HCPL-0370-560E View Datasheet(PDF) - Avago Technologies

Part Name

Description

View to exact match

HCPL-0370-560E

Low Input Current/ High Gain Optocouplers

Avago Technologies 

Figure 13. External threshold voltage level selection.

Electrical Considerations

The HCPL-0370/3700/3760 optocoup­lers have internal

temperature compens­ ated, predictable volta­ ge and cur-

rent threshold points which allow selection of an exter-

nal resistor, RX, to determine larger external threshold

voltage levels. For a desired external threshold voltage,

V±, a corre­sponding typical value of RX can be obt­ ained

from Figure 12. Specific calculation of RX can be obtained

from Equation (1). Specification of both V+ and V- voltage

threshold levels simult­ aneously can be obtained by the

use of RX and RP as shown in Figure 13 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 of a relay or switch, the HCPL-

0370/3700/3760 in combina­tion with RX and RP can be

used to allow a specific current to be conducted 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

1). It is recom­mended that the low clamp condition be

used when possible.

The low clamp condition in conjunction with the low

input current feature will ensure extremely low input

power dissipation.

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 prot­­ ect the

detector IC from destruc­tively high surge currents. See

Note 13 for deter­mination of RCC. In addi­tion, it is recom­

mended that a ceramic disc by­pass capacitor of 0.01 µF

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 kW and 20 µF capacitor. This application requires a

Schmitt trigger gate to avoid slow rise time chatter prob-

lems. 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+ - VTH+

(-)   (-)

RX =

(1)

ITH+

   (-)

For two specifically selected external threshold voltage

levels, V+ and V-, the use of RX and RP will permit this selec-

tion via equations (2), (3) provided the following condi-

tions are met. If the denominator of equation (2) is posi-

tive, then

V+ VTH+ V+ - VTH+ ITH+

≥ and

<

V- VTH- V- - VTH- ITH-

Conversely, if the denominator of

equation (2) is negative, then

V+ VTH+ V+ - VTH+ ITH+

­≤ and >

V- VTH- V- - VTH- ITH-

VTH- (V+) - VTH+ (V-)

RX =

(2)

ITH+ (VTH-) - ITH- (VTH+)

VTH- (V+) - VTH+ (V-)

RP =

(3)

ITH+(V--VTH-)+ITH-(VTH+-V+)

For product information and a complete list of distributors, please go to our website: www.avagotech.com

Avago, Avago Technologies, and the A logo are trademarks of Avago Technologies in the United States and other countries.

Data subject to change. Copyright © 2005-2009 Avago Technologies. All rights reserved. Obsoletes AV01-0542EN

AV02-2107EN - September 2, 2009

Share Link: