July 2000
PRELIMINARY
ML4836
*
Compact Fluorescent
Electronic Dimming Ballast Controller
1
GENERAL DESCRIPTION
The ML4836 is a complete solution for a dimmable or a
non-dimmable high efficiency electronic ballast especially
tailored for a compact fluorescent lamp (CFL). The
Bi-CMOS ML4836 contains controllers for dimming
ballast with end-of-life detection capability.
The ballast controller section provides for programmable
starting sequence with individual adjustable preheat and
lamp out-of-socket interrupt times. The ML4836 provides
latch type shut down comparator for ballast controllers in
the event of end-of-life for the CFL.
BLOCK DIAGRAM
FEATURES
s
Programmable start scenario for rapid/instant start lamps
s
Triple frequency control network for dimming or
starting to handle various lamp sizes
s
Programmable restart for lamp out condition to reduce
ballast heating.
s
Internal over-temperature shutdown
s
Low start-up current; < 0.55mA
(* Indicates Part is End Of Life as of July 1, 2000)
4
RSET
6
RT/CT
5
RT2
9
PWDET
7
INTERRUPT
2
LAMP FB
3
LEAO
13
OUT A
12
OUT B
11
PGND
8
RX/CX
14
VCC
1
REF
10
AGND
OUTPUT
DRIVERS
PRE-HEAT AND
INTERRUPT TIMERS
LAMP OUT DETECT
AND
AUTOMATIC LAMP
RESTART
UNDER-VOLTAGE
AND
THERMAL SHUTDOWN
END-OF-LAMP DETECT
AND
POWER SHUTOFF
ANTI-FLASH
COMPENSATION
AND
DIMMING LEVEL
INTERFACE
THREE-FREQUENCY
CONTROL SEQUENCER
VCO
VARIABLE FREQUENCY
OSCILLATOR
CONTROL
AND
GATING
LOGIC
ML4836
2
PIN CONFIGURATION
PIN DESCRIPTION
PIN
NAME
FUNCTION
1
REF
Buffered output for the 7.5V reference
2
LAMP FB
Inverting input of the lamp error
amplifier, used to sense and regulate
lamp arc current. Also the input node
for dimmable control.
3
LEAO
Output of the lamp current error
transconductance amplifier used for
lamp current loop compensation
4
R
SET
External resistor which SETS oscillator
F
MAX
, and R
X
/C
X
charging current
5
R
T2
Oscillator timing component to set
start frequency
6
R
T
/C
T
Oscillator timing components
PIN
NAME
FUNCTION
7
INTERRUPT Input used for lamp-out detection and
restart. A voltage less than 1V will reset
the IC and cause a restart after a
programmable interval.
8
R
X
/C
X
Sets the timing for preheat and
interrupt.
9
PWDET
Lamp output power detection
10
AGND
Analog ground
11
PGND
Power ground.
12
OUT B
Ballast MOSFET driver output
13
OUT A
Ballast MOSFET driver output
14
V
CC
Positive supply voltage
ML4836
14-Pin SOIC (S14)
14-Pin DIP (P14)
1
2
3
4
5
6
7
14
13
12
11
10
9
8
TOP VIEW
REF
LAMP FB
LEAO
RSET
RT2
RT/CT
INTERRUPT
VCC
OUTA
OUT B
PGND
AGND
PWDET
RX/CX
ML4836
3
ABSOLUTE MAXIMUM RATINGS
Absolute maximum ratings are those values beyond which
the device could be permanently damaged. Absolute
maximum ratings are stress ratings only and functional
device operation is not implied.
Supply Current (I
CC) ............................................................
50mA
Output Current, Source or Sink
(OUT A, OUT B) DC ............................................ 250mA
PIFB Input Voltage ............................................ 3V to 2V
Maximum Forced Voltage
(PEAO, LEAO) ............................................ 0.3V to 7.7V
Maximum Forced Current
(LEAO) ................................................................. 20mA
Junction Temperature .............................................. 150C
Storage Temperature Range...................... 65C to 150C
Lead Temperature (Soldering, 10 sec) ...................... 260C
Thermal Resistance (
q
JA
)
ML4836CP ............................................................... C/W
ML4836CS ............................................................... C/W
OPERATING CONDITIONS
Temperature Range ........................................ 0C to 85C
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, V
CC
= V
CCZ
0.5V, R
SET
= 11.8k
W, R
T
= 14.7k
W, R
T2
= 53.6k
W, C
T
= 1.5nF,
T
A
= Operating Temperature Range (Note 1)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
