LINER LT3080-1

LT3008 Series
3µA IQ, 20mA, 45V
Low Dropout Linear Regulators
FEATURES
DESCRIPTION
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The LT®3008 series are micropower, low dropout voltage
(LDO) linear regulators. The devices supply 20mA output
current with a dropout voltage of 300mV. No-load quiescent
current is 3μA. Ground pin current remains at less than
5% of output current as load increases. In shutdown,
quiescent current is less than 1μA.
n
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Ultralow Quiescent Current: 3μA
Input Voltage Range: 2.0V to 45V
Output Current: 20mA
Dropout Voltage: 300mV
Adjustable Output (VADJ = VOUT(MIN) = 600mV)
Fixed Output Voltages: 1.2V, 1.5V, 1.8V, 2.5V, 3.3V, 5V
Output Tolerance: ±2% Over Load, Line and
Temperature
Stable with Low ESR, Ceramic Output Capacitors
(2.2μF Minimum)
Shutdown Current: <1μA
Current Limit Protection
Reverse-Battery Protection
Thermal Limit Protection
TSOT-23 and 2mm × 2mm DFN Packages
APPLICATIONS
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Automotive
Low Current Battery-Powered Systems
Keep-Alive Power Supplies
Remote Monitoring
Utility Meters
Low Power Industrial Applications
The LT3008 regulators optimize stability and transient
response with low ESR ceramic capacitors, requiring a
minimum of only 2.2μF. The regulators do not require
the addition of ESR as is common with other regulators.
Internal protection circuitry includes current limiting,
thermal limiting, reverse-battery protection and reversecurrent protection.
The LT3008 series are ideal for applications that require
moderate output drive capability coupled with ultralow
standby power consumption. The device is available in
fixed output voltages of 1.2V, 1.5V, 1.8V, 2.5V, 3.3V and
5V, and an adjustable version with an output voltage range
of 0.6V to 44.5V. The LT3008 is available in the thermally
enhanced 6-lead DFN and 8-lead TSOT-23 packages.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
3.3V, 20mA Supply with Shutdown
Dropout Voltage/Quiescent Current
500
OUT
2.2μF
1μF
VOUT
3.3V
20mA
LT3008-3.3
SHDN
SENSE
GND
3008 TA01a
DROPOUT VOLTAGE (mV)
IN
6
ILOAD = 20mA
DROPOUT
VOLTAGE
400
350
5
4
300
250
IQ
3
200
2
150
100
QUIESCENT CURRENT (μA)
VIN
3.8V TO
45V
450
1
50
0
–50 –25
0
0
25 50 75 100 125 150
TEMPERATURE (°C)
3008 TA01b
3008fc
1
LT3008 Series
ABSOLUTE MAXIMUM RATINGS
(Note 1)
IN Pin Voltage .........................................................±50V
OUT Pin Voltage ......................................................±50V
Input-to-Output Differential Voltage ........................±50V
ADJ Pin Voltage ......................................................±50V
SENSE Pin Voltage ..................................................±50V
SHDN Pin Voltage (Note 8) .....................................±50V
Output Short-Circuit Duration .......................... Indefinite
Operating Junction Temperature Range (Notes 2, 3)
E, I Grade ...........................................–40°C to 125°C
MP Grade...........................................–55°C to 125°C
Storage Temperature Range...................–65°C to 150°C
Lead Temperature: Soldering, 10 sec
TS8 Package Only ............................................. 300°C
PIN CONFIGURATION
TOP VIEW
TOP VIEW
6 GND
**SENSE/ADJ 1
OUT 2
7
OUT 3
SHDN
GND
GND
GND
5 SHDN
4 IN
1
2
3
4
8
7
6
5
NC
ADJ/SENSE**
OUT
IN
TS8 PACKAGE
8-LEAD PLASTIC TSOT-23
DC PACKAGE
6-LEAD (2mm s 2mm) PLASTIC DFN
TJMAX = 125°C, θJA = 65°C/W TO 85°C/W*
EXPOSED PAD (PIN 7) IS GND, MUST BE SOLDERED TO PCB
TJMAX = 125°C, θJA = 65°C/W TO 85°C/W*
* See the Applications Information Section.
** SENSE for Fixed Voltage Output Versions.
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LT3008EDC#PBF
LT3008EDC#TRPBF
LDPS
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008IDC#PBF
LT3008IDC#TRPBF
LDPS
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008EDC-1.2#PBF
LT3008EDC-1.2#TRPBF
LFHC
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008IDC-1.2#PBF
LT3008IDC-1.2#TRPBF
LFHC
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008EDC-1.5#PBF
LT3008EDC-1.5#TRPBF
LFHF
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008IDC-1.5#PBF
LT3008IDC-1.5#TRPBF
LFHF
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008EDC-1.8#PBF
LT3008EDC-1.8#TRPBF
LFHH
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008IDC-1.8#PBF
LT3008IDC-1.8#TRPBF
LFHH
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008EDC-2.5#PBF
LT3008EDC-2.5#TRPBF
LFHK
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008IDC-2.5#PBF
LT3008IDC-2.5#TRPBF
LFHK
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008EDC-3.3#PBF
LT3008EDC-3.3#TRPBF
LFHN
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008IDC-3.3#PBF
LT3008IDC-3.3#TRPBF
LFHN
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008EDC-5#PBF
LT3008EDC-5#TRPBF
LFHQ
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008IDC-5#PBF
LT3008IDC-5#TRPBF
LFHQ
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008ETS8#PBF
LT3008ETS8#TRPBF
LTDSX
8-Lead Plastic TSOT-23
–40°C to 125°C
3008fc
2
LT3008 Series
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LT3008ITS8#PBF
LT3008ITS8#TRPBF
LTDSX
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008MPTS8#PBF
LT3008MPTS8#TRPBF
LTDSX
8-Lead Plastic TSOT-23
–55°C to 125°C
LT3008ETS8-1.2#PBF
