S1F75510 Epson Electronics America, Inc., S1F75510 Datasheet - Page 10

• Manufacturer Part Number: S1F75510
• Description: Charge-pump Dc/dc Converter & Voltage Regulator
• Manufacturer: Epson Electronics America, Inc.

S1F75510
*1 When I
*2 When I
HIGH(V
HIGH(V
MODE pin
MODE pin
10
LOW(V
LOW(V
Mode changeover circuit
Timing signal forming circuit
By external settings of the mode changeover signal MODE and the internal/external clock selection signal
OSCSEL, the charge pump boosting can be driven under optimum frequencies. Since the current consumption
of the IC can be suppressed drastically under the blank mode, it is possible to achieve high power conversion
efficiency even under light load operations.
The closer to 50% the external clock duty in the blank mode gets, the more optimum it becomes.
I
I
This circuit generates the clock signals necessary for charge pump boosting using the internal oscillation or
using external clock signals.
Two different types of capacitors are being used as the charge pump capacitors, one being the flying capacitor
which shifts between the charging state and the discharging state and the other being the smoothing capacitor
which preserves the electric charge. The operating frequency of the flying capacitor should equal to the fre-
quency of the charge pump clock being generated by this timing signal forming circuit.
Under the shut down state (POFFX = V
operations of this IC will be interrupted. The operating frequencies of the flying capacitor are as follows.
OUT2
OUT2
SS
SS
DD
DD
(Max.) < 0.50mA – (3
(Max.) < 16.0mA – (3
OUT3
OUT3
)
)
)
)
HIGH(V
HIGH(V
HIGH(V
HIGH(V
LOW(V
LOW(V
LOW(V
LOW(V
OSCSEL
OSCSEL
= 300 A, I
= 30 A, I
pin
pin
SS
SS
SS
SS
DD
DD
DD
DD
)
)
)
)
)
)
)
)
OUT3
(external oscillation)
OUT3
(internal oscillation)
duty=50% when
CL =
Normal mode
Normal mode
Mode name
CL = 1.25kHz
Mode name
Blank mode
Blank mode
Blank mode
Blank mode
= 30 A:
= 300 A:
fosc
I
I
OUT3
OUT3
(Hz)
+ 3
+ 3
SS
the positive direction the positive direction the negative direction
I
I
level), the charge pump clock stops operation and all the boosting
V
V
V
V
V
V
V
V
V
OUT4
OUT4
OUT2
OUT3
OUT4
OUT2
OUT3
OUT4
OUT2
OUT3
OUT4
1/2
Max. output current
2 boosting in
) must be satisfied.
) must be satisfied.
625kHz
: 14mA *1
: 0.7k
: 1k
: 300 A *2
: 4.0k
: 4.0k
: 300 A *2
: 4.0k
: 4.0k
10kHz
fosc Hz
Operating frequencies of the flying capacitor
1/2
3 boosting in
625kHz
10kHz
oscillation circuit
In operation
In operation
In standstill
fosc Hz
Built-in CR
1/2
3 boosting in
625kHz
10kHz
fosc Hz
Rev. 1.1