Programmable power circuit of meter bus slave

Abstract

The invention relates to a power circuit of a meter bus slave, belonging to the technical field of apparatus meters. The programmable power circuit of the meter bus slave consists of a program-controlled reference voltage generating circuit and an emitter follower, wherein the program-controlled reference voltage generating circuit consists of resistors, two voltage-stabilizing diodes, a reinforced NMOS (n-channel metal oxide semiconductor) tube and a singlechip MCU (micro control unit); a resistor R1 is serially connected with the two voltage-stabilizing diodes; the reinforced NMOS tube which is connected with one voltage-stabilizing diode in parallel is connected with a grid electrode of an NMOS tube VM through an I / O (input / output) port of the singlechip MCU; a resistor R2 is connected between the I / O port of the singlechip MCU and the grid electrode of the NMOS tube VM; a resistor R3 is connected between the I / O port of the singlechip MCU and a positive power supply; the emitter follower comprises two dynatrons V1 and V2 which are connected in a Darlington way; collector electrodes of the two dynatrons V1 and V2 are connected with a high voltage end of the meter bus; emitter electrodes of the dynatrons are connected on a slave load RL; and a substrate of the emitter follower formed by the two dynatrons is connected with the output of the program-controlled reference voltage generating circuit.

Description

Technical field [0001] The invention relates to a power circuit of an instrument bus slave, belonging to the technical field of instrumentation. Background technique [0002] Chinese Patent Application No. 200910218395.1 discloses a "low power consumption circuit of instrument bus slave", which consists of a constant voltage source circuit with high withstand voltage and low quiescent current and a low pass filter circuit. The constant voltage source The circuit consists of two transistors connected in Darlington form as emitter followers. The base of this emitter follower is connected to a standard voltage generated by a voltage reference, and a voltage with very low output resistance is output from the emitter. , Thereby forming a constant voltage source; the low-pass filter circuit is formed by a low-resistance resistor and a capacitor in series; the emitter of the emitter follower is connected with the resistor of the low-pass filter circuit. [0003] Meter-Bus (M-Bus for shor...

AI Technical Summary

Problems solved by technology

Since the traditional technology cannot switch the power supply voltage of the instrument bus slave, the designer can only use a compromise method to determine the power supply voltage of the instrument bus slave—choose a power supply that can ensure the normal operation of the activated slave and keep the voltage as low as possible. Voltage

In the currently popular photoelectric direct-reading instrument bus slaves, the level of power supply voltage is often related to the accuracy of readings. This compromise choice will inevitably lead to a decline in the total number of slaves in the network and the accuracy of infrared photoelectric readings.

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