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  • Briefly describe the LT3825/37 pin function?

    * Question

    Briefly describe the LT3825/37 pin function?


    (1) SG (1PIN): Secondary side synchronous rectification drive output.The gate of the secondary side synchronous rectification MOSFET has strong driving capability and dynamic characteristics.

    (2) VCC (2PIN): IC power supply voltage supply terminal.

    (3) TON (3PIN): Connect a Resistors to GND to set the minimum on-time. Turn on the switch at the beginning of each cycle. The minimum on-time simplifies the isolation feedback method.

    (4) ENDLY (4PIN): Connect an external Resistors to set the delay time for enabling.

    (6) SFST (6PIN): This terminal is connected to GND with a capacitor to control the upper slope of the peak primary current for controlling the inrush current during starting.

    (7) OSC (7PIN): Connect a capacitor to GND and set the oscillator frequency, about l00kHzxl00/pF.It is the output of the feedback amplifier and is the input to the current comparator. The frequency compensation component of the switch is usually connected to this terminal to GND.This terminal voltage is proportional to the primary peak switching current.The feedback amplifier output is disabled during the turn-on of the sync switch.The bias current at this end has a window. When the UVL0 threshold is exceeded, a current is sourced. The added window is equivalent to the multiple of the bias current. The user can control the total amount of the window and change the voltage divider ratio.If this function is available, connect UVL0 to VCC.The threshold is 98mV at maximum current.Signal blanking will occur at the minimum on time.(12) COMP (13PIN): An external filter capacitor is used to select the load compensation function, and the load compensation reduces the influence on the parasitic resistance in the feedback detection channel.

    (14) PGDLY (15 PIN): An external adjustable Resistors sets the delay time from the turn-off of the synchronous rectification drive to the turn-on of the gate drive.

    (15) PG (16PIN): The gate drive output of the primary side MOSFET, which has a large dynamic current passing capability.


    DISQUS: 0