ST1843 - ST1845

Pin connection

Doc ID 019049 Rev 1

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4

Pin connection

Figure 2.

Pin connection

Table 4.

Pin functions

No

Function

Description

1

COMP

This pin is the error amplifier output and is made available for loop compensation.

2

This is the inverting input of the error amplifier. It is normally connected to the

switching power supply output through a resistor divider.

3

A voltage proportional to inductor current is connected to this input. The PWM uses

this information to terminate the output switch conduction.

4

The oscillator frequency and maximum output duty cycle are programmed by

connecting resistor RT to Vref and capacitor CT to ground. Operation to 500 kHz is

possible.

5

GROUND This pin is the combined control circuitry and power ground.

6

OUTPUT

This output directly drives the gate of a power MOSFET. Peak currents up to 1A are

sourced and sunk by this pin.

7

This pin is the positive supply of the control IC.

8

This is the reference output. It provides charging current for capacitor CT through

resistor RT.