Stable with Aluminum, Tantalum or
Ceramic Capacitors
■
Reverse Battery Protected
■
No Reverse Current
■
No Protection Diodes Needed
■
Overcurrent and Overtemperature Protected
U
APPLICATIO S
■
Cellular Phones
■
Pagers
■
Battery-Powered Systems
■
Frequency Synthesizers
■
Wireless Modems
LT1761 Series
100mA, Low Noise,
LDO Micropower
Regulators in SOT-23
U
DESCRIPTIO
The LT®1761 series are micropower, low noise, low
dropout regulators. With an external 0.01µF bypass
capacitor, output noise drops to 20µV
100kHz bandwidth. Designed for use in battery-powered
systems, the low 20µA quiescent current makes them an
ideal choice. In shutdown, quiescent current drops to less
than 0.1µA. The devices are capable of operating over an
input voltage from 1.8V to 20V, and can supply 100mA of
output current with a dropout voltage of 300mV. Quiescent current is well controlled, not rising in dropout as it
does with many other regulators.
The LT1761 regulators are stable with output capacitors
as low as 1µF. Small ceramic capacitors can be used
without the series resistance required by other regulators.
Internal protection circuitry includes reverse battery protection, current limiting, thermal limiting and reverse
current protection. The device is available in fixed output
voltages of 1.5V, 1.8V, 2V, 2.5V, 2.8V, 3V, 3.3V and 5V,
and as an adjustable device with a 1.22V reference voltage.
The LT1761 regulators are available in the 5-lead SOT-23
package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
over a 10Hz to
RMS
TYPICAL APPLICATIO
5V Low Noise Regulator
V
5.4V TO
20V
IN
1µF
IN
SHDN
OUT
LT1761-5
BYP
GND
U
0.01µF
+
5V AT100mA
20µV
10µF
RMS
NOISE
1761 TA01
V
OUT
100µV/DIV
10Hz to 100kHz Output Noise
1761 G48
20µV
RMS
1
LT1761 Series
WWWU
ABSOLUTE AXI U RATI GS
(Note 1)
IN Pin Voltage........................................................ ±20V
OUT Pin Voltage .................................................... ±20V
Input to Output Differential Voltage ....................... ±20V
ADJ Pin Voltage ...................................................... ±7V
Quiescent Current in ShutdownVIN = 6V, V
Ripple Rejection (Note 3)VIN – V
Current LimitVIN = 7V, V
Input Reverse Leakage CurrentVIN = –20V, V
Reverse Output CurrentLT1761-1.5V
(Note 10)LT1761-1.8V
= Off to On●0.82V
OUT
V
= On to Off●0.250.65V
OUT
= 0V●00.5µA
SHDN
= 20V●13µA
SHDN
= 0V0.010.1µA
SHDN
= 1.5V (Avg), V
OUT
I
= 50mA
LOAD
= 0V200mA
= V
OUT(NOMINAL)
OUT
+ 1V, ∆V
= 0V●1mA
OUT
= 1.5V, VIN < 1.5V1020µA
OUT
= 1.8V, VIN < 1.8V1020µA
OUT
= 2V, VIN < 2V1020µA
OUT
= 2.5V, VIN < 2.5V1020µA
OUT
= 2.8V, VIN < 2.8V1020µA
OUT
= 3V, VIN < 3V1020µA
OUT
= 3.3V, VIN < 3.3V1020µA
OUT
= 5V, VIN < 5V1020µA
OUT
= 1.22V, VIN < 1.22V510µA
OUT
V
IN
LT1761-2V
LT1761-2.5V
LT1761-2.8V
LT1761-3V
LT1761-3.3V
LT1761-5V
LT1761 (Note 3) V
= 1mA to 50mA1020mV
LOAD
= 1mA to 50mA●40mV
LOAD
= 1mA to 100mA2040mV
LOAD
= 1mA to 100mA●100mV
LOAD
= 1mA to 50mA1530mV
LOAD
= 1mA to 50mA●60mV
LOAD
= 1mA to 100mA2565mV
LOAD
= 1mA to 100mA●150mV
LOAD
= 1mA to 50mA16mV
LOAD
= 1mA to 50mA●12mV
LOAD
= 1mA to 100mA112mV
LOAD
= 1mA to 100mA●50mV
LOAD
= 100mA, BW = 10Hz to 100kHz20µV
LOAD
= 0.5V
RIPPLE
= –5%●110mA
OUT
P-P
, f
= 120Hz,5565dB
RIPPLE
RMS
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LT1761 regulators are tested and specified under pulse load
conditions such that T
≈ TA. The LT1761 is 100% production tested at
J
4
TA = 25°C. Performance at –40°C and 125°C is assured by design,
characterization and correlation with statistical process controls.
