Cirrus Logic CRD1615-8W - Manual (Page 14)

CRD1615-8W
14 DS1002RD3
7. TRANSFORMER CONSTRUCTION
The CRD1615-8W provides power factor correction and dimmer compatibility with a constant output current, quasi-
resonant flyback stage. The following sections describe the flyback transformer installed on the CRD1615-8W.
7.1 Flyback Transformer
The flyback transformer stage is a quasi-resonant peak current-regulated DC-DC converter capable of delivering
the highest possible efficiency with constant current output while minimizing line frequency ripple. The auxiliary wind-
ing is used for zero-current detection and overvoltage protection.
7.1.1 Electrical Specifications
Characteristics conditions:
• Operating temperature range: -25 °C to +120 °C (including coil heat)
Notes: 1. Time = 2sec.
2. Measured across pins 4 and 5.
3. Measured across pins B and A.
4. Measured across pins 12 and 7.
Parameter Condition Symbol Min Typ Max Unit
Flyback Transformer
Electrical Strength
(Note 1) f
operate
=50/60Hz - 3.75 - kV
RMS
Primary Inductance (Note 2) f
resonant
=10kHz, 0.3V at 20°C L
P
2.34 2.6 2.86 mH
Primary Leakage Inductance (Note 2) f
resonant
=10kHz, 0.3V at 20°C L
K
- - 55 H
Primary DC Resistance (Note 2) t
DCR
=20°C 4.64 5.8 6.96 
Secondary DC Resistance (Note 3) t
DCR
=20°C 0.208 0.26 0.312 m 
Auxiliary DC Resistance (Note 4) t
DCR
=20°C 0.44 0.55 0.66 m 
91T
#34 AWG
(0.15 mm)
105T
# 34AWG
(0.15mm)
34T
# 31AWG
(0.23mm)
Primary
4
6
5
12
Auxiliary
7
Secondary
34T
#28AWG
(0.30mm)
A
B
Figure 10. Flyback Transformer Schematic