Datasheet LT8303 (Analog Devices) - 6

LT8303
pin FuncTions EN/UVLO (Pin 1):
Enable/Undervoltage Lockout. The trimmed 12.23k resistor, times the internal bandgap EN/UVLO pin is used to enable the LT8303. Pull the pin reference, determines the output voltage (plus the effect below 0.3V to shut down the LT8303. This pin has an ac- of any non-unity transformer turns ratio). Minimize trace curate 1.223V threshold and can be used to program a VIN area at this pin. undervoltage lockout (UVLO) threshold using a resistor
SW (Pin 4):
Drain of the 150V Internal DMOS Power divider from VIN to ground. A 2.5µA current hysteresis Switch. Minimize trace area at this pin to reduce EMI and allows the programming of VIN UVLO hysteresis. If neither voltage spikes. function is used, tie this pin directly to VIN.
V GND (Pin 2):
Ground. Tie this pin directly to local ground
IN (Pin 5):
Input Supply. The VIN pin supplies current to internal circuitry and serves as a reference voltage for plane. the feedback circuitry connected to the RFB pin. Locally
RFB (Pin 3):
Input Pin for External Feedback Resistor. bypass this pin to ground with a capacitor. Connect a resistor from this pin to the transformer pri- mary SW pin. The ratio of the RFB resistor to the internal
block DiagraM
T1 DOUT VIN NPS:1 V + OUT • CIN LPRI LSEC COUT • RFB V – OUT 5 3 4 VIN RFB SW BOUNDARY DETECTOR 1:4 M3 M2 OSCILLATOR – – gm 25µA RREF + S 12.23kΩ 1.223V A3 R Q DRIVER M1 + R1 EN/UVLO – + 1 A2 RSENSE 2.5µA A1 R2 + – 1.223V VIN GND 2 M4 REFERENCE REGULATORS 8303 BD 8303fa 6 For more information www.linear.com/LT8303 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Typical Application Related Parts