CPC1590

8

www.ixysic.com

R01

between 10V and 16V. The capacitor’s voltage rating

should be two to three times this range.

The designer should select the storage capacitor

based on the particular application requirements. If the

final product requires operating at a higher ambient

temperature range of -40°C to +110°C, then it is better

to select COG/NPO capacitors in order to meet

minimum capacitance requirements.

4.3 Transistor Selection

The CPC1590 charges and discharges an external

MOSFET transistor. The selection of the MOSFET is

determined by the user to meet the specific power

requirements for the load. The CPC1590 output

voltage is listed in the specification, but, as mentioned

earlier, there must be little or no gate leakage.

Another parameter that plays a significant role in the

selection of the transistor is the gate drive voltage

available from the part. The CPC1590 uses

photovoltaic cells to collect the optical energy

generated by the internal LED; to generate more

voltage, the photovoltaic diodes are stacked. As such,

the voltage of the photovoltaic stack reduces with

increased temperature. The user must select a

transistor that will maintain the load current at the

specifications.

5. CPC1590 Used as an AC Switch

The CPC1590 can be used in other configurations.

One typical configuration is shown in Figure 3, which

is called an AC Switch. This simply means that either

terminal can be positive or negative. This configuration

requires a second MOSFET (Q2) and two rectifying

diodes (D1 and D2).

The design considerations are identical for this

application. Diodes D1 and D2 must have voltage

ratings greater than the breakdown voltage of the

MOSFETs.

Figure 3. Application Circuit for Using the CPC1590 as an AC Switch

6. Conclusion

See IXYS Integrated Circuits Division’s Application Note, AN-202, for a thorough discussion, and for examples of

device usage, component selection, and over-voltage protection circuitry.

2

3

1

4

NC

NC

8

5

6

7

CPC1590

LED +

LED -

V

CAP

V

G

C

ST

+/- V

LOAD

+/- V

LOAD

Q1

Q2

LOAD

V

L1

V

L2

D2

D1