HCPL-5760 Datasheet, PDF(9/10 Page) AVAGO TECHNOLOGIES LIMITED – AC/DC to Logic Interface Hermetically Sealed Optocouplers

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HCPL-5760 Datasheet, PDF (9/10 Pages) AVAGO TECHNOLOGIES LIMITED – AC/DC to Logic Interface Hermetically Sealed Optocouplers

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Electrical Considerations

The HCPL-5760, HCPL-5761, HCPL-576K or 5962-89477

optocoupler has internal temperature compensated,

predictable voltage and current threshold points which

allow selection of an external resistor, Rx, to determine

larger external threshold voltage levels. For a desired

external threshold voltage, VÂ±, a corresponding typical

value of Rx can be obtained from Figure 10. Specific

calculation of Rx can be obtained from Equation (1)

of Figure 11. Specification of both V+ and V- voltage

threshold levels simultaneously can be obtained by the

use of Rx and Rp as shown in Figure 11 and determined by

Equations (2) and (3).

Rx can provide over-current transient protection by

limiting input current during a transient condition. For

monitoring contacts with a relay or switch, the HCPL-

5760/1/K, or 5962-89477 combin-ation with Rx and Rp

can be used to allow a specific current to be con-ducted

through the contacts for cleaning purposes (wetting

current).

The choice of which input voltage clamp level to choose

depends upon the application of this device (see Figure 3).

It is recommended that the low clamp condition be used

when possible to lower the input power dissipation as

well as the LED current, which minimizes LED degradation

over time.

In applications where dVCM/dt may be extremely large

(such as static discharge), a series resistor, RCC, should

be connected in series with VCC and Pin 8 to protect the

detector IC from destructively high surge currents. See

note 14 for determination of RCC. In addition, it is recom-

mended that a ceramic disc bypass capacitor of 0.01 ïF to

0.1 ïF be placed between Pins 8 and 5 to reduce the effect

of power supply noise.

For interfacing ac signals to TTL systems, output low pass

filtering can be performed with a pullup resistor of 1.5 kï

and 20 ïF capacitor. This application requires a Schmitt

trigger gate to avoid slow rise time chatter problems.

For ac input applications, a filter capacitor can be placed

across the dc input terminals for either signal or transient

filtering.

Either AC (Pins 1, 4) or DC (Pins 2, 3) input can be used to

determine external threshold levels.

For one specifically selected external threshold voltage

level V+ or V-, Rx can be determined without use of Rp via

V+(-) â VTH+(-)

ITH+(-)

(1)

For two specifically selected external threshold voltage

levels, V+ and V-, the use of Rx and Rp will permit this

selection via equations (2), (3) provided the following con-

ditions are met:

V+

V-

â¥

VTH+

VTH-

and

V+ â VTH+

V- â VTH-

ITH+

ITH-

VTH+ (V+)

ITH+ (VTH-)

â VTH+ (V-)

â ITH- (VTH+)

(2)

ITH+

VTH+ (V+) â VTH+ (V-)

(V- â VTH-) â ITH- (VTH+

V+)

(3)

See Application Note 1004 for more information.

Figure 9. Operating circuit for burn-in and steady state life tests.

Figure 10. Typical external threshold characteristic, VÂ± vs. Rx.

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