Vehicle-mounted external microphone power supply circuit

Abstract

The utility model discloses a vehicle-mounted external microphone power supply circuit which comprises a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a first triode, a second triode, a third triode and a fourth triode. The first end of the first capacitor is respectively connected with the first end of the third resistor, the first end of the first resistor and the emitting electrode of the first triode, the second end of the first capacitor is grounded, the second end of the first resistor is connected with the second end of the second resistor, and the second end of the fourth resistor is connected with the emitting electrode of the second triode; the first end of the fourth resistor is respectively connected with the collector electrode of the first triode, the base electrode of the second triode and the first end of the fifth resistor, the low-cost power supply scheme of the external microphone is realized by applying the simple triodes and the precise resistors, and meanwhile, the over-current protection function is realized.

Description

TECHNICAL FIELD

[0001] The utility model relates to vehicle-mounted microphone power supply technical field, concretely relates to a vehicle-mounted external microphone power supply circuit. BACKGROUND

[0002] Current vehicle entertainment system has voice interaction function, in order to realize better voice interaction experience, usually vehicle entertainment system is connected with external microphone, and the stability of vehicle-mounted microphone operating voltage directly influences the performance and the stability of the work of microphone. There are some special chips for microphone power supply on the market, but its cost is higher, now vehicle entertainment system usually installs two or four external microphones, which will lead to the increase of the number of special power supply chip, influence the BOM cost of product, so a low-cost external microphone power supply circuit needs to be researched. UTILITY MODEL CONTENTS

[0003] In view of the problems existing in the prior art, the utility model provides a vehicle-mounted external microphone power supply circuit, which can adjust the voltage according to the power supply demand of the external microphone, and can also limit the working current of the microphone.

[0004] In order to achieve the above object, the utility model discloses a vehicle-mounted external microphone power supply circuit, including first electric capacity, second electric capacity, third electric capacity, fourth electric capacity, fifth electric capacity, first resistance, second resistance, third resistance, fourth resistance, fifth resistance, six resistance, seventh resistance, eighth resistance, ninth resistance, first triode, second triode, third triode, fourth triode, the 1st end of first electric capacity is connected to the 1st end of third resistance, the 1st end of first resistance and the emitter of first triode respectively, the 2nd end of first electric capacity is grounded, the 2nd end of first resistance is connected with the 2nd end of second resistance, the 2nd end of fourth resistance is connected with the emitter of second triode, the 1st end of fourth resistance is connected to the collector of first triode, the base of second triode and the 1st end of fifth resistance respectively, the 1st end of second resistance is connected to the base of first triode, the 2nd end of fifth resistance is connected to the 6th end of third triode, the 2nd end of third resistance is connected to the 3rd end of third triode, the collector of second triode is connected to the 1st end of sixth resistance, the 2nd end of second electric capacity is connected to the 1st end of third electric capacity, the 1st end of second electric capacity and the 2nd end of third electric capacity are grounded respectively, the 2nd end of sixth resistance is connected with the 5th end of third triode and the 1st end of seventh resistance respectively, the 2nd end of seventh resistance is grounded, the 4th end of third triode is short-circuited with the 1st end and is connected to the 2nd end of eighth resistance simultaneously, the 1st end of eighth resistance is grounded, the 1st end of ninth resistance is connected with the collector of fourth triode, the 2nd end of fifth electric capacity is connected to the 2nd end of third triode, the 2nd end of fourth electric capacity is connected to the base of fourth triode, the 1st end of fourth electric capacity is grounded, and the emitter of fourth triode and the 1st end of fifth electric capacity are grounded respectively.

[0005] In conclusion, the utility model provides a vehicle-mounted external microphone power supply circuit, compared with prior art, the utility model has the advantages that: the circuit uses simple triodes and precision resistors to realize the low-cost power supply scheme of external microphone, and has the function of overcurrent protection. BRIEF DESCRIPTION OF DRAWINGS

[0006] Figure 1 It is vehicle-mounted external microphone power supply circuit circuit schematic drawing of the utility model; DETAILED DESCRIPTION

[0007] The utility model will be further described below in combination with the drawings.

