Rainbow Electronics MAX5069 - Manual (Page 13)

For example: To minimize power loss on this resistor, choose a high-
er value for R1 than the one calculated above (if a
longer startup time can be tolerated).
The above startup method applies to a circuit similar to
the one shown in Figure 1. In this circuit, the tertiary
winding has the same phase as the secondary wind-
ings. Thus, the voltage on the tertiary winding at any
given time is proportional to the output voltage. The
minimum discharge time of C1 from 22V to 10V must
be greater than the soft-start time (t
SS ).
I
V x F
ms
A
R
V V
A A
k
C1
24 4 7
500
225
1
36 12
225 90
76
.
= =
≅
+
=
−
µ
µ
µ µ
Ω
MAX5069
High-Frequency, Current-Mode PWM Controller
with Accurate Oscillator and Dual FET Drivers
______________________________________________________________________________________ 13
IN
UVLO/EN
NDRVA
NDRVB
V CC
FB
CS
PGND AGND
REG5
FLTINT
RT
DT
SCOMP
COMP
HYST
R1
C1
C2
C3
C4
R2
R3
R4
C5
R6
R7
R5
R8
V OUT
V IN
Q2
Q1
C6
R HYST
C7
C8
R9
C10
MAX8515
R13
R14
PS2913
V CC
R10
R11
R12
MAX5069B
Figure 6. Secondary-Side, Regulated, Isolated Power Supply