E-L6598 STMicroelectronics, E-L6598 Datasheet - Page 9

• Manufacturer Part Number: E-L6598
• Description: Switching Converters, Regulators & Controllers High Volt Reson Cont
• Manufacturer: STMicroelectronics

Specifications of E-L6598

• Output Voltage: 4.6 V
• Mounting Style: Through Hole
• Package / Case: PDIP-16
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

L6598
5
5.1
5.2
Block diagram description
High/low side driving section
An high and low side driving section provide the proper driving to the external power MOS or
IGBT. An high sink/source driving current (450/250 mA typ) ensure fast switching times also
when size for power MOS are used. The internal logic ensures a minimum dead time to
avoid cross-conduction of the power devices.
Timing and oscillator section
The device is provided of a soft start function. It consists in a period of time, T
the switching frequency shifts from fstart to fmin. This feature is explained in the following
description (ref. fig.7 and fig.8).
Figure 6.
During the soft start time the current I
ramp which is delivered to a transconductance amplifier, as shown in fig. 7. Thus this
voltage signal is converted in a growing current which is subtracted to Ifstart. Therefore the
current which drives the oscillator to set the frequency during the soft start is equal to:
Equation 1
Equation 2
Soft start and frequency shifting block
I
osc
where
=
I
fmin
+
Doc ID 6554 Rev 7
(
I
I
fstart
fmin
SS
–
=
g
V
------------- - I
R
m
charges the capacitor C
REF
fmin
V
Css
,
t ( )
fstart
)
=
=
I
fmin
--------------- - V
R
V
fstart
REF
+
⎛
⎝
,
I
fstart
REF
Block diagram description
SS,
–
=
g
------------- -
2V
C
m
generating a voltage
ss
I
ss
⎞
⎠
SS
, in which
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