RU169307U1 - IC FOR TRANSFORMER DRIVER WITH DISABLED OUTPUT - Google Patents

Abstract

The utility model relates to a pulse technique and can be used as an energy-saving imaging device for out-of-phase pulses on an inductive load, in particular a transformer of a DC-DC converter. The technical result consists in disconnecting the outputs of the microcircuit from the load in the absence of an input clock signal during the absence of an input clock signal. To achieve this technical result in the transformer driver chip with a switchable output containing a low-power generator, a reference frequency divider, built on four countable triggers, and logic elements for organizing the logical multiplication of the clock signal and the first three signals of the counting triggers of the frequency divider, forming the signal pa zy equal to the pulse width of the reference frequency signal, which, when logically multiplied by the antiphase output signals of the fourth counting trigger, generates antiphase signals at the output of the microcircuit with a pause between them, a circuit for switching off the antiphase outputs in the absence of an input clock signal is introduced, including a timing circuit built on a resistor and capacitor and controlled by a clock signal through a key MOS transistor and discharge resistor, and a threshold Schmidt trigger circuit, whose signal is inverted when logically multiplied by the antiphase output signals of the fourth counting trigger, it turns off both outputs of the microcircuit and resets the counting triggers of the divider.

Description

A transformer driver microcircuit with a switchable output refers to a pulse technique and can be used as an energy-saving in-phase pulse shaper for an inductive load, in particular a transformer of a DC-DC converter.

Known chips MAX253 (1994 Maxim Integrated Products, www.maxim-ic.com) and MAX845 (1997 Maxim Integrated Products, www.maxim-ic.com), containing an economical built-in generator with a large duty cycle of the reference frequency, the division of which by counting trigger provides inverse signals at the outputs of the trigger. These signals connected to the gates of n-MOS transistors provide control of the transformer of the DC-DC converter with out-of-phase signals.

The disadvantage of these microcircuits is the coincidence in time of the front and the fall of antiphase signals, which at the moment of this coincidence leads to the passage of through current through the transformer and the release of stray power.

As a prototype, a transformer driver microcircuit was selected (RU 160154 U1 IPC Н03К 3/00, published March 10, 2016), which contains a low-power generator, a reference frequency divider, built on four countable triggers, and logic elements for organizing the logical multiplication of the clock signal and the first three signals counting triggers of the frequency divider, forming a pause signal equal to the pulse width of the reference frequency signal, which, when logically multiplied by the antiphase output signals of the fourth counting trigger, forms at the output e chip opposite signals with a pause in between.

The main disadvantage of the prototype is that when you turn off the input signal from the generator, one of the output transistors remains in the on state, which leads to the flow of through current in one of the transformer windings.

The utility model is aimed at obtaining a technical result - disconnecting the outputs of the microcircuit from the load while there is no input clock signal.

This goal is achieved by the fact that in the transformer driver microcircuit with a switched-off output containing a low-power generator, a reference frequency divider, built on four countable triggers, and logic elements for organizing the logical multiplication of the clock signal and the first three signals of the counting triggers of the frequency divider, forming a pause signal equal to the pulse width of the reference frequency signal, which, when logically multiplied by the antiphase output signals of the fourth counting trigger, forms the output of the micro antiphase signals with a pause between them, a circuit for switching off the antiphase outputs in the absence of an input clock signal is introduced, including a timing circuit built on a resistor and capacitor and controlled by a clock signal through a MOSFET and a discharge resistor, and a threshold Schmidt trigger circuit, whose signal is inverted when logically multiplied by the antiphase output signals of the fourth counting trigger, it turns off both outputs of the microcircuit and resets the counting triggers of the divider.

In FIG. 1 is a structural diagram of a transformer driver microcircuit with a switchable output. Timing diagrams of the signals of the transformer driver microcircuit with switchable output are presented in FIG. 2.

