KA384X datasheet(4/12 Pages) ESTEK

4 / 12 page

KA384x

www.estek.com.cn

Version 0.2

27 July 2011

Electrical Characteristics

(Con.)

(TA=25 °C, VCC=15V, RT=10KΩ, CT=3.3nF, TA=0

oC to +70oC, unless otherwise specified .)

Symbol

Parameter

Test Condition

Min.

Typ.

Max.

Unit

PWM Section

KA3842 / KA3843

100

D(Max.)

Max. Duty Cycle

KA3844 / KA3845

D(Min.)

Min. Duty Cycle

Total Standby Current

KA3843 / KA3845

0.13

0.3

IST

Start-Up Current

KA3842 / KA3844

0.2

0.3

ICC(OPR)

Operating Supply Current

Vpin3=Vpin2=0V

Zener Voltage

ICC=25mA

* Adjust VCC above the start threshold before setting it to 15V.

Notes:

Note 1: Parameter measured at trip point of latch with Vpin2=0.

Note 2: Gain defined as A=△Vpin1/△Vpin3; 0≤Vpin3≤0.8V

Note 3: These parameters, although guaranteed, are not 100% tested in production.

Pin Function

Function

Description

COMP

This pin is the Error Amplifier output and is made for loop compensation.

VFB

This is the inverting input of the Error Amplifier. It is normally connected to the switching power

supply output through a resistor divider.

ISENSE

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

information to terminate the output switch conduction.

RT/CT

The oscillator frequency and maximum output duty cycle are programmed by connecting resistor

RT to VREF and capacitor CT to ground.

GND

This pin is the combined control circuitry and power ground.

OUT

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

sink by this pin.

VCC

This pin is the positive supply of the integrated circuit.

VREF

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

ET-

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