S-1721 Seiko Instruments, S-1721 Datasheet - Page 21

• Manufacturer Part Number: S-1721
• Description: SUPER-SMALL PACKAGE 2-CIRCUIT HIGH RIPPLE-REJECTION LOW CURRENT CONSUMPTION LOW DROPOUT CMOS VOLTAGE REGULATOR
• Manufacturer: Seiko Instruments

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Rev.1.1
Precautions
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SUPER-SMALL PACKAGE 2-CIRCUIT HIGH RIPPLE-REJECTION LOW CURRENT CONSUMPTION LOW DROPOUT CMOS VOLTAGE REGULATOR
Wiring patterns for the VIN, VOUT and GND pins should be designed so that the impedance is low. When mounting
an output capacitor between the VOUT and VSS pin (C
and VSS pin (C
Note that the output voltage may increase when a series regulator is used at low load current (1.0 mA or less).
Note that the output voltage may increase due to the leakage current from a driver when a series regulator is used
at high temperature.
Generally a series regulator may cause oscillation, depending on the selection of external parts. The following
conditions are recommended for this IC. However, be sure to perform sufficient evaluation under the actual usage
conditions for selection, including evaluation of temperature characteristics. See “(5) Example of Equivalent Series
Resistance vs. Output Current Characteristics (Ta = 25°C)” in “
equivalent series resistance (R
The voltage regulator may oscillate when the impedance of the power supply is high and the input capacitor is small
or an input capacitor is not connected. Note that, if the capacitance of the output capacitor is greater than that of the
input capacitor, the voltage regulator may oscillate.
Note that an oscillation may occur when the load current is high (100 mA or higher) and the difference between the
voltage input and output is around the dropout voltage if the inductance of the power supply is high. Perform
sufficient evaluation including electrical characteristics under the actual use conditions to select an input capacitor.
Concerning the fluctuation of output voltage due to power-supplying and load, confirm with the actual device.
If the power supply suddenly increases, a momentary overshoot may be output. It is therefore important to
sufficiently evaluate the output voltage at power application in the actual equipment.
The application conditions for the input voltage, output voltage, and load current should not exceed the package
power dissipation.
Do not apply an electrostatic discharge to this IC that exceeds the performance ratings of the built-in electrostatic
protection circuit.
In determining the output current, attention should be paid to the output current value specified in Table 7 in “
Electrical Characteristics” and footnote *5 of the table.
SII claims no responsibility for any disputes arising out of or in connection with any infringement by products
including this IC of patents owned by a third party.
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Input capacitor (C
Output capacitor (C
IN
), the distance from the capacitors to these pins should be as short as possible.
IN
) :
L1
, C
L2
) :
ESR
) of the output capacitor.
Seiko Instruments Inc.
1.0 µF or more
1.0 µF or more
L1
, C
L2
) and a capacitor for stabilizing the input between VIN
Reference Data (Per Circuit)” for the
S-1721 Series
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