S-8355 Seiko Instruments, S-8355 Datasheet - Page 28

• Manufacturer Part Number: S-8355
• Description: (S-8355 - S-8358) PWM/PFM SWITCHING CONTROL STEP-UP SWITCHING REGULATOR
• Manufacturer: Seiko Instruments

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STEP-UP, SUPER-SMALL PACKAGE, 600 kHz, PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER
S-8355/56/57/58 Series
External Parts Selection
The relationship between the major characteristics of the step-up circuit and the characteristics parameters of the
external parts are shown in Figure 16 .
Smaller direct current resistance of inductor
For larger output current ?
Larger output capacitance
Smaller inductance
Figure 16 Relationship between Major Characteristics of Step-up Circuit and External Parts
With MOS FET,
smaller ON resistance
With bipolar transistor,
smaller external resistance R
Operation
efficiency
b
Seiko Instruments Inc.
For higher efficiency ?
Larger inductance
With bipolar transistor, larger
external resistance R
With MOS FET,
smaller input capacitance
efficiency
Stand-by
b
For smaller ripple voltage ?
Larger output capacitance
Rev.6.6
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