S-1721 datasheet(21/38 Pages) SII

21 / 38 page

SUPER-SMALL PACKAGE 2-CIRCUIT HIGH RIPPLE-REJECTION LOW CURRENT CONSUMPTION LOW DROPOUT CMOS VOLTAGE REGULATOR

Rev.1.1_00

S-1721 Series

Seiko Instruments Inc.

Precautions

• 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 (CL1, CL2) and a capacitor for stabilizing the input between VIN

and VSS pin (CIN), the distance from the capacitors to these pins should be as short as possible.

• 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 “

Reference Data (Per Circuit)” for the

equivalent series resistance (RESR) of the output capacitor.

Input capacitor (CIN) :

1.0

µF or more

Output capacitor (CL1, CL2) :

1.0

µF or more

• 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.

S-1721 Datasheet(PDF) 21 Page - Seiko Instruments Inc