LT3008 [Linear]
3μA IQ, 20mA, 45V Low Dropout Linear Regulators; 3μA IQ , 20mA时, 45V低压降线性稳压器型号: | LT3008 |
厂家: | Linear |
描述: | 3μA IQ, 20mA, 45V Low Dropout Linear Regulators |
文件: | 总20页 (文件大小:449K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
LT3008 Series
µA I , 20mA, 45V
3
Q
Low Dropout Linear Regulators
FEATURES
DESCRIPTION
The LT®3008 series are micropower, low dropout voltage
(LDO) linear regulators. The devices supply 20mA output
currentwithadropoutvoltageof300mV.No-loadquiescent
current is 3μA. Ground pin current remains at less than
5% of output current as load increases. In 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 (V
= V
= 600mV)
ADJ
OUT(MIN)
n
n
Fixed Output Voltages: 1.2V, 1.5V, 1.8V, 2.5V, 3.3V, 5V
Output Tolerance: 2% Over Load, Line and
Temperature
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.
n
Stable with Low ESR, Ceramic Output Capacitors
(2.2μF Minimum)
n
n
n
n
n
Shutdown Current: <1μA
Current Limit Protection
Reverse-Battery Protection
Thermal Limit 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.
TSOT-23 and 2mm × 2mm DFN Packages
APPLICATIONS
n
Automotive
n
Low Current Battery-Powered Systems
n
Keep-Alive Power Supplies
Remote Monitoring
Utility Meters
n
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.
n
n
Low Power Industrial Applications
TYPICAL APPLICATION
3.3V, 20mA Supply with Shutdown
Dropout Voltage/Quiescent Current
500
450
400
350
300
250
200
150
100
50
6
5
4
3
2
1
0
I
= 20mA
LOAD
DROPOUT
VOLTAGE
V
OUT
3.3V
IN
OUT
LT3008-3.3
V
IN
20mA
3.8V TO
45V
2.2μF
1μF
SHDN SENSE
I
Q
GND
3008 TA01a
0
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
3008 TA01b
3008fa
1
LT3008 Series
(Note 1)
ABSOLUTE MAXIMUM RATINGS
Operating Junction Temperature Range (Notes 2, 3)
LT3008E.............................................–40°C to 125°C
LT3008I..............................................–40°C to 125°C
Storage Temperature Range...................–65°C to 150°C
Lead Temperature: Soldering, 10 sec
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
TS8 Package Only............................................. 300°C
PIN CONFIGURATION
TOP VIEW
TOP VIEW
6
5
4
GND
SHDN
IN
**SENSE/ADJ
OUT
1
2
3
8
7
6
5
NC
SHDN
GND
GND
GND
1
2
3
4
ADJ/SENSE**
OUT
IN
7
OUT
TS8 PACKAGE
8-LEAD PLASTIC TSOT-23
DC PACKAGE
6-LEAD (2mm s 2mm) PLASTIC DFN
T
= 125°C, θ = 65°C/W TO 85°C/W*
JA
JMAX
T
= 125°C, θ = 65°C/W TO 85°C/W*
JA
EXPOSED PAD (PIN 7) IS GND, MUST BE SOLDERED TO PCB
JMAX
* See the Applications Information Section.
