LT1103 Datasheet, PDF (22/32 Pages) Linear Technology – Offline Switching Regulator

LT1103/LT1105
APPLICATIONS INFORMATION
Flyback Waveform for Continuous Mode Operation
a
b
c
d
e
f
∆I
V_ZENER
PRIMARY SWITCH VOLTAGE
[V_OUT + Vf + (I_SEC • R_P)]/N
V_IN
AREA “a” = AREA “b” TO MAINTAIN
ZERO VOLTS ACROSS PRIMARY
0V
SECONDARY WINDING VOLTAGE
[V_OUT + Vf + (I_SEC • R_P)]
0V
AREA “c” = AREA “d” TO MAINTAIN
ZERO VOLTS ACROSS SECONDARY
N • V_IN
BIAS WINDING VOLTAGE
[V_OUT + Vf + (I_SEC • R_P)]/N1
0V
AREA “e” = AREA “f” TO MAINTAIN
ZERO VOLTS ACROSS BIAS WINDING
N2 • V_IN
I_PRI
PRIMARY CURRENT
Flyback Waveform for Discontinuous Mode Operation
a
b
c
d
V_ZENER
PRIMARY SWITCH VOLTAGE
[V_OUT + Vf + (I_SEC • R_P)]/ N
V_IN
AREA “a” = AREA “b” TO MAINTAIN
ZERO VOLTS ACROSS PRIMARY
0V
SECONDARY WINDING VOLTAGE
[V_OUT + Vf + (I_SEC • R_P)]
0V
AREA “c” = AREA “d” TO MAINTAIN
ZERO VOLTS ACROSS SECONDARY
N • V_IN
e
f
BIAS WINDING VOLTAGE
[V_OUT + Vf + (I_SEC • R_P)]/ N1
0V
AREA “e” = AREA “f” TO MAINTAIN
ZERO VOLTS ACROSS BIAS WINDING
N2 • V_IN
I_PRI
∆I
PRIMARY CURRENT
0A
I_{SEC =} I_PRI/N
SECONDARY CURRENT
0A
I_{SEC =} I_PRI/ N
SECONDARY CURRENT
0A
I_PRI
∆I
SWITCH CURRENT
0A
I_PRI
∆I
SWITCH CURRENT
0A
I_PRI
SNUBBER DIODE CURRENT
0A
∆t = (I_PRI)[L(lk_PRI)]/ V_SNUB
0A
I_PRI
SNUBBER DIODE CURRENT
0A
∆t = (I_PRI)[L(lk_PRI)]/ V_SNUB
LT1103 WF01
22