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PDF MAX8892 Data sheet ( Hoja de datos )
| Número de pieza | MAX8892 | |
| Descripción | (MAX8891 / MAX8892) 150mA Linear Regulators | |
| Fabricantes | Maxim Integrated Products | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de MAX8892 (archivo pdf) en la parte inferior de esta página. Total 8 Páginas | ||
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19-4537; Rev 0; 3/09
www.DataSheet4U.com
High PSRR, Low-Dropout, 150mA
Linear Regulators
General Description
The MAX8891/MAX8892 low-dropout (LDO) linear regu-
lators are designed to deliver up to 150mA continuous
output current. These regulators achieve a low 120mV
dropout for 120mA load current.
The MAX8891 only requires an input/output capacitor,
hence achieving the smallest PCB area. The
MAX8892’s output voltage can be adjusted with an
external divider.
The MAX8891 is preset to a variety of voltages in the
1.5V to 4.5V range. Designed with a p-channel
MOSFET series pass transistor, the MAX8891/MAX8892
maintain very low ground current (40µA).
The regulators are designed and optimized to work with
low-value, low-cost ceramic capacitors. The MAX8891/
MAX8892 require only 1µF (typ) of output capacitance
for stability with any load. When disabled, current con-
sumption drops to below 1µA.
These regulators are available in a tiny 5-pin SC70
package.
Applications
Cellular and Cordless Phones
PDA and Palmtop Computers
Base Stations
Bluetooth Portable Radios and Accessories
Wireless LANs
Digital Cameras
Personal Stereos
Portable and Battery-Powered Equipment
Output Voltage Selector Guide appears at end of data sheet.
Pin Configuration
Features
♦ Space-Saving SC70 Package
♦ 65dB PSRR at 10kHz
♦ 120mV Dropout at 120mA Load
♦ Stable with 1µF Ceramic Capacitor for Any Load
♦ Guaranteed 150mA Output
♦ Only Need Input and Output Capacitors (MAX8891)
♦ Output Voltages: 1.5V, 1.8V, 2.5V, 2.6V, 2.7V, 2.8V,
2.85V, 3V, 3.3V, 4.5V (MAX8891) and Adjustable
(MAX8892)
♦ Low 40µA Ground Current
♦ Excellent Load/Line Transient
♦ Overcurrent and Thermal Protection
Ordering Information
PART*
TEMP RANGE PIN-PACKAGE
MAX8891EXKxy+T -40°C to +85°C 5 SC70
MAX8892EXK+T
-40°C to +85°C 5 SC70
*xy is the output voltage code (see Output Voltage Selector
Guide). Other versions between 1.5V and 4.5V are available in
100mV increments. Contact factory for other versions.
+Denotes a lead(Pb)-free/RoHS-compliant package.
Typical Operating Circuits
INPUT
2V TO 6V
CIN = 1µF
ON
OFF
OUTPUT PRESET
1.5V TO 4.5V
IN OUT
MAX8891
SHDN
COUT = 1µF
GND
TOP VIEW
+
IN 1
5 OUT
MAX8891/
GND 2 MAX8892
SHDN 3
4
N.C. (MAX8891)
FB (MAX8892)
SC70
INPUT
2V TO 6V
CIN = 1µF
ON
OFF
IN OUT
MAX8892
SHDN
FB
GND
OUTPUT ADJUSTABLE
1.5V TO 4.5V
R1
COUT = 1µF
R2
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
1 page  
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PIN
MAX8891 MAX8892
11
22
33
—4
4—
55
High PSRR, Low-Dropout, 150mA
Linear Regulators
Pin Description
NAME
IN
GND
SHDN
FB
N.C.
OUT
FUNCTION
Unregulated Input Supply
Ground
Shutdown. Pull low to disable the regulator.
Adjustable Output Feedback Point
Not Internally Connected
Regulated Output Voltage. Bypass with a capacitor to GND. See the Capacitor Selection
and Regulator Stability section for more details.
Detailed Description
The MAX8891/MAX8892 are low-dropout, low-quies-
cent current linear regulators designed for space-
restricted applications. The parts are available with
preset output voltages ranging from 1.5V to 4.5V in
100mV increments. These devices can supply loads up
to 150mA. As shown in the Functional Diagram, the
MAX8891 consists of an innovative bandgap core, error
amplifier, p-channel pass transistor, and internal feed-
back voltage-divider. The MAX8892 allows for
adjustable output with an external feedback network.
Additional blocks include a current limiter, thermal sen-
sor, and shutdown logic.
The 1.225V bandgap reference is connected to the
error amplifier’s inverting input. The error amplifier com-
pares this reference with the feedback voltage and
amplifies the difference. If the feedback voltage is lower
than the reference voltage, the pass-transistor gate is
pulled low. This allows more current to pass to the out-
put and increases the output voltage. If the feedback
voltage is too high, the pass transistor gate is pulled
high, allowing less current to pass to the output. The
output voltage is fed back through an internal (external
for the MAX8892) resistor voltage-divider connected to
the OUT pin.
Internal P-Channel Pass Transistor
The MAX8891/MAX8892 feature a 1Ω (typ) p-channel
MOSFET pass transistor. This provides several advan-
tages over similar designs using a PNP pass transistor,
including longer battery life. The p-channel MOSFET
requires no base drive, which considerably reduces qui-
escent current. PNP-based regulators waste consider-
able current in dropout when the pass transistor
saturates. They also use high base-drive current under
heavy loads. The MAX8891/MAX8892 do not suffer from
these problems and consume only 40µA of quiescent
current in light load and 220µA in dropout (see the
Typical Operating Characteristics).
Output Voltage Selection
The MAX8891 is supplied with factory-set output volt-
ages from 1.5V to 4.5V, in 100mV increments (see the
Ordering Information). The MAX8892 features a user-
adjustable output through an external feedback net-
work (see the Typical Operating Circuits).
To set the output of the MAX8892, use the following
equation:
R1 =
R2
X
⎛
⎝⎜
VOUT
VREF
-1⎞⎠⎟
where R2 is chosen to be less than 240kΩ and VREF =
1.225V. Use 1% or better resistors.
Shutdown
The MAX8891/MAX8892 feature a low-power shutdown
mode that reduces quiescent current less than 1µA.
Driving SHDN low disables the voltage reference, error
amplifier, gate-drive circuitry, and pass transistor (see
the Functional Diagram), and the device output enters a
high-impedance state. Connect SHDN to IN for normal
operation.
Current Limit
The MAX8891/MAX8892 include a current limiter, which
monitors and controls the pass transistor’s gate volt-
age, limiting the output current to 200mA. The output
can be continuously shorted to ground without damag-
ing the part.
_______________________________________________________________________________________ 5
5 Page | ||
| Páginas | Total 8 Páginas | |
| PDF Descargar | [ Datasheet MAX8892.PDF ] | |
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