AME8819_12 Datasheet, PDF (12/22 Pages) Analog Microelectronics – Low Dropout 600mA CMOS Regulator

AME
AME8819
Low Dropout
600mA CMOS Regulator
n Detailed Description
The AME8819 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 600mA.
n Circuit Limit
The AME8819 contains current limiters which monitor and
control the pass transistor's Gate voltage, limiting the guar-
anteed maximum output current to 650mA minimum. The
output can be shorted to ground for an indefinite time without
damaging the part.
n Thermal-Overload Protection
n Capacitor Selection and
Regulator Stability
Use 1µF capacitor on the OUT. Larger input capaci-
tor values and lower ESR provide better supply noise
rejection and line transient response. To reduce out-
put 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 600mA, input and output capacitors should
be a minimum of 2.2µF 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
4.7µF or more for up to 600mA load current to ensure
stability at temperatures below -10^oC. With X7R or
X5R dielectrics, 2.2µF is sufficient at all operating tem-
peratures. These regulators are optimized for ceramic
capacitors. Tantalum capacitors are not recommended.
Thermal-overload protection limits total power dissipation
in the AME8819. When the junction temperature arrive T_J =
160^oC approximately, the thermal sensor signals the shut-
down logic, turning off the pass transistor and allowing the IC
to cool.
n PSRR and Operation from
sources Other than Batteries
The AME8819 is designed to deliver low-dropout voltage
and low quiescent currents in battery-powered system.
Power-supply rejection ratio is 60dB(Typ.) at 1KHz (see
PSRR vs Frequency Curve).When operating from sources
other than batteries, PSRR and transient response can be
improved by increasing input, output capacitors.
n Adjustable Version
The adjustable version uses external feedback re-
sistors to generate an output voltage anywhere from
0.98V to 4.5V. V_ADJ is trimmed to 0.98V and V_OUT is
given by the equation:
V_OUT = V_ADJ ( 1 + R1 / R2 )
Feedback resistors R1 and R2 should be high enough
to keep quiescent current low, but increasing R1 + R2
will reduce stability. In general, R1 and R2 in the 10's
of kΩ will produce adequate stability, given reason-
able layout precautions. To improve stability charac-
teristics, keep parasitics on the ADJ pin to a mini-
mum, and lower R1 and R2 values.
12
Rev.D.04