U209B_07 Datasheet, PDF (9/19 Pages) ATMEL Corporation – Phase Control IC for Tacho Applications

Figure 3-3. Explanation of Terms in Phase Relationship
V
Mains
Supply
V_GT
Trigger
Pulse
V_L
Load
Voltage
π/2
π
3/2π
2π
t_p
t_pp = 4.5 t_p
IL
Load
Current
ϕ
Φ
U209B
3.10 Design Calculations for Mains Supply
The following equations can be used for the evaluation of the series resistor R₁ for worst case
conditions:
R_1max
=
0.85
-^V----^M----^m----ⁱ-ⁿ----–----^V-----^S---^m----^a---^x
2 I_tot
R_1min
=
V_{-----M-----–-----}V_{----S---m----i-n-}
2 I_Smax
P _{( R1max )}
=
(_---V_{----M----m----a---x----–----}V_{----S----m----i-n---})_--²_-
2 R₁
where:
V_M
V_S
I_tot
I_Smax
I_p
I_x
= Mains voltage 230 V
= Supply voltage on pin 3
= Total DC current requirement of the circuit
= I_S + I_p + I_x
= Current requirement of the IC in mA
= Average current requirement of the triggering pulse
= Current requirement of other peripheral components
R₁ can be easily evaluated from Figure 6-10 on page 15 to Figure 6-12 on page 16.
9
4765C–INDCO–02/07