Datasheet

MCP1700
DS21826B-page 12 © 2007 Microchip Technology Inc.
5.0 FUNCTIONAL DESCRIPTION
The MCP1700 CMOS low dropout linear regulator is
intended for applications that need the lowest current
consumption while maintaining output voltage
regulation. The operating continuous load range of the
MCP1700 is from 0 mA to 250 mA (V
R
2.5V). The
input operating voltage range is from 2.3V to 6.0V,
making it capable of operating from two, three or four
alkaline cells or a single Li-Ion cell battery input.
5.1 Input
The input of the MCP1700 is connected to the source
of the P-Channel PMOS pass transistor. As with all
LDO circuits, a relatively low source impedance (10Ω)
is needed to prevent the input impedance from causing
the LDO to become unstable. The size and type of the
capacitor needed depends heavily on the input source
type (battery, power supply) and the output current
range of the application. For most applications (up to
100 mA), a 1 µF ceramic capacitor will be sufficient to
ensure circuit stability. Larger values can be used to
improve circuit AC performance.
5.2 Output
The maximum rated continuous output current for the
MCP1700 is 250 mA (V
R
2.5V). For applications
where V
R
< 2.5V, the maximum output current is
200 mA.
A minimum output capacitance of 1.0 µF is required for
small signal stability in applications that have up to
250 mA output current capability. The capacitor type
can be ceramic, tantalum or aluminum electrolytic. The
esr range on the output capacitor can range from 0Ω to
2.0Ω.
5.3 Output Rise time
When powering up the internal reference output, the
typical output rise time of 500 µs is controlled to
prevent overshoot of the output voltage.