Datasheet
+
VOUT2
D1
C4
T1
9.5V
+
+
+
V
IN
BST
RON
RTN
SW
VCC
FB
VIN
VOUT1
R6
R2
R3
C3
C2
C1
R4
R1
UVLO
C6
LM34927
20V-100V
1
2
3
4
5
6
8
7
(TP7)
+
C5
2.2 F
0.47 F
127 NŸ
8.25 NŸ
130 NŸ
GND
(TP1)
(TP2)
UVLO
U1
R5
(TP3)
(TP4)
GND
R8
C7
C8
+
D2
R9
EXP
0Ÿ
1 NŸ
7.32 NŸ
1 F
0Ÿ
33 H
0.01 F
1 F
3300 pF
0.1 F
46.4 NŸ
(TP11)
SW
10V
(1:1)
(TP6)
2200 pF
IGND
C9
2000V
1F
(TP5)
TP8
TP10
2 NŸ
R7
0Ÿ
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Board Connection And Start-Up
The magnetics in this design is optimized for solution size, and therefore limits the output power. The total
load at the output should not exceed 300 mA otherwise the coupled inductor will saturate/overheat
which can destroy both the coupled inductor and the regulator IC U1. If a sustained over-current
situation is to be tolerated, a coupled inductor with higher saturation and rms ratings should be used. The
board schematic is shown in Figure 2.
Figure 2. Complete Evaluation Board Schematic
3
SNVA633A–March 2012–Revised April 2013 AN-2202 LM34927 Integrated Secondary Side Bias Regulator for Isolated
DC-DC Converters
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