IL4116-X019T 데이터 시트보기 (PDF) - Vishay Semiconductors

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IL4116-X019T

Optocoupler, Phototriac Output, Zero Crossing, Very Low Input Current

Vishay Semiconductors 

IL4116, IL4117, IL4118

Optocoupler, Phototriac Output, Zero Vishay Semiconductors

Crossing, Very Low Input Current

TRIGGER CURRENT VS. TEMPERATURE AND VOLTAGE

The trigger current of the IL4116, IL4117, IL4118 has a

positive temperature gradient and also is dependent on the

terminal voltage as shown as the fig. 7.

For the operating voltage 250 VRMS over the temperature

range - 40 °C to 85 °C, the IF should be at least 2.3 x of the

IFT1 (1.3 mA, max.).

Considering - 30 % degradation over time, the trigger

2.5

current minimum is IF = 1.3 x 2.3 x 130 % = 4 mA

100 °C

2.0

85 °C

1.5

1.0

50 °C

0.5

25 °C

0.0

0

21611

50 100 150 200 250 300 350

VRMS (V)

Fig. 7 - Trigger Current vs.

Temperature and Operating Voltage (50 Hz)

INDUCTIVE AND RESISTIVE LOADS

For inductive loads, there is phase shift between voltage and current, shown in the fig. 8.

IF(on)

IF(off)

IF(on)

IF(off)

AC line

voltage

AC line

voltage

Commutating dV/dt

AC current

through

triac

Voltage

across triac

Commutating dV/dt

AC current

through

triac

Voltage

across triac

21607

Resistive load

Inductive load

Fig. 8 - Waveforms of Resistive and Inductive Loads

The voltage across the triac will rise rapidly at the time the

current through the power handling triac falls below the

holding current and the triac ceases to conduct. The rise

rate of voltage at the current commutation is called

commutating dV/dt. There would be two potential problems

for ZC phototriac control if the commutating dV/dt is too

high. One is lost control to turn off, another is failed to keep

the triac on.

Lost control to turn off

If the commutating dV/dt is too high, more than its critical

rate (dV/dtcrq), the triac may resume conduction even if the

LED drive current IF is off and control is lost.

In order to achieve control with certain inductive loads of

power factors is less than 0.8, the rate of rise in voltage

(dV/dt) must be limited by a series RC network placed in

parallel with the power handling triac. The RC network is

called snubber circuit. Note that the value of the capacitor

increases as a function of the load current as shown in fig. 9.

Failed to keep on

As a zero-crossing phototriac, the commutating dV/dt

spikes can inhibit one half of the TRIAC from keeping on If

the spike potential exceeds the inhibit voltage of the zero

cross detection circuit, even if the LED drive current IF is on.

Document Number: 83628

Rev. 1.8, 20-Oct-10

For technical questions, contact: optocoupleranswers@vishay.com

www.vishay.com

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