SCI7660 Series
SCI7000 Series
EPSON
1–7
Technical Manual
DC/DC
Converter
FUNCTIONAL DESCRIPTION
RC Oscillator
The on-chip RC oscillator network frequency is deter-
mined by the external resistor, R
OSC
, connected be-
tween OSC1 and OSC2. This oscillator can be disabled
in favor of an external clock by leaving OSC2 open and
applying an external clock signal to OSC1.
OSC1
Oscillator
External clock
R
OSC
OSC2
OSC1
OSC2
External clock
signal
100
90
80
70
60
50
40
30
20
10
0
40
36
32
28
24
20
16
12
8
4
0
0
1
2
3
4
5
6
7
8
9
10
P
eff [%]
I
I
[mA]
I
O
[mA]
Ta = 25
°
C
V
I
= –2.0V
I
I
Peff
Multiplication efficiency/input current vs.
Output current
Voltage Multiplier
The voltage multiplier uses the clock signal from the
oscillator to double the input voltage. This requires two
external capacitors—a charge-pump capacitor, C1, be-
tween CAP1+ and CAP1–, and a smoothing capacitor,
C2, between V
I
and V
O
.
5 V
C1
10
µ
F
C2
10
µ
F
V
O1
= –10V (2V
I
)
V
DD
= 0 V
V
I
= –5 V
1M
Ω
+
+
8
7
6
5
1
2
3
4
Doubled potential levels
V
CC
(+5V)
(–5V)
GND
V
O
= (2V
I
)
= –10 V
V
I
= –5 V
V
DD
= 0 V
Summary of Contents for SCI 7660 SERIES
Page 1: ...1 DC DC Converter ...