The transformer driver microcircuit operates as follows. The reference frequency signal from the generator 1 is input to the microcircuit. The signal from the generator 1 of FIG. 1 goes to the inverting logic elements 2 (Schmidt trigger) and 3 (inverter) to ensure noise immunity at the input of the generator.

A negative pulse with 2 opens the r-channel transistor 23 of the timed chain and charges the capacitance 26 (signal C in Fig. 2) from the supply bus 22 through the resistor 24. At the same time, a low logic level is generated at the output of the Schmidt trigger 27 of the timed chain, which is fed to the reset inputs counting triggers 6, 8, 9 and 12, allowing them to perform the function of dividing the frequency by 2.

The output of the inverter 28 is formed a high logical level, which allows through the elements 3I-NOT 14 and 15 to pass to the output of the chip signal from the counting trigger 12.

Inverting logic elements 4 and 5 generate antiphase signals to control the counting trigger 6 when there is a high logic level at the output of the inverter 28.

At the output of trigger 6, a signal is formed with a frequency divided by 2 relative to the reference frequency. Sequentially, trigger 6 in FIG. 1, triggers 8, 9, 12 are included, which also successively divide the frequency by 2, which is represented by signals DD4, DD5, DD7, DD8, DD11 in FIG. 2

The signals from the outputs of elements 5, 6 and 8, 9 of FIG. 1 arrive at the inputs of elements 2I-NOT 7 and 10, respectively. From the outputs of elements 7 and 10, the signals are fed to the AND element, which performs the function 2OR-NOT. As a result, a signal is generated at output 11 that implements the function of logical multiplication of signals from elements 5, 6, 8, 9: DD10 = DD4⋅DD5⋅DD7⋅DD8. This signal from the element 11 for controlling the output signals through the elements 3I-NOT 14 and 15 is inverted on the element 13 and shown in FIG. 2, like DD12.

The signals from the outputs of the counting trigger 12, corresponding to the input frequency divided by 16, receive elements 14 and 15. The output signals from 14 and 15 are fed to inverters 16 and 17, respectively. Signals DD15 and DD16 from outputs 16 and 17 are respectively shown in FIG. 2. The signals are in antiphase, but at the same time, when changing phases between the signals, there is a time interval equal to the pulse width of the reference frequency signal. Output transistors 18 and 19 open sequentially with a pause, eliminating the passage of through current in the transformer.

In the absence of a clock signal from the generator at the output of element 2, a high logic level is fixed, which closes the p-channel transistor 23 of the timing chain. The capacitor 26 is discharged through resistors 24, 25. At the output 27, a high logic level is formed, which resets the counting triggers 6, 8, 9 and 12. A low logic level with 28 blocks the passage of the clock signal to the input of the counting triggers 6, 8, 9 and 12 to a stable charge 26 and generates a low logic level at the outputs 16 and 17, which keeps the output transistors 18 and 19 closed for the duration of the absence of an input clock signal.

The technical result is achieved by switching both antiphase outputs of the microcircuit to the closed state while there is no input clock signal.

Claims (1)

A transformer driver microcircuit with a switchable output, containing a low-power generator, a reference frequency divider, built on four counting triggers, and logic elements for organizing a logical multiplication of the clock signal and the first three signals of the counting triggers of the frequency divider, generating a pause signal equal to the pulse width of the reference frequency signal, which, when logically multiplied by the antiphase output signals of the fourth counting trigger, generates antiphase signals with a pause at the output of the microcircuit They are distinguished by the fact that a circuit for switching off antiphase outputs in the absence of an input clock signal is introduced into the microcircuit, including a timing circuit built on a resistor and capacitor and controlled by a clock signal through a MOSFET and a discharge resistor, and a threshold Schmidt trigger circuit, whose signal is inverted when logically multiplied by the antiphase output signals of the fourth counting trigger, it turns off both outputs of the microcircuit and resets the counting triggers of the divider.

Images