HCPL-576X Datasheet, PDF (9/11 Pages) Agilent(Hewlett-Packard) – AC/DC to Logic Interface Hermetically Sealed Optocouplers

HCPL-576x, 5962-8947701
Data Sheet
Electrical Considerations
The HCPL-5760, HCPL-5761, HCPL-576K, or 5962-89477
optocoupler has internal temperature-compensated,
predictable voltage and current threshold points that allow
selection of an external resistor, R_x, to determine larger
external threshold voltage levels. For a desired external
threshold voltage, V_±, a corresponding typical value of R_x can
be obtained from Figure 10. Specific calculation of R_x 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 R_x and R_p as shown in Figure 11 and
determined by Equations 2 and 3.
R_x can provide overcurrent 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 combination with R_x and R_p 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 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 dV_CM/dt might be extremely large (such
as static discharge), a series resistor, R_CC, should be connected
in series with V_CC and Pin 8 to protect the detector IC from
destructively high surge currents.¹ In addition, it is
recommended that a ceramic disc bypass capacitor of 0.01 μF
to 0.1 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 pull-up resistor of 1.5 kΩ and
20 μF capacitor. This application requires a Schmitt trigger gate
to avoid slow rise time chatter problems. For ac input applica­
tions, 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_–, R_x can be determined without use of R_p via the following
equation.
Equation 1
R_x=
V_{----+---(----)--–-----}V_{----T--H---+---(---)}
I_TH+(-)
For two specifically selected external threshold voltage levels,
V+ and V_–, the use of R_x and R_p will permit this selection via
equations 2, 3 provided the following conditions are met:
V_----+-
V_-
≥ ^V----^T--^H---⁺--and
V_TH-
V_{--V--+-----––-----}VV_{---TT---HH---+--}
<
I_--T--H---+--
I_TH-
Equation 2
Equation 3
R_X = _I--_T-^V-_H--^T--₊-^H--₍-⁺-_V--⁽--_T^V--_H--⁺-_---₎₎---–-–----_IV--_T--^TH--^H-_---₍⁺--_V--⁽--_T-^V-_H--^--₊-⁾--₎-
R_P = -_I-_T--_H---₊----₍--_V-^V---_--^T--–^H---⁺-_V---⁽-_T-^V-_H---^+---₎-⁾--–-–----_I-^V-_T--_HT---^H---₍-⁺-_V---⁽-_T-^V-_H---^-+--⁾--–-----_V---₊----₎
See Application Note 1004 for more information.
1. In applications where dV_CM/dt might exceed 50,000 V/μs (such as static
discharge), a series resistor, R_CC, should be included to protect the
detector IC from destructively high surge currents. The recommended
value for R_CC is 240Ω per volt of allowable drop in V_CC (between Pin 8
and V_CC) with a minimum value of 240Ω.
Broadcom
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