5. FUNCTIONAL DESCRIPTION
4
EPSON
S1F76540M0C Series Technical Manual
(Rev.1.1)
5. FUNCTIONAL DESCRIPTION
5.1 Clock Generator
S1F76540, which contains a clock generator for boosting control, requires no external parts.
The clock frequency varies depending on the FC pin level (see Table 5.1), and you can select either the low
output mode or high output mode. This results in you being able to select the clock frequency based on the load
current and value of the capacitor to be used because the boosting output impedance varies depending on the
clock frequency and the values of the external capacitors for boosting.
Table 5.1 FC pin settings
Selection judgment characteristics
FC pin
Mode
name
Clock
frequency
Consumption
current
Output ripple
Output
impedance
Capacitor
capacity
H(V
DD
) Low
output
4.0kHz
（
Typ.
）
IOP (Note 1)
VRP (Note 2)
See Figure.5.1
See Figure.5.1
L(VI) High
output
16.0kHz
（
Typ.
）
IOP (Note 1)
VRP (Note 2)
See Figure.5.1
See Figure.5.1
(Note 1) For the consumption current value, see 7.1 DC Characteristics Table.
(Note 2) For information about how to define and roughly estimate the output ripple value, see 9.4.
150
200
250
300
350
400
450
500
550
1 10
100
C[
µ
F]
Boost
ing out
put
im
pedance [
Ω
]
VI=-3V FC=High
VI=-3V FC=Low
VI=-5V FC=High
VI=-5V FC=Low
Quadruple boosting
Ta=25
°
C Io=10mA
C
I
=C
1
=C
2
=C
3
=C
O
(Tantalum capacitor)
Figure 5.1 Capacitor capacity value - output impedance characteristics diagram
