T2117 데이터 시트보기 (PDF) - Atmel Corporation

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T2117

Zero-voltage Switch with Adjustable Ramp

Atmel Corporation 

T2117

3. General Description

The integrated circuit T2117 is a triac controller for zero-crossing mode. It is designed to control

power in switching resistive loads of mains supplies.

Information regarding synchronous supply is provided at pin 8 via resistor RSync. To avoid a DC

load on the mains, the full-wave logic guarantees that complete mains cycles are used for load

switching.

A fire pulse is released when the inverting input of the comparator is negative (pin 4) with

respect to the non-inverting input (pin 3) and internal reference voltage. A ramp generator with

freely selectable duration can be performed by capacitor C2 at pin 2. The ramp function is used

for open-loop control (Figure 3-2), but also for applications with proportional band regulation

(Figure 10-3 on page 10). Ramp voltage available at capacitor C2 is decoupled across the emit-

ter follower at pin 1. To maintain the lamp flicker specification, the ramp duration is adjusted

according to the controlling load. One can use internal reference voltage for simple applications.

In that case, pin 3 is inactive and connected to pin 7 (GND), see Figure 10-5 on page 12.

Figure 3-1. Pin 1 Internal Network

T2117

1

R4

-VS

Ramp

control

2

C2

Figure 3-2. Threshold Voltage of the Ramp at VS = -8.8 V

V1

-1.6 V

-7.6 V

t

Final voltage

Vmin

Initial voltage

T

Vmax

3

4768B–INDCO–10/05

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