LTC1844 Series
150mA, Micropower,
Low Noise, VLDO
Linear Regulator
FEATURES
■
DESCRIPTIO
■
■
■
■
■
■
■
■
■
■
■
■
■
■
■
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: 60µV
RMS
(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
The LTC
®
1844 Series are low noise VLDO
TM
(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
30µV
RMS
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 (ThinSOT
TM
) 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.
APPLICATIO S
■
■
■
■
Portable Instruments and Battery-Powered Systems
Bluetooth/802.11 Cards
Cellular Phones
PDAs and Notebook Computers
TYPICAL APPLICATIO
V
IN
3.3V TO 6.5V
1µF
OFF ON
LTC1844-3.3 Dropout Voltage vs Load Current
120
Fixed Voltage Low Noise, VLDO Linear Regulator
100
IN
OUT
LTC1844-3.3
BYP
SHDN
GND
1µF
V
OUT
3.3V
DROPOUT VOLTAGE (mV)
80
60
40
20
0
0.1µF
1844 TA01
0
25
U
50
75
100
I
OUT
(mA)
125
150
1844 TA02
U
U
1844fa
1
LTC1844 Series
ABSOLUTE
AXI U
RATI GS
(Note 1)
Output Short-Circuit Duration ......................... Indefinite
Operating Junction Temperature Range
(Notes 2, 10) .....................................–40°C to 125°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
Supply Voltage (IN) ....................................... – 7V to 7V
Input Voltage
SHDN, BYP, ADJ .................................... – 0.3V to 7V
Output Voltage
OUT ........................................................ – 0.3V to 7V
OUT to IN .................................................. – 7V to 7V
PACKAGE/ORDER I FOR ATIO
TOP VIEW
IN 1
GND 2
SHDN 3
4 BYP
5 OUT
IN 1
GND 2
SHDN 3
S5 PACKAGE
5-LEAD PLASTIC TSOT-23
S5 PACKAGE
5-LEAD PLASTIC TSOT-23
T
JMAX
= 125°C,
θ
JA
= 250°C/ W,
θ
JC
= 90°C/ W
SEE THE APPLICATIONS INFORMATION SECTION
T
JMAX
= 125°C,
θ
JA
= 250°C/ W,
θ
JC
= 90°C/ W
SEE THE APPLICATIONS INFORMATION SECTION
ORDER PART
NUMBER
LTC1844ES5-1.5
LTC1844ES5-1.8
LTC1844ES5-2.5
LTC1844ES5-2.8
LTC1844ES5-3.3
S5 PART
MARKING
LTF1
LTF2
LTF3
LTQK
LTF4
ORDER PART
NUMBER
LTC1844ES5-SD
Order Options
Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking:
http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
SYMBOL
V
IN
I
IN
I
INSHDN
V
OUT%
PARAMETER
Input Voltage
Quiescent Current
V
IN
Shutdown Supply Current
Regulated Output Voltage
(Notes 3, 4, 5)
SHDN = V
IN
CONDITIONS
The
●
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= V
OUT
+ 0.5V, unless otherwise noted. (Note 2)
MIN
●
●
SHDN = 0V
LTC1844-3.3
LTC1844-3.3
LTC1844-2.8
LTC1844-2.8
LTC1844-2.5
LTC1844-2.5
LTC1844-1.8
LTC1844-1.8
V
IN
= 3.8V to 6.5V, I
OUT
= 0mA to 150mA
V
IN
= 3.8V to 6.5V, I
OUT
= 0mA to 150mA
V
IN
= 3.3V to 6.5V, I
OUT
= 0mA to 150mA
V
IN
= 3.3V to 6.5V, I
OUT