** SENSE for Fixed Voltage Output Versions.
ORDER INFORMATION
LEAD FREE FINISH
LT3008EDC#PBF
TAPE AND REEL
PART MARKING*
LDPS
PACKAGE DESCRIPTION
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
LT3008EDC#TRPBF
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
LT3008IDC#PBF
LT3008IDC#TRPBF
LDPS
LT3008EDC-1.2#PBF
LT3008IDC-1.2#PBF
LT3008EDC-1.5#PBF
LT3008IDC-1.5#PBF
LT3008EDC-1.8#PBF
LT3008IDC-1.8#PBF
LT3008EDC-2.5#PBF
LT3008IDC-2.5#PBF
LT3008EDC-1.2#TRPBF
LT3008IDC-1.2#TRPBF
LT3008EDC-1.5#TRPBF
LT3008IDC-1.5#TRPBF
LT3008EDC-1.8#TRPBF
LT3008IDC-1.8#TRPBF
LT3008EDC-2.5#TRPBF
LT3008IDC-2.5#TRPBF
LFHC
LFHC
LFHF
LFHF
LFHH
LFHH
LFHK
LFHK
3008fa
2
LT3008 Series
ORDER INFORMATION
LEAD FREE FINISH
LT3008EDC-3.3#PBF
LT3008IDC-3.3#PBF
LT3008EDC-5#PBF
LT3008IDC-5#PBF
LT3008ETS8#PBF
LT3008ITS8#PBF
LT3008ETS8-1.2#PBF
LT3008ITS8-1.2#PBF
LT3008ETS8-1.5#PBF
LT3008ITS8-1.5#PBF
LT3008ETS8-1.8#PBF
LT3008ITS8-1.8#PBF
LT3008ETS8-2.5#PBF
LT3008ITS8-2.5#PBF
LT3008ETS8-3.3#PBF
LT3008ITS8-3.3#PBF
LT3008ETS8-5#PBF
LT3008ITS8-5#PBF
LEAD BASED FINISH
LT3008EDC
TAPE AND REEL
PART MARKING*
LFHN
PACKAGE DESCRIPTION
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
LT3008EDC-3.3#TRPBF
LT3008IDC-3.3#TRPBF
LT3008EDC-5#TRPBF
LT3008IDC-5#TRPBF
LT3008ETS8#TRPBF
LT3008ITS8#TRPBF
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
8-Lead Plastic TSOT-23
LFHN
LFHQ
LFHQ
LTDSX
LTDSX
8-Lead Plastic TSOT-23
LT3008ETS8-1.2#TRPBF LTFHD
LT3008ITS8-1.2#TRPBF LTFHD
LT3008ETS8-1.5#TRPBF LTFHG
LT3008ITS8-1.5#TRPBF LTFHG
LT3008ETS8-1.8#TRPBF LTFHJ
LT3008ITS8-1.8#TRPBF LTFHJ
LT3008ETS8-2.5#TRPBF LTFHM
LT3008ITS8-2.5#TRPBF LTFHM
LT3008ETS8-3.3#TRPBF LTFHP
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
LT3008ITS8-3.3#TRPBF
LT3008ETS8-5#TRPBF
LT3008ITS8-5#TRPBF
TAPE AND REEL
LTFHP
LTFHR
LTFHR
PART MARKING*
LDPS
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
PACKAGE DESCRIPTION
LT3008EDC#TR
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
8-Lead Plastic TSOT-23
LT3008IDC
LT3008IDC#TR
LDPS
LT3008EDC-1.2
LT3008EDC-1.2#TR
LT3008IDC-1.2#TR
LT3008EDC-1.5#TR
LT3008IDC-1.5#TR
LT3008EDC-1.8#TR
LT3008IDC-1.8#TR
LT3008EDC-2.5#TR
LT3008IDC-2.5#TR
LT3008EDC-3.3#TR
LT3008IDC-3.3#TR
LT3008EDC-5#TR
LT3008IDC-5#TR
LT3008ETS8#TR
LFHC
LT3008IDC-1.2
LFHC
LT3008EDC-1.5
LFHF
LT3008IDC-1.5
LFHF
LT3008EDC-1.8
LFHH
LT3008IDC-1.8
LFHH
LT3008EDC-2.5
LFHK
LT3008IDC-2.5
LFHK
LT3008EDC-3.3
LFHN
LT3008IDC-3.3
LFHN
LT3008EDC-5
LFHQ
LT3008IDC-5
LFHQ
LT3008ETS8
LTDSX
LTDSX
LT3008ITS8
LT3008ITS8#TR
8-Lead Plastic TSOT-23
3008fa
3
LT3008 Series
ORDER INFORMATION
LEAD FREE FINISH
LT3008ETS8-1.2
LT3008ITS8-1.2
LT3008ETS8-1.5
LT3008ITS8-1.5
LT3008ETS8-1.8
LT3008ITS8-1.8
LT3008ETS8-2.5
LT3008ITS8-2.5
LT3008ETS8-3.3
LT3008ITS8-3.3
