ML4832 데이터 시트보기 (PDF) - Micro Linear Corporation

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ML4832

Electronic Dimming Ballast Controller

Micro Linear Corporation 

July 2000

PRELIMINARY

ML4832*

Electronic Dimming Ballast Controller

GENERAL DESCRIPTION

The ML4832 is a complete solution for a dimmable/non-

dimmable, high power factor, high efficiency electronic

ballast. The BiCMOS ML4832 contains controllers for

“boost” type power factor correction as well as for a

dimming ballast.

The power factor circuit uses the average current sensing

method with a gain modulator and overvoltage protection.

This system produces a power factor of better than 0.99

with low input current THD at > 95% efficiency. Special

care has been taken in the design of the ML4832 to

increase system noise immunity by using a high amplitude

oscillator, and a current-fed multiplier. An overvoltage

protection comparator inhibits the PFC section in the

event of a lamp out or lamp failure condition.

The ballast section provides for programmable starting

scenarios with programmable preheat and lamp out-of-

socket interrupt times. The IC controls lamp output through

frequency modulation using lamp current feedback.

FEATURES

s

Complete power factor correction and dimming

ballast control in one IC

s

Low distortion, high efficiency continuous boost,

average current sensing PFC section

s

Programmable start scenario for rapid or instant

start lamps

s

Lamp current feedback for dimming control

s

Variable frequency dimming and starting

s

Programmable restart for lamp out condition to

reduce ballast heating

s

Over-temperature shutdown replaces external

heat sensor for safety

s

PFC overvoltage comparator eliminates output

“runaway” due to load removal

s

Large oscillator amplitude and gain modulator

improves noise immunity

s

Low start-up current <0.5mA

(* Indicates part is End Of Life as of July 1, 2000)

BLOCK DIAGRAM

RSET

7

RT/CT

8

VARIABLE FREQUENCY

OSCILLATOR

RX/CX

10

PRE-HEAT

AND INTERRUPT

TIMERS

IA OUT

2

IA+

4

ISINE

3

EA OUT

1

EA–/OVP

18

POWER

FACTOR

CONTROLLER

CONTROL

&

GATING LOGIC

UNDER-VOLTAGE

AND THERMAL

SHUTDOWN

OUTPUT

DRIVERS

INTERRUPT

9

LAMP FB

5

LFB OUT

6

OUT A

14

OUT B

13

PFC OUT

15

PGND

12

VCC

16

VREF

17

GND

11

1

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