= 0mA to 150mA
V
IN
= 3.0V to 6.5V, I
OUT
= 0mA to 150mA
V
IN
= 3.0V to 6.5V, I
OUT
= 0mA to 150mA
V
IN
= 2.3V to 6.5V, I
OUT
= 0mA to 150mA
V
IN
= 2.3V to 6.5V, I
OUT
= 0mA to 150mA
2
U
U
W
W W
U
W
TOP VIEW
5 OUT
IN 1
GND 2
TOP VIEW
5 OUT
4 ADJ
BYP 3
4 ADJ
S5 PACKAGE
5-LEAD PLASTIC TSOT-23
T
JMAX
= 125°C,
θ
JA
= 250°C/ W,
θ
JC
= 90°C/ W
SEE THE APPLICATIONS INFORMATION SECTION
S5 PART
MARKING
LTE8
ORDER PART
NUMBER
LTC1844ES5-BYP
S5 PART
MARKING
LTE9
TYP
35
MAX
6.5
55
80
1
1.50
1.75
1.50
1.75
1.50
1.75
1.50
1.75
UNITS
V
µA
µA
µA
%V
OUT
%V
OUT
%V
OUT
%V
OUT
%V
OUT
%V
OUT
%V
OUT
%V
OUT
1844fa
1.6
●
●
●
●
●
0.01
–1.50
–1.75
–1.50
–1.75
–1.50
–1.75
–1.50
–1.75
LTC1844 Series
ELECTRICAL CHARACTERISTICS
SYMBOL
PARAMETER
CONDITIONS
LTC1844-1.5
LTC1844-1.5
LTC1844-1.5
LTC1844-BYP
LTC1844-BYP
LTC1844-BYP
LTC1844-SD
LTC1844-SD
LTC1844-SD
V
ADJ
ADJ Pin Voltage (Notes 3, 5)
LTC1844-BYP
LTC1844-BYP
LTC1844-BYP
LTC1844-SD
LTC1844-SD
LTC1844-SD
∆V
LNR
Line Regulation (Notes 3, 5)
LTC1844-3.3
LTC1844-2.8
LTC1844-2.5
LTC1844-1.8
V
IN
= 2.0V to 6.5V, I
OUT
= 0mA to 150mA
V
IN
= 2.2V to 6.5V, I
OUT
= 0mA to 150mA
V
IN
= 2.0V to 6.5V, I
OUT
= 0mA to 100mA
V
IN
= 1.75V to 6.5V, I
OUT
= 0mA to 150mA
V
IN
= 2.2V to 6.5V, I
OUT
= 0mA to 150mA
V
IN
= 1.75V to 6.5V, I
OUT
= 0mA to 100mA
V
IN
= 1.75V to 6.5V, I
OUT
= 0mA to 150mA
V
IN
= 2.2V to 6.5V, I
OUT
= 0mA to 150mA
V
IN
= 1.75V to 6.5V, I
OUT
= 0mA to 100mA
V
IN
= 1.75V to 6.5V, I
OUT
= 0mA to 150mA
V
IN
= 2.2V to 6.5V, I
OUT
= 0mA to 150mA
V
IN
= 1.75V to 6.5V, I
OUT
= 0mA to 100mA
V
IN
= 1.75V to 6.5V, I
OUT
= 0mA to 150mA
V
IN
= 2.2V to 6.5V, I
OUT
= 0mA to 150mA
V
IN
= 1.75V to 6.5V, I
OUT
= 0mA to 100mA
V
IN
= 3.4V to 6.5V, I
L
= 1mA
V
IN
= 2.9V to 6.5V, I
L
= 1mA
V
IN
= 2.6V to 6.5V, I
L
= 1mA
V
IN
= 2.2V to 6.5V, I
L
= 1mA
V
IN
= 1.9V to 6.5V, I
L
= 1mA
V
IN
= 1.9V to 6.5V, I
L
= 1mA
V
IN
= 2.2V to 6.5V, I
L
= 1mA
V
IN
= 1.6V to 6.5V, I
L
= 1mA
V
IN
= 1.6V to 6.5V, I
L
= 1mA
V
IN
= 2.2V to 6.5V, I
L
= 1mA
V
IN
= 1.6V to 6.5V, I
L
= 1mA
V
IN
= 1.6V to 6.5V, I
L
= 1mA
V
IN
= 2.2V to 6.5V, I
L
= 1mA
V
IN
= 1.6V to 6.5V, I
L
= 1mA
V
IN
= 1.6V to 6.5V, I
L
= 1mA
V
IN
= 3.8V, I
OUT
= 0mA to 150mA
V
IN
= 3.3V, I
OUT
= 0mA to 150mA
V
IN
= 3.0V, I
OUT
= 0mA to 150mA
V
IN
= 2.3V, I
OUT
= 0mA to 150mA
V
IN
= 2.2V, I
OUT
= 0mA to 150mA
V
IN
= 2.0V, I
OUT
= 0mA to 100mA
V
IN
= 2.2V, I
OUT
= 0mA to 150mA
V
IN
= 1.75V, I
OUT
= 0mA to 100mA
V
IN
= 2.2V, I
OUT
= 0mA to 150mA
V
IN
= 1.75V, I
OUT
= 0mA to 100mA
I
OUT
= 50mA
I
OUT
= 150mA
I
OUT
= 50mA
I
OUT
= 150mA
I
OUT
= 50mA
I
OUT
= 150mA
I
OUT
= 50mA
I
OUT
= 150mA
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
The
●