LT3008ETS8-5
TAPE AND REEL
PART MARKING*
LTFHD
PACKAGE DESCRIPTION
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
LT3008ETS8-1.2#TR
LT3008ITS8-1.2#TR
LT3008ETS8-1.5#TR
LT3008ITS8-1.5#TR
LT3008ETS8-1.8#TR
LT3008ITS8-1.8#TR
LT3008ETS8-2.5#TR
LT3008ITS8-2.5#TR
LT3008ETS8-3.3#TR
LT3008ITS8-3.3#TR
LT3008ETS8-5#TR
LT3008ITS8-5#TR
LTFHD
LTFHG
LTFHG
LTFHJ
LTFHJ
LTFHM
LTFHM
LTFHP
LTFHP
LTFHR
LT3008ITS8-5
LTFHR
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
TYP
MAX
UNITS
l
l
l
l
l
l
l
l
Operating Voltage
Regulated Output Voltage
2
45
V
LT3008-1.2: V = 2V, I
= 100μA
< 20mA
1.188
1.176
1.2
1.2
1.212
1.224
V
V
IN
LOAD
LOAD
2V < V < 45V, 1μA < I
IN
LT3008-1.5: V = 2.05V, I
= 100μA
< 20mA
1.485
1.47
1.5
1.5
1.515
1.53
V
V
IN
LOAD
LOAD
2.05V < V < 45V, 1μA < I
IN
LT3008-1.8: V = 2.35V, I
= 100μA
< 20mA
1.782
1.764
1.8
1.8
1.818
1.836
V
V
IN
LOAD
LOAD
2.35V < V < 45V, 1μA < I
IN
LT3008-2.5: V = 3.05V, I
= 100μA
< 20mA
2.475
2.45
2.5
2.5
2.525
2.55
V
V
IN
LOAD
LOAD
3.05V < V < 45V, 1μA < I
IN
LT3008-3.3: V = 3.85V, I
= 100μA
< 20mA
3.267
3.234
3.3
3.3
3.333
3.366
V
V
IN
LOAD
LOAD
3.85V < V < 45V, 1μA < I
IN
LT3008-5: V = 5.55V, I
= 100μA
LOAD
< 20mA
LOAD
4.95
4.9
5
5
5.05
5.1
V
V
IN
5.55V < V < 45V, 1μA < I
IN
ADJ Pin Voltage (Notes 3, 4)
Line Regulation (Note 3)
V
= 2V, I
IN
= 100μA
594
588
600
600
606
612
mV
mV
IN
LOAD
2V < V < 45V, 1μA < I
< 20mA
LOAD
l
l
l
l
l
l
l
1.2
1.5
1.8
2.5
3.3
5
6
7.5
9
mV
mV
mV
mV
mV
mV
mV
LT3008-1.2: ΔV = 2V to 45V, I
= 1mA
IN
LOAD
LT3008-1.5: ΔV = 2.05V to 45V, I
= 1mA
IN
LOAD
LOAD
LOAD
LOAD
LT3008-1.8: ΔV = 2.35V to 45V, I
= 1mA
= 1mA
= 1mA
IN
12.5
16.5
25
LT3008-2.5: ΔV = 3.05V to 45V, I
IN
LT3008-3.3: ΔV = 3.85V to 45V, I
IN
LT3008-5: ΔV = 5.55V to 45V, I
= 1mA
LOAD
IN
0.6
3
LT3008: ΔV = 2V to 45V, I
= 1mA
IN
LOAD
3008fa
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
LT3008-1.2: V = 2V, I
MIN
TYP
MAX
UNITS
l
l
Load Regulation (Note 3)
= 1μA to 10mA
= 1μA to 20mA
0.8
1
4
10
mV
mV
IN
LOAD
LOAD
V
= 2V, I
IN
l
l
LT3008-1.5: V = 2.05V, I
= 1μA to 10mA
= 1μA to 20mA
1
1.3
5
13
mV
mV
IN
LOAD
LOAD
V
= 2.05V, I
IN
l
l
LT3008-1.8: V = 2.35V, I
= 1μA to 10mA
= 1μA to 20mA
1.2
1.5
6
15
mV
mV
IN
LOAD
LOAD
V
= 2.35V, I
IN
l
l
LT3008-2.5: V = 3.05V, I
= 1μA to 10mA
= 1μA to 20mA
1.7
2.1
8.3
21
mV
mV
IN
LOAD
LOAD
V
= 3.05V, I
IN
l
l
LT3008-3.3: V = 3.85V, I
= 1μA to 10mA
= 1μA to 20mA
2.2
2.8
11
28
mV
mV
IN
LOAD
LOAD
V
= 3.85V, I
IN
l
l
LT3008-5:
LT3008:
V
V
= 5.55V, I
= 5.55V, I
= 1μA to 10mA
= 1μA to 20mA
3.4
4.2
17
42
mV
mV
IN
IN
LOAD
LOAD
l
l
V
V
= 2V, I
= 2V, I
= 1μA to 10mA
= 1μA to 20mA
0.4
0.5
2
5
mV
mV
IN
IN
LOAD
LOAD
Dropout Voltage
IN
I
I
= 100μA
= 100μA
115
170
270
300
3
180
250
mV
mV
LOAD
LOAD
l
l
l
l
l
V
= V
(Notes 5, 6)
OUT(NOMINAL)
I
I
= 1mA
