Constant voltage drive type driver circuit

A constant voltage type driver circuit coupled to receive control signals, comprising:

• a transformer having primary and secondary windings, the primary winding having first and second terminals;
• means for supplying a voltage to the primary winding of said pulse transformer in a first mode and for cutting off the supply of the voltage to the primary winding in a second mode in response to the control signals;
• and
• means for short-circuiting the first and second terminals of the primary winding of said transformer for a predetermined time from a time when the second mode begins.

A method for driving a pulse transformer having primary and secondary windings, the primary winding having first and second terminals, comprising:

• (a) supplying a voltage to the primary winding of the pulse transformer in a first mode;
• (b) cutting off the supply of the voltage to the primary winding in a second mode;
• and
• (c) short-circuiting the first and second terminals of the primary winding of the pulse transformer for a predetermined time from a time when the second mode begins.

A constant voltage drive type driver circuit coupled to receive control signals and coupled to an equivalent load impedance, comprising:

• a pulse transformer for outputting output pulses having a predetermined peak value, said pulse transformer having primary and secondary windings, said primary winding having first and second terminals, the equivalent load impedance being connected to the secondary winding when viewed from said pulse transformer, excluding an impedance of the secondary winding itself;
• power source means for supplying a voltage;
• switching circuit means, coupled to said power source means, for supplying the voltage from said power source means to the primary winding of said pulse transformer in a first mode and for cutting off the supply of the voltage to the primary winding in a second mode in response to the control signals;
• and
• short-circuiting means, coupled between said switching circuit means and the primary winding of said pulse transformer, for short-circuiting the first and second terminals of the primary winding of said pulse transformer for a predetermined time from a time when said switching circuit means assumes the second mode, the first and second terminals of the primary winding of said pulse transformer being released after the predetermined time has elapsed from the time when said switching circuit means assumes the second mode.

A method for driving a pulse transformer having primary and secondary windings, the primary winding having first and second terminals, comprising:

• (a) supplying a voltage to the primary winding of the pulse transformer in a first mode;
• (b) cutting off the supply of the voltage to the primary winding in a second mode;
• and
• (c) suppressing undershoot of output pulses of the pulse transformer by short-circuiting the first and second terminals of the primary winding of the pulse transformer for a predetermined time from the time when the second mode begins.