HIGH RIPPLE-REJECTION AND LOW DROPOUT MIDDLE-OUTPUT CURRENT CMOS VOLTAGE REGULATOR
Rev.2.1_00
S-1133 Series
Precautions
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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 pins (CL) and a capacitor for stabilizing the input between
VIN and VSS pins (CIN), the distance from the capacitors to these pins should be as short as possible.
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When setting the output voltage using the external resistor, connect the resistors, Ra between the VOUT and VADJ
pins and Rb between the VADJ and VSS pins close to the respective pins.
In the product that users set the output voltage externally, it is possible to set a voltage arbitrarily; by feeding back
the voltage which is from VOUT to the VADJ pin, after dividing it with the dividers connected between the VOUT and
VADJ pin and the VADJ and VSS pin.
Note that if any device other than the divider specified above is connected between the VOUT and VADJ pin or the
VADJ and VSS pin, S-1133 Series may not work stably as a voltage regulator IC.
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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 driver leakage when a series regulator is used at high
temperatures.
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A general series regulator may oscillate, depending on the external components selected. 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.
Input capacitor (CIN) :
1.0 µF or more*1
1.0 µF or more*1
1.0 Ω or less
Output capacitor (CL) :
Equivalent series resistance (ESR) :
*1. The capacitance is 2.2 µF or more for products whose output voltage is 1.7 V or less.
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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.
The power supply fluctuation and load fluctuation characteristics become worse. It is therefore important to
sufficiently evaluate the output voltage fluctuation in the actual equipment.
If the power supply suddenly increases sharply, a momentary overshoot may be output. It is therefore important to
sufficiently evaluate the output voltage at power application in the actual equipment.
When the thermal shutdown circuit starts operating and the regulator stops, input voltage may exceed the absolute
maximum ratings.
It will be affected largely when input voltage, output current and inductance of power supply are high.
Perform thorough evaluation using the actual application.
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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 Tables 5 and 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.
20
Seiko Instruments Inc.
SII [ SEIKO INSTRUMENTS INC ]
