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PDF LTC1844 Data sheet ( Hoja de datos )
| Número de pieza | LTC1844 | |
| Descripción | 150mA/ Micropower/ Low Noise/ VLDO Linear Regulator | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de LTC1844 (archivo pdf) en la parte inferior de esta página. Total 12 Páginas | ||
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FEATURES
■ Very Low Dropout:
90mV at 150mA
30mV at 50mA (LTC1844-3.3)
■ Wide Input Voltage Range: 1.6V to 6.5V
■ Low 35µA Supply Current, Even in Dropout
■ Low Noise: 60µVRMS (10Hz to 100kHz)
■ ±1.75% Voltage Accuracy Over Temperature,
Voltage and Current Ranges
■ Fast Transient Response
■ 10nA Supply Current in Shutdown
■ Fixed Output Voltages: 1.5V, 1.8V, 2.5V, 2.8V, 3.3V
■ Adjustable Output Voltage: 1.25V to 6V
■ Output Current Limit
■ Reverse-Battery and Reverse-Current Protection
■ No Protection Diodes Needed
■ Stable with 1µF Output Capacitor
■ Stable with Ceramic Capacitors
■ Short-Circuit and Thermal Overload Protection
■ Low Profile (1mm) SOT-23 Package
U
APPLICATIO S
■ Portable Instruments and Battery-Powered Systems
■ Bluetooth/802.11 Cards
■ Cellular Phones
■ PDAs and Notebook Computers
LTC1844 Series
150mA, Micropower,
Low Noise, VLDO
Linear Regulator
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, stability 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.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATIO
Fixed Voltage Low Noise, VLDO Linear Regulator
VIN
3.3V TO 6.5V
OFF ON
IN OUT
1µF
LTC1844-3.3
SHDN BYP
GND
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
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1
1 page  
TYPICAL PERFOR A CE CHARACTERISTICS
LTC1844 Series
VOUT vs Temperature
1.520
VOUT = 1.5V
1.515
1.510
1.505
1.500
1.495
1.490
1.485
1.480
– 50 – 25
0 25 50 75
TEMPERATURE (°C)
100 125
1844 G01
VOUT vs Temperature
2.820
VOUT = 2.8V
2.815
2.810
2.805
2.800
2.795
2.790
2.785
2.780
– 50 – 25
0 25 50 75
TEMPERATURE (°C)
100 125
1844 G04
Quiescent Current vs Temperature
70
60
50
40
30
20
10
0
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
1844 G07
VOUT vs Temperature
1.820
VOUT = 1.8V
1.815
1.810
1.805
1.800
1.795
1.790
1.785
1.780
– 50 – 25
0 25 50 75
TEMPERATURE (°C)
100 125
1844 G02
VOUT vs Temperature
3.320
VOUT = 3.3V
3.315
3.310
3.305
3.300
3.295
3.290
3.285
3.280
– 50 – 25
0 25 50 75
TEMPERATURE (°C)
100 125
1844 G05
Current Limit vs Temperature
500
VOUT = 2.8V
450
400
350
300
250
200
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
1844 G08
VOUT vs Temperature
2.520
VOUT = 2.5V
2.515
2.510
2.505
2.500
2.495
2.490
2.485
2.480
– 50 – 25
0 25 50 75
TEMPERATURE (°C)
100 125
1844 G03
VOUT vs Temperature
1.270
VOUT = ADJ
1.265
1.260
1.255
1.250
1.245
1.240
1.235
1.230
– 50 – 25
0 25 50 75
TEMPERATURE (°C)
100 125
1844 G05
SHDN Threshold vs Temperature
800
ILOAD = 1mA
750
700
650
600
550
500
450
400
– 50 – 25
0 25 50 75
TEMPERATURE (°C)
100 125
1844 G09
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LTC1844 Series
APPLICATIONS INFORMATION
In circuits where a backup battery is required, several
different input/output conditions can occur. The output
voltage may be held up externally while the input is either
pulled to ground, pulled to some intermediate voltage or
left open circuit. The LTC1844 features reverse current
protection to limit current draw from any supplementary
power source at the output. When VIN is pulled to ground
or is left open circuit, IIN and IOUT are less than 0.1µA for
VOUT = 0V to 7V.
When VIN is held constant and VOUT varied, current flow
will follow the curves shown in Figure 7. With VOUT held
below VOUT(NOM), the LTC1844 will be in current limit
trying to pull VOUT up. With VOUT held between VOUT(NOM)
and VIN, IIN will be at the normal quiescent current level
and IOUT will be 1µA to 2µA. As VOUT is pulled above VIN,
IOUT temporarily increases to 30µA until the reverse cur-
rent protection circuitry activates and reduces IOUT to less
than 10µA.
Alternatively, when VOUT is held constant and VIN varied,
current flow will follow Figure 8’s curves. IOUT will be less
than 10µA at all times except for a brief spike just below
2.7V before the reverse current protection circuitry
activates.
50
LTC1844-2.8
45 TJ = 25°C
40
VIN = 3.3V
CURRENT FLOWS
35 INTO PINS
30
IN CURRENT
25 LIMIT BELOW
2.8V
20
15
IOUT
IIN
10
5
0
01
2 34
5 67
OUTPUT VOLTAGE (V)
1844 F07
Figure 7. Reverse Current vs Output Voltage
100
LTC1844-2.8
90 TJ = 25°C
80
VOUT = 2.7V
CURRENT FLOW
70 INTO PINS
IN CURRENT
LIMIT ABOVE
2.7V
60
50
40
30
IIN
20
10
0
0
IOUT
0.5 1.0 1.5 2.0 2.5
INPUT VOLTAGE (V)
3.0
1844 F08
Figure 8. Reverse Current vs Input Voltage
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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11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet LTC1844.PDF ] | |
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