S-1172 Datasheet, PDF (17/34 Pages) Seiko Instruments Inc – HIGH RIPPLE-REJECTION LOW DROPOUT HIGH OUTPUT CURRENT CMOS VOLTAGE REGULATOR

Rev.1.1_00
HIGH RIPPLE-REJECTION LOW DROPOUT HIGH OUTPUT CURRENT CMOS VOLTAGE REGULATOR
S-1172 Series
„ 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 (C_L) and a capacitor for stabilizing the input between the VIN
and VSS pin (C_IN), 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 generally increase due to the leakage current from a driver when a series regulator
is used at high temperature.
• Generally series regulator may oscillate, 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 the temperature characteristics. Regarding the equivalent series resistance (R_ESR) for the output
capacitor, refer to (5) Example of Equivalent Series Resistance vs. Output Current Characteristics (Ta = 25°C)
in “„ Reference Data”.
Input capacitor (C_IN) : 4.7 µF or more
Output capacitor (C_L) : 4.7 µF or more
• 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. Note that the voltage regulator may oscillate when the value of the
input capacitor is greater than that of the output capacitor.
• Ringing may occur when these three conditions below are satisfied. Before selecting an input capacitor, be sure to
evaluate sufficiently under the actual usage conditions, including the temperature characteristics.
The power supply inductance is high.
The load current is 100 mA or more.
The difference between the input voltage and the output voltage is close to the value of dropout voltage.
• If the output capacitance is small, power supply’s fluctuation and the characteristics of load fluctuation become worse.
Sufficiently evaluate the output voltage’s fluctuation with the actual device.
• A momentary overshoot may be output when the power supply suddenly increases, and the output capacitance is
small. It is therefore important to sufficiently evaluate the output voltage at power application in actual device.
• The application conditions for the input voltage, output voltage, and load current should not exceed power dissipation
of the package.
• 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.
Seiko Instruments Inc.
17