Datasheet

 2011-2013 Microchip Technology Inc. DS20002276C-page 17
MCP1754/MCP1754S
4.0 DEVICE OVERVIEW
The MCP1754/MCP1754S is a 150 mA output current,
Low Dropout (LDO) voltage regulator. The low dropout
voltage of 300 mV typical at 150 mA of current makes
it ideal for battery-powered applications. The input
voltage range is 3.6V to 16.0V. Unlike other high output
current LDOs, the MCP1754/MCP1754S typically
draws only 150 µA of quiescent current for a 150 mA
load. The MCP1754 adds a shutdown control input pin
and a power good output pin. The output voltage
options are fixed.
4.1 LDO Output Voltage
The MCP1754/MCP1754S LDO has a fixed output
voltage. The output voltage range is 1.8V to 5.5V.
4.2 Output Current and Current
Limiting
The MCP1754/MCP1754S LDO is tested and ensured
to supply a minimum of 150 mA of output current. The
MCP1754/MCP1754S has no minimum output load, so
the output load current can go to 0 mA and the LDO will
continue to regulate the output voltage to within
tolerance.
The MCP1754/MCP1754S also incorporates a true
output current foldback. If the output load presents an
excessive load due to a low-impedance short circuit
condition, the output current and voltage will fold back
towards 30 mA and 0V, respectively.
The output voltage and current resume normal levels
when the excessive load is removed. If the overload
condition is a soft overload, the MCP1754/MCP1754S
supplies higher load currents of up to typically 250 mA.
This allows for device usage in applications that have
pulsed load currents having an average output current
value of 150 mA or less.
Output overload conditions may also result in an
overtemperature shutdown of the device. If the junction
temperature rises above +150°C (typical), the LDO
shuts down the output. See Section 4.8
“Overtemperature Protection” for more information
on overtemperature shutdown.
4.3 Output Capacitor
The MCP1754/MCP1754S requires a minimum output
capacitance of 1 µF for output voltage stability. Ceramic
capacitors are recommended because of their size,
cost and environmentally robust qualities.
Aluminum-electrolytic and tantalum capacitors can be
used on the LDO output as well. The Equivalent Series
Resistance (ESR) of the electrolytic output capacitor
should be no greater than 2.0. The output capacitor
should be located as close to the LDO output as is
practical. Ceramic materials X7R and X5R have low
temperature coefficients and are well within the
acceptable ESR range required. A typical 1 µF X7R
0805 capacitor has an ESR of 50 milliohms.
Larger LDO output capacitors are used with the
MCP1754/MCP1754S to improve dynamic
performance and power supply ripple rejection
performance. A maximum of 1000 µF is
recommended. Aluminum-electrolytic capacitors are
not recommended for low temperature applications of
<-25°C.
FIGURE 4-1: Typical Current Foldback.
0
1
2
3
4
5
6
0.000 0.050 0.100 0.150 0.200 0.250
V
OUT
(V)
I
OUT
(A)
Typical Current FoldBack - 5V Output
Increasing Load Decreasing Load