Datasheet

MCP1790/MCP1791
DS22075B-page 16 © 2010 Microchip Technology Inc.
4.8 Output Current and Current
Limiting
The MCP1790/MCP1791 devices are tested and
ensured to supply a minimum of 70 mA of output
current.
The MCP1790/MCP1791 also incorporate an output
current limit foldback. When the regulator is in an
overcurrent condition, V
OUT
will decrease with
increasing load. When V
OUT
falls below 30% (typical)
of V
R
, the output current will start to fold back. The
output current will fold back to less than 100 mA
(typical) when V
OUT
is near 0 volts.
The 5.0V regulator has an overload current limiting of
approximately 120 mA. If V
REG
is lower than 3.5V, I
OUT
will start to fold back and decrease along with V
REG
until IOUT is less than 105 mA and V
REG
is near 0 volts.
The 3.3V regulator has an overload current limiting of
approximately 130 mA. If V
REG
is lower than 2.5V, I
OUT
will start to fold back and decrease along with V
REG
until IOUT is less than 99 mA and V
REG
is near 0 volts.
FIGURE 4-3: ESR Curves for Load Capacitor Selection.
Load Capacitor [uF]
ESR Curves
ESR [ohm]
10
1
0.1
0.01
0.001
10
100
1000
10.1
Instable
Instable
Instable
Stable only
with Tantalum or
Electrolytic cap.
Stable with
Tantalum,
Electrolytic and
Ceramic cap.