-type transistor P2 in the second mirror unit 142 becomes larger (the sum of the first reference current ir1 and the second reference current ir2). In other words, after proper design, when the output voltage Vout is increased so that the output current Iout exceeds the limit of the voltage regulator 11, but the circuit is not damaged, the amplification current source module 145 can be in the original In addition to a current source IS1, the second current source IS2 is added to increase the upper limit of the output current Iout by the voltage regulator 11.

It should be noted that the reference voltages REF1 REF REF4 or the temperature reference voltage TREF mentioned in the various embodiments of the present invention are appropriately set in the actual application, and are appropriately designed, for example, the resistors of the voltage dividing circuit. Alternatively, the voltage levels of the reference voltages REF1 to REF4 or the temperature reference voltage TREF may be equal, but the present invention is not limited to the above.

FIG. 10 is an embodiment of a current limiting unit according to a seventh embodiment of the present invention. The present embodiment can be regarded as a simplified embodiment of the current limiting unit 140. Referring to FIG. 10, the current limiting unit 160 includes a first resistor R71, a second resistor R72, a fifth P-type transistor P5, and a third N-type transistor N3. The first end of the first resistor R71 is coupled to the current sensing unit 130, and the second end of the first resistor R71 is coupled to the third reference voltage REF3. The first end of the second resistor R72 is coupled to the power supply voltage VCC. The gate of the fifth P-type transistor P5 is coupled to the second end of the second resistor R72, and the source of the fifth P-type transistor P5 is coupled to the power supply voltage VCC, and the drain of the fifth P-type transistor P5 is coupled. Connect to the output of the error amplifier OPO. The drain of the third N-type transistor N3 is coupled to the second end of the second resistor R72, and the source of the third N-type transistor N3 is coupled to the third reference voltage REF3, and the gate of the third N-type transistor N3 The pole is coupled to the first end of the first resistor R71.

The first resistor R71 and the second resistor R72 can be regarded as a simplified implementation of the first current mirror unit and the second current mirror unit. The resistor R71 receives the sensing current Is, so when the sensing current Is is higher than a lower limit, the transistor N3 can operate as a stable current source, and when the sense current is below the lower limit, the transistor N3 is turned off. The transistor P5 operates in the same manner as the above-mentioned pull-up unit. When the voltage of the gate of the transistor P5 from the second end of the resistor R72 is lower than a lower limit, the transistor P5 is turned on, and the output terminal of the error amplifier OP1 is pulled up. The voltage is close to the power supply voltage VCC, and the output of the voltage generating unit 110 is turned off.

In summary, the present invention provides a voltage regulator capable of limiting the output voltage within a predetermined range to avoid unintended conditions such as occurs when the voltage regulator is activated, resulting in an excessive output voltage or circuit and its The condition of component damage. In addition, the present invention also provides a protection mechanism for limiting the current in a predetermined range and an excessively high battery temperature in the load, so as to provide a more comprehensive protection circuit from damage caused by external emergencies, and even affect other connected components. .

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

11. . . Voltage regulator

110. . . Voltage generating unit

120. . . Voltage comparison unit

121. . . Voltage dividing circuit

122, COM2 ~ COM3. . . Comparators

123, 124. . . Switch unit

130. . . Current sensing unit

140. . . Current limiting unit

141, 142. . . Current mirror unit

143. . . Pull-up unit

150. . . load

160. . . Temperature sensing unit

OP1. . . Error amplifier

SW1, SW3, SW5, P1 ~ P5. . . NMOS transistor

SW2, SW4, N1 ~ N3. . . PMOS transistor

R1 to R3, R71, R72. . . resistance

IS1, IS2. . . Battery

RIN. . . Voltage generating unit reference

FIN. . . Voltage generating unit

CIN. . . Voltage comparison unit input

OUT. . . Voltage generating unit output

COUT. . . Voltage comparison unit output

OPIN1, OPIN2. . . Error amplifier input

OPO. . . Error amplifier output

CIN11, CIN12. . . First comparator input

REF1, REF2, REF3, REF4, TREF. . . Reference voltage

TV. . . Temperature and voltage

Vout. . . The output voltage

OPout. . . Error amplifier output voltage

FB, FB1 ~ FB2. . . Feedback voltage

VOS. . . Output voltage divider

Iout. . . Output current

Is. . . Sense current

Im1. . . First mirror current

Im2. . . Second mirror current

Ir1. . . First reference current

Ir2. . . Second reference current

S501～S505. . . step

FIG. 1 is a circuit diagram of a voltage regulator according to a conventional technique.

2 is a functional block diagram of a voltage regulator according to a first embodiment of the present invention.

3 is a functional block diagram of a voltage regulator according to a second embodiment of the present invention.

Fig. 4 is a view showing an embodiment of a voltage regulator in the second embodiment shown in Fig. 3.

FIG. 5 is a flow chart of a method for operating a voltage regulator according to an embodiment of the invention.

