CPC1580

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R01

(averaged over the switching voltage range) found in

by the CPC1580 unloaded discharge characteristic

and should be reviewed in light of the final application

component selections if critical.

component selection. The storage capacitor charge

recovery time (seconds) is computed as:

Which reduces to:

elements that are present in the application circuit

diagram (see Figure 3).

The term inside the logarithm reflects the discharge

component selection, this can be simplified as

described above.

Use this information to calculate the maximum

switching frequency in Section 7 below.

remote power is otherwise unavailable. If the

LED is also powered remotely, care must be

taken to ensure that parasitic transient signals

are reliably filtered from the input control signal.

Large transient currents will mutually couple

energy between cables and a simple R-C

filtering of the CPC1580 input may be sufficient

to suppress false turn-on.

Figure 2. CPC1580 AC Application Circuit

5. CPC1580 Over-Voltage Protection

Over-voltage protection is generally required for the

CPC1580 because of parasitic inductance in the load,

wires, board traces, and axial leads of protectors.

Purely resistive loads or loads with low voltage

switching may be able to rely on the transistor to

handle any parasitic energy and thereby not require

protection for the CPC1580. For very low inductance

loads and traces, over-voltage suppression may be

Figure 3). For more moderate load inductance, or

remote switching of a load (i.e. through a long cable) a

voltage suppressor can be used. For heavily inductive

)

(

2

3

1

4

NC

NC

8

5

6

7

C

ST

+/- V

LOAD

+/- V

LOAD

CPC1580

LED +

LED -

V

CAP

V

D

V

G

V

S

Q1

Q2

LOAD

*