LT3008 Series
1
3008fc
TEMPERATURE (°C)
DROPOUT VOLTAGE (mV)
QUIESCENT CURRENT (µA)
400
3008 TA01b
200
100
50
0
500
300
250
150
5
350
2
3
1
0
6
450
4
–50 –25 0 25 50 75 100 125 150
ILOAD = 20mA DROPOUT
VOLTAGE
IQ
TYPICAL APPLICATION
FEATURES
APPLICATIONS
DESCRIPTION
3
µ
A IQ, 20mA, 45V
Low Dropout Linear Regulators
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.
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 reverse-
current 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
fi xed 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.
3.3V, 20mA Supply with Shutdown
n Ultralow Quiescent Current: 3μA
n Input Voltage Range: 2.0V to 45V
n Output Current: 20mA
n Dropout Voltage: 300mV
n Adjustable Output (VADJ = VOUT(MIN) = 600mV)
n Fixed Output Voltages: 1.2V, 1.5V, 1.8V, 2.5V, 3.3V, 5V
n Output Tolerance: ±2% Over Load, Line and
Temperature
n Stable with Low ESR, Ceramic Output Capacitors
(2.2µF Minimum)
n Shutdown Current: <1µA
n Current Limit Protection
n Reverse-Battery Protection
n Thermal Limit Protection
n TSOT-23 and 2mm × 2mm DFN Packages
n Automotive
n Low Current Battery-Powered Systems
n Keep-Alive Power Supplies
n Remote Monitoring
n Utility Meters
n Low Power Industrial Applications
IN
SHDN
2.2µF
3008 TA01a
OUT
SENSE
VIN
3.8V TO
45V
GND
LT3008-3.3
VOUT
3.3V
20mA
1µF
Dropout Voltage/Quiescent Current
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.
LT3008 Series
2
3008fc
PIN CONFIGURATION
ABSOLUTE MAXIMUM RATINGS
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 .......................... Indefi nite
(Note 1)
TOP VIEW
GND
SHDN
IN
**SENSE/ADJ
OUT
OUT
DC PACKAGE
6-LEAD (2mm s 2mm) PLASTIC DFN
4
5
7
6
3
2
1
TJMAX = 125°C, θJA = 65°C/W TO 85°C/W*
EXPOSED PAD (PIN 7) IS GND, MUST BE SOLDERED TO PCB
SHDN 1
GND 2
GND 3
GND 4
8 NC
7 ADJ/SENSE**
6 OUT
5 IN
TOP VIEW
TS8 PACKAGE
8-LEAD PLASTIC TSOT-23
TJMAX = 125°C, θJA = 65°C/W TO 85°C/W*
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
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
* See the Applications Information Section.
