S-8363B-I6T1U2 Datasheet, PDF (8/50 Pages) Seiko Instruments Inc – PWM/PFM SWITCHABLE SWITCHING REGULATOR

STEP-UP, SUPER-SMALL PACKAGE, 1.2 MHz PWM/PFM SWITCHABLE SWITCHING REGULATOR
S-8363 Series
Rev.2.0_01
 Operation
1. Switching control method
The S-8363 Series switching regulator automatically switches between the pulse width modulation method (PWM)
and pulse frequency modulation method (PFM) according to the load current.
A low ripple power can be supplied by operating on PWM control for which the pulse width changes up to 88% in
the range where the output load current is large.
The S-8363 Series operates on PFM control when the output load current is small and the pulses are skipped
according to the amount of the load current. Therefore, the oscillation circuit intermittently oscillates, reducing the
self-current consumption. This prevents decrease in efficiency when the output load current is small. The ripple
voltage during the PFM control is very small, so that the S-8363 Series realizes high efficiency and the low-noise
power supply.
The point at which PWM control switches to PFM control varies depending on the external element (inductor, diode,
etc.), input voltage value, and output voltage value, and this method achieves high efficiency in the output load
current of about 100 μA.
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