AME
AME8818
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Detailed Description
The AME8818 is low-dropout, low quiescent-current linear
regulator designed primarily for battery-powered applications.
It is available with present output voltage ranging from 1.2V
to 4.5V, and can supply loads up to 300mA.
Low Dropout
300mA CMOS Regulator
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Capacitor Selection and
Regulator Stability
Use a 1µF capacitor on the AME8818 input and a
1µF capacitor on the OUT. Larger input capacitor val-
ues and lower ESR provide better supply noise rejec-
tion and line transient response. To reduce output
noise and improve load transient voltage dips, use
larger output capacitors up to 4.7µF. For stable op-
eration over the full temperature range with load cur-
rents up to 300mA, input and output capacitors should
be a minimum of 1µF by X7R.
Note that some ceramic dielectrics large capacitance
and ESR variation with temperature. With dielectrics
such as Z5U and Y5V, it may be necessary to use
2.2µF or more for up to 300mA load current to ensure
stability at temperatures below -10
o
C. With X7R or
X5R dielectrics, 1µF is sufficient at all operating tem-
peratures. These regulators are optimized for ceramic
capacitors. Tantalum capacitors are not recommended.
Bypass capacitor can be in between 0.1µF~0.001µF.
A larger capacitor improves AC ripple rejection, but
also make the output come up slowly.
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Shutdown Mode
The AME8818 has enable-control-pin. Drive EN low to shut-
down OUT. Drive EN to shutdown the entire chip, reducing
supply current to 5µA. Connected EN to logic-high or IN for
normal operation.
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Circuit Limit
The AME8818 contains current limiters which monitor and
control the pass transistor's Gate voltage, limiting the guar-
anteed maximum output current to 330mA minimum. The
output can be shorted to ground for an indefinite time without
damaging the part.
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Thermal-Overload Protection
Thermal-overload protection limits total power dissipation
in the AME8818. When the junction temperature arrive T
J
=
160
o
C approximately, the thermal sensor signals the shut-
down logic, turning off the pass transistor and allowing the IC
to cool.
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PSRR and Operation from
sources Other than Batteries
The AME8818 is designed to deliver low-dropout
voltage and low quiescent currents in battery-powered
system. Power-supply rejection ratio is 60dB (Typ.)
at 1KHz. When operating from sources other than
betteries, PSRR and transient response can be im-
proved by increasing input, output and bypass
capacitors(see PSRR vs Frequency Curve).
8
Rev.A.01
AMETHERM [ AMETHERM CIRCUIT PROTECTION THERMISTORS ]
