Datasheet
2012 Microchip Technology Inc. DS25160A-page 19
MCP1755/1755S
FIGURE 4-4: Shutdown Input Timing
Diagram.
4.7 Dropout Voltage and Undervoltage
Lockout
Dropout voltage is defined as the input-to-output
voltage differential at which the output voltage drops
2% below the nominal value that was measured with a
V
R
+ 1.0V differential applied. The MCP1755/1755S
LDO has a very low dropout voltage specification of
300 mV (typical) at 300 mA of output current. See
Section 1.0 “Electrical Characteristics” for
maximum dropout voltage specifications.
The MCP1755/1755S LDO operates across an input
voltage range of 3.6V to 16.0V and incorporates input
undervoltage lockout (UVLO) circuitry that keeps the
LDO output voltage off until the input voltage reaches a
minimum of 3.00V (typical) on the rising edge of the
input voltage. As the input voltage falls, the LDO output
will remain on until the input voltage level reaches
2.70V (typical).
For high-current applications, voltage drops across the
PCB traces must be taken into account. The trace
resistances can cause significant voltage drops
between the input voltage source and the LDO. For
applications with input voltages near 3.0V, these PCB
trace voltage drops can sometimes lower the input
voltage enough to trigger a shutdown due to
undervoltage lockout.
4.8 Overtemperature Protection
The MCP1755/1755S LDO has temperature-sensing
circuitry to prevent the junction temperature from
exceeding approximately +150
°C. If the LDO junction
temperature does reach +150
°C, the LDO output will
be turned off until the junction temperature cools to
approximately +140
°C, at which point the LDO output
will automatically resume normal operation. If the
internal power dissipation continues to be excessive,
the device will again shut off. The junction temperature
of the die is a function of power dissipation, ambient
temperature and package thermal resistance. See
Section 5.0 “Application Circuits and Issues” for
more information on LDO power dissipation and
junction temperature.
SHDN
V
OUT
135 µs
T
DELAY_SHDN
400 ns (typical)
C
LOAD
= 1.0 µF