Epson Power Supply IC S1F70000 Technical Manual page 56

Power supply ic
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Serial Connection
Connecting two or more chips in series obtains a higher
output voltage than can be obtained using a parallel
<Precautions when connecting loads>
In case of series connections, when connecting loads
between the first stage V
DD
second stage V
or up) and the second stage V
DD
shown in Fig. 2-13, be cautions about the following
point.
* When normal output is not occurring at the V
minal such as at times of starting up or when turning
the V
off by P
signals, if current flows into the
REG
OFF
second stage V
terminal through the load from
REG
V
= 0V
DD
10 F
+
5V
10 F
V
= –5V
I
+
Positive Voltage Conversion
Adding diodes converts a negative voltage to a positive
one.
To convert the voltage tripler shown earlier to a voltage
doubler, remove C2 and D2, and short circuit D3. Small
Schottky diodes are recommended for all these diodes.
The resulting voltage is lowered by V
in the forward direction for each diode used. For ex-
ample, if V
= 0V, V
= –5V, and V
DD
I
sulting voltages would be as follows.
• For a voltage tripler,
V
= 10 – (3
0.6) = 8.2V
O
• For a voltage doubler,
V
= 5 – (2
0.6) = 3.8V
O
S1F70000 Series
Technical Manual
(or other potential of the
as
REG
ter-
REG
1
14
10 F
2
13
1M
3
12
10 F
4
11
5
10
6
9
V
= –10V= V
O
I
7
8
, the voltage drop
F
= 0.6V, the re-
F
EPSON
connection, however, this also raises the output imped-
ance.
the first stage V
(or other potential of the second
DD
stage V
or up) to cause a voltage exceeding the
DD
absolute maximum rating for the second stage V
the V
terminal, normal operation of the IC may be
REG
hampered. Consequently, When making a series
connection, insert a diode D1 between the second
stage V
and V
as shown in Fig. 2-13 so that a
I
REG
voltage exceeding the second stage V
not be applied to the V
REG
V
' = V
DD
I
1
14
+
2
13
3
12
+
4
11
5
10
6
9
7
8
V
= –20V
O
10 F
D1
V
= 0 V
DD
C1
D1
10 F
+
D2
C2
10 F
5 V
+
D3
+
V
= 8.2 V
C3
O
10 F
V
= –5 V
I
S1F76610 Series
at
DD
or up may
DD
terminal.
= –5V
Load
100k
to
1M
10 F
V
' = –15V
REG
1
14
2
13
R
OSC
1 M
3
12
4
11
5
10
6
9
7
8
2–13

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