LT3008ETS8-1.2#TRPBF
LTFHD
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008ITS8-1.2#PBF
LT3008ITS8-1.2#TRPBF
LTFHD
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008MPTS8-1.2#PBF
LT3008MPTS8-1.2#TRPBF
LTFHD
8-Lead Plastic TSOT-23
–55°C to 125°C
LT3008ETS8-1.5#PBF
LT3008ETS8-1.5#TRPBF
LTFHG
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008ITS8-1.5#PBF
LT3008ITS8-1.5#TRPBF
LTFHG
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008MPTS8-1.5#PBF
LT3008MPTS8-1.5#TRPBF
LTFHG
8-Lead Plastic TSOT-23
–55°C to 125°C
LT3008ETS8-1.8#PBF
LT3008ETS8-1.8#TRPBF
LTFHJ
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008ITS8-1.8#PBF
LT3008ITS8-1.8#TRPBF
LTFHJ
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008MPTS8-1.8#PBF
LT3008MPTS8-1.8#TRPBF
LTFHJ
8-Lead Plastic TSOT-23
–55°C to 125°C
LT3008ETS8-2.5#PBF
LT3008ETS8-2.5#TRPBF
LTFHM
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008ITS8-2.5#PBF
LT3008ITS8-2.5#TRPBF
LTFHM
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008MPTS8-2.5#PBF
LT3008MPTS8-2.5#TRPBF
LTFHM
8-Lead Plastic TSOT-23
–55°C to 125°C
LT3008ETS8-3.3#PBF
LT3008ETS8-3.3#TRPBF
LTFHP
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008ITS8-3.3#PBF
LT3008ITS8-3.3#TRPBF
LTFHP
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008MPTS8-3.3#PBF
LT3008MPTS8-3.3#TRPBF
LTFHP
8-Lead Plastic TSOT-23
–55°C to 125°C
LT3008ETS8-5#PBF
LT3008ETS8-5#TRPBF
LTFHR
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008ITS8-5#PBF
LT3008ITS8-5#TRPBF
LTFHR
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008MPTS8-5#PBF
LT3008MPTS8-5#TRPBF
LTFHR
8-Lead Plastic TSOT-23
–55°C to 125°C
LEAD BASED FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LT3008EDC
LT3008EDC#TR
LDPS
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008IDC
LT3008IDC#TR
LDPS
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008EDC-1.2
LT3008EDC-1.2#TR
LFHC
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008IDC-1.2
LT3008IDC-1.2#TR
LFHC
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008EDC-1.5
LT3008EDC-1.5#TR
LFHF
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008IDC-1.5
LT3008IDC-1.5#TR
LFHF
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008EDC-1.8
LT3008EDC-1.8#TR
LFHH
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008IDC-1.8
LT3008IDC-1.8#TR
LFHH
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008EDC-2.5
LT3008EDC-2.5#TR
LFHK
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008IDC-2.5
LT3008IDC-2.5#TR
LFHK
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008EDC-3.3
LT3008EDC-3.3#TR
LFHN
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008IDC-3.3
LT3008IDC-3.3#TR
LFHN
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008EDC-5
LT3008EDC-5#TR
LFHQ
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008IDC-5
LT3008IDC-5#TR
LFHQ
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
LT3008ETS8
LT3008ETS8#TR
LTDSX
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008ITS8
LT3008ITS8#TR
LTDSX
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008MPTS8
LT3008MPTS8#TR
LTDSX
8-Lead Plastic TSOT-23
–55°C to 125°C
LT3008ETS8-1.2
LT3008ETS8-1.2#TR
LTFHD
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008ITS8-1.2
LT3008ITS8-1.2#TR
LTFHD
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008MPTS8-1.2
LT3008MPTS8-1.2#TR
LTFHD
8-Lead Plastic TSOT-23
–55°C to 125°C
3008fc
3
LT3008 Series
ORDER INFORMATION
LEAD BASED FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LT3008ETS8-1.5
LT3008ETS8-1.5#TR
LTFHG
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008ITS8-1.5
LT3008ITS8-1.5#TR
LTFHG
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008MPTS8-1.5
LT3008MPTS8-1.5#TR
LTFHG
8-Lead Plastic TSOT-23
–55°C to 125°C
LT3008ETS8-1.8
LT3008ETS8-1.8#TR
LTFHJ
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008ITS8-1.8
LT3008ITS8-1.8#TR
LTFHJ
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008MPTS8-1.8
LT3008MPTS8-1.8#TR
LTFHJ
8-Lead Plastic TSOT-23
–55°C to 125°C
LT3008ETS8-2.5
LT3008ETS8-2.5#TR
LTFHM
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008ITS8-2.5
LT3008ITS8-2.5#TR
LTFHM
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008MPTS8-2.5
LT3008MPTS8-2.5#TR
LTFHM
8-Lead Plastic TSOT-23
–55°C to 125°C
LT3008ETS8-3.3
LT3008ETS8-3.3#TR
LTFHP
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008ITS8-3.3
LT3008ITS8-3.3#TR
LTFHP
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008MPTS8-3.3
LT3008MPTS8-3.3#TR
LTFHP
8-Lead Plastic TSOT-23
–55°C to 125°C
LT3008ETS8-5
LT3008ETS8-5#TR
LTFHR
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008ITS8-5
LT3008ITS8-5#TR
LTFHR
8-Lead Plastic TSOT-23
–40°C to 125°C
LT3008MPTS8-5
LT3008MPTS8-5#TR
LTFHR
8-Lead Plastic TSOT-23
–55°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TJ = 25°C. (Note 2)
PARAMETER
CONDITIONS
MIN
l
2
LT3008-1.2: VIN = 2V, ILOAD = 100μA
2V < VIN < 45V, 1μA < ILOAD < 20mA
l
1.188
1.176
LT3008-1.5: VIN = 2.05V, ILOAD = 100μA
2.05V < VIN < 45V, 1μA < ILOAD < 20mA
l
LT3008-1.8: VIN = 2.35V, ILOAD = 100μA
2.35V < VIN < 45V, 1μA < ILOAD < 20mA
TYP
MAX
UNITS
45
V
1.2
1.2
1.212
1.224
V
V
1.485
1.47
1.5
1.5
1.515
1.53
V
V
l
1.782
1.764
1.8
1.8
1.818
1.836
V
V
LT3008-2.5: VIN = 3.05V, ILOAD = 100μA
3.05V < VIN < 45V, 1μA < ILOAD < 20mA
l
2.475
2.45
2.5
2.5
2.525
2.55
V
V
LT3008-3.3: VIN = 3.85V, ILOAD = 100μA