** SENSE for Fixed Voltage Output Versions.
LT3008 Series
3
3008fc
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
LT3008 Series
4
3008fc
ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at TJ = 25°C. (Note 2)
PARAMETER CONDITIONS MIN TYP MAX UNITS
Operating Voltage l245V
Regulated Output Voltage LT3008-1.2: VIN = 2V, ILOAD = 100µA
2V < VIN < 45V, 1µA < ILOAD < 20mA l
1.188
1.176
1.2
1.2
1.212
1.224
V
V
LT3008-1.5: VIN = 2.05V, ILOAD = 100µA
2.05V < VIN < 45V, 1µA < ILOAD < 20mA l
1.485
1.47
1.5
1.5
1.515
1.53
V
V
LT3008-1.8: VIN = 2.35V, ILOAD = 100µA
2.35V < VIN < 45V, 1µA < ILOAD < 20mA 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: ∆VIN = 2V to 45V, ILOAD = 1mA
LT3008-1.5: ∆VIN = 2.05V to 45V, ILOAD = 1mA
LT3008-1.8: ∆VIN = 2.35V to 45V, ILOAD = 1mA
LT3008-2.5: ∆VIN = 3.05V to 45V, ILOAD = 1mA
LT3008-3.3: ∆VIN = 3.85V to 45V, ILOAD = 1mA
LT3008-5: ∆VIN = 5.55V to 45V, ILOAD = 1mA
LT3008: ∆VIN = 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
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 specifi ed with wider operating temperature ranges. *The temperature grade is identifi ed 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 specifi cations, go to: http://www.linear.com/tapeandreel/
ORDER INFORMATION
LT3008 Series
5
3008fc
PARAMETER CONDITIONS MIN TYP MAX UNITS
Load Regulation (Note 3) LT3008-1.2: VIN = 2V, ILOAD = 1µA to 10mA
V
IN = 2V, ILOAD = 1µA to 20mA
l
l
0.8
1
4
10
mV
mV
LT3008-1.5: VIN = 2.05V, ILOAD = 1µA to 10mA
V
IN = 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
V
IN = 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
V
IN = 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
V
IN = 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
V
IN = 5.55V, ILOAD = 1µA to 20mA
l
l
3.4
4.2
17
42
mV
mV
LT3008: VIN = 2V, ILOAD = 1µA to 10mA
V
IN = 2V, ILOAD = 1µA to 20mA
l
l
0.4
0.5
2
5
mV
mV
Dropout Voltage
VIN = VOUT(NOMINAL) (Notes 5, 6)
ILOAD = 100µA
ILOAD = 100µA l
115 180
250
mV
mV
ILOAD = 1mA
ILOAD = 1mA l
170 250
350
mV
mV
ILOAD = 10mA
ILOAD = 10mA l
270 340
470
mV
mV
ILOAD = 20mA
ILOAD = 20mA l
300 365
500
mV
mV
Quiescent Current (Notes 6, 7) ILOAD = 0µA
ILOAD = 0µA l
3
6
µA
µA
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
3
6
21
160
350
6
12
50
500
1200
µA
µA
µA
µA
µA
Output Voltage Noise (Note 9) COUT = 2.2µF, ILOAD = 20mA, BW = 10Hz to 100kHz 92 µVRMS
ADJ Pin Bias Current –10 0.4 10 nA
Shutdown Threshold VOUT = Off to On
VOUT = On to Off
l
l0.25
0.67
0.61
1.5 V
V
SHDN Pin Current VSHDN = 0V, VIN = 45V
VSHDN = 45V, VIN = 45V
l
l0.65
±1
2
µA
µA
Quiescent Current in Shutdown VIN = 6V, VSHDN = 0V l<1 µA
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
58
54
53
52
49
47
42
70
66
65
64
61
59
54
dB
dB
dB
dB
dB
dB
dB
ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at TJ = 25°C. (Note 2)
LT3008 Series
6
3008fc
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 specifi ed under pulse
load conditions such that TJ ≅ TA. The LT3008E is guaranteed to meet
performance specifi cations from 0°C to 125°C operating junction
temperature. Specifi cations 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 specifi ed 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 specifi cation 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.
Note 5: Dropout voltage is the minimum input to output voltage differential
needed to maintain regulation at a specifi ed output current. In dropout, the
output voltage equals (VIN – VDROPOUT). For the LT3008-1.2 and LT3008-
1.5, 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 specifi ed 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
fi xed output voltage versions, an internal resistor divider will add about
1A 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.
ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at TJ = 25°C. (Note 2)
PARAMETER CONDITIONS MIN TYP MAX UNITS
Current Limit VIN = 45V, VOUT = 0
VIN = VOUT(NOMINAL) + 1V, ∆VOUT = –5% l22
75 mA
mA
Input Reverse-Leakage Current VIN = –45V, VOUT = 0 l130 µA
Reverse-Output Current VOUT = 1.2V, VIN = 0 0.6 10 µA
LT3008 Series
7
3008fc
0
0.6
0.4
0.2
0.8
1
1.2
1.4
1.6
1.8
2
TEMPERATURE (°C)
MINIMUM INPUT VOLTAGE (V)
3008 G03
ILOAD = 20mA
–50 –25 0 25 50 75 100 125 150
OUTPUT CURRENT (mA)
0
0
DROPOUT VOLTAGE (mV)
50
150
200
250
10 12 14 20
450
100
2468 1618
300
350
400
3008 G01
TJ = 125°C
TJ = 25°C
TEMPERATURE (°C)
0
DROPOUT VOLTAGE (mV)
50
150
200
250
450
100
300
350
400
3008 G02
20mA
10mA
1mA
100µA
–50 –25 0 25 50 75 100 125 150
Dropout Voltage Dropout Voltage Minimum Input Voltage
TYPICAL PERFORMANCE CHARACTERISTICS
TA = 25°C, unless otherwise noted.
Output Voltage
LT3008-1.8
TEMPERATURE (°C)
OUTPUT VOLTAGE (V)
3008 G07
1.788
1.824
1.830
1.836
1.770
1.776
1.812
1.800
1.782
1.816
1.764
1.806
1.794
–50 –25 0 25 50 75 100 125 15
0
ILOAD = 100µA
Output Voltage
LT3008-3.3
TEMPERATURE (°C)
OUTPUT VOLTAGE (V)
3008 G08
2.480
2.540
2.550
2.460
2.520
2.500
2.470
2.530
2.450
2.510
2.490
–50 –25 0 25 50 75 100 125 150
ILOAD = 100µA
Output Voltage
LT3008-2.5
TEMPERATURE (°C)
OUTPUT VOLTAGE (V)
3008 G09
3.267
3.278
3.355
3.366
3.245
3.322
3.300
3.256
3.333
3.344
3.234
3.311
3.289
–50 –25 0 25 50 75 100 125 150
ILOAD = 100µA
ADJ Pin Voltage
TEMPERATURE (°C)
ADJ PIN VOLTAGE (V)
3008 G04
0.596
0.608
0.610
0.612
0.590
0.592
0.604
0.600
0.594
0.606
0.588
0.602
0.598
–50 –25 0 25 50 75 100 125 150
IL = 100µA
Output Voltage
LT3008-1.2
Output Voltage
LT3008-1.5
TEMPERATURE (°C)
OUTPUT VOLTAGE (V)
3008 G05
1.192
1.216
1.220
1.224
1.180
1.184
1.208
1.200
1.188
1.212
1.176
1.204
1.196
–50 –25 0 25 50 75 100 125 150
ILOAD = 100µA
TEMPERATURE (°C)
OUTPUT VOLTAGE (V)
3008 G06
1.490
1.520
1.525
1.530
1.475
1.480
1.510
1.500
1.485
1.515
1.470
1.505
1.495
–50 –25 0 25 50 75 100 125 150
ILOAD = 100µA
LT3008 Series
8
3008fc
TYPICAL PERFORMANCE CHARACTERISTICS
TA = 25°C, unless otherwise noted.
