U2008B_07 Datasheet, PDF (3/13 Pages) ATMEL Corporation – Low-cost Phase-control IC with Soft Start

2. Pin Configuration
Figure 2-1. Pinning
ISENSE 1
8 OUTPUT
Cϕ 2
CONTROL ₃
U2008B
7 VSYNC
6 ^Rϕ
GND ₄
5 ^-VS
U2008B
Table 2-1.
Pin
1
2
3
4
5
6
7
8
Pin Description
Symbol Function
ISENSE Load current sensing
Cϕ
Ramp voltage
CONTROL Control input/compensation output
GND
Ground
-VS
Supply voltage
Rϕ
Ramp current adjustment
VSYNC Voltage synchronization
OUTPUT Trigger output
2.1 Mains Supply, Pin 5
The integrated circuit U2008B, which also contains voltage limiting, can be connected via D₁ and
R₁ to the mains supply, see Figure 1-2 on page 2. Supply voltage, between Pin 4 (pos., ⊥) and
Pin 5, is smoothed by C₁.
The series resistance R1 can be calculated as follows:
R_1max = 0.85 × ^V-----^M--₂---–--_×---^V--_I--_tS-_o--^m-_t---^a--^x-
where:
V_M
V_Smax
I_tot
I_Smax
I_x
= Mains voltage
= Maximum supply voltage
= I_Smax + I_x = Total current compensation
= Maximum current consumption of the IC
= Current consumption of the external components
Operation with externally stabilized DC voltage is not recommended.
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4712C–AUTO–07/07