= 1mA
250
350
mV
mV
LOAD
LOAD
I
I
= 10mA
= 10mA
340
470
mV
mV
LOAD
LOAD
I
I
= 20mA
= 20mA
365
500
mV
mV
LOAD
LOAD
Quiescent Current (Notes 6, 7)
GND Pin Current
I
I
= 0μA
= 0μA
μA
μA
LOAD
LOAD
6
l
l
l
l
l
I
I
I
I
I
= 0μA
3
6
21
160
350
6
12
50
500
1200
μA
μA
μA
μA
μA
LOAD
LOAD
LOAD
LOAD
LOAD
V
= V
+ 0.5V (Notes 6, 7)
OUT(NOMINAL)
= 100μA
= 1mA
IN
= 10mA
= 20mA
Output Voltage Noise (Note 9)
ADJ Pin Bias Current
C
= 2.2μF, I
= 20mA, BW = 10Hz to 100kHz
92
μV
RMS
OUT
LOAD
–10
0.4
10
nA
l
l
Shutdown Threshold
V
V
= Off to On
= On to Off
0.67
0.61
1.5
V
V
OUT
OUT
0.25
l
l
SHDN Pin Current
V
SHDN
V
SHDN
= 0V, V = 45V
μA
μA
1
2
IN
= 45V, V = 45V
0.65
IN
l
Quiescent Current in Shutdown
Ripple Rejection (Note 3)
V
= 6V, V
= 0V
<1
μA
IN
SHDN
V
– V
= 2V, V
= 0.5V
,
IN
OUT
= 120Hz, I
RIPPLE
P-P
f
= 20mA
LOAD
RIPPLE
LT3008
58
54
53
52
49
47
42
70
66
65
64
61
59
54
dB
dB
dB
dB
dB
dB
dB
LT3008-1.2
LT3008-1.5
LT3008-1.8
LT3008-2.5
LT3008-3.3
LT3008-5
3008fa
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
MIN
TYP
MAX
UNITS
Current Limit
V
V
= 45V, V
= 0
75
mA
mA
IN
IN
OUT
OUT(NOMINAL)
l
l
= V
+ 1V, ΔV
= –5%
22
OUT
Input Reverse-Leakage Current
Reverse-Output Current
V
V
= –45V, V
= 0
OUT
1
30
10
μA
μA
IN
= 1.2V, V = 0
0.6
OUT
IN
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.
dropout, the output voltage equals (V – V
and LT3008-1.5, dropout voltage will be limited by the minimum input
voltage.
). For the LT3008-1.2
DROPOUT
IN
Note 6: To satisfy minimum input voltage requirements, the LT3008
Note 2: The LT3008 regulators are tested and specified under pulse load
adjustable version is tested and specified for these conditions with an
conditions such that T ≅ T . The LT3008E is 100% tested at T =25°C.
external resistor divider (61.9k bottom, 280k top) which sets V
to 3.3V.
J
A
A
OUT
Performance at –40°C and 125°C is assured by design, characterization
and correlation with statistical process controls. The LT3008I is guaran-
teed over the full –40°C to 125°C operating junction temperature range.
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 V = V
+ 0.55V and
IN
OUT(NOMINAL)
Note 3: The LT3008 adjustable version is tested and specified for these
conditions with the ADJ pin connected to the OUT pin.
a current source load. GND pin current will increase in dropout. For the
fixed output voltage versions, an internal resistor divider will add about
1ꢀA 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.
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.
Note 5: Dropout voltage is the minimum input to output voltage
differential needed to maintain regulation at a specified output current. In
3008fa
6
LT3008 Series
TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted.
