AN1673 Datasheet, PDF (1/24 Pages) STMicroelectronics – L6598 OFF-LINE CONTROLLER FOR RESONANT CONVERTERS

AN1673
APPLICATION NOTE
L6598 OFF-LINE CONTROLLER FOR
RESONANT CONVERTERS
INTRODUCTION
Because of the much high efficiency that can be achieved (higher than the traditional PWM) and the re-
duction of the high frequency electromagnetic interference (thanks to the utilization of parasitic parameters
of the circuit), the interest for resonant topologies is recently growing in power conversion market. In fact
this kind of topologies allows high power/weight ratio and low power dissipation of the power parts.
Several power supply application segments such as Adapters, Television, Monitor, Telecom and Car Ra-
dio can benefit by using converters based on the topology.
The L6598 is designed for half bridge configuration.
This paper deals on how to use this device. At the end, it will be discussed concerning some design criteria
and application tips.
FEATURED DEVICE DESCRIPTION
The device, whose internal block diagram is shown in fig.1, is an integrated circuit realized in Off-Line tech-
nology. Able to drive Powermos or IGBT, in half bridge topology, it is provided with all the features (such
as VCO, Soft-Start, OP-Amp and Enables) needed to implement and control properly a resonant SMPS
with the minimum components count.
Even though the device is able to withstand high voltage, it can operate at low voltage starting from its
operative supply. It is available in DIP16 and SO16N packages.
The most significant peculiarities are:
–
High voltage rail (up to 600V) and
d_----v_--
dt
immunity (± 50 V/ns) at full temperature range.
– 250 mA (source) / 450 mA (sink) driver current capability.
– Under voltage lockout.
– Precise current controlled oscillator and frequency shift for soft-star function.
– Integrated bootstrap driver for C-boot charging.
Figure 1. Internal Block diagram
C_{FIL VS}
OPOUT
OPIN-
OPIN+
12
OP AMP
5
+
-
6
7
Ifmin
VREF
Rfmin
4
Ifstart
VREF
2
Rfstart
3
Cf
VCO
H.V. BUS
16 VBOOT
UV
DETECTION
BOOTSTRAP
DRIVER
HVG
DRIVER
DEAD
TIME
CONTROL
LOGIC
DRIVING
LOGIC
I_SS
LEVEL
SHIFTER
LVG DRIVER
Vthe1
+
-
Vthe2
+
-
15 HVG
14 OUT
V_S
11 LVG
10 GND
8
EN1
9
EN2
1
D03IN1429
CBOOT
LOAD
C_SS
April 2004
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