3.85V < VIN < 45V, 1μA < ILOAD < 20mA
l
3.267
3.234
3.3
3.3
3.333
3.366
V
V
LT3008-5: VIN = 5.55V, ILOAD = 100μA
5.55V < VIN < 45V, 1μA < ILOAD < 20mA
l
4.95
4.9
5
5
5.05
5.1
V
V
ADJ Pin Voltage (Notes 3, 4)
VIN = 2V, ILOAD = 100μA
2V < VIN < 45V, 1μA < ILOAD < 20mA
l
594
588
600
600
606
612
mV
mV
Line Regulation (Note 3)
LT3008-1.2: ΔVIN = 2V to 45V, ILOAD = 1mA
LT3008-1.5: ΔVIN = 2.05V to 45V, ILOAD = 1mA
LT3008-1.8: ΔVIN = 2.35V to 45V, ILOAD = 1mA
LT3008-2.5: ΔVIN = 3.05V to 45V, ILOAD = 1mA
LT3008-3.3: ΔVIN = 3.85V to 45V, ILOAD = 1mA
LT3008-5: ΔVIN = 5.55V to 45V, ILOAD = 1mA
LT3008: ΔVIN = 2V to 45V, ILOAD = 1mA
l
l
l
l
l
l
l
1.2
1.5
1.8
2.5
3.3
5
0.6
6
7.5
9
12.5
16.5
25
3
mV
mV
mV
mV
mV
mV
mV
Operating Voltage
Regulated Output Voltage
3008fc
4
LT3008 Series
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TJ = 25°C. (Note 2)
PARAMETER
CONDITIONS
Load Regulation (Note 3)
LT3008-1.2: VIN = 2V, ILOAD = 1μA to 10mA
VIN = 2V, ILOAD = 1μA to 20mA
Dropout Voltage
VIN = VOUT(NOMINAL) (Notes 5, 6)
MIN
TYP
MAX
l
l
0.8
1
4
10
mV
mV
LT3008-1.5: VIN = 2.05V, ILOAD = 1μA to 10mA
VIN = 2.05V, ILOAD = 1μA to 20mA
l
l
1
1.3
5
13
mV
mV
LT3008-1.8: VIN = 2.35V, ILOAD = 1μA to 10mA
VIN = 2.35V, ILOAD = 1μA to 20mA
l
l
1.2
1.5
6
15
mV
mV
LT3008-2.5: VIN = 3.05V, ILOAD = 1μA to 10mA
VIN = 3.05V, ILOAD = 1μA to 20mA
l
l
1.7
2.1
8.3
21
mV
mV
LT3008-3.3: VIN = 3.85V, ILOAD = 1μA to 10mA
VIN = 3.85V, ILOAD = 1μA to 20mA
l
l
2.2
2.8
11
28
mV
mV
LT3008-5:
VIN = 5.55V, ILOAD = 1μA to 10mA
VIN = 5.55V, ILOAD = 1μA to 20mA
l
l
3.4
4.2
17
42
mV
mV
LT3008:
VIN = 2V, ILOAD = 1μA to 10mA
VIN = 2V, ILOAD = 1μA to 20mA
l
l
0.4
0.5
2
5
mV
mV
115
180
250
mV
mV
170
250
350
mV
mV
270
340
470
mV
mV
300
365
500
mV
mV
6
μA
μA
6
12
50
500
1200
μA
μA
μA
μA
μA
ILOAD = 100μA
ILOAD = 100μA
l
ILOAD = 1mA
ILOAD = 1mA
l
ILOAD = 10mA
ILOAD = 10mA
l
ILOAD = 20mA
ILOAD = 20mA
l
ILOAD = 0μA
ILOAD = 0μA
l
GND Pin Current
VIN = VOUT(NOMINAL) + 0.5V (Notes 6, 7)
ILOAD = 0μA
ILOAD = 100μA
ILOAD = 1mA
ILOAD = 10mA
ILOAD = 20mA
l
l
l
l
l
Output Voltage Noise (Note 9)
COUT = 2.2μF, ILOAD = 20mA, BW = 10Hz to 100kHz
Quiescent Current (Notes 6, 7)
VOUT = Off to On
VOUT = On to Off
l
l
VSHDN = 0V, VIN = 45V
VSHDN = 45V, VIN = 45V
l
l
Quiescent Current in Shutdown
VIN = 6V, VSHDN = 0V
l
Ripple Rejection (Note 3)
VIN – VOUT = 2V, VRIPPLE = 0.5VP-P,
fRIPPLE = 120Hz, ILOAD = 20mA
LT3008
LT3008-1.2
LT3008-1.5
LT3008-1.8
LT3008-2.5
LT3008-3.3
LT3008-5
SHDN Pin Current
3
6
21
160
350
92
ADJ Pin Bias Current
Shutdown Threshold
3
UNITS
μVRMS
–10
0.4
10
nA
0.67
0.61
1.5
0.25
V
V
±1
2
μA
μA
<1
μA
0.65
58
54
53
52
49
47
42
70
66
65
64
61
59
54
dB
dB
dB
dB
dB
dB
dB
3008fc
5
LT3008 Series
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TJ = 25°C. (Note 2)
PARAMETER
CONDITIONS
Current Limit
VIN = 45V, VOUT = 0
VIN = VOUT(NOMINAL) + 1V, ΔVOUT = – 5%
l
Input Reverse-Leakage Current
VIN = –45V, VOUT = 0
l
Reverse-Output Current
VOUT = 1.2V, VIN = 0
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LT3008 regulators are tested and specified under pulse
load conditions such that TJ ≅ TA. The LT3008E is guaranteed to meet
performance specifications from 0°C to 125°C operating junction
temperature. Specifications over the –40°C to 125°C operating junction
temperature range are assured by design, characterization and correlation
with statistical process controls. The LT3008I is guaranteed over the full
– 40°C to 125°C operating junction temperature range. The LT3008MP is
100% tested and guaranteed over the –55°C to 125°C operating junction
temperature range.
Note 3: The LT3008 adjustable version is tested and specified for these
conditions with the ADJ pin connected to the OUT pin.
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 the maximum input voltage, the output current range must be
limited. When operating at the maximum output current, the input voltage
must be limited.
MIN
TYP
MAX
75
UNITS
mA
mA
22
1
30
μA
0.6
10
μA
Note 5: Dropout voltage is the minimum input to output voltage differential
needed to maintain regulation at a specified output current. In dropout, the
output voltage equals (VIN – VDROPOUT). For the LT3008-1.2 and LT30081.5, dropout voltage will be limited by the minimum input voltage.
Note 6: To satisfy minimum input voltage requirements, the LT3008
adjustable version is tested and specified for these conditions with an
external resistor divider (61.9k bottom, 280k top) which sets VOUT to 3.3V.
The external resistor divider adds 9.69μA of DC load on the output. This
external current is not factored into GND pin current.
Note 7: GND pin current is tested with VIN = VOUT(NOMINAL) + 0.55V and
a current source load. GND pin current will increase in dropout. For the
fixed output voltage versions, an internal resistor divider will add about
1μA to the GND pin current. See the GND Pin Current curves in the Typical
Performance Characteristics section.
Note 8: The SHDN pin can be driven below GND only when tied to the IN
pin directly or through a pull-up resistor. If the SHDN pin is driven below
GND by more than –0.3V while IN is powered, the output will turn on.
Note 9: Output noise is listed for the adjustable version with the ADJ pin
connected to the OUT pin. See the RMS Output Noise vs Load Current
curve in the Typical Performance Characteristics Section.
