SU1388988A2 - Voltage-to-frequency converter - Google Patents

Abstract

The invention relates to devices for converting analog signals to pulse frequency. The invention allows reliable autorun of an integrating type converter with periodic restoration of the integrator 1 by a calibrated charge formed on a special metering capacitor. When the oscillations break, the diode 11 is locked and the voltage at the control input of the key unit starts to increase due to the charge of the capacitor 1 2 from the source of the reference voltage 9 through the resistor 10. When the voltage reaches the threshold level, the transistor 8 and the current from the reference voltage source open 9, the voltage on the integrating capacitor returns to the operating value range. In the normal operation mode, due to the short duration of the integrator recovery phase, the autorun scheme does not affect the efficiency of the converter, 2 sludge. i (Л С

Description

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The invention relates to instrumentation, in particular, devices for converting analog signals to pulse frequency, and can be used in analog-digital converters, information-measuring systems and devices for wide-band magnetic FM recording.

The purpose of the invention is to increase reliability,

FIG. 1 shows a functional diagram of the converter} in FIG. 2 shows an embodiment of the converter based on the 564 LN2 chip.

The converter comprises an integrator 1 consisting of an integrating capacitor 2 and a source 3 of a flowing current. The comparator input 4 and the combined second info, the main 5 and additional 6 key inputs, each of which are made on complementary field-effect transistors 7 and 8, are connected to the integrator output. The first information inputs of both keys are interconnected and connected to a positive reference voltage source 9 to which the output of the additional key block and the resistor 10 are connected. Another lead of the resistor 10 is connected to the control input of the additional 1 key block 6, the anode of the 1I diode and the additional a capacitor 12, to the output of the main unit 5 of the keys; connecting Echen dosing capacitor 13. The cathode of diode 11 is connected to the connection point of the comparator output with the input of the logic level converter 14; Block 6 of keys, resistor 10, diode 1 and additional condenser ™ sator 12 form the startup and recovery circuit after an overload with an input signal.

The Converter operates as follows.

Under the action of a signal current proportional to the input voltage Ug, the voltage across the capacitor 2 decreases linearly. When it reaches the threshold voltage, the comparator 4 is triggered and the level converter 14 and the key block 5 are switched. The dosing capacitor 13 is discharged through the opened transistor 8 to the capacitor 2. The voltage at the latter is increased to the initial level and the process repeats. Thus, during normal operation, the voltage at the input of the comparator for most of the period is above its threshold value.

In this case, at the output of the comparator, the voltage is close to zero. The diode 11 is displaced in the forward direction through the resistor 10, and at the control input of the block 6 of keys the voltage is also close to zero.

In this case, the transistor 7 of the key block 6 is openJ and the transistor 8 is closed. At the time of the operation of the comparator, the diode 11 is closed and the capacitor I2 begins to charge through the resistor 10.

The time constant of this circuit is chosen such that during the recovery time of the charge on the integrating capacitor 2, the voltage on the capacitor 12 could not reach the switching threshold level of the 6-key unit.

The transistor 7 of the key block 6 remains open, and the transistor 8 is closed. In such a state, the startup scheme does not affect the operation of the converter.

If the power supply did not cause oscillations. it is in the operating range, a high voltage level is set at the output of the comparator 4.

The capacitor 12 in this case has time to charge up to the threshold switching level of the block of 6 keys.

In this case, through the opened transistor 8 of the block of 6 keys, the current from the source 9 of the reference voltage recovers the charge on the capacitor 2.

When the voltage across it becomes greater than the threshold, comparator 4 returns to the zero state at the output. The capacitor 12 is discharged through the newly opened diode 11 and the autorun circuit is automatically turned off.

When using a chip of type 564 J1H2, individual logic inverters (Fig. 2) perform the functions of blocks 5 and 6 of keys. As the capacitor 12, the total input capacitance of one inverter, which serves as unit 6, and the four inverters remaining unused is used.

Claims (1)

Invention Formula Voltage to Frequency Converter St. No. 1272508, characterized in that, in order to increase reliability, an additional key block is introduced into it, similar to the main additional capacitor, resistor, diode, the cathode of which is connected to the output of the converter, the anode is combined with the control input of the additional key block, the first terminals of the additional capacitor, and a resistor, the second output of which is combined with the first information input Additional key block and connected to the output of the reference voltage source and the output of the additional key block, the second output of the additional capacitor is connected to the common bus, and the second information input of the additional key block is connected to the first lead of the integrator capacitor. cpue.Z .