0
200
450
500
246
100
350
150
400
50
0
300
250
13810
579
3008 G15
INPUT VOLTAGE (V)
GND PIN CURRENT (µA)
RL = 75, IL = 20mA
RL = 150, IL = 10mA
RL = 1.5k, IL = 1mA
RL = 15k, IL = 100µA
0
200
450
500
246
100
350
150
400
50
0
300
250
13810
579
3008 G14
INPUT VOLTAGE (V)
GND PIN CURRENT (µA)
RL = 60, IL = 20mA
RL = 120, IL = 10mA
RL = 1.2k, IL = 1mA
RL = 12k, IL = 100µA
GND Pin Current
LT3008-1.2
GND Pin Current
LT3008-1.5
GND Pin Current
LT3008-1.8
0
200
450
500
246
100
350
150
400
50
0
300
250
13810
579
3008 G16
INPUT VOLTAGE (V)
GND PIN CURRENT (µA)
RL = 90, IL = 20mA
RL = 180, IL = 10mA
RL = 1.8k, IL = 1mA
RL = 18k, IL = 100µA
GND Pin Current
LT3008-2.5
GND Pin Current
LT3008-3.3
0
200
450
500
246
100
350
150
400
50
0
300
250
13810
579
3008 G17
INPUT VOLTAGE (V)
GND PIN CURRENT (µA)
RL = 125, IL = 20mA
RL = 250, IL = 10mA
RL = 2.5k, IL = 1mA
RL = 25k, IL = 100µA
0
200
450
500
246
100
350
150
400
50
0
300
250
13810
579
3008 G18
INPUT VOLTAGE (V)
GND PIN CURRENT (µA)
RL = 165, IL = 20mA
RL = 330, IL = 10mA
RL = 3.3k, IL = 1mA
RL = 33k, IL = 100µA
Quiescent Current
INPUT VOLTAGE (V)
QUIESCENT CURRENT (µA)
3008 G13
12
30
3
6
18
21
9
0
27
24
15
021435687910
LT3008-1.2
LT3008-1.5
LT3008-1.8
LT3008-2.5
LT3008-3.3
LT3008-5
TEMPERATURE (°C)
OUTPUT VOLTAGE (V)
3008 G10
4.950
5.075
5.100
5.025
5.000
4.925
5.050
4.900
4.975
–50 –25 0 25 50 75 100 125 150
ILOAD = 100µA
Output Voltage
LT3008-5 ADJ Pin Bias Current Adjustable Quiescent Current
TEMPERATURE (°C)
ADJ PIN BIAS CURRENT (nA)
3008 G05
–4
8
10
–10
–8
4
0
–6
6
2
–2
–50 –25 0 25 50 75 100 125 150
TEMPERATURE (°C)
QUIESCENT CURRENT (µA)
3008 G06
2
5
6
1
4
3
0
–50 –25 0 25 50 75 100 125 150
LT3008 Series
9
3008fc
TYPICAL PERFORMANCE CHARACTERISTICS
TA = 25°C, unless otherwise noted.
SHDN Pin Input Current SHDN Pin Input Current
0
0.8
1.8
2
10 20 30
0.4
1.4
0.6
1.6
0.2
0
1.2
1
515 4525 35 40
3008 G22
SHDN PIN VOLTAGE (V)
SHDN PIN INPUT CURRENT (µA)
–50
0.8
2
025 75
0.4
1.6
0.6
1.8
0.2
0
1.4
1
1.2
–25 100 150
50 125
3008 G23
TEMPERATURE (°C)
SHDN PIN INPUT CURRENT (µA)
VSHDN = 45V
Current Limit
Reverse-Output Current
40
100
20
70
80
30
90
10
0
60
50
3008 G24
TEMPERATURE (°C)
CURRENT LIMIT (mA)
–50 0 75
–25 25 150
50 100 125
VIN = 2V
VIN = 45V
3008 G25
TEMPERATURE (°C)
REVERSE OUTPUT CURRENT (µA)
20
50
10
35
40
15
45
5
0
30
25
–50 0 75
–25 25 150
50 100 125
OUT
ADJ
OUT = ADJ = 1.2V
IN = SHDN = GND
Input Ripple Rejection
0
10
30
20
40
50
70
60
90
80
FREQUENCY (Hz)
3008 G26
10 100 1000 10000010000 1000000
INPUT RIPPLE REJECTION (dB)
VIN = 2.1V + 50mVRMS
VOUT = 600mV
ILOAD = 20mA
2.2µF
10µF
Input Ripple Rejection
INPUT RIPPLE REJECTION (dB)
60
80
30
40
50
70
20
10
0
3008 G27
TEMPERATURE (°C)
–50 0 75
–25 25 150
50 100 125
VIN = VOUT (NOMINAL) + 2V + 0.5VP-P
RIPPLE AT f = 120Hz
ILOAD = 20mA
GND Pin Current
LT3008-5
0
200
