S-882136AMH-M2LTFG(Rev3_1) Просмотр технического описания (PDF) - Seiko Instruments Inc
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S-882136AMH-M2LTFG
(Rev.:Rev3_1)
(Rev.:Rev3_1)
Seiko Instruments Inc
S-882136AMH-M2LTFG Datasheet PDF : 19 Pages
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VOLTAGE REGULATION STEP-UP CHARGE PUMP DC-DC CONVERTER
S-8821 Series
Rev.3.1_00
Operation
1. Basic operation
Figure 6 shows the block diagram of the S-8821 Series.
The S-8821 series controls the output voltage by using the pulse frequency modulation (PFM) method.
The SW1 to SW4 switching transistors are switched ON/OFF with the clock generated by the internal
oscillator circuit, and operates the step-up charge pump.
The output voltage is fed back and the voltage split by feedback resistances Rs and Rf and reference
voltage (Vref) are compared by a comparator. This comparator signal is used to modulate the oscillation
pulse frequency in order to keep the output voltage constant.
VIN
CIN=4.7 μF
SW1
C+
CPUMP=0.10 μF
C−
SW2
SW3
SW4
Switch
control
circuit
Soft start
circuit
PFM control
oscillator
circuit
(1.0 MHz)
Rs
+
Rf
-
ON/OFF
circuit
Reference
voltage
VOUT
COUT=10 μF
ON/OFF
GND
Figure 6
8
Seiko Instruments Inc.
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