Coilcraft HA3905 Flyback Transformer for Microsemi PoE PD Power supply
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SMT Flyback Transformer for
Microsemi PoE PD Power Supply

  • Developed for use with Microsemi UC3844 Current Mode Controller and LX1752 Buck Regulator
  • T1 on PoE PD Power Supply Evaluation Board (AN-37)
  • Designed for 36 V to 57 V input; 200 kHz.
  • 1500 Vrms,one minute isolation from primary, auxiliary and reset to secondary;
    500 Vrms, one minute isolation from primary and reset to auxiliary
  • RoHS-compliant. 260°C compatible. Tin-silver (96.5/3.5) over tin over nickel over phos bronze terminations


Part number1
Click to get parts
L at 0A2
L at Ipk3
DCR max4
Leakage L
max (µH)5
Turns ratio Ipk3
pri : sec pri : aux pri : reset
HA3905-CL_ 27.0 24.3 0.170 (pri)
0.015 (sec)
0.385 (aux)
0.371 (reset)
1.9 3.75 : 1 1.36 : 1 1 : 1 1.2 5 V, 2.5 A
1 When ordering, please specify termination and packaging codes: e.g. HA3905-CLD
  Termination: L = RoHS compliant tin-silver over tin over nickel over phos bronze
Special order, added cost: T = RoHS tin-silver-copper (95.5/4/0.5) or
= non-RoHS tin-lead (63/37).
Packaging: D = 13" reel, machine-ready 
EIA-481 embossed plastic tape (175parts per full reel).
B = Less than full reel
In tape, but not machine-ready. To have a leader and trailer added ($25 charge), use code letter D instead.
2 Inductance is for the primary, measured at 250 kHz, 1.0 Vrms, 0.
3 Ipk: Peak primary current drawn at minimum input voltage.
4 DCR measured at 25°C. For other operating temperatures, use this DCR at Temperature calculator.
5 Leakage inductance for the primary is with all secondary pins shorted.
6 Output is with the secondary windings connected in parallel. Auxiliary winding output is 12 V, 20 mA.
7 Ambient temperature range: −40°C to +125°C
8 Storage temperature range: Component: −40°C to +125°C
Tape and reel packaging: −40°C to +80°C
9 Electrical specifications at 25°C.
Refer to Soldering Coilcraft Components before soldering.
PCB washing: Tested to MIL-STD-202 Method 215 plus an additional aqueous wash. More info.

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Updated: April 16, 2018