450
500
246
100
350
150
400
50
0
300
250
13810
579
3008 G19
INPUT VOLTAGE (V)
GND PIN CURRENT (µA)
RL = 250, IL = 20mA
RL = 500, IL = 10mA
RL = 5k, IL = 1mA
RL = 50k, IL = 100µA
GND Pin Current vs ILOAD
1
10
100
1000
LOAD (mA)
GND CURRENT (µA)
3008 G20
0.001 0.01 0.1 1 10 100
VIN = 3.8V
VOUT = 3.3V
–50
0.6
1.4
1.5
075
0.3
1.2
1.1
0.4
0.5
1.3
0.1
0.2
0
1
0.9
0.8
0.7
–25 25 150
50 100 125
3008 G21
TEMPERATURE (°C)
SHDN PIN THRESHOLD (V)
OFF TO ON
ON TO OFF
SHDN Pin Thresholds
LT3008 Series
10
3008fc
TYPICAL PERFORMANCE CHARACTERISTICS
TA = 25°C, unless otherwise noted.
Transient Response
500µs/DIV
VOUT
50mV/DIV
IOUT
20mA/DIV
3008 G31
IOUT = 1mA TO 20mA
VIN = 5.5V
VOUT = 5V
COUT = 2.2µF
Transient Response
500µs/DIV
VOUT
50mV/DIV
IOUT
20mA/DIV
3008 G32
IOUT = 1mA TO 20mA
VIN = 5.5V
VOUT = 5V
COUT = 10µF
Transient Response (Load Dump)
1ms/DIV
VOUT
50mV/DIV
45V
12V
VIN
10V/DIV
3008 G33
VOUT = 5V
IOUT = 20mA
COUT = 4.7µF
Load Regulation Output Noise Spectral Density
FREQUENCY (Hz)
0.1
OUTPUT NOISE SPECTRAL DENSITY (µV Hz)
1
100
10
3008 G29
10 100 1k 10k 100k
5V
3.3V
2.5V
1.8V
1.5V
1V
0.6V
COUT = 2.2µF
ILOAD = 20mA
0
0.5
2
2.5
1.5
1
3
3.5
4
4.5
5
LOAD REGULATION (mV)
3008 G28
TEMPERATURE (°C)
–50 0 75
–25 25 150
50 100 125
$IL = 1µA to 20mA
VOUT = 600mV
VIN = 2V
RMS Output Noise
vs Load Current
ILOAD (mA)
0.001
350
450
400
500
10
3008 G30
300
250
0.01 0.1 1 100
200
100
150
50
0
OUTPUT NOISE (µVRMS)
3.3V
2.5V
1.8V
1.2V
0.6V
1.5V
5V
COUT = 10µF
LT3008 Series
11
3008fc
PIN FUNCTIONS
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 fi lter 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 suffi ce. 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 fl ows 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 amplifi er’s
inverting terminal. Its 400pA typical input bias current
fl ows 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 fl oated, 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 fi xed voltage versions of
the LT3008 (LT3008-1.2, LT3008-1.5, LT3008-1.8, LT3008-
2.5, LT3008-3.3, LT3008-5), the SENSE pin is the input to
the error amplifi er. 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.
(TSOT-23/DFN)
IN
SHDN
3008 F01
RP
OUT
VIN
SENSE
GND
LT3008
RP
+
+LOAD
Figure 1. Kelvin Sense Connection
LT3008 Series
12
3008fc
APPLICATIONS INFORMATION
The LT3008 is a low dropout linear regulator with ultra-
low 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 fl ow. 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, fl ows 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
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.
Specifi cations 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
0.6V •(−0.5mV) =−4.17mV
Table 1 shows resistor divider values for some com-
mon output voltages with a resistor divider current of
about 1µA.
