AN993 Datasheet, PDF (5/27 Pages) STMicroelectronics – Electronic ballast with PFC using L6574 and L6561

AN993
2
L6574 ballast driver
L6574 ballast driver
The L6574, whose internal block diagram is shown in Figure 2, is an IC intended to drive two
power MOSFETs or IGBTs in half-bridge topology, ensuring all the features needed to
properly drive and control a fluorescent bulb. Moreover, by varying the switching frequency,
it is possible to modulate the current in the lamp and as a consequence, the output power as
well. The device is available in DIP16 and SO16N packages.
The L6574 has the following distinctive features.
● High voltage rail up to 600 V
● dV/dt immunity ± 50 V/ns in full temperature range
● Driver current capability (250 mA source and 450 mA sink)
● Switching times 80/40 ns rise fall with 1 nF load
● CMOS shutdown input
● Under-voltage lock-out
● Preheat and frequency shifting timing
● Sense operational amplifier for closed-loop control or protection features
● High-accuracy current-controlled oscillator
● Integrated bootstrap diode
● Clamping on VS
● SO16, DIP16 package.
Figure 2. Internal block diagram of the L6574
OPOUT ₅
OPIN- ⁶
OPIN+
7
OP AMP
+
-
Imin
VREF
Rign
4
Rpre
Imax
2
VREF
3
VCO
Cf
VS
12
UV
DETECTION
BOOTSTRAP
DRIVER
CONTROL
LOGIC
DEAD
TIME
Ifs Ipre
DRIVING
LOGIC
+
- ^Vthpre
+
-
1
Cpre
16 _Vboot
HVG
DRIVER
LEVEL
SHIFTER
15 HVG
14 OUT
VS
11 LVG
LVG
DRIVER
+ ^VTHE
-
+ ^VTHE
-
10 _GND
8 EN1
9 EN2
H.V.Bus
Cboot
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AM01310v1
Doc ID 5656 Rev 10
5/27