ML4831
ELECTRICAL CHARACTERISTICS
(Continued)
PARAMETER
OVP Comparator (Pin 18)
OVP Threshold
Hysteresis
Propagation Delay
Outputs
Output Voltage Low
I
OUT
= 20mA
I
OUT
= 200mA
Output Voltage High
I
OUT
= –20mA
I
OUT
= –200mA
Output Voltage Low in UVLO
Output Rise/Fall Time
Under-Voltage Lockout and Bias Circuits
IC Shunt Voltage (V
CCZ
)
V
CCZ
Load Regulation
V
CCZ
Total Variation
Start-up Current
Operating Current
Start-up Threshold
Shutdown Threshold
Shutdown Temperature (T
J
)
Hysteresis (T
J
)
I
CC
= 25mA
25mA < I
CC
< 68mA
Load, Temp
V
CC
≤
12.3V
V
CC
= V
CCZ
– 0.5V
12.4
1.3
15
V
CCZ
– 0.5
V
CCZ
– 3.5
120
30
12.8
13.5
150
14.2
300
14.6
1.7
19
V
mV
V
mA
mA
V
V
°C
°C
I
OUT
= 10mA, V
CC
= 8V
C
L
= 1000pF
V
CC
– 2.5
V
CC
– 3.0
0.4
2.1
V
CC
– 1.9
V
CC
– 2.2
0.8
50
1.5
0.8
3.0
V
V
V
V
V
ns
2.6
2.7
0.25
500
2.8
V
V
ns
CONDITIONS
MIN
TYP
MAX
UNITS
FUNCTIONAL DESCRIPTION
OVERVIEW
The ML4831 consists of an Average Current controlled
continuous boost Power Factor front end section with a
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.
POWER FACTOR SECTION
The ML4831 Power Factor section is an average current
sensing boost mode PFC control circuit which is
architecturally similar to that found in the ML4821. For
detailed information on this control architecture, please
refer to Application Note 16 and the ML4821 data sheet.
GAIN MODULATOR
The ML4831 gain modulator provides high immunity to
the disturbances caused by high power switching. The
rectified line input sine wave is converted to a current via
a dropping resistor. In this way, small amounts of ground
noise produce an insignificant effect on the reference to
the PWM comparator.
The output of the gain modulator appears on the positive
terminal of the IA amplifier to form the reference for the
current error amplifier. Please refer to Figure 1.
V
MUL
≈
where:
[
I(SINE)
×
(VEA
−
1.1V)
]
4.17mA
(1)
I(SINE) is the current in the dropping resistor,
V(EA) is the output of the error amplifier (Pin 1).
The output of the gain modulator is limited to 1.0V.
5
MICRO-LINEAR [ MICRO LINEAR CORPORATION ]
