Datasheet Analog Devices LT3001 — Datenblatt

LT3001
36V 4W No-Opto Isolated
Flyback Converter
FEATURES DESCRIPTION 4V to 36V Input Voltage Range
nn 1.2A, 65V Internal DMOS Power Switch
nn Low Quiescent Current
nn Boundary Mode Operation at Heavy Load
nn Low-Ripple Burst Mode® Operation at Light Load
nn Minimum Load VSW(MAX) VSW(MAX) = VIN(MAX) + VZENER(MAX)
Example: VIN(HYS) = 2.5µA • R1
Example:
Choose 2V of hysteresis, R1 = 806k
Determine the UVLO thresholds and calculate R2
resistor value: VREVERSE > 53V
A 100V, 0.25A diode from Central Semiconductor
(CMHD4448) is chosen. VIN(UVLO+) = 1.242V • (R1+R2)
R2 Example:
Set VIN UVLO rising threshold to 7.5V, Step 6: Select the RFB Resistor. R2 = 232k Use the following equation to calculate the starting value
for RFB: VIN(UVLO+) = 7.5V R FB = NPS • (VOUT + VF )
100µA 3 • (5V + 0.3V)
100µA VIN(UVLO–) = 5.5V
Step 8: Ensure minimum load.
The theoretical minimum load can be approximately estimated as: Example: …