AME8852A Datasheet, PDF (9/29 Pages) Analog Microelectronics – High PSRR, Low Noise, 150mA CMOS Regulator

AME
AME8852A
n Detailed Description
The AME8852A family of CMOS regulators contain a
PMOS pass transistor, voltage reference, error amplifier,
over-current protection, thermal shutdown, and Power
Good detection circuitry.
The P-channel pass transistor receives data from the
error amplifier, over-current shutdown, and thermal pro-
tection circuits. During normal operation, the error ampli-
fier compares the output voltage to a precision reference.
Over-current and Thermal shutdown circuits become ac-
tive when the junction temperature exceeds 150^oC, or
the current exceeds 150mA. During thermal shutdown,
the output voltage remains low. Normal operation is re-
stored when the junction temperature drops more 20^oC.
High PSRR, Low Noise, 150mA
CMOS Regulator
Capacitor Selection and Regulator Stability
The maximum output power of the AME8852 is limited
by the maximum power dissipation of the package. By
calculation the power dissipation of the package as a
function of the input voltage, output voltage and output
current, the maximum input voltage can be obtained. The
maximum power dissipation should not exceed the
package’ s maximum power rating.
P_MAX = (V_IN(MAX)-V_OUT) x I_OUT
Where:
V_IN(MAX) = maximum input voltage
P_MAX = maximum power dissipation of the package
Capacitor Selection and Regulator Stability
The AME8852A is stable with an output capacitor to
ground of 1µF or greater. Ceramic capacitors have the
lowest ESR, and will offer the best AC performance.
Conversely, Aluminum Electrolytic capacitors exhibit the
highest ESR, resulting in the poorest AC response. Un-
fortunately, large value ceramic capacitors are compara-
tively expensive. One option is to parallel a 0.1µF ce-
ramic capacitor with a 10µF Aluminum Electrolytic. The
benefit is low ESR, high capacitance, and low overall cost.
A second capacitor is recommended between the in-
put and ground to stabilize V_IN. The input capacitor should
be at least 0.1µF to have a beneficial effect.
Enable Pin
The Enable Pin is pull-low. When activated pulled low,
the MOS pass transistor shuts off, and all internal cir-
cuits are powered down. In this state, the stand by cur-
rent is than 1µA.
Rev. A.01
9