ML4831 Datasheet, PDF (1/14 Pages) Micro Linear Corporation – Electronic Ballast Controller

JULY 2000
ML4831*
Electronic Ballast Controller
GENERAL DESCRIPTION
The ML4831 is a complete solution for a dimmable, high
power factor, high efficiency electronic ballast. Contained
in the ML4831 are 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 over-voltage
protection. This system produces power factors of better
than 0.99 with low input current THD at > 95%
efficiency. Special care has been taken in the design of the
ML4831 to increase system noise immunity by using a
high amplitude oscillator, and a current fed multiplier. An
over-voltage 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 either frequency modulation using lamp current
feedback.
The ML4831 is designed using Micro Linear‘s Semi-
Standard tile array technology. Customized versions of this
IC, optimized to specific ballast architectures can be made
available. Contact Micro Linear or an authorized
representative for more information.
FEATURES
s Complete Power Factor Correction and Dimming
Ballast Control on 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 Over-Voltage comparator eliminates output
“runaway” due to load removal
s Large oscillator amplitude and gain modulator
improves noise immunity
* This product is End Of Life as of July 1, 2000
BLOCK DIAGRAM
R(SET)
7
R(T)/C(T)
8
OSCILLATOR
R(X)/C(X)
10
PRE-HEAT
AND INTERRUPT
TIMERS
CONTROL
&
GATING LOGIC
OUTPUT
DRIVERS
INTERRUPT
9
LAMP F.B.
5
LFB OUT
6
OUT A
14
OUT B
13
IA OUT
2
IA+
4
I(SINE)
3
EA OUT
1
EA–/OVP
18
POWER
FACTOR
CONTROLLER
UNDER-VOLTAGE
AND THERMAL
SHUTDOWN
PFC OUT
15
PGND
12
VCC
16
VREF
17
GND
11
1