S-8330A22FS-T2-G Seiko Instruments, S-8330A22FS-T2-G Datasheet - Page 14

• Manufacturer Part Number: S-8330A22FS-T2-G
• Description: IC REG SW PWM SHTDN 10-22V 8SSOP
• Manufacturer: Seiko Instruments
• Type: Step-Up (Boost)r

Specifications of S-8330A22FS-T2-G

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 10 ~ 22 V
• Current - Output: 5mA
• Frequency - Switching: 180kHz
• Voltage - Input: 2 ~ 9 V
• Operating Temperature: -20°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 8-SSOP
• Power - Output: 300mW
• Output Voltage: 22 V
• Operating Temperature Range: - 20 C to + 70 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

14
STEP-UP, FOR LCD BIAS SUPPLY, 1-CHANNEL SWITCHING REGULATOR
S-8330/8331 Series
Operation
1.
The S-8330/31 Series is a DC-DC converter using a pulse width modulation method (PWM) with low
current consumption.
in the ripple voltage occurs because pulses are skipped when low output load current flows and the
ripple frequency of the output voltage varies. In the S-8330/31 Series, the pulse width varies in the
range of 0 % to 72 % depending upon the load current, but the switching frequency does not vary.
This allows the ripple voltage due to switching to be reduced with a filter. Also, the internal soft start
circuit controls the rush current and the output voltage overshoot to be generated when the IC starts the
step-up operation by setting the power off pin to "H" level. At powering ON the IC, the rush current
flows to charge up capacitive components of output capacitor "C
The following are fundamental equations of step-up switching regulators [ (1) to (7) ] (see Figure 6).
The pin voltage at CONT immediatetly after M1 is turned ON (current I
Change in I
Integreation of the above equation (I
I
The peak current (I
The energy stored in L is represented by 1/2 L (I
When M1 is turned OFF (t
voltage (V
Step-Up DC-DC Converter
L
flows into L during t
V
(V
I
I
dI
L
PK
dt
A
S
L
=
= V
=
: Not saturated voltage of M1)
=
⎛
⎜
⎝
⎛
⎜
⎝
V
V
V
L
IN
S
L
L
IN
L
) generates.
−
L
=
L
−
V
with time:
V
S
V
S
IN
⎞
• ⎟
⎠
L
⎞
• ⎟
⎠
−
t
V
t
PK
V
ON
S
) after t
IN
ON
ON/OFF
. The time is determined depending upon the oscillating frequency of the OSC.
Conventional PFM DC/DC converters have a drawback. Namely, an increase
OFF
ON
:
), the energy stored in L is transmitted through a diode. Then reverse
OSC
L
Figure 6 Step-Up DC-DC Converter
L
Seiko Instruments Inc.
) is as follows:
CONT
M1
PK
)
Di
2
.
V
OUT
OUT
" and load via coils and diodes.
Electric
Volume
L
+
−
+
-
which flows into L is zero):
C
OUT
Rev.6.0
(1)
(2)
(3)
(4)
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