Figure 2. Adjustable Operation
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
SHDN
R2
R1
3008 F02
OUT
VIN
VOUT = 600mV • (1 + R2/R1) – (IADJ • R2)
VADJ = 600mV
IADJ = 0.4nA at 25°C
OUTPUT RANGE = 0.6V to 44.5V ADJ
GND
L
T3008
VOUT
LT3008 Series
13
3008fc
APPLICATIONS INFORMATION
DC BIAS VOLTAGE (V)
CHANGE IN VALUE (%)
3008 F03
20
0
–20
–40
–60
–80
–100 04810
26 12 14
X5R
Y5V
16
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10µF
TEMPERATURE (°C)
–50
40
20
0
–20
–40
–60
–80
–100
25 75
3008 F04
–25 0 50 100 125
Y5V
CHANGE IN VALUE (%)
X5R
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10µF
Figure 3. Ceramic Capacitor DC Bias Characteristics Figure 4. Ceramic Capacitor Temperature Characteristics
Because the ADJ pin is relatively high impedance (de-
pending 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 ex-
ternal 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 signifi cant 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 fi xed
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 3 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
specifi ed 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 coeffi cients 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 signifi cant 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 verifi ed.
Voltage and temperature coeffi cients are not the only
sources of problems. Some ceramic capacitors have a
LT3008 Series
14
3008fc
APPLICATIONS INFORMATION
Figure 5. Noise Resulting from Tapping
on a Ceramic Capacitor
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.
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.
100ms/DIV
VOUT
500µV/DIV
3008 F0
5
VOUT = 0.6V
COUT = 22µF
ILOAD = 10µA
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.
Table 2: Measured Thermal Resistance for DC Package
COPPER AREA BOARD
AREA
THERMAL RESISTANCE
(JUNCTION-TO-AMBIENT)TOPSIDE* BACKSIDE
2500mm22500mm22500mm265°C/W
1000mm22500mm22500mm270°C/W
225mm22500mm22500mm275°C/W
100mm22500mm22500mm280°C/W
50mm22500mm22500mm285°C/W
*Device is mounted on the topside.
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:
1. Output current multiplied by the input/output voltage
differential: IOUT • (VIN – VOUT)
2. GND pin current multiplied by the input voltage:
IGND • VIN
LT3008 Series
15
3008fc
APPLICATIONS INFORMATION
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:
T
J(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 ad-
dition 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-to-
input voltages.
Current limit protection and thermal overload protec-
tion protect the device against current overload condi-
tions 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 fl ow 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.
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:
I
OUT(MAX) (VIN(MAX) – VOUT) + IGND (VIN(MAX))
where,
I
OUT(MAX) = 20mA
V
IN(MAX) = 12.6V
I
GND at (IOUT = 20mA, VIN = 12.6V) = 0.3mA
Table 3: Measured Thermal Resistance for TSOT-23 Package
COPPER AREA BOARD
AREA
THERMAL RESISTANCE
(JUNCTION-TO-AMBIENT)TOPSIDE* BACKSIDE
2500mm22500mm22500mm265°C/W
1000mm22500mm22500mm267°C/W
225mm22500mm22500mm270°C/W
100mm22500mm22500mm275°C/W
50mm22500mm22500mm285°C/W
*Device is mounted on the topside.
LT3008 Series
16
3008fc
APPLICATIONS INFORMATION
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.
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 fl ows from the
pass transistor connected to OUT. However, current fl ows
in (but is limited by) the resistor divider that sets output
voltage. Current fl ows 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
OUTPUT AND ADJ VOLTAGE (V)
0
60
80
100
8
40
20
50
70
90
30
10
021 43 67 9
510
3008 F06
REVERSE CURRENT (µA)
OUT CURRENT
ADJ CURRENT
Figure 6. Reverse-Output Current
to ground, pulled to some intermediate voltage or is left
open circuit. Current fl ow 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.