3008fc
6
LT3008 Series
TYPICAL PERFORMANCE CHARACTERISTICS
Dropout Voltage
Dropout Voltage
350
300
DROPOUT VOLTAGE (mV)
DROPOUT VOLTAGE (mV)
TJ = 125°C
TJ = 25°C
250
200
150
100
2
400
1.8
350
200
100μA
100
0
6 8 10 12 14 16 18 20
OUTPUT CURRENT (mA)
1mA
150
0
4
10mA
250
50
2
20mA
300
50
0
Minimum Input Voltage
450
–50 –25
1.4
1.2
1
0.8
0.6
0.4
0
25
50
75
0
100 125 150
–50 –25
1.224
IL = 100μA
1.220
1.530
ILOAD = 100μA
1.525
1.520
1.212
1.515
0.596
0.594
OUTPUT VOLTAGE (V)
1.216
0.598
1.208
1.204
1.200
1.196
1.192
1.188
1.510
1.505
1.500
1.495
1.490
1.485
1.184
1.480
0.590
1.180
1.176
–50 –25
1.475
1.470
–50 –25
0
25
50
75
100 125 150
0
TEMPERATURE (°C)
25
100 125 150
ILOAD = 100μA
0.592
0.588
–50 –25
75
Output Voltage
LT3008-1.5
0.606
0.600
50
3008 G03
0.608
0.602
25
TEMPERATURE (°C)
Output Voltage
LT3008-1.2
0.604
0
3008 G02
OUTPUT VOLTAGE (V)
ADJ PIN VOLTAGE (V)
1.6
TEMPERATURE (°C)
ADJ Pin Voltage
0.610
ILOAD = 20mA
0.2
3008 G01
0.612
MINIMUM INPUT VOLTAGE (V)
450
400
TA = 25°C, unless otherwise noted.
50
75
TEMPERATURE (°C)
100 125 150
0
25
50
75
TEMPERATURE (°C)
3008 G05
100 125 150
3008 G06
3008 G04
Output Voltage
LT3008-1.8
1.830
2.550
ILOAD = 100μA
2.540
1.812
1.806
1.800
1.794
1.788
1.782
3.355
3.344
2.520
2.510
2.500
2.490
2.480
2.470
1.776
1.770
1.764
–50 –25
3.366
ILOAD = 100μA
2.530
1.816
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
1.824
Output Voltage
LT3008-3.3
OUTPUT VOLTAGE (V)
1.836
Output Voltage
LT3008-2.5
0
25
50
75
TEMPERATURE (°C)
100 125 150
3008 G07
3.333
3.322
3.311
3.300
3.289
3.278
3.267
3.256
2.460
2.450
–50 –25
ILOAD = 100μA
3.245
0
25
50
75
TEMPERATURE (°C)
100 125 150
3008 G08
3.234
–50 –25
0
25
50
75
TEMPERATURE (°C)
100 125 150
3008 G09
3008fc
7
LT3008 Series
TYPICAL PERFORMANCE CHARACTERISTICS
Output Voltage
LT3008-5
ADJ Pin Bias Current
5.100
Adjustable Quiescent Current
10
ILOAD = 100μA
6
8
5.050
5.025
5.000
4.975
4.950
4.925
5
6
QUIESCENT CURRENT (μA)
ADJ PIN BIAS CURRENT (nA)
5.075
OUTPUT VOLTAGE (V)
TA = 25°C, unless otherwise noted.
4
2
0
–2
–4
–6
4
3
2
1
–8
4.900
–50 –25
0
25
50
75
–10
100 125 150
TEMPERATURE (°C)
–50 –25
0
25
50
75
0
–50 –25
100 125 150
0
TEMPERATURE (°C)
3008 G10
25
50
75
100 125 150
TEMPERATURE (°C)
3008 G05
GND Pin Current
LT3008-1.2
Quiescent Current
QUIESCENT CURRENT (μA)
24
21
18
GND PIN CURRENT (μA)
LT3008-1.2
LT3008-1.5
LT3008-1.8
LT3008-2.5
LT3008-3.3
LT3008-5
27
15
12
9
500
500
450
450
400
400
350
250
200
100
50
0
0
3
4
5
6
7
8
RL = 120Ω, IL = 10mA
150
3
2
RL = 60Ω, IL = 20mA
300
6
1
GND Pin Current
LT3008-1.5
GND PIN CURRENT (μA)
30
0
3008 G06
9 10
350
RL = 75Ω, IL = 20mA
300
250
200
RL = 150Ω, IL = 10mA
150
100
RL = 12k, IL = 100μA
RL = 15k, IL = 100μA
50
RL = 1.2k, IL = 1mA
RL = 1.5k, IL = 1mA
0
0
1
2
INPUT VOLTAGE (V)
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
3008 G14
9
10
3008 G15
3008 G13
GND Pin Current
LT3008-2.5
GND Pin Current
LT3008-3.3
500
500
450
450
450
400
400
400
350
RL = 90Ω, IL = 20mA
300
250
200
RL = 180Ω, IL = 10mA
150
100
RL = 125Ω, IL = 20mA
300
250
200
RL = 250Ω, IL = 10mA
150
100
RL = 18k, IL = 100μA
50
350
0
RL = 2.5k, IL = 1mA
0
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
3008 G16
RL = 165Ω, IL = 20mA
350
300
250
200
RL = 330Ω, IL = 10mA
150
100
RL = 25k, IL = 100μA
50
RL = 1.8k, IL = 1mA
GND PIN CURRENT (μA)
500
GND PIN CURRENT (μA)
GND PIN CURRENT (μA)
GND Pin Current
LT3008-1.8
RL = 33k, IL = 100μA
50
RL = 3.3k, IL = 1mA
0
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
3008 G17
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
3008 G18
3008fc
8
LT3008 Series
TYPICAL PERFORMANCE CHARACTERISTICS
GND Pin Current
LT3008-5
TA = 25°C, unless otherwise noted.
