EUP7913/A
Application Note
Input Capacitor
An input capacitance of 1µF or higher is required between the EUP7913/A input pin IN and ground (the amount of
the capacitance may be increased without limit). This capacitor must be located a distance of not more than 1cm
from the input pin and returned to a clean analog ground. Any good quality ceramic, tantalum, or film capacitor
may be used at the input. If a tantalum capacitor is used at the input, it must be guaranteed by the manufacturer to
have a surge current rating sufficient for the application. There are no requirements for the ESR on the input
capacitor, but tolerance and temperature coefficient must be considered when selecting the capacitor to ensure the
capacitance will be 1µF over the entire operating temperature range.
Output Capacitor
The EUP7913/A is designed specifically to work with very small ceramic output capacitors. A ceramic capacitor
(temperature characteristics X7R or X5R) in 1µF to 10µF range with 5mꢀ to 500mꢀ ESR range is suitable in the
EUP7913/A application circuit. The output capacitor must meet the requirement for minimum amount of
capacitance to maintain good loop stability and phase margin. See the table below.
Output Voltage
Output Capacitor Minimum Value
1.2~1.45
1.5~3.6
2.2uF
1uF
No-Load Stability
The EUP7913/A is stable without any external load. This is specially important for CMOS RAM keep-alive
applications.
On/Off Input Operation
The EUP7913A is turned off by pulling the EN pin low, and turned on by pulling it high. If this pin is floating, the
regulator will always be on .To assure proper operation, the signal source used to drive the VEN input must be able
to swing above and below the specified turn-on/off voltage thresholds listed in the Electrical Characteristics.
When EN is logic low, output is internally discharged to GND through a 500 resistor.
DS7913/A Ver1.1 Dec. 2008
9
EUTECH [ EUTECH MICROELECTRONICS INC ]
