Typical Applications - Epson Power Supply IC S1F70000 Technical Manual

S1F76300 Series
Powering up
Ensure that V is at least the minimum operating volt-
O
age (0.9V) before switching on the booster circuit. One
way to do this is to connect a capacitor between PS and
GND so that the chip connects V
is applied for the first time.

TYPICAL APPLICATIONS

Example Circuits
The output current, I , and power conversion efficiency
O
Peff, of a particular device in the series depends on fac-
S1F76330 series
L
V
I
S1F76330M
GND
PS CL
Notes
100 H L 1mH, C
S1F76330M1B0
• Peff = 70% when L = 220 H (leadless inductor),
f
V = 1.5V, = 32kHz, I
I1 CLK
• Peff = 75% when L = 220 H (drum coil),
f
V = 1.5V, = 32kHz, I
I1 CLK
• Peff = 80% when L = 300 H (toroidal coil),
f
V = 1.5V, = 32kHz, I
I1 CLK
External Components
The performance characteristics of switching regulators
depend greatly on the choice of external components.
Observing the following guidelines will ensure high
performance and maximum efficiency.
4–28
to V when the power
O I
D
V
SW
V
O
C1
C
rystal
C C
G D
O
10 F, D: Schottky diode
= 8mA
O
= 9mA
O
= 10mA
O
Battery
tors such as the switching frequency, type of coil, and
the size and type of other external components.
Inductor
Use an inductor with low direct-current resistance and
low losses.
Leadless
Pre-wound, leadless inductors using surface-mount
technology are the most suitable for portable equipment
and other space-critical applications.
Drum coll
Avoid drum coils because their magnetic field can in-
duce noise.
Toroidal coil
Use a toroidal coil to virtually eliminate magnetic field
leakage, reduce losses and improve performance.
EPSON
V
I2
PS
S1F76330M
C
S1F70000 Series
Technical Manual