SHDN Pin Thresholds
GND Pin Current vs ILOAD
1000
500
450
VIN = 3.8V
VOUT = 3.3V
300
250
200
RL = 500Ω, IL = 10mA
150
SHDN PIN THRESHOLD (V)
RL = 250Ω, IL = 20mA
350
GND CURRENT (μA)
GND PIN CURRENT (μA)
400
100
10
RL = 50k, IL = 100μA
100
50
RL = 5k, IL = 1mA
0
0
1
3 4 5 6 7
INPUT VOLTAGE (V)
2
8
9
1
0.001
10
0.01
0.1
1
10
100
1.5
1.4
1.3
1.2
1.1
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
–50 –25
OFF TO ON
ON TO OFF
0
LOAD (mA)
3008 G19
25 50 75 100 125 150
TEMPERATURE (°C)
3008 G21
3008 G20
SHDN Pin Input Current
Current Limit
100
1.8
1.8
90
1.6
80
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
5
10
15 20 25 30 35
SHDN PIN VOLTAGE (V)
1.2
1
VSHDN = 45V
0.8
0.6
40 45
INPUT RIPPLE REJECTION (dB)
REVERSE OUTPUT CURRENT (μA)
30
25
20
15
ADJ
0
–50 –25
OUT
0
25 50 75 100 125 150
TEMPERATURE (°C)
3008 G25
25 50 75 100 125 150
TEMPERATURE (°C)
Input Ripple Rejection
VIN = 2.1V + 50mVRMS
VOUT = 600mV
ILOAD = 20mA
80
35
0
3008 G24
Input Ripple Rejection
90
40
5
0
–50 –25
25 50 75 100 125 150
TEMPERATURE (°C)
3008 G23
OUT = ADJ = 1.2V
IN = SHDN = GND
10
30
10
Reverse-Output Current
45
VIN = 2V
40
20
3008 G22
50
60
50
0.2
0
VIN = 45V
70
0.4
70
60
50
40
10μF
30
20
2.2μF
10
100
1000
10000
70
60
50
40
30
20
10
10
0
80
INPUT RIPPLE REJECTION (dB)
0
1.4
0
–50 –25
0
CURRENT LIMIT (mA)
2
SHDN PIN INPUT CURRENT (μA)
SHDN PIN INPUT CURRENT (μA)
SHDN Pin Input Current
2
100000 1000000
FREQUENCY (Hz)
3008 G26
VIN = VOUT (NOMINAL) + 2V + 0.5VP-P
RIPPLE AT f = 120Hz
ILOAD = 20mA
0
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
3008 G27
3008fc
9
LT3008 Series
TYPICAL PERFORMANCE CHARACTERISTICS
$IL = 1μA to 20mA
VOUT = 600mV
VIN = 2V
4
LOAD REGULATION (mV)
OUTPUT NOISE SPECTRAL DENSITY (μV Hz)
5
4.5
3.5
3
2.5
2
1.5
1
0.5
0
–50 –25
0
RMS Output Noise
vs Load Current
Output Noise Spectral Density
25 50 75 100 125 150
TEMPERATURE (°C)
100
COUT = 2.2μF
ILOAD = 20mA
5V
3.3V
2.5V
1.8V
1.5V
1V
0.6V
10
1
0.1
10
100
1k
10k
FREQUENCY (Hz)
100k
500
450
5V
350
3.3V
300
2.5V
250
1.8V
200
1.5V
150
100
1.2V
50
0.6V
0
0.001
0.01
0.1
1
3008 G30
Transient Response
Transient Response
IOUT = 1mA TO 20mA
VIN = 5.5V
VOUT = 5V
COUT = 2.2μF
100
10
ILOAD (mA)
3008 G29
3008 G28
Transient Response (Load Dump)
IOUT = 1mA TO 20mA
VIN = 5.5V
VOUT = 5V
COUT = 10μF
VOUT
50mV/DIV
COUT = 10μF
400
OUTPUT NOISE (μVRMS)
Load Regulation
TA = 25°C, unless otherwise noted.
VOUT
50mV/DIV
VOUT
50mV/DIV
IOUT
20mA/DIV
500μs/DIV
3008 G31
45V
VOUT = 5V
IOUT = 20mA
COUT = 4.7μF
VIN
10V/DIV
IOUT
20mA/DIV
500μs/DIV
3008 G32
1ms/DIV
12V
3008 G33
3008fc
10
LT3008 Series
PIN FUNCTIONS
(TSOT-23/DFN)
SHDN (Pin 1/Pin 5): Shutdown. Pulling the SHDN pin
low puts the LT3008 into a low power state and turns the
output off. If unused, tie the SHDN pin to VIN. The LT3008
does not function if the SHDN pin is not connected. The
SHDN pin cannot be driven below GND unless tied to the
IN pin. If the SHDN pin is driven below GND while IN is
powered, the output will turn on. SHDN pin logic cannot
be referenced to a negative rail.
GND (Pins 2, 3, 4/Pin 6): Ground. Connect the bottom
of the resistor divider that sets output voltage directly to
GND for the best regulation.
IN (Pin 5/Pin 4): Input. The IN pin supplies power to the
device. The LT3008 requires a bypass capacitor at IN if
the device is more than six inches away from the main
input filter capacitor. In general, the output impedance of
a battery rises with frequency, so it is advisable to include
a bypass capacitor in battery-powered circuits. A bypass
capacitor in the range of 0.1μF to 10μF will suffice. The
LT3008 withstands reverse voltages on the IN pin with
respect to ground and the OUT pin. In the case of a reversed
input, which occurs with a battery plugged in backwards,
the LT3008 acts as if a blocking diode is in series with its
input. No reverse current flows into the LT3008 and no
reverse voltage appears at the load. The device protects
both itself and the load.
OUT (Pin 6/Pins 2, 3): Output. This pin supplies power
to the load. Use a minimum output capacitor of 2.2μF
to prevent oscillations. Large load transient applications
require larger output capacitors to limit peak voltage
transients. See the Applications Information section for
more information on output capacitance and reverse-output
characteristics.
ADJ (Pin 7/Pin 1): Adjust. This pin is the error amplifier’s
inverting terminal. Its 400pA typical input bias current
flows out of the pin (see curve of ADJ Pin Bias Current vs
Temperature in the Typical Performance Characteristics
section). The ADJ pin voltage is 600mV referenced to GND
and the output voltage range is 600mV to 44.5V.
NC (Pin 8, TSOT-23 Package Only): No Connect. Pin 8
is an NC pin in the TSOT-23 package. This pin is not tied
to any internal circuitry. It may be floated, tied to VIN or
tied to GND.
GND (Exposed Pad Pin 7, DFN Package Only): Ground. The
exposed pad (backside) of the DFN package is an electrical
connection to GND. To ensure optimum performance,
solder Pin 7 to the PCB and tie directly to Pin 6.
SENSE (Pin 7/Pin 1): Sense. For fixed voltage versions of
the LT3008 (LT3008-1.2, LT3008-1.5, LT3008-1.8, LT30082.5, LT3008-3.3, LT3008-5), the SENSE pin is the input to
the error amplifier. Optimum regulation is obtained at the
point where the SENSE pin is connected to the OUT pin of
the regulator. In critical applications, small voltage drops
are caused by the resistance (RP) of PC traces between
the regulator and the load. These may be eliminated by
connecting the SENSE pin to the output at the load as
shown in Figure 1 (Kelvin Sense Connection). Note that
the voltage drop across the external PC traces add to the
dropout voltage of the regulator. The SENSE pin bias current
is 1μA at the nominal rated output voltage. The SENSE pin
can be pulled below ground (as in a dual supply system
where the regulator load is returned to a negative supply)
and still allow the device to start and operate.
RP
IN
OUT
LT3008
+
VIN
SHDN
+
SENSE
LOAD
GND
RP
3008 F01
Figure 1. Kelvin Sense Connection
3008fc
11
LT3008 Series
APPLICATIONS INFORMATION
The LT3008 is a low dropout linear regulator with ultralow quiescent current and shutdown. Quiescent current
is extremely low at 3μA and drops well below 1μA in
shutdown. The device supplies up to 20mA of output current.
