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PDF L6574 Data sheet ( Hoja de datos )
| Número de pieza | L6574 | |
| Descripción | CFL/TL BALLAST DRIVER PREHEAT AND DIMMING | |
| Fabricantes | STMicroelectronics | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de L6574 (archivo pdf) en la parte inferior de esta página. Total 9 Páginas | ||
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® L6574
CFL/TL BALLAST DRIVER PREHEAT AND DIMMING
HIGH VOLTAGE RAIL UP TO 600V
dV/dt IMMUNITY ± 50 V/ns IN FULL TEM-
PERATURE RANGE
DRIVER CURRENT CAPABILITY:
250mMA SOURCE
450mA SINK
SWITCHING TIMES 80/40ns RISE/FALL
WITH 1nF LOAD
CMOS SHUT DOWN INPUT
UNDER VOLTAGE LOCK OUT
PREHEAT AND FREQUENCY SHIFTING TIMING
SENSE OP AMP FOR CLOSED LOOP CON-
TROL OR PROTECTION FEATURES
HIGH ACCURACY CURRENT CONTROLLED
OSCILLATOR
INTEGRATED BOOTSTRAP DIODE
CLAMPING ON VS.
SO16, DIP 16 PACKAGE
DESCRIPTION
In order to ensure voltage ratings in excess of
600V, the L6574 is manufactured with BCD OFF
LINE technology, which makes it well suited for
lamp ballast applications.
BLOCK DIAGRAM
SO16N
DIP16
ORDERING NUMBERS:
L6574D
L6574
The device is intended to drive two power MOS-
FETS, in the classical half bridge topology, ensur-
ing all the features needed to drive and properly
control a fluorescent bulb.
A dedicated timing section in the L6574 allows
the user set the necessary parameters for proper
preheat and ignition of the lamp.
Also, an OP AMP is available to implement
closed loop control of the lamp current during
normal lamp burning.
An integrated bootstrap section, eliminating the
normally required bootstrap diode and the zener
clamping on Vs, makes the L6574 well suited for
low cost applications where few additional com-
ponents are needed to build a high performance
ballast.
OPOUT
OPIN-
OPIN+
RING
RPRE
Cf
OP AMP
+
-
Imin
VREF
Imax
VREF
VCO
VS
UV
DETECTION
BOOTSTRAP
DRIVER
HVG
DRIVER
CONTROL
LOGIC
DEAD
TIME
Ifs Ipre
+
Vthpre
-
+
-
DRIVING
LOGIC
LEVEL
SHIFTER
LVG DRIVER
VS
+ VTHE
-
+ VTHE
-
VBOOT
HVG
OUT
LVG
GND
EN1
EN2
CPRE
D97IN493A
H.V.
CBOOT
LOAD
February 2000
1/9
1 page  
L6574
fing are the highest and lowest allowed oscillation
frequencies.
Closed loop control of the lamp current under
normal operation can be achieved with the
L6574. This is accomplished by automatic ad-
justment of the oscillator frequency. The OP
AMP output is fed through a resistor diode net-
work to the Ring pin. See AN 993.
OP AMP Section:
The integrated OP AMP offers low output imped-
ance, wide bandwidth, high input impedance and
wide common mode range. It can be readily
used to implement closed loop control (see Oscil-
lator Section) of the lamp current.
EN1, EN2 Comparators:
Two CMOS comparators, with thresholds set at
0.6 V (typical) are available to implement protec-
tion methods (such as overvoltage, lamp re-
moval, etc.). Short pulses (>200nsec) at the
comparator inputs are recognized.
The EN1 input (active high) forces the L6574 in
the shut down state (e.g. LVG low, HVG low, os-
cillator stopped) in the event of an undervoltage
condition. Normal operating condition is resumed
after a power-off power-on sequence or when
EN2 input is high.
The EN2 input (active high) also restarts a pre-
heat sequence (see timing diagrams).
TIMING DIAGRAMS
VCC
VSUVP
LVG
HVG
EN1
D97IN490
TIMING DIAGRAMS
VCC
VSUVP
fOUT fPRE
fING
EN2
D97IN491B
tPRE tSH
tPRE tSH
5/9
5 Page | ||
| Páginas | Total 9 Páginas | |
| PDF Descargar | [ Datasheet L6574.PDF ] | |
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