* Question
| Briefly describe the pin function of the 100V flyback isolation controller – LT3748? |
* Answer
| (1) VIN (1PIN): Input voltage terminal.This terminal supplies current to the internal start-up circuit and generates a reference voltage at the RFB terminal for use by the feedback circuit. This terminal must have a bypass capacitor.
(2) EN/UVLO (3P1N): Enable/undervoltage latch end.At 1.223V or higher, all internal circuits start working.The SS terminal sources 5 吣 current.When EN/UVL0 drops to l.Below 223V, 2.49A current is given from this end, providing an adjustable window as an undervoltage latch. (3) INTVCC (5PIN): Gate drive bias voltage terminal.The level is between INTVCC and GND. (5) SENSE (7PIN): current detection input.For the control loop, Kelvin connects this terminal to the positive voltage terminal of the switch current sense Resistors. At the source of the N-channel MOSFET, the negative terminal of the sense Resistors is connected to GND and close to the IC. (6) GND (8PIN, 9PIN), IC common.For the internal error amplifier, externally connect an RC series network to GND to compensate the switching regulator’s amplifier, and use a 100pF capacitor in parallel to help eliminate noise. (9) TC (12PIN): Output voltage compensation.This terminal resistance is 6.04kf2. For the ratio of the selected Resistors divider, this value can range from 5.76 to 6.34k.Q, the Resistors should be close to the LT3748 layout. (11) RFB (16P1N): External feedback Resistors input. |
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