S-882145AMH-M2UTFG Seiko Instruments, S-882145AMH-M2UTFG Datasheet - Page 9

• Manufacturer Part Number: S-882145AMH-M2UTFG
• Description: IC CHARGE PUMP CONV 4.5V SOT23-6
• Manufacturer: Seiko Instruments
• Type: Step-Up (Boost), Switched Capacitor (Charge Pump)r

Specifications of S-882145AMH-M2UTFG

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 4.5V
• Current - Output: 25mA
• Frequency - Switching: 1MHz
• Voltage - Input: 1.6 ~ 5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-6
• Power - Output: 300mW
• Function: Step Up
• Output Voltage: 4.5 V
• Output Current: 25 mA
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Rev.5.0
Operation
1. Basic operation
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 R
voltage (V
pulse frequency in order to keep the output voltage constant.
Figure 7 shows the block diagram of the S-8821 Series.
C
PUMP
_00
C
IN
=0.10 μF
=4.7 μF
ref
VOLTAGE REGULATION STEP-UP CHARGE PUMP DC-DC CONVERTER
) are compared by a comparator. This comparator signal is used to modulate the oscillation
VIN
C+
C−
SW2
SW1
SW3
SW4
Switch
control
circuit
Seiko Instruments Inc.
Soft start
circuit
ON/OFF
Figure 7
PFM control
(1.0 MHz)
oscillator
circuit
ON/OFF
circuit
Reference
voltage
+
-
R
R
s
s
f
and R
GND
S-8821 Series
f
and reference
VOUT
C
OUT
=10 μF
9