MCP1754 Microchip Technology Inc., MCP1754 Datasheet - Page 19

• Manufacturer Part Number: MCP1754
• Description: 150 Ma, 16v, High Performance Ldo
• Manufacturer: Microchip Technology Inc.

The SHDN input will ignore low-going pulses (pulses
meant to shut down the LDO) that are up to 400 ns in
pulse width. If the shutdown input is pulled low for more
than 400 ns, the LDO will enter Shutdown mode. This
small bit of filtering helps to reject any system noise
spikes on the shutdown input signal.
On the rising edge of the SHDN input, the shutdown
circuitry has a 30 µs delay before allowing the LDO
output to turn on. This delay helps to reject any false
turn-on signals or noise on the SHDN input signal. After
the 30 µs delay, the LDO output enters its soft-start
period as it rises from 0V to its final regulation value. If
the SHDN input signal is pulled low during the 30 µs
delay period, the timer will be reset and the delay time
will start over again on the next rising edge of the
SHDN input. The total time from the SHDN input going
high (turn-on) to the LDO output being in regulation is
typically 100 µs. See
the SHDN input.
FIGURE 4-4:
Diagram.
4.7
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
MCP1754S LDO has a very low dropout voltage
specification of 300 mV (typical) at 150 mA of output
current. See
for maximum dropout voltage specifications.
The MCP1754/MCP1754S 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 2.95V (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).
© 2011 Microchip Technology Inc.
R
V
SHDN
OUT
+ 1.0V differential applied. The MCP1754/
30 µs
Dropout Voltage and Undervoltage
Lockout
Section 1.0 “Electrical Characteristics”
T
70 µs
DELAY_SHDN
Figure 4-4
Shutdown Input Timing
for a timing diagram of
400 ns (typ)
MCP1754/MCP1754S
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
The MCP1754/MCP1754S LDO has temperature-
sensing circuitry to prevent the junction temperature
from exceeding approximately 150
junction temperature does reach 150
output will be turned off until the junction temperature
cools to approximately 137
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
Issues”
dissipation and junction temperature.
Overtemperature Protection
for more information on LDO power
Section 5.0 “Application Circuits &
°
C, at which point the LDO
DS22276A-page 19
°
C. If the LDO
°
C, the LDO