MAX17499 Maxim Integrated Products, MAX17499 Datasheet - Page 14

• Manufacturer Part Number: MAX17499
• Description: (MAX17499 / MAX17500) Current-Mode PWM Controllers
• Manufacturer: Maxim Integrated Products

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Figure 6 shows a complete circuit of a dual-output
power supply with a 36V to 72V telecom voltage range.
An important aspect of this power supply is that it is pri-
mary-side regulated. The regulation through the tertiary
winding also supplies bias for the MAX17500.
In the circuit of Figure 6, cross-regulation has been
improved (tertiary and 5V outputs) by using chip induc-
tors, L1 and L2, and R7 || R12 across C12. R7 || R12
presents enough loading on the tertiary winding output
to allow ±10% load regulation on the 5V output over a
150mA to 1.5A load current range (Figure 7).
Current-Mode PWM Controllers with
Programmable Switching Frequency
Figure 6. Primary-Side-Regulated, Dual-Output, Isolated Telecom Power Supply
14
1.37MΩ
51.1kΩ
______________________________________________________________________________________
1%
NOTE: MOSFET N1 = IR IRF7464.
R3
R4
FB_P
+VIN
36V TO 72V
+VIN
-VIN
OPEN
SHDN
C17
22.6kΩ
2.49kΩ
1%
1%
R1
R2
+VIN
Isolated Telecom Power Supply
1
2
JU1
IN
75kΩ
UFLG_PULL
1%
R6
33kΩ
R9
C1
1μF
100V
UFLG
3900pF
0.22μF
100pF
C14
Primary-Side-Regulated,
10kΩ
C7
R13
C9
C16
1μF
35V
C2
1μF
100V
D8
3
4
1
9
2
FB_P
FB
COMP
UVLO/EN
V
UFLG
CC
C12
15μF
35V
MAX17500A
U1
R7
1.2kΩ
NDRV
GND
CS
RT
IN
R12
1.2kΩ
10
8
5
7
6
IN
R8
OPEN
C11
0.22μF
C8
OPEN
R14
14.3kΩ
1%
D7
OPEN
D6
100Ω
4.7Ω
R10
R11
C10
OPEN
OPEN
R15
750Ω
C18
0.1μF
D3
4
Figure 7. Output Voltage Regulation for the Circuit in Figure 6
L2
5
1
6
35μH
2
15T
28T
7
N1 IRF7464
3
8
4
R5
0.600Ω
1%
C19
OPEN
5 T1
3
2
1
9
10
7
5.6
5.5
5.4
5.3
5.2
5.1
5.0
4.9
4.8
8
6
12T
5T
0.15
C6
0.0047μF
250V AC
D2
D1
0.30 0.45 0.60
5V OUTPUT LOAD REGULATION
C5
47μF
25V
C3
68μF
6.3V
0.75
I
OUT
D5
D4
15V/100mA
0.90
(A)
L1
NO LOAD AT 15V
OUTPUT
V
V
1.05
IN+
IN-
= 0V
= 40V
1.20
5V/1.5A
C15
1μF
C13
1μF
1.35
1.50
C4
22μF
6.3V
VOUT2
SGND
VOUT1
SGND
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