U2100B-MFP Datasheet, PDF (4/13 Pages) List of Unclassifed Manufacturers – Timer Control for Triac and Relay

Figure 4. Three-wire Circuit
L
Control
N
For three-wire switch systems, two operational modes are possible:
– Zero voltage switch operation for triac control
– Static operation for relay control
Mode Selection Pin 4 and The operational modes can be selected by the external voltage at the synchronous input
Supply Voltage Pin 2
pin 4 (clamping). The mode selection determines the current requirement of the relay's
or triac's driver stage and hence the selection of the supply voltage.
Zero Voltage Switch
Operation (Figure 5)
Selection condition:
V₄ = internal synchronous limitation, without external clamping
R₁ ≈
0.85
-^V----^M-----–-----^V----^S-
2 I_tot
I_tot = I_S + I_p + I_X
where:
I_S = Supply current of the IC without load
I_P = Average trigger current I_G
I_X = External circuit current requirement
V_M = Mains voltage
Required firing pulse width t_p
t_p
=
2_{-ω- arcsin}
⎛
⎝
-^IP-^L-----^××-----^V-----₂^M--_⎠⎞
where:
I_L = Triac latching current
P = Power at load Z
R_sync[kΩ] ≈
-^V----^M----^[--^V----^]---^×----------²----^s---ⁱ-ⁿ-----⁽---^ω----^×------^t--^p---^[-^s---^]---⁾---–-----⁰---^.--⁷- – 176
1.8 × 10^-2
4 U2100B
4769B–INDCO–12/04