S1131 Datasheet, PDF (15/30 Pages) Seiko Instruments Inc – HIGH RIPPLE-REJECTION AND LOW DROPOUT

HIGH RIPPLE-REJECTION LOW DROPOUT MIDDLE OUTPUT CURRENT CMOS VOLTAGE REGULATOR
Rev.4.1_00
S-1131 Series
„ Precautions
• Wiring patterns for the VIN pin, the VOUT pin and GND should be designed so that the impedance is
low. When mounting an output capacitor between the VOUT pin and the VSS pin (C_L) and a capacitor
for stabilizing the input between the VIN pin and the VSS pin (C_IN), the distance from the capacitors to
these pins should be as short as possible.
• Note that generally the output voltage may increase when a series regulator is used at low load current
(1.0 mA or less).
• The S-1131 Series performs phase compensation by using an internal phase compensator and the ESR
of an output capacitor. Therefore, always place a capacitor of 2.2 μF or more between the VOUT pin
and the VSS pin. A tantalum type capacitor is recommended. Moreover, to secure stable operation of
the S-1131 Series, it is necessary to employ a capacitor with an ESR within an optimum range (0.5 Ω to
5 Ω). Using a capacitor whose ESR is outside the optimum range (approximately 0.5 Ω to 5 Ω), whether
larger or smaller, may cause an unstable output, resulting in oscillation. Perform sufficient evaluation
under the actual usage conditions for selection, including evaluation of temperature characteristics.
• The voltage regulator may oscillate when the impedance of the power supply is high and the input
capacitance is small or an input capacitor is not connected.
• Overshoot may occur in the output voltage momentarily if the voltage is rapidly raised at power-on or
when the power supply fluctuates. Sufficiently evaluate the output voltage at power-on with the actual
device.
• The application conditions for the input voltage, the output voltage, and the 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
6 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.
Seiko Instruments Inc.
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