Datasheet

W 78
-xxx
STANDARD APPLICATION CIRCUIT
+Uin +Uout
Uout
Uin
GND
PIN ASSIGNMENTS
W 78
-xxx
COMPONENT
SIDE
GND
+Uin+Uout
W 78
-xxx
HOT PLUGGING SAFELY
+Uin +Uout
Uout
Uin
GND
C1
10µF
>35V
+
The low loss input capacitor of the W 78-xxx combined
with stray inductance (wire or pcb track) in series with
the power source forms an underdamped tank circuit.
The voltage at the Uin pin can ring to twice the nominal
input voltage, possibly exceeding the W78-xxx max.(34V)
rating and damaging the part.
An aluminium electrolytic capacitor (C1) has been added.
This capacitor’s high equivalent series resistance damps
the tank circuit and eliminates the voltage overshoot.
The extra capacitor improves low frequency ripple filtering
and can slightly improve the efficiency.
W 78
-xxx
REVERSED OUTPUT PROTECTION
+Uin +Uout
Uout
Uin
GND
A another danger situation is given in systems
where the output will be held high when the
input to the W 78-xxx is absent.
This may occur in battery charging applications
or in battery backup systems.
Add a blocking diode (D1) to +Uout if current
can flow backwards into the output, this can
damage the W 78-xxx !
D1
MBR 340
BACKUP
Note:
This DC/DC converter is a “non-CE-checked” component. The utilisation must comply with the CE norms.
Item No:Type:
W 78 - 3V3
W 78 - 5V0
W 78 - 9V0
W 78 - 12V
16 78 03
16 78 05
16 78 09
16 78 12
These operating instructions are published by:
Conrad Electronic SE, Klaus-Conrad-Straße 1, D-92240 Hirschau/Germany
The operating instructions reflect the current technical specifications at time of print.
We reserve the right to change the technical or physical specifications.
© Copyright 2009 by Conrad Electronic SE. *01/09-NB
RoHS
konform
EFFICIENCY (%):
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W 78 - 12V
Current (A)
0
0.2
0.4
0.6
0.8
1
75
80
85
90
95
100
Uin Min
Uin Max
77.77
87.38
90.36
91.75
92.52
92.98
93.27
93.45
93.56
93.61
90.50
94.55
95.64
96.07
96.26 96.32
96.33
96.29
96.22
96.13
W 78 - 9V0
Uin Min
Uin Max
Current (A)
0
0.2
0.4
0.6
0.8
1
75
80
85
90
95
100
83.75
87.44
89.19
90.16
90.76
91.13
91.36
91.51
91.59
90.45
94.35
95.34
95.71
95.84
95.85
95.79
95.70
95.58
95.44
70
72.36
W 78 - 5V0
Uin Min
Uin Max
Current (A)
0
0.2
0.4
0.6
0.8
1
55
75
80
85
90
95
100
60
65
70
73.99
79.28
81.90
83.40
84.33
84.92
85.30
85.53
85.67
87.53
92.01
93.09
93.42
93.47
93.38
93.22
93.00
92.76
92.50
59.32
W 78 - 3V3
Uin Min
Uin Max
Current (A)
0
0.2
0.4
0.6
0.8
1
55
75
80
85
90
95
100
60
65
70
45
50
83.63
88.91
90.15
90.50
90.49
90.32
90.07
89.75
89.40
89.03
65.19
71.54
74.82
76.74
77.94
78.71
79.21
79.53
79.71
49.09
1 Amp, WIDE INPUT RANGE, STEP-DOWN CONVERTER