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= V
OUT
+ 0.5V, unless otherwise noted. (Note 2)
MIN
–1.50
–2.00
–2.50
–1.50
–1.75
–3.50
–1.50
–1.75
–3.50
1.233
1.230
1.208
1.233
1.230
1.208
1.25
TYP
MAX
1.50
2.00
2.00
1.50
1.75
1.75
1.50
1.75
1.75
1.271
1.274
1.274
1.271
1.274
1.274
20
20
20
20
20
30
20
20
80
20
20
80
20
20
80
20
20
20
20
20
40
20
50
20
50
55
150
60
165
75
200
120
300
UNITS
%V
OUT
%V
OUT
%V
OUT
%V
OUT
%V
OUT
%V
OUT
%V
OUT
%V
OUT
%V
OUT
V
V
V
V
V
V
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
1844fa
1.25
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
9
9
9
9
9
9
9
9
9
9
30
90
35
105
45
135
85
230
LTC1844-1.5
LTC1844-BYP
LTC1844-SD
∆V
LDR
Load Regulation (Notes 3, 5)
LTC1844-3.3
LTC1844-2.8
LTC1844-2.5
LTC1844-1.8
LTC1844-1.5
LTC1844-BYP
LTC1844-SD
∆V
DO
Dropout Voltage (Notes 6, 7)
LTC1844-3.3
LTC1844-2.8
LTC1844-2.5
LTC1844-1.8
3
LTC1844 Series
ELECTRICAL CHARACTERISTICS
SYMBOL
PARAMETER
CONDITIONS
LTC1844-1.5
LTC1844-BYP
LTC1844-SD
I
LIM
e
n
V
SHDN
t
DELAY
T
SHDN
∆T
SHDN
I
ADJ
I
IRL
Output Current Limit
Output Voltage Noise
SHDN Input Threshold
Shutdown Exit Delay
Thermal Shutdown Limit
Thermal Shutdown Hysteresis
ADJ Pin Bias Current
Input Reverse Leakage Current
(Notes 3, 8)
LTC1844-3.3, LTC1844-2.8, LTC1844-2.5, LTC1844-1.8,
LTC1844-1.5, V
IN
= –5V, V
OUT
= 0V
LTC1844-BYP, LTC1844-SD, V
IN
= –5V, V
OUT
= 0V
I
ORL
V
OSH
V
RP
Output Reverse Leakage Current
(Note 9)
Start-Up Overshoot
Output Ripple Rejection
V
IN
= 0V, V
OUT
= V
OUT(NOMINAL)
V
IN
= 0V, V
OUT
= V
OUT(NOMINAL)
R
L
= 1k, SHDN Rise Time
≤
1µs
(V
IN
– V
OUT
) = 1V (Avg), V
RIPPLE
= 0.5V
P-P
,
f
RIPPLE
= 120Hz, I
LOAD
= 100mA
●
●
●
●
The
●
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= V
OUT
+ 0.5V, unless otherwise noted. (Note 2)
MIN
I
OUT
= 50mA
I
OUT
= 150mA
I
OUT
= 50mA
I
OUT
= 150mA
I
OUT
= 50mA
I
OUT
= 150mA
●
●
●
●
●
●
●
TYP
115
350
45
135
45
135
MAX
160
450
75
200
75
200
UNITS
mV
mV
mV
mV
mV
mV
mA
µV
RMS
µV
RMS
160
350
60
65
f = 10Hz to 100kHz, C
BP
= 0.1µF, C
OUT
= 10µF, I
L
= 150mA
f = 10Hz to 100kHz, C
BP
= 0.1µF, C
OUT
= 1µF, I
L
= 150mA
●
0.35
0.65
70
0.9
100
200
V
µs
µs
°C
°C
C
BP
= 0.01µF, C
OUT
= 1µF, No load
C
BP
= 0.01µF, C
OUT
= 1µF, No load
●
155
10
30
200
1000
0.01
2
50
100
500
1500
0.1
1.2
nA
µA
µA
µA
µA
%V
OUT
dB
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
The LTC1844 is tested and specified under pulse load conditions
such that T
J
≈
T
A
. The LTC1844E is guaranteed to meet performance
specifications from 0°C to 70°C. Specifications over the – 40°C to 125°C
operating junction temperature range are assured by design,
characterization and correlation with statistical process controls.