Dropout voltage at 20mA is typically 300mV. The LT3008
incorporates several protection features, making it ideal for
use in battery-powered systems. The device protects itself
against both reverse-input and reverse-output voltages.
In battery backup applications, where a backup battery
holds up the output when the input is pulled to ground,
the LT3008 acts as if a blocking diode is in series with its
output and prevents reverse current flow. In applications
where the regulator load returns to a negative supply, the
output can be pulled below ground by as much as 50V
without affecting start-up or normal operation.
Adjustable Operation
The LT3008 has an output voltage range of 0.6V to 44.5V.
Figure 2 shows that output voltage is set by the ratio of two
external resistors. The IC regulates the output to maintain
the ADJ pin voltage at 600mV referenced to ground. The
current in R1 equals 600mV/R1 and the current in R2 is
the current in R1 minus the ADJ pin bias current. The ADJ
pin bias current, typically 400pA at 25°C, flows out of the
pin. Calculate the output voltage using the formula in Figure
2. An R1 value of 619k sets the divider current to 0.97μA.
Do not make R1’s value any greater than 619k to minimize
output voltage errors due to the ADJ pin bias current and
VOUT = 600mV • (1 + R2/R1) – (IADJ • R2)
VADJ = 600mV
IADJ = 0.4nA at 25°C
OUTPUT RANGE = 0.6V to 44.5V
to insure stability under minimum load conditions. In
shutdown, the output turns off and the divider current is
zero. Curves of ADJ Pin Voltage vs Temperature and ADJ
Pin Bias Current vs Temperature appear in the Typical
Performance Characteristics.
Specifications for output voltages greater than 0.6V are
proportional to the ratio of the desired output voltage to
0.6V: VOUT/0.6V. For example, load regulation for an output
current change of 100μA to 20mA is –0.5mV typical at
VOUT = 0.6V. At VOUT = 5V, load regulation is:
5V
• (−0.5mV) = −4.17mV
0.6V
Table 1 shows resistor divider values for some common output voltages with a resistor divider current of
about 1μA.
Table 1. Output Voltage Resistor Divider Values
VOUT
R1
R2
1V
604k
402k
1.2V
590k
590k
1.5V
590k
887k
1.8V
590k
1.18M
2.5V
590k
1.87M
3V
590k
2.37M
3.3V
619k
2.8M
5V
590k
4.32M
IN
VIN
VOUT
OUT
LT3008
SHDN
GND
R2
ADJ
R1
3008 F02
Figure 2. Adjustable Operation
3008fc
12
LT3008 Series
APPLICATIONS INFORMATION
Because the ADJ pin is relatively high impedance (depending on the resistor divider used), stray capacitances
at this pin should be minimized. Special attention should
be given to any stray capacitances that can couple external signals onto the ADJ pin, producing undesirable
output transients or ripple.
Extra care should be taken in assembly when using high
valued resistors. Small amounts of board contamination
can lead to significant shifts in output voltage. Appropriate
post-assembly board cleaning measures should be
implemented to prevent board contamination. If the
board is to be subjected to humidity cycling or if board
cleaning measures cannot be guaranteed, consideration
should be given to using resistors an order of magnitude
smaller than in Table 1 to prevent contamination from
causing unwanted shifts in the output voltage. A fixed
voltage option in the LT3008 series will not need these
special considerations.
Output Capacitance and Transient Response
The LT3008 is stable with a wide range of output capacitors.
The ESR of the output capacitor affects stability, most
notably with small capacitors. Use a minimum output
capacitor of 2.2μF with an ESR of 3Ω or less to prevent
oscillations. The LT3008 is a micropower device and output
load transient response is a function of output capacitance.
Larger values of output capacitance decrease the peak
deviations and provide improved transient response for
larger load current changes.
Give extra consideration to the use of ceramic capacitors.
Manufacturers make ceramic capacitors with a variety of
dielectrics, each with different behavior across temperature
and applied voltage. The most common dielectrics are
specified with EIA temperature characteristic codes of
Z5U, Y5V, X5R and X7R. The Z5U and Y5V dielectrics
provide high C-V products in a small package at low cost,
but exhibit strong voltage and temperature coefficients as
shown in Figures 3 and 4. When used with a 5V regulator,
a 16V 10μF Y5V capacitor can exhibit an effective value
as low as 1μF to 2μF for the DC bias voltage applied and
over the operating temperature range. The X5R and
X7R dielectrics yield more stable characteristics and are
more suitable for use as the output capacitor. The X7R
type has better stability across temperature, while the
X5R is less expensive and is available in higher values.
One must still exercise care when using X5R and X7R
capacitors; the X5R and X7R codes only specify operating
temperature range and maximum capacitance change
over temperature. Capacitance change due to DC bias
with X5R and X7R capacitors is better than Y5V and Z5U
capacitors, but can still be significant enough to drop
capacitor values below appropriate levels. Capacitor DC
bias characteristics tend to improve as component case
size increases, but expected capacitance at operating
voltage should be verified.
Voltage and temperature coefficients are not the only
sources of problems. Some ceramic capacitors have a
40
20
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10μF
20
X5R
CHANGE IN VALUE (%)
CHANGE IN VALUE (%)
0
–20
–40
–60
Y5V
–80
–100
–20
–40
2
4
8
6
10 12
DC BIAS VOLTAGE (V)
14
16
3008 F03
Figure 3. Ceramic Capacitor DC Bias Characteristics
Y5V
–60
–80
0
X5R
0
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10μF
–100
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
125
3008 F04
Figure 4. Ceramic Capacitor Temperature Characteristics
3008fc
13
LT3008 Series
APPLICATIONS INFORMATION
piezoelectric response. A piezoelectric device generates
voltage across its terminals due to mechanical stress,
similar to the way a piezoelectric accelerometer or
microphone works. For a ceramic capacitor, the stress
can be induced by vibrations in the system or thermal
transients. The resulting voltages produced can cause
appreciable amounts of noise, especially when a ceramic
capacitor is used for noise bypassing. A ceramic capacitor
produced Figure 5’s trace in response to light tapping from a
pencil. Similar vibration induced behavior can masquerade
as increased output voltage noise.
VOUT = 0.6V
COUT = 22μF
ILOAD = 10μA
VOUT
500μV/DIV
GND pin current is found by examining the GND Pin
Current curves in the Typical Performance Characteristics
section. Power dissipation is equal to the sum of the two
components listed prior.
The LT3008 regulator has internal thermal limiting designed
to protect the device during overload conditions. For
continuous normal conditions, do not exceed the maximum
junction temperature rating of 125°C. Carefully consider
all sources of thermal resistance from junction to ambient
including other heat sources mounted in proximity to
the LT3008. For surface mount devices, heat sinking is
accomplished by using the heat spreading capabilities of
the PC board and its copper traces. Copper board stiffeners
and plated through-holes can also be used to spread the
heat generated by power devices.
