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PDF LTC1844ES5-BYP Data sheet ( Hoja de datos )
| Número de pieza | LTC1844ES5-BYP | |
| Descripción | 150mA/ Micropower/ Low Noise/ VLDO Linear Regulator | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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FEATURES
s Very Low Dropout:
90mV at 150mA
30mV at 50mA (LTC1844-3.3)
s Wide Input Voltage Range: 1.6V to 6.5V
s Low 35µA Supply Current, Even in Dropout
s Low Noise: 30µVRMS (10Hz to 100kHz)
s ±1.75% Voltage Accuracy Over Temperature,
Voltage and Current Ranges
s Fast Transient Response
s 10nA Supply Current in Shutdown
s Fixed Output Voltages: 1.5V, 1.8V, 2.5V, 2.8V, 3.3V
s Adjustable Output Voltage: 1.25V to 6V
s Output Current Limit
s Reverse-Battery and Reverse-Current Protection
s No Protection Diodes Needed
s Stable with 1µF Output Capacitor
s Stable with Ceramic Capacitors
s Short-Circuit and Thermal Overload Protection
s Low Profile (1mm) SOT-23 Package
U
APPLICATIO S
s Bluetooth/802.11 Cards
s PDAs and Notebook Computers
s Portable Instruments and Battery-Powered Systems
s Cellular Phones
Final Electrical Specifications
LTC1844 Series
150mA, Micropower,
Low Noise, VLDO
Linear Regulator
May 2003
DESCRIPTIO
The LTC®1844 Series are low noise VLDOTM (very low
dropout) linear regulators designed for low power/portable
applications. These regulators can operate from input
voltages as low as 1.6V. Typical output noise is only
30µVRMS and typical dropout for the LTC1844-3.3 is just
90mV at the maximum load current of 150mA, reducing to
30mV at 50mA.
The internal P-channel MOSFET pass transistor requires
no base current, allowing the device to draw only 35µA
during normal operation, independent of the dropout
voltage and load current. The quiescent current falls to a
negligible 10nA during shutdown.
Other features include high output voltage accuracy,
excellent transient response, stablity with ultralow ESR
ceramic capacitors as small as 1µF, reverse-battery and
reverse-current protection, short-circuit and thermal
overload protection and output current limiting.
The LTC1844 regulators are available in a low profile
(1mm) SOT-23 (ThinSOTTM) package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
VLDO and ThinSOT are trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
Fixed Voltage Low Noise, VLDO Linear Regulator
VIN
3.3V TO 6.5V
OFF ON
1 IN
OUT 5
1µF LTC1844-3.3
3 SHDN
BYP 4
GND
2
VOUT
3.3V
1µF
0.1µF
1844 TA01
LTC1844-3.3 Dropout Voltage vs Load Current
120
100
80
60
40
20
0
0 25 50 75 100 125 150
IOUT (mA)
1844 TA02
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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1 page  
LTC1844 Series
PI FU CTIO S
IN(Pin 1): Power for LTC1844 and Load. Power is supplied
to the device through the IN pin. The IN pin should be
locally bypassed to ground if the LTC1844 is more than a
few inches away from another source of bulk capacitance.
In general, the output impedance of a battery rises with
frequency, so it is usually adviseable to include an input
bypass capacitor in battery-powered circuits. A capacitor
in the range of 0.1µF to 1µF is usually sufficient. The
LTC1844 is designed to withstand reverse voltages on the
IN pin with respect to both ground and the output pin. In
the case of a reversed input, which can happen if a battery
is plugged in backwards, the LTC1844 will act as if there
is a large resistor in series with its input with only a small
amount of current flow.
GND (Pin 2): Ground and Heat Sink. Solder to a ground
plane or large pad to maximize heat dissipation.
SHDN (Pin 3, Fixed and SD Devices): Shutdown, Active
Low. This pin is used to put the LTC1844 into shutdown.
The SHDN pin current is typically less than 10nA. The
SHDN pin cannot be left floating and must be tied to the
input pin if not used. If reverse-battery protection is
desired, the SHDN pin must be tied to the input pin through
a large value resistor (10k to 1M).
ADJ (Pin 4, Adjustable Devices): Output Adjust. For the
adjustable versions of the LTC1844, this is the input to the
error amplifier. It has a typical bias current of 30nA flowing
into the pin. The ADJ pin reference voltage is 1.25V
referenced to ground. The output voltage range is 1.25V to
6V and is typically set by connecting ADJ to a resistor
divider from OUT to GND. See Figure 2.
BYP (Pin 4, Fixed/Pin 3, BYP Devices): Noise Bypass.
The BYP pin is used to augment the internal noise filter to
improve low noise performance. A small low leakage
bypass capacitor from this pin to ground will filter the input
of the error amplifier to lower the output voltage noise.
Any value may be used; larger values will result in lower
output noise, but will increase initial power-up time.
Shutdown exit delay time after a brief shutdown (<10ms)
will not be affected. If not used, this pin must be left
unconnected.
OUT (Pin 5): Voltage Regulated Output. The OUT pin
supplies power to the load. A minimum output capacitor of
1µF is required to ensure stability. Larger output capacitors
may be required for applications with large transient loads
to limit peak voltage transients. See the Applications
Information section for more information on output
capacitance.
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5 Page 
PACKAGE DESCRIPTIO
0.62 0.95
MAX REF
S5 Package
5-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1635)
1.22 REF
LTC1844 Series
2.90 BSC
(NOTE 4)
3.85 MAX 2.62 REF
1.4 MIN
2.80 BSC
1.50 – 1.75
(NOTE 4)
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
0.20 BSC
DATUM ‘A’
0.30 – 0.50 REF
0.09 – 0.20
NOTE:
(NOTE 3)
1. DIMENSIONS ARE IN MILLIMETERS
2. DRAWING NOT TO SCALE
3. DIMENSIONS ARE INCLUSIVE OF PLATING
4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
5. MOLD FLASH SHALL NOT EXCEED 0.254mm
6. JEDEC PACKAGE REFERENCE IS MO-193
PIN ONE
0.95 BSC
0.80 – 0.90
1.00 MAX
1.90 BSC
0.30 – 0.45 TYP
5 PLCS (NOTE 3)
0.01 – 0.10
S5 TSOT-23 0302
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| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet LTC1844ES5-BYP.PDF ] | |
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