Cirrus Logic AN375 - Manual (Page 4)

AN375
4 AN375REV4
2.2 Definition of Symbols
Symbol Description
F
SW
Switching frequency
TT Switching period
T1 Primary FET ‘ON’ time
T2 Secondary rectifier diode conduction time
T3 Time when the FET and diode are ‘OFF’
V
Reflected Voltage across secondary winding reflected onto primary during T2
V
Zener Primary clamping voltage above flyback input voltage
I
PK Peak current in primary-side FET
R
CTRL1 Resistor used to set the minimum input current being pulled by the flyback
R
Sense Primary current sense resistor
R
CTRL2 Resistor used to set the output current through the LED string
R
NTC Negative temperature coefficient resistance
L
P Flyback transformer primary inductance
I
hold TRIAC holding current
N Flyback transformer turns ratio N
P
/N
S
V
OUT
Secondary output DC voltage and the LED string supply voltage
V
IN
AC RMS line voltage
P
OUT
Load power = Power to the LED string
I
OUT
Nominal LED string DC current
P
IN
Input power
 Power stage efficiency
 Duty ratio (T1/TT)
I
fb
Dimmer current at full brightness. Line current required to guarantee I
OUT
under worst case conditions
I
P(RMS) Primary RMS current
I
S(RMS) Secondary RMS current
 Duty correction
V
INPK
Peak line voltage
I
INPK
Peak line current
Z Ratio V
IN
/V
Reflected
I
IN(CC)
Constant input current
V
rect
Primary input voltage