LT3008 Series
17
3008fc
TYPICAL APPLICATIONS
IN
SHDN
3.3V
3009 TA02
OUT
1µF 2.2µF
SENSE
GND
L
T3008-3.3
NO PROTECTION
DIODES NEEDED!
VIN
12V
LOAD:
SYSTEM MONITOR,
VOLATILE MEMORY, ETC.
IN
SHDN
5V
3008 TA03
OUT FAULT
1µF
SUPERCAP 2.2µF
SENSE
PWR
TO
MONITORING
CENTER
SENSE
GND
GND
L
T3008-5
LINE POWER
VLINE
12V TO 15V
DCHARGE
RLIMIT
LINE
INTERRUPT
DETECT
Keep-Alive Power Supply
Last-Gasp Circuit
PACKAGE DESCRIPTION
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
2.00 ±0.10
(4 SIDES)
0.75 ±0.05
PIN 1 BAR
TOP MARK
(SEE NOTE 6)
0.200 REF
0.00 – 0.05
0.25 ±0.05
1.42 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
0.61 ±0.05
(2 SIDES)
1.15 ±0.05
0.70 ±0.05
2.55 ±0.05
PACKAGE
OUTLINE
0.50 BSC
0.40 ±0.10
BOTTOM VIEW—EXPOSED PAD
0.56 ±0.05
(2 SIDES)
R = 0.125
TYP
R = 0.05
TYP
1.37 ±0.05
(2 SIDES)
1
3
64
(DC6) DFN REV B 1309
0.25 ±0.05
0.50 BSC
PIN 1 NOTCH
R = 0.20 OR
0.25 × 45°
CHAMFER
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
DC6 Package
6-Lead Plastic DFN (2mm × 2mm)
(Reference LTC DWG # 05-08-1703 Rev B)
LT3008 Series
18
3008fc
1.50 – 1.75
(NOTE 4)
2.80 BSC
0.22 – 0.36
8 PLCS (NOTE 3)
DATUM ‘A’
0.09 – 0.20
(NOTE 3)
TS8 TSOT-23 0710 REV A
2.90 BSC
(NOTE 4)
0.65 BSC
1.95 BSC
0.80 – 0.90
1.00 MAX 0.01 – 0.10
0.20 BSC
0.30 – 0.50 REF
PIN ONE ID
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
3.85 MAX
0.40
MAX
0.65
REF
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
1.4 MIN
2.62 REF
1.22 REF
TS8 Package
8-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1637 Rev A)
PACKAGE DESCRIPTION
LT3008 Series
19
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 representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
REVISION HISTORY
REV DATE DESCRIPTION PAGE NUMBER
B 02/10 Added MP grade in TS8 package
Revised curve G04 in Typical Performance Characteristics
2-4, 6
7
C 04/12 Clarifi ed E-Grade Operating Temperature
Updated Package Drawings
6
17, 18
(Revision history begins at Rev B)
LT3008 Series
20
3008fc
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2007
LT 0412 REV C • PRINTED IN USA
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 500mA, Parallelable, Low Noise,
Low Dropout Linear Regulator
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
ThinSOT is a trademark of Linear Technology Corporation.
IN
SHDN
2.2µF
3.3V
3008 TA04a
OUT
1µF
SENSE
GND
L
T3008-3.3
VIN
12V
LOW DUTY CYCLE
PULSED LOAD
0mA TO 10mA
Low Duty Cycle Applications Average Power Savings for Low Duty Cycle Applications
0mA to 10mA Pulsed Load, IN = 12V
DUTY CYCLE (%)
0.1
70
60
80
90
100
3008 TA04b
40
50
30
110
20
10
0
POWER SAVINGS (%)
10µA IQ
100µA IQ
30µA IQ
TYPICAL APPLICATION