Note 3: The LT1761 (adjustable versions) are tested and specified for
these conditions with the ADJ pin connected to the OUT pin.
TEMPERATURE (°C)
–50
OUTPUT VOLTAGE (V)
100
1761 G06
050
1.84
1.83
1.82
1.81
1.80
1.79
1.78
1.77
1.76
–252575125
IL = 1mA
ELECTRICAL CHARACTERISTICS
LT1761 Series
Note 4: Operating conditions are limited by maximum junction
temperature. The regulated output voltage specification will not apply for
all possible combinations of input voltage and output current. When
operating at maximum input voltage, the output current range must be
limited. When operating at maximum output current, the input voltage
range must be limited.
Note 5: To satisfy requirements for minimum input voltage, the LT1761
(adjustable version) is tested and specified for these conditions with an
external resistor divider (two 250k resistors) for an output voltage of
2.44V. The external resistor divider will add a 5µA DC load on the output.Note 6: Dropout voltage is the minimum input to output voltage differential
needed to maintain regulation at a specified output current. In dropout, the
output voltage will be equal to: V
– V
IN
DROPOUT
.
Note 7: GND pin current is tested with VIN = V
(whichever is greater) and a current source load. This means the device is
tested while operating in its dropout region or at the minimum input
voltage specification. This is the worst-case GND pin current. The GND pin
current will decrease slightly at higher input voltages.
Note 8: ADJ pin bias current flows into the ADJ pin.
Note 9: SHDN pin current flows into the SHDN pin.
Note 10: Reverse output current is tested with the IN pin grounded and the
OUT pin forced to the rated output voltage. This current flows into the OUT
pin and out the GND pin.
Note 11: For the LT1761, LT1761-1.5, LT1761-1.8 and LT1761-2 dropout
voltage will be limited by the minimum input voltage specification under
some output voltage/load conditions. See the curve of Minimum Input
Voltage in the Typical Performance Characteristics.
UW
TYPICAL PERFOR A CE CHARACTERISTICS
Typical Dropout Voltage
500
450
400
350
300
250
200
150
DROPOUT VOLTAGE (mV)
100
50
0
0 102030
40
OUTPUT CURRENT (mA)
TJ = 125°C
TJ = 25°C
60 70 80 90 100
50
1761 G00
Guaranteed Dropout Voltage
500
= TEST POINTS
450
400
350
300
250
200
150
DROPOUT VOLTAGE (mV)
100
50
0
0 102030
TJ ≤ 125°C
TJ ≤ 25°C
40
50
OUTPUT CURRENT (mA)
60 70 80 90 100
1761 G01
OUT(NOMINAL)
Dropout Voltage
500
450
400
350
300
250
200
150
DROPOUT VOLTAGE (mV)
100
50
0
–50
–25
IL = 100mA
0
TEMPERATURE (°C)
or VIN = 2.3V
IL = 50mA
IL = 10mA
IL = 1mA
50
25
75
100
125
1761 G01.1
40
35
30
25
20
15
10
QUIESCENT CURRENT (µA)
5
0
–50
Quiescent Current
VIN = 6V
= ∞ (250k FOR LT1761-BYP, -SD)
R
L
= 0 (5µA FOR LT1761-BYP, -SD)
I
L
V
= V
SHDN
IN
V
= 0V
SHDN
–252575125
050
TEMPERATURE (°C)
100
1761 G03
LT1761-1.5
Output Voltage
1.528
IL = 1mA
1.521
1.514
1.507
1.500
1.493
OUTPUT VOLTAGE (V)
1.486
1.479
1.472
–252575125
–50
050
TEMPERATURE (°C)
LT1761-1.8
Output Voltage
100
1761 G51
5
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