Note 3:
The LTC1844 adjustable versions are tested and specified for
these conditions with the ADJ pin connected to the OUT pin for a
V
OUT(NOMINAL)
of 1.25V.
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:
The LTC1844’s high precision degrades slightly at high
temperatures (T
J
> 70°C) with input voltages below 2.2V. The lower output
voltage versions have been split into higher and lower accuracy input
voltage ranges to reflect this.
Note 6:
To ensure adequate input supply voltage, the LTC1844 adjustable
versions are tested and specified for these conditions with an external
resistor divider (two 100k resistors) for an output voltage of 2.50V. The
external resistor divider will add a 5µA load on the output.
Note 7:
Dropout voltage is (V
IN
– V
OUT
) when V
OUT
falls to 100mV below
its nominal value measured at V
IN
= V
OUT
+ 0.5V. For example, the
LTC1844-3.3 is tested by measuring the V
OUT
at V
IN
= 3.8V, then V
IN
is
lowered until V
OUT
falls 100mV below the measured value. The difference
(V
IN
– V
OUT
) is then measured and defined as
∆V
DO
.
Note 8:
ADJ pin bias current flows into the ADJ pin.
Note 9:
Output reverse leakage current is tested with the IN pin grounded
and the OUT pin forced to the rated output voltage.
Note 10:
This IC includes overtemperature protection that is intended to
protect the device during momentary overload conditions. Junction
temperature will exceed 125°C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may impair device reliability.
1844fa
4
LTC1844 Series
TYPICAL PERFOR A CE CHARACTERISTICS
V
OUT
vs Temperature
1.520
1.515
1.510
V
OUT
(V)
V
OUT
= 1.5V
1.500
1.495
1.490
1.485
1.480
– 50 – 25
0
50
75
25
TEMPERATURE (°C)
100
125
V
OUT
(V)
V
OUT
(V)
1.505
V
OUT
vs Temperature
2.820
2.815
2.810
V
OUT
= 2.8V
3.320
3.315
3.310
V
OUT
(V)
V
OUT
(V)
2.800
2.795
2.790
2.785
2.780
– 50 – 25
0
50
75
25
TEMPERATURE (°C)
100
125
3.300
3.295
3.290
3.285
3.280
– 50 – 25
0
50
75
25
TEMPERATURE (°C)
100
125
V
OUT
(V)
2.805
Quiescent Current vs Temperature
70
60
50
500
450
400
350
300
250
SHDN THRESHOLD (mV)
CURRENT LIMIT (mA)
I
Q
(µA)
40
30
20
10
0
–50 –25
50
25
75
0
TEMPERATURE (°C)
U W
1844 G01
1844 G04
V
OUT
vs Temperature
1.820
1.815
1.810
1.805
1.800
1.795
1.790
1.785
1.780
– 50 – 25
0
50
75
25
TEMPERATURE (°C)
100
125
V
OUT
= 1.8V
2.520
2.515
2.510
2.505
2.500
2.495
2.490
2.485
V
OUT
vs Temperature
V
OUT
= 2.5V
2.480
– 50 – 25
0
50
75
25
TEMPERATURE (°C)
100
125
1844 G02
1844 G03
V
OUT
vs Temperature
V
OUT
= 3.3V
1.270
1.265
1.260
1.255
1.250
1.245
1.240
1.235
V
OUT
vs Temperature
V
OUT
= ADJ
3.305
1.230
– 50 – 25
0
50
75
25
TEMPERATURE (°C)
100
125
1844 G05
1844 G05
Current Limit vs Temperature
V
OUT
= 2.8V
800
750
700
650
600
550
500
450
50
25
75
0
TEMPERATURE (°C)
100
125
SHDN Threshold vs Temperature
I
LOAD
= 1mA
100
125
200
–50 –25
400
– 50 – 25
0
50
75
25
TEMPERATURE (°C)
100
125
1844 G07
1844 G08
1844 G09
1844fa
5
51单片机
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