FIG. 6 is an embodiment of a voltage regulator according to a third embodiment of the present invention.

FIG. 7 is a schematic diagram of a function of a voltage regulator according to a fourth embodiment of the present invention.

FIG. 8 is an embodiment of a voltage regulator according to a fifth embodiment of the present invention.

FIG. 9 is an embodiment of a voltage regulator according to a sixth embodiment of the present invention.

FIG. 10 illustrates an embodiment of a current sensing unit and a current limiting unit according to a seventh embodiment of the present invention.

11. . . Voltage regulator

110. . . Voltage generating unit

120. . . Voltage comparison unit

150. . . load

RIN. . . Reference end

FIN. . . Feedback end

CIN. . . Input

OUT, COUT. . . Output

REF1, REF2, REF3. . . Reference voltage

Vout. . . The output voltage

Claims (17)

A voltage regulator includes: a voltage generating unit having a reference terminal, a feedback terminal, and an output terminal, the reference terminal of the voltage generating unit receiving a first reference voltage, wherein the reference is generated according to the voltage generating unit The voltage generating unit correspondingly generates an output voltage to a load via the output terminal; and a voltage comparing unit, wherein an input end of the voltage comparing unit is coupled to the voltage generating unit The output terminal of the voltage comparison unit is coupled to the feedback terminal of the voltage generating unit, and the voltage comparison unit compares the voltage of the output terminal of the voltage generating unit with a second reference voltage, where When the voltage of the output terminal of the voltage generating unit is less than the second reference voltage, the voltage comparing unit provides a feedback path between the output end of the voltage generating unit and the feedback terminal, and when the voltage generating unit When the voltage of the output terminal is greater than the second reference voltage, the voltage comparison unit cuts off the feedback path and provides a third reference voltage to the Pressure generating means side of the feedback. The voltage regulator of claim 1, wherein the voltage comparison unit comprises: a voltage dividing circuit coupled between the output terminal of the voltage generating unit and the third reference voltage, and the voltage divider Generating at least a first feedback voltage and a second feedback voltage; a first comparator having a first input terminal, a second input terminal, and an output terminal, wherein the first input of the first comparator The second input end of the first comparator is coupled to the first feedback voltage, and the first switch unit has a first end, a second end, and a control end. The first end of the first switch unit is coupled to the feedback end of the voltage generating unit, the second end of the first switch unit is coupled to the third reference voltage, and the control end of the first switch unit The first switching terminal is coupled to the output terminal, and the second switching unit has a first end, a second end, and a control end, wherein the first end of the second switching unit is coupled to the voltage Generating the feedback end of the unit, and coupling the second end of the second switch unit Connected to the second feedback voltage, and the control end of the second switching unit is coupled to the output of the first comparator. The voltage regulator of claim 1, wherein the voltage generating unit comprises: an error amplifier having a first input end and a second input end coupled to the output end of the voltage comparison unit and the first a reference voltage; and an output transistor having a control terminal, a first terminal and a second terminal, the control terminal of the output transistor being coupled to an output of the error amplifier, the first of the output transistors The terminal is coupled to a power supply voltage, and the second end of the output transistor is coupled to the output end of the voltage generating unit. The voltage regulator according to claim 3, further comprising: a current sensing unit coupled to the output end of the voltage generating unit, the current sensing unit sensing an output current of the output end of the voltage generating unit And generating a current sensing result; and a current limiting unit coupled to the voltage generating unit and the current sensing unit, the current limiting unit comparing a first reference current and the current sensing result, and limiting according to the comparison result The output current of the output of the voltage generating unit. The voltage regulator of claim 4, wherein the current sensing unit comprises: a first P-type transistor having a gate coupled to the output of the error amplifier, a source coupled to the source The power supply voltage, and a drain output the current sensing result to the current limiting unit. The voltage regulator of claim 4, wherein the current limiting unit comprises: a first current source to generate the first reference current; a first current mirroring unit coupled to the current sensing unit, Receiving the current sensing result and mirroring to generate a first mirror current; a second current mirroring unit coupled to the first current mirror unit and the first current source, receiving the first reference current and mirroring Generating a second mirror current; and a pull-up unit coupled to the first current mirror unit and the first current mirror unit, determining whether to be based on the first mirror current and the second mirror current Pull the voltage at the control terminal of the output transistor. The voltage regulator of claim 6, wherein the pull-up unit comprises: a fourth P-type transistor, a gate of the fourth P-type transistor coupled to the first mirror current and the a second mirror current, a source of the fourth P-type transistor is coupled to the power supply voltage, and a drain of the fourth P-type transistor is coupled to the output of the error amplifier. The voltage regulator of claim 6, wherein the current limiting unit further comprises: a second comparator having a positive input coupled to a fourth reference voltage and a negative input coupled to the voltage generated An output of the unit; a second current source to generate a second reference current; and a third switching unit, a first end of the third switching unit being coupled in parallel with the first current source to the second current mirror The second terminal of the third switching unit is coupled to the second current source, and a control end of the third switching unit is coupled to the output of the second comparator. The