LAMP CURRENT AMPLIFIER (LAMP FB, LEAO)
Input Bias Current
-0.3
-1.0
A
Small Signal Transconductance
35
75
105
W
Input Bias Voltage
-0.3
5.0
V
Output Low
LAMP FB = 3V, R
L
=
0.2
0.4
V
Output High
LAMP FB = 2V, R
L
=
7.1
7.5
V
Source Current
LAMP FB = 0V, LEAO = 6V
-80
-220
A
Sink Current
LAMP FB = 5V, LEAO = 0.3V
80
220
A
OSCILLATOR
Initial Accuracy (F
MIN
)
T
A
= 25C
39.2
40
40.8
kHz
Total Variation (F
MIN
)
Line, Temperature
39.2
40.8
kHz
Initial Accuracy (START)
T
A
= 25C
49
50
51
kHz
Total Variation (START)
Line, Temperature
49
51
kHz
Ramp Valley to Peak
2.6
V
Initial Accuracy (Preheat)
TA = 25C
60.8
64
67.2
kHz
Total Variation (Preheat)
Line, Temperature
60.8
64
67.2
kHz
C
T
Discharge Current
V
RTCT
= 2.5V
6.0
7.5
9.0
mA
Output Drive Deadtime
C
T
= 1.5nF
0.7
us
REFERENCE BUFFER
Output Voltage
T
A
= 25C, I
O
= 0mA
7.4
7.5
7.6
V
Line Regulation
V
CCZ
4V < V
CC
< V
CCZ
0.5V
10
25
mV
Load Regulation
1mA < I
O
< 10mA
2
15
mV
Temperature Stability
0.4
%
Total Variation
Line, Load, Temperature
7.35
7.65
V
Long Term Stabilty
Tj = 125C, 1000 hrs
5
mV
ML4836
4
ELECTRICAL CHARACTERISTICS
(Continued)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
REFERENCE BUFFER (Continued)
Short Circuit Current
40
mA
R
SET
Voltage
2.4
2.5
2.6
V
PREHEAT AND INTERRUPT TIMER (R
X
= 346k
W, C
X
= 10F)
R
X
/C
X
Charging Current
48
52
56
A
R
X
/C
X
Open Circuit Voltage
0.4
0.7
1.0
V
R
X
/C
X
Maximum Voltage
7.0
7.3
7.8
V
Preheat Lower Threshold
1.6
1.75
1.9
V
Preheat Upper Threshold
4.4
4.65
4.9
V
Start Period End Threshold
6.2
6.6
6.9
V
Interrupt Disable Threshold
1.1
1.25
1.4
V
Hysteresis
0.16
0.26
0.36
V
Input Bias Current
1
A
POWER SHUTDOWN
Power Shutdown Voltage
0.9
1.0
1.1
V
OUTPUTS (OUT A, OUT B, PFC OUT)
Output Voltage Low
I
OUT
= 20mA
0.1
0.2
V
I
OUT
= 200mA
1.0
2.0
V
Output Voltage High
I
OUT
= 20mA
V
CC
0.2 V
CC
0.1
V
Output Voltage High
I
OUT
= 200mA
V
CC
2.0 V
CC
1.0
V
Output Voltage Low in UVLO
I
OUT
= 20mA, V
CC
< V
CC
START
0.2
V
Output Rise and Fall Time
CL = 1000pF
50
ns
UNDER VOLTAGE LOCKOUT AND BIAS CIRCUITS
IC Shunt Voltage (V
CCZ
)
ICC = 15mA
14.0
14.8
15.5
V
Start-up Threshold (V
CC START
)
V
CCz
1.5 V
CCz
1.0 V
CCz
0.5
V
Hysteresis
3.0
3.7
4.4
V
Start-up Current
V
CC START
0.2V
350
550
A
Interrupt Current
(V
CCz
0.5V), INTERRUPT = 0V
500
750
A
Operating Current
(V
CCz
0.5V)
4.0
8.0
mA
Shutdown Temperature
140
C
Hysteresis
30
C
Note 1:
Limits are guaranteed by 100% testing, sampling, or correlation with worst case test conditions.
ML4836
5
FUNCTIONAL DESCRIPTION
The ML4836 consists of flexible ballast control section.
Start-up and lamp-out retry timing are controlled by the
selection of external timing components, allowing for
control of a wide variety of different lamp types. The
ballast section controls the lamp power using frequency
modulation (FM) with additional programmability
provided to adjust the VCO frequency range. This allows
for the IC to be used with a variety of different output
networks. Figure 1 depicts a detailed block diagram of
ML4836.
The ML4836 provides several safety features. See the
corresponding sections for more details:
End-of-lamp life detection to detect EOL and shut-off
lamps; See End Of Life Section.
Thermal shutdown for temperature sensing extremes;
See IC Bias, Under-Voltage Lockout and Thermal
Shutdown Section.
Relamping starting with anti-flash for programmable
restart for lamp out conditions while minimizing
"flashing" when powering from full power to dimming
levels; See Starting, Re-Start, Preheat and Interrupt
Section
Figure 1. Detailed Block Diagram
VCC
14
REF
1
AGND
10
RSET
4
LAMP FB
2
LEAO
3
RT2
5
INTERRUPT
7
PWDET
9
PGND
11
OUT B
12
OUT A
13
REF
+
14V
+
6.75V
Q
Q
T
1.20V/1V
RX/CX
6.65V/1.25V
2.5V
+
1.05V
Q
Q
S
R
CLK
UVLO
REF_OK
PREHEAT
THERMAL SHUTDOWN
RT/CT
6
OSCILLATOR
V
TO
I
+
4.65V/
1.75V
S
Q
Q
R
+
COMP
+
+
+
TEMP
140C/100C
RX/CX
8
V
TO
I
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