CPC1590

6

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2. Introduction

The CPC1590 is a MOSFET Gate Driver that requires

no external power supply. It can regulate an input

voltage, up to 200V, down to 12.2V for internal use. It

is specifically designed for low-duty-cycle switching

frequencies that drive 4nF of gate capacitance.

3. Functional Description

The CPC1590 is used in conjunction with a single

MOSFET transistor for remote switching of DC loads

(Figure 2), and two MOSFETS and a diode for remote

switching of low-frequency AC loads (Figure 3) where

isolated power is unavailable.

The device uses external components, most notably a

charge storage capacitor, to satisfy design switching

and over-voltage protection requirements. Because of

this design flexibility, the designer may choose a great

number of MOSFETs for use in a wide variety of

applications. The designer simply needs to know the

information a capacitor can be chosen. The

capacitance of the storage capacitor should be greater

The CPC1590 has two states of operation:

(1) sufficient input control current is flowing, the LED is

turned on, and the gate current is being applied. The

light from the LED is being reflected onto the

photovoltaic, which then produces a photocurrent that

turns on the NPN bipolar transistor and provides the

charge (I x t = Q), or the gate current that is being

applied to turn on the MOSFET. (2) Sufficient input

control current is not flowing, the LED is turned off,

and gate current is not flowing. The LED is off

and not enough current is being applied. This turns on

the PNP bipolar transistor, providing a path for gate

capacitor begins to charge. The charge is sent through

a bootstrap diode to prevent the charge from escaping

and discharging through a turned-on MOSFET. The

J-FET then regulates the voltage between 10V and

16V. The input control current is applied, then the

charge is transferred from the storage capacitor

through the NPN bipolar transistor, along with the

charge from the photovoltaic, to the MOSFET gate to

accomplish a rapid turn-on. After the capacitor has

discharged and the MOSFET has turned on, the

photocurrent from the input optocoupler continues to

flow into the gate to keep the MOSFET turned on.

When the input control current is removed, the gate

current stops flowing and the PNP bipolar transistor is

on and is discharging the MOSFET gate. The

MOSFET is now off. At this point the capacitor begins

to recharge for the next turn on cycle.

The circuit below does not include over-voltage

protection.

Figure 2. CPC1590 DC Application Circuit

2

3

1

4

NC

NC

8

5

6

7

CPC1590

LED +

LED -

CAP

+V

LOAD

G

-V

LOAD

C

ST

LOAD

A

B