It senses the above rails and responds to their combination by varying current of optocouple M2, which in turn affects duty cycle of PWM. Error amplifier is implemented with M7, which is a 3-terminal shunt regulator, such as TL431. This power supply uses combined regulation of +5V and +12V. The negative 12V voltage is regulated by a 3-terminal linear regulator M1. The coil 1-15 works in flyback mode- it conducts when Q1, Q25 are OFF. The inductor L4 has three coils for +5V, +12V and -12V outputs. This signal is used for current mode control and power limit. Primary current is sensed via resistor R14.
#Ic 7800 power supply schematic driver
They could just put a dual driver IC with complementary outputs on the primary side of T3 and just 10-30 Ohm resistors on the secondaries. In my view, for this power level, such a complex implementation of gate drive is absolutely unnecessary. This creates positive voltages on dotted sides of all the secondaries, which in turn forward biases output rectifiers D4, D9, and after a while D28 as well.īoth MOSFETs are driven via gate drive transformer T3 with a bunch of pulse shaping components. When Q1 and Q25 are turned ON, DC-link voltage B+ gets applied to the primary of transformer T1. Its primary section contains fast MOSFET switches Q1, Q25, and reset diodes D36, D39. Output converter is configured as 2-switch forward converter.
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