[0008] As Figure 1 Indicated:

[0009] The utility model relates to a kind of vehicle-mounted external microphone power supply circuit, including first capacitor, second capacitor, third capacitor, fourth capacitor, fifth capacitor, first resistance, second resistance, third resistance, fourth resistance, fifth resistance, six resistance, seventh resistance, eighth resistance, ninth resistance, first triode, second triode, third triode, fourth triode, the 1st end of first capacitor is respectively connected to the 1st end of third resistance, the 1st end of first resistance and the emitter of first triode, the 2nd end of first capacitor is grounded, the 2nd end of first resistance is connected to the 2nd end of second resistance, the 2nd end of fourth resistance is connected to the emitter of second triode, the 1st end of fourth resistance is respectively connected to the collector of first triode, the base of second triode and the 1st end of fifth resistance, the 1st end of second resistance is connected to the base of first triode, the 2nd end of fifth resistance is connected to the 6th end of third triode, the 2nd end of third resistance is connected to the 3rd end of third triode, the collector of second triode is connected to the 1st end of sixth resistance, the 2nd end of second capacitor is connected to the 1st end of third capacitor, the 1st end of second capacitor and the 2nd end of third capacitor are respectively grounded, the 2nd end of sixth resistance is respectively connected to the 5th end of third triode and the 1st end of seventh resistance, the 2nd end of seventh resistance is grounded, the 4th end of third triode is short-circuited with the 1st end, and simultaneously connected to the 2nd end of eighth resistance, the 1st end of eighth resistance is grounded, the 1st end of ninth resistance is connected to the collector of fourth triode, the 2nd end of fifth capacitor is connected to the 2nd end of third triode, the 2nd end of fourth capacitor is connected to the base of fourth triode, the 1st end of fourth capacitor is grounded, and the emitter of fourth triode and the 1st end of fifth capacitor are respectively grounded.

[0010] The utility model uses the working principle of LDO (low voltage differential amplifier), +14V is the power supply of this circuit, 3V3 forms a 3.3V reference power supply through two symmetrical triodes inside Q3 and R8, forms bias circuit through second triode, sets the output voltage of microphone through resistance R6 and R7, adjusts the current limit value by adjusting the resistance value of R1.

[0011] This circuit requires outputting a 8.5V voltage, and the output current is ≤21mA, when the output current is >21mA, it is judged as overcurrent.

[0012] Circuit implementation:

[0013] When MIC_PWR_EN (pin of power supply) is low, triode Q4 is in cut-off state, 3V3 voltage passes through resistor R9, triode Q3 and resistor R8, voltage at the 4th pin of Q3 is 2.6V (3.3V-0.7V), because resistor R3 and triode Q3 form a bias circuit, voltage at the 5th pin of Q3 is 3.3V (3.6V+0.7V), so voltage on resistor R7 is 3.3V, because triode Q2 is in bias state, voltage at the collector of Q2 is 3.3V / 9.1K*(9.1K+14.7K)=8.5V (MIC_POWER_8V5).

[0014] When MIC_PWR_EN is high, triode Q4 is on, triode Q3 and Q2 are in cut-off state, 8.5V power supply of the microphone is closed.

[0015] When output current increases, current passing through resistor R1 increases, when output current exceeds 21mA, when voltage on resistor R1 reaches about 0.7V, triode Q1 is on, which causes base voltage of triode Q2 to rise to 14V, triode Q2 enters cut-off state, at this time, 8.5V voltage output is stopped, if overcurrent state is not removed, triode Q1 is on and triode Q2 is cut off, triode Q1 is cut off and triode Q2 is on, so this cycle continues, thereby overcurrent protection is realized, when overcurrent state is removed, current returns to normal working state.

[0016] The embodiments in the utility model are only used for describing the utility model, and do not constitute the limitation to the scope of claims, other substantially equivalent alternatives that can be thought of by the person skilled in the art are all within the protection scope of the utility model.

Claims

1. An on-vehicle external microphone power supply circuit characterized by comprising: The application relates to a circuit, which comprises a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a first triode, a second triode, a third triode, a fourth triode, the first end of the first capacitor is connected to the first end of the third resistor, the first end of the first resistor and the emitter of the first triode respectively, the second end of the first capacitor is grounded, the second end of the first resistor is connected to the second end of the second resistor, the second end of the fourth resistor is connected to the emitter of the second triode, the first end of the fourth resistor is connected to the collector of the first triode, the base of the second triode and the first end of the fifth resistor respectively, the first end of the second resistor is connected to the base of the first triode, the second end of the fifth resistor is connected to the sixth end of the third triode, the second end of the third resistor is connected to the third end of the third triode, the collector of the second triode is connected to the first end of the sixth resistor, the second end of the second capacitor is connected to the first end of the third capacitor, the first end of the second capacitor and the second end of the third capacitor are grounded respectively, the second end of the sixth resistor is connected to the fifth end of the third triode and the first end of the seventh resistor respectively, the second end of the seventh resistor is grounded, the fourth end of the third triode is short-circuited with the first end and connected to the second end of the eighth resistor, the first end of the eighth resistor is grounded, the first end of the ninth resistor is connected to the collector of the fourth triode, the second end of the fifth capacitor is connected to the second end of the third triode, the second end of the fourth capacitor is connected to the base of the fourth triode, the first end of the fourth capacitor is grounded, and the emitter of the fourth triode and the first end of the fifth capacitor are grounded respectively.

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