Dropout Voltage
Dropout Voltage
Minimum Input Voltage
450
400
350
300
250
200
150
100
50
450
400
350
300
250
200
150
100
50
2
1.8
1.6
1.4
1.2
1
I
= 20mA
LOAD
T
= 125°C
J
20mA
1mA
T
= 25°C
10mA
100μA
J
0.8
0.6
0.4
0.2
0
0
0
–50 –25
0
25 50 75 100 125 150
–50 –25
0
25 50 75 100 125 150
0
2
4
6
8
10 12 14 16 18 20
TEMPERATURE (°C)
TEMPERATURE (°C)
OUTPUT CURRENT (mA)
3008 G02
3008 G03
3008 G01
Output Voltage
LT3008-1.2
Output Voltage
LT3008-1.5
ADJ Pin Voltage
0.612
0.610
0.608
0.606
0.604
0.602
0.600
0.598
0.596
0.594
0.592
0.590
0.588
1.224
1.220
1.216
1.212
1.208
1.204
1.200
1.196
1.192
1.188
1.184
1.180
1.176
1.530
1.525
1.520
1.515
1.510
1.505
1.500
1.495
1.490
1.485
1.480
1.475
1.470
I
= 100μA
I
= 100μA
LOAD
I
= 100μA
LOAD
L
–50 –25
0
25 50 75 100 125 150
–50 –25
0
25 50 75 100 125 150
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
3008 G05
3008 G06
3008 G04
Output Voltage
LT3008-1.8
Output Voltage
LT3008-2.5
Output Voltage
LT3008-3.3
3.366
2.550
2.540
1.836
1.830
1.824
1.816
1.812
1.806
1.800
1.794
1.788
1.782
1.776
1.770
1.764
I
= 100μA
I
= 100μA
LOAD
I
= 100μA
LOAD
LOAD
3.355
3.344
2.530
2.520
3.333
3.322
3.311
3.300
3.289
3.278
3.267
3.256
3.245
3.234
2.510
2.500
2.490
2.480
2.470
2.460
2.450
–50 –25
0
25 50 75 100 125 150
–50 –25
0
25 50 75 100 125 150
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
3008 G08
3008 G09
3008 G07
3008fa
7
LT3008 Series
TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted.
Output Voltage
LT3008-5
ADJ Pin Bias Current
Adjustable Quiescent Current
5.100
5.075
5.050
5.025
10
8
6
5
4
3
2
1
0
I
= 100μA
LOAD
6
4
2
5.000
4.975
4.950
4.925
4.900
0
–2
–4
–6
–8
–10
–50 –25
0
25 50 75 100 125 150
–50 –25
0
25 50 75 100 125 150
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
3008 G10
3008 G05
3008 G06
GND Pin Current
LT3008-1.2
GND Pin Current
LT3008-1.5
Quiescent Current
30
27
24
21
18
15
12
9
500
450
400
350
300
250
200
150
100
50
500
450
400
350
300
250
200
150
100
50
LT3008-1.2
LT3008-1.5
LT3008-1.8
LT3008-2.5
LT3008-3.3
LT3008-5
R
= 75Ω, I = 20mA
L L
R
= 60Ω, I = 20mA
L
L
R
= 150Ω, I = 10mA
L
R
= 120Ω, I = 10mA
L
L
L
6
R
L
= 15k, I = 100μA
L
R
= 12k, I = 100μA
L
L
3
R
= 1.5k, I = 1mA
L
R
= 1.2k, I = 1mA
L
L
L
0
0
0
0
1
2
3
4
5
6
7
8
9 10
0
2
3
4
5
6
7
8
9
10
0
2
3
4
5
6
7
8
9
10
1
1
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
3008 G14
3008 G15
3008 G13
GND Pin Current
LT3008-1.8
GND Pin Current
LT3008-2.5
GND Pin Current
LT3008-3.3
500
450
400
350
300
250
200
150
100
50
500
450
400
350
300
250
200
150
100
50
500
450
400
350
300
250
200
150
100
50
R
= 165Ω, I = 20mA
L
L
R
= 90Ω, I = 20mA
L
R
= 125Ω, I = 20mA
L L
L
R
= 330Ω, I = 10mA
L
R
= 180Ω, I = 10mA
L
R
= 250Ω, I = 10mA
L L
L
L
R
L
= 33k, I = 100μA
L
R
2
= 25k, I = 100μA
L
R
L
= 18k, I = 100μA
L
L
R
= 1.8k, I = 1mA
R = 3.3k, I = 1mA
L L
R
L
= 2.5k, I = 1mA
L
L
L
0
0
0
0
2
3
4
5
6
7
8
9
10
0
3
4
5
6
7
8
9
10
0
2
3
4
5
6
7
8
9
10
1
1
1
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
3008 G16
3008 G17
3008 G18
3008fa
8
LT3008 Series
TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted.