The following tables list thermal resistance for several
different board sizes and copper areas. All measurements
were taken in still air on 3/32" FR-4 two-layer boards with
one ounce copper.
100ms/DIV
3008 F05
Figure 5. Noise Resulting from Tapping
on a Ceramic Capacitor
Thermal Considerations
The LT3008’s maximum rated junction temperature of
125°C limits its power-handling capability. Two components
comprise the power dissipated by the device:
PCB layers, copper weight, board layout and thermal vias
affect the resultant thermal resistance. Although Tables
2 and 3 provide thermal resistance numbers for 2-layer
boards with 1 ounce copper, modern multilayer PCBs
provide better performance than found in these tables.
Table 2: Measured Thermal Resistance for DC Package
COPPER AREA
TOPSIDE*
BACKSIDE
BOARD
AREA
THERMAL RESISTANCE
(JUNCTION-TO-AMBIENT)
1. Output current multiplied by the input/output voltage
differential: IOUT • (VIN – VOUT)
2500mm2
2500mm2
2500mm2
65°C/W
1000mm2
2500mm2
2500mm2
70°C/W
2. GND pin current multiplied by the input voltage:
IGND • VIN
225mm2
2500mm2
2500mm2
75°C/W
100mm2
2500mm2
2500mm2
80°C/W
50mm2
2500mm2
2500mm2
85°C/W
*Device is mounted on the topside.
3008fc
14
LT3008 Series
APPLICATIONS INFORMATION
Table 3: Measured Thermal Resistance for TSOT-23 Package
COPPER AREA
TOPSIDE*
BACKSIDE
BOARD
AREA
THERMAL RESISTANCE
(JUNCTION-TO-AMBIENT)
2500mm2
2500mm2
2500mm2
65°C/W
1000mm2
2500mm2
2500mm2
67°C/W
225mm2
2500mm2
2500mm2
70°C/W
100mm2
2500mm2
2500mm2
75°C/W
50mm2
2500mm2
2500mm2
85°C/W
*Device is mounted on the topside.
For example, a 4-layer, 1 ounce copper PCB board with
3 thermal vias from the DFN exposed backside or the
3 fused TSOT-23 GND pins to inner layer GND planes
achieves 45°C/W thermal resistance. Demo circuit DC
1388A’s board layout achieves this 45°C/W performance.
This is approximately a 30% improvement over the lowest
numbers shown in Tables 2 and 3.
Calculating Junction Temperature
Example: Given an output voltage of 3.3V, an input voltage
range of 12V ±5%, an output current range of 0mA to 20mA
and a maximum ambient temperature of 85°C, what will
the maximum junction temperature be for an application
using the DC package?
The power dissipated by the device is equal to:
IOUT(MAX) (VIN(MAX) – VOUT) + IGND (VIN(MAX))
where,
IOUT(MAX) = 20mA
VIN(MAX) = 12.6V
IGND at (IOUT = 20mA, VIN = 12.6V) = 0.3mA
So,
P = 20mA(12.6V – 3.3V) + 0.3mA(12.6V) = 189.8mW
The thermal resistance ranges from 65°C/W to 85°C/W
depending on the copper area. So, the junction temperature
rise above ambient approximately equals:
0.1898W(75°C/W) = 14.2°C
The maximum junction temperature equals the maximum
junction temperature rise above ambient plus the maximum
ambient temperature or:
TJ(MAX) = 85°C + 14.2°C = 99.2°C
Protection Features
The LT3008 incorporates several protection features that
make it ideal for use in battery-powered circuits. In addition to the normal protection features associated with
monolithic regulators, such as current limiting and thermal
limiting, the device also protects against reverse-input
voltages, reverse-output voltages and reverse output-toinput voltages.
Current limit protection and thermal overload protection protect the device against current overload conditions at the output of the device. For normal operation,
do not exceed a junction temperature of 125°C. The
typical thermal shutdown circuitry temperature threshold
is 160°C.
The IN pin withstands reverse voltages of 50V. The device
limits current flow to less than 30μA (typically less than
1μA) and no negative voltage appears at OUT. The device
protects both itself and the load against batteries that are
plugged in backwards.
3008fc
15
LT3008 Series
APPLICATIONS INFORMATION
The LT3008 incurs no damage if OUT is pulled below
ground. If IN is left open circuit or grounded, OUT can be
pulled below ground by 50V. No current flows from the
pass transistor connected to OUT. However, current flows
in (but is limited by) the resistor divider that sets output
voltage. Current flows from the bottom resistor in the
divider and from the ADJ pin’s internal clamp through the
top resistor in the divider to the external circuitry pulling
OUT below ground. If IN is powered by a voltage source,
OUT sources current equal to its current limit capability and
the LT3008 protects itself by thermal limiting if necessary.
In this case, grounding the SHDN pin turns off the LT3008
and stops OUT from sourcing current.
The LT3008 incurs no damage if the ADJ pin is pulled
above or below ground by 50V. If IN is left open circuit or
grounded, ADJ acts like a 100k resistor in series with a
diode when pulled above or below ground.
In circuits where a backup battery is required, several
different input/output conditions can occur. The output
voltage may be held up while the input is either pulled
to ground, pulled to some intermediate voltage or is left
open circuit. Current flow back into the output follows the
curve shown in Figure 6.
If the LT3008 IN pin is forced below the OUT pin or the
OUT pin is pulled above the IN pin, input current typically
drops to less than 1μA. This occurs if the LT3008 input is
connected to a discharged (low voltage) battery and either
a backup battery or a second regulator circuit holds up
the output. The state of the SHDN pin has no effect in the
reverse current if OUT is pulled above IN.
100
90
REVERSE CURRENT (μA)
The SHDN pin cannot be driven below GND unless tied to
the IN pin. If the SHDN pin is driven below GND while IN
is powered, the output will turn on. SHDN pin logic cannot
be referenced to a negative rail.
80
70
ADJ CURRENT
60
50
40
30
20
OUT CURRENT
10
0
0
1
2 3 4 5 6 7 8 9
OUTPUT AND ADJ VOLTAGE (V)
10
3008 F06
Figure 6. Reverse-Output Current
3008fc
16
LT3008 Series
TYPICAL APPLICATIONS
Keep-Alive Power Supply
NO PROTECTION
DIODES NEEDED!
VIN
12V
IN
1μF
3.3V
OUT
2.2μF
LT3008-3.3
SHDN
LOAD:
SYSTEM MONITOR,
VOLATILE MEMORY, ETC.
