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Número de pieza | AME8861 | |
Descripción | 600mA CMOS LDO | |
Fabricantes | Analog Microelectronics | |
Logotipo | ||
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No Preview Available ! AME, Inc.
AME8861
600mA CMOS LDO
n General Description
The AME8861 family of positive, linear regulators fea-
ture low quiescent current (30µA typ.) with low dropout
voltage, making them ideal for battery applications. The
space-saving SOT-25 package is attractive for "Pocket"
and "Hand Held" applications.
These rugged devices have both Thermal Shutdown,
and Current Fold-back to prevent device failure under the
"Worst" of operating conditions.
In applications requiring a low noise, regulated supply,
place a 1000 pF capacitor between Bypass and ground.
The AME8861 is stable with an output capacitance of
2.2µF or greater.
n Features
l Very Low Dropout Voltage
l 600mA Output
l Accurate to within 1.5%
l 30µA Quiescent Current
l Over-Temperature Shutdown
l Current Limiting
l Short Circuit Current Fold-back
l Noise Reduction Bypass Capacitor
l Power-Saving Shutdown Mode
l Space-Saving SOT-25 Package
l Factory Pre-set Output Voltages
l Low Temperature Coefficient
n Functional Block Diagram
IN OUT
Overcurrent
Shutdown
EN
BYP
Thermal
Shutdown
AMP
R1
Vref=1.215V
R2
GND
n Typical Application
INPUT
IN OUT
AME8861
BYP
GND
EN
C1 C2
5V
1µF 1000pF
OUTPUT
C3
2.2µF
n Applications
l Instrumentation
l Portable Electronics
l Wireless Devices
l Cordless Phones
l PC Peripherals
l Battery Powered Widgets
l Electronic Scales
1
Free Datasheet http://www.datasheet4u.com/
1 page AME, Inc.
AME8861
600mA CMOS LDO
n Detailed Description
The AME8861 family of CMOS regulators contain a
PMOS pass transistor, voltage reference, error amplifier,
over-current protection, and thermal shutdown.
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 150oC, or
the current exceeds 600mA. During thermal shutdown,
the output voltage remains low. Normal operation is re-
stored when the junction temperature drops below 120oC.
The AME8861 switches from voltage mode to current
mode when the load exceeds the rated output current.
This prevents over-stress. The AME8861 also incorpo-
rates current foldback to reduce power dissipation when
the output is short circuited. This feature becomes ac-
tive when the output drops below 0.8 volts, and reduces
the current flow by 65%. Full current is restored when
the voltage exceeds 0.8 volts.
All capacitors should be placed in close proximity to
the pins. A "Quiet" ground termination is desirable. This
can be achieved with a "Star" connection.
n Enable
The Enable pin normally floats high. When actively,
pulled low, the PMOS pass transistor shuts off, and all
internal circuits are powered down. In this state, the qui-
escent current is less than 1µA. This pin behaves much
like an electronic switch.
n External Capacitors
The AME8861 is stable with an output capacitor to
ground of 2.2µF or greater. Ceramic capacitors have the
lowest ESR, and will offer the best AC performance. Con-
versely, Aluminum Electrolytic capacitors exhibit the high-
est ESR, resulting in the poorest AC response. Unfortu-
nately, large value ceramic capacitors are comparatively
expensive. One option is to parallel a 0.1µF ceramic
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 Vin. The input capacitor should
be at least 0.1µF to have a beneficial effect.
A third capacitor can be connected between the BY-
PASS pin and GND. This capacitor can be a low cost
Polyester Film variety between the value of 0.001 ~
0.01µF. A larger capacitor improves the AC ripple rejec-
tion, but also makes the output come up slowly. This
"Soft" turn-on is desirable in some applications to limit
turn-on surges.
5
Free Datasheet http://www.datasheet4u.com/
5 Page |
Páginas | Total 9 Páginas | |
PDF Descargar | [ Datasheet AME8861.PDF ] |
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