L6598 STMicroelectronics, L6598 Datasheet - Page 10

• Manufacturer Part Number: L6598
• Description: IC CTRLR UVLO HV 16DIP
• Manufacturer: STMicroelectronics

Specifications of L6598

• Output Isolation: Isolated
• Frequency Range: 61.8 ~ 400kHz
• Voltage - Input: 8 ~ 16.6 V
• Voltage - Output: 600V
• Operating Temperature: -40°C ~ 150°C
• Package / Case: 16-DIP (0.300", 7.62mm)
• Output Voltage: 4.6 V
• Output Current: 450 mA
• Input Voltage: 10 V to 16.6 V
• Switching Frequency: 400 KHz
• Operating Temperature Range: - 40 C to + 150 C
• Mounting Style: Through Hole
• Duty Cycle (max): 52 %
• Driver Current Capability: 250 mA source 450 mA sink
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-6704-5; L6598

Block diagram description
10/24
At the start-up (t = 0) the oscillator frequency is set by:
Equation 3
At the end of soft start (t = T
frequency is set only by Imin (i.e. R
Equation 4
Since the second term of eq.1 is equal to zero, we have:
Equation 5
Note that there is not a fixed threshold of the voltage across C
finishes (i.e. the end of the frequency shifting), and T
(eq. 5). Making T
of I
Equation 6
In this way the soft start time depends only on the capacitor C
constant (Soft start timing constant) is 0.15 s/μF.
The current I
generating the triangular wave on the oscillator capacitor C
structure of the oscillator (fig.7), a good relationship to compute an approximate value of the
oscillator frequency in normal operation is:
Equation 7
fstart
, so:
osc
is fed to the oscillator as shown in fig. 7. It is twice mirrored (x4 and x8)
I
SS
SS
independent of I
=
I
------------- -
fstart
K
I
OSC
I
SS
fstart
→
0 ( )
) the second term of eq.1 decreases to zero and the switching
T
Doc ID 6554 Rev 7
SS
=
–
I
I
g
------------- - T
fmin
=
OSC
C
fmin
m
fstart
ss
------------------------- -
g
I
C
ss
m
ss
+
(
):
f
I
T
min
fstart
, the I
I
I
SS
SS
fstart
fstart
)
=
=
=
K
=
------------------- -
R
SS
0
→
I
fmin
1.41
fmin
V
→
T
current has been designed to be a fraction
REF
SS
T
=
C
SS
f
⎛
⎝
V
------------- -
R
SS
=
------------- -
R
REF
fmin
=
fmin
1
-----------
g
C
depends on C
C
----------------------- -
m
ss
ss
g
K
+
m
f
. Referring to the internal
I
→
fstart
--------------- -
R
I
ss
SS
fstart
SS
T
1
. The typical value of the k
SS
in which the soft start
⎞
⎠
–
k
SS
SS
C
, I
SS
fstart
, g
m
, and I
L6598
SS
SS