voltage regulator of claim 3, wherein the load comprises a battery, and the voltage regulator further comprises: a third comparator having a positive input coupled to a temperature reference voltage and a negative The input end is coupled to a temperature voltage of the battery; and a fourth switch unit, a first end of the fourth switch unit is coupled to the power supply voltage, and a second end of the fourth switch unit is coupled to the error amplifier The output end and a control end of the fourth switch unit are coupled to the output end of the third comparator. A method for operating a voltage regulator includes: configuring a voltage generating unit, wherein the voltage generating unit has a reference end, a feedback end, and an output end, and the voltage generating unit is configured according to the reference end and the feedback end The voltage relationship correspondingly generates an output voltage to a load via the output end; providing a first reference voltage to the reference end of the voltage generating unit; comparing the voltage of the output end of the voltage generating unit with a second reference voltage; When a voltage of the output terminal of the voltage generating unit is less than the second reference voltage, providing a feedback path between the output end of the voltage generating unit and the feedback terminal; and when the output end of the voltage generating unit When the voltage is greater than the second reference voltage, the feedback path is cut off and a third reference voltage is supplied to the feedback terminal of the voltage generating unit. A voltage regulator includes: an error amplifier having a first input terminal, a second input terminal, and an output terminal, wherein the second input terminal of the error amplifier is coupled to a first reference voltage; an output transistor, a first end, a second end, and a control end, wherein the control end of the output transistor is coupled to the output end of the error amplifier, the first end of the output transistor is coupled to a power supply voltage, and the The second end of the output transistor corresponds to an output voltage to a load; and a voltage comparison unit, an input end of the voltage comparison unit is coupled to the second end of the output transistor, and an output of the voltage comparison unit And coupled to the first input end of the error amplifier, the voltage comparison unit provides a feedback path between the second end of the output transistor and the first input end of the error amplifier, and the voltage comparison unit compares the output a voltage of the second end of the transistor and a second reference voltage, wherein when the voltage of the second end of the output transistor is greater than the second reference voltage, the voltage comparison unit provides a Three reference voltage to the control terminal of the output transistor. The voltage regulator according to claim 11, wherein the voltage comparison unit comprises: a voltage dividing circuit coupled between the second end of the output transistor and the third reference voltage, and the voltage divider Generating at least a first feedback voltage and a second feedback voltage; a first comparator having a first input terminal, a second input terminal, and an output terminal, wherein the first input of the first comparator The second input end of the first comparator is coupled to the first feedback voltage; and the first switch unit has a first end, a second end, and a control end The first end of the first switch unit is coupled to the control end of the output transistor, the second end of the first switch unit is coupled to the third reference voltage, and the control end of the first switch unit is coupled Connected to the output of the first comparator. The voltage regulator of claim 11, further comprising: a first P-type transistor, the gate of the first P-type transistor being coupled to the output end of the error amplifier, the first P-type The source of the crystal is coupled to a power supply voltage; and a current limiting unit coupled to the control end of the output transistor and the drain of the first P-type transistor, the current limiting unit comparing a first reference current with the The drain current of the first P-type transistor limits the output current of the output transistor according to the comparison result. The voltage regulator according to claim 13, wherein the current limiting unit comprises: a first current source to generate the first reference current; and a first current mirroring unit to receive the first P-type transistor Deuterium current and mirroring to generate a first mirror current; a second current mirroring unit coupled to the first current mirror unit and the first current source, receiving the first reference current and mirroring to generate a a second mirror current; and a pull-up unit coupled to the first current mirror unit and the first current mirror unit, determining whether to pull up according to the first mirror current and the second mirror current The gate voltage of the output transistor. The voltage regulator of claim 14, wherein the pull-up unit comprises: a fourth P-type transistor, a gate of the fourth P-type transistor coupled to the first mirror current and the a second mirror current, a source of the fourth P-type transistor is coupled to the power supply voltage, and a drain of the fourth P-type transistor is coupled to the control terminal of the output transistor. The voltage regulator of claim 14, wherein the current limiting unit further comprises: a second comparator having a positive input coupled to a fourth reference voltage and a negative input coupled to the output a second end of the crystal; a second current source to generate a second reference current; and a third switching unit, a first end of the third switching unit being coupled in parallel with the first current source to the second current mirror The second terminal of the third switching unit is coupled to the second current source, and a control terminal of the third switching unit is coupled to the output of the second comparator. The voltage regulator of claim 11, wherein the load comprises a battery, and the voltage regulator further comprises: a third comparator having a positive input coupled to a temperature reference voltage and a negative The input end is coupled to a temperature voltage of the battery; and a fourth switch unit, a first end of the fourth switch unit is coupled to the power supply voltage, and a second end of the fourth switch unit is coupled to the output transistor The control terminal and a control terminal of the fourth switch unit are coupled to the output end of the third comparator.