SENSE
GND
3009 TA02
Last-Gasp Circuit
LINE POWER
VLINE
12V TO 15V
SENSE
DCHARGE
LINE
INTERRUPT
DETECT
RLIMIT
IN
SUPERCAP
1μF
OUT
LT3008-5
5V
TO
MONITORING
CENTER
FAULT
PWR
GND
2.2μF
3008 TA03
SHDN
SENSE
GND
PACKAGE DESCRIPTION
DC6 Package
6-Lead Plastic DFN (2mm × 2mm)
(Reference LTC DWG # 05-08-1703 Rev B)
R = 0.125
TYP
0.56 ±0.05
(2 SIDES)
0.70 ±0.05
2.55 ±0.05
1.15 ±0.05 0.61 ±0.05
(2 SIDES)
PIN 1 BAR
PACKAGE
TOP MARK
OUTLINE
(SEE NOTE 6)
0.25 ±0.05
0.50 BSC
1.42 ±0.05
(2 SIDES)
0.200 REF
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WCCD-2)
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
0.40 ±0.10
4
6
2.00 ±0.10
(4 SIDES)
PIN 1 NOTCH
R = 0.20 OR
0.25 × 45°
CHAMFER
R = 0.05
TYP
0.75 ±0.05
(DC6) DFN REV B 1309
3
1
0.25 ±0.05
0.50 BSC
1.37 ±0.05
(2 SIDES)
0.00 – 0.05
BOTTOM VIEW—EXPOSED PAD
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE
TOP AND BOTTOM OF PACKAGE
3008fc
17
LT3008 Series
PACKAGE DESCRIPTION
TS8 Package
8-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1637 Rev A)
0.40
MAX
2.90 BSC
(NOTE 4)
0.65
REF
1.22 REF
1.4 MIN
3.85 MAX 2.62 REF
2.80 BSC
1.50 – 1.75
(NOTE 4)
PIN ONE ID
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
0.22 – 0.36
8 PLCS (NOTE 3)
0.65 BSC
0.80 – 0.90
0.20 BSC
0.01 – 0.10
1.00 MAX
DATUM ‘A’
0.30 – 0.50 REF
0.09 – 0.20
(NOTE 3)
1.95 BSC
TS8 TSOT-23 0710 REV A
NOTE:
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
3008fc
18
LT3008 Series
REVISION HISTORY
(Revision history begins at Rev B)
REV
DATE
DESCRIPTION
PAGE NUMBER
B
02/10
Added MP grade in TS8 package
Revised curve G04 in Typical Performance Characteristics
7
C
04/12
Clarified E-Grade Operating Temperature
6
Updated Package Drawings
2-4, 6
17, 18
3008fc
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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
19
LT3008 Series
TYPICAL APPLICATION
Low Duty Cycle Applications
IN
1μF
OUT
100
3.3V
90
2.2μF
LT3008-3.3
SHDN
LOW DUTY CYCLE
PULSED LOAD
0mA TO 10mA
SENSE
GND
3008 TA04a
80
POWER SAVINGS (%)
VIN
12V
Average Power Savings for Low Duty Cycle Applications
0mA to 10mA Pulsed Load, IN = 12V
70
60
100μA IQ
50
40
30μA IQ
30
20
10
0
0.1
10μA IQ
1
10
DUTY CYCLE (%)
3008 TA04b
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT1761
100mA, Low Noise Micropower LDO
VIN : 1.8V to 20V, VOUT = 1.22V, VDO = 0.3V, IQ = 20μA, ISD < 1μA, Low Noise: < 20μVRMS ,
Stable with 1μF Ceramic Capacitors, ThinSOTTM Package
LT1762
150mA, Low Noise Micropower LDO
VIN : 1.8V to 20V, VOUT = 1.22V, VDO = 0.3V, IQ = 25μA, ISD < 1μA, Low Noise: < 20μVRMS ,
MS8 Package
LT1763
500mA, Low Noise Micropower LDO
VIN : 1.8V to 20V, VOUT = 1.22V, VDO = 0.3V, IQ = 30μA, ISD < 1μA, Low Noise: < 20μVRMS ,
S8 Package
LT1764/LT1764A
3A, Low Noise, Fast Transient
Response LDOs
VIN : 2.7V to 20V, VOUT = 1.21V, VDO = 0.34V, IQ = 1mA, ISD < 1μA, Low Noise: < 40μVRMS ,
LT1764A Version Stable with Ceramic Capacitors, DD and TO220-5 Packages
LT1962
300mA, Low Noise Micropower LDO
VIN : 1.8V to 20V, VOUT(MIN) = 1.22V, VDO = 0.27V, IQ = 30μA, ISD < 1μA,
Low Noise: < 20μVRMS , MS8 Package
LT1963/LT1963A
1.5A, Low Noise, Fast Transient
Response LDOs
VIN : 2.1V to 20V, VOUT(MIN) = 1.21V, VDO = 0.34V, IQ = 1mA, ISD < 1μA,
Low Noise: < 40μVRMS , LT1963A Version Stable with Ceramic Capacitors, DD, TO220-5,
SOT223 and S8 Packages
LT3009
20mA, 3μA IQ Micropower LDO
VIN : 1.6V to 20V, Low IQ: 3μA, VDO = 0.28V, 2mm × 2mm DFN and SC70-8 Packages
LT3020
100mA, Low Voltage VLDO
VIN : 0.9V to 10V, VOUT(MIN) = 0.20V, VDO = 0.15V, IQ = 120μA, ISD < 1μA, 3mm × 3mm DFN
and MS8 Packages
LT3021
500mA, Low Voltage VLDO
VIN : 0.9V to 10V, VOUT(MIN) = 0.20V, VDO = 0.16V, IQ = 120μA, ISD < 3μA, 5mm × 5mm DFN
and SO8 Packages
LT3080/ LT3080-1 1.1A, Parallelable, Low Noise,
Low Dropout Linear Regulator
300mV Dropout Voltage (2-Supply Operation), Low Noise: 40μVRMS, VIN: 1.2V to 36V,
VOUT: 0V to 35.7V, Current-Based Reference with 1-Resistor VOUT Set; Directly Parallelable
(No Op Amp Required), Stable with Ceramic Caps, TO-220, SOT-223, MSOP and 3mm ×
3mm DFN Packages; LT3080-1 Version Has Integrated Internal Ballast Resistor
LT3085
275mV Dropout Voltage (2-Supply Operation), Low Noise: 40μVRMS , VIN: 1.2V to 36V,
VOUT: 0V to 35.7V, Current-Based Reference with 1-Resistor VOUT Set; Directly Parallelable
(No Op Amp Required), Stable with Ceramic Caps, MSOP-8 and 2mm × 3mm DFN Packages
500mA, Parallelable, Low Noise,
Low Dropout Linear Regulator
ThinSOT is a trademark of Linear Technology Corporation.
3008fc
20 Linear Technology Corporation
LT 0412 REV C • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2007