GND Pin Current
LT3008-5
GND Pin Current vs ILOAD
SHDN Pin Thresholds
500
450
400
350
300
250
200
150
100
50
1000
100
10
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
V
V
= 3.8V
IN
OUT
= 3.3V
R
= 250Ω, I = 20mA
L
L
OFF TO ON
ON TO OFF
R
= 500Ω, I = 10mA
L
L
R
L
= 50k, I = 100μA
L
R
= 5k, I = 1mA
L
L
0
1
0.001
0.01
0.1
1
10
100
125 150
0
2
3
4
5
6
7
8
9
10
–50 –25
0
25 50 75 100
TEMPERATURE (°C)
1
INPUT VOLTAGE (V)
LOAD (mA)
3008 G19
3008 G21
3008 G20
Current Limit
SHDN Pin Input Current
SHDN Pin Input Current
2
1.8
1.6
1.4
1.2
1
100
90
80
70
60
50
40
30
20
10
0
2
1.8
1.6
1.4
1.2
1
V
= 45V
IN
V
= 2V
IN
V
= 45V
0.8
0.6
0.4
0.2
0
SHDN
0.8
0.6
0.4
0.2
0
–50
0
25 50 75 100 125 150
TEMPERATURE (°C)
3008 G23
0
5
10 15 20 25 30 35 40 45
SHDN PIN VOLTAGE (V)
3008 G22
–25
–50
0
25 50 75 100 125 150
TEMPERATURE (°C)
3008 G24
–25
Reverse-Output Current
Input Ripple Rejection
Input Ripple Rejection
80
70
60
50
40
30
20
10
0
50
45
40
35
30
25
20
15
10
5
90
80
70
60
50
40
30
20
10
0
V
V
= 2.1V + 50mV
RMS
OUT
LOAD
OUT = ADJ = 1.2V
IN = SHDN = GND
IN
= 600mV
= 20mA
I
10μF
ADJ
V
= V
(NOMINAL) + 2V + 0.5V
OUT P-P
2.2μF
IN
RIPPLE AT f = 120Hz
= 20mA
OUT
I
LOAD
0
10
100
1000
10000 100000 1000000
–50
0
25 50 75 100 125 150
TEMPERATURE (°C)
3008 G25
–50
0
25 50 75
125 150
100
–25
–25
TEMPERATURE (°C)
FREQUENCY (Hz)
3008 G26
3008 G27
3008fa
9
LT3008 Series
TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted.
RMS Output Noise
vs Load Current
Load Regulation
Output Noise Spectral Density
500
450
5
4.5
4
100
10
1
C
= 10μF
5V
C
I
= 2.2μF
= 20mA
OUT
5V
OUT
$I = 1μA to 20mA
L
OUT
IN
3.3V
2.5V
1.8V
1.5V
1V
LOAD
V
V
= 600mV
= 2V
400
350
3.5
3
3.3V
300
250
200
150
0.6V
2.5V
1.8V
2.5
2
1.5V
1.5
1
1.2V
0.6V
100
50
0
0.5
0
–50
0.1
0.01
0.1
I
1
100
0.001
10
10
100
1k
10k
100k
0
25 50 75 100 125 150
TEMPERATURE (°C)
–25
(mA)
FREQUENCY (Hz)
LOAD
3008 G29
3008 G28
3008 G30
Transient Response
Transient Response
Transient Response (Load Dump)
I
= 1mA TO 20mA
= 5.5V
OUT
IN
I
= 1mA TO 20mA
= 5.5V
OUT
IN
V
V
C
V
V
C
V
= 5V
OUT
OUT
OUT
= 5V
OUT
OUT
50mV/DIV
= 2.2μF
= 10μF
V
OUT
V
OUT
50mV/DIV
45V
50mV/DIV
V
I
= 5V
= 20mA
= 4.7μF
OUT
OUT
OUT
V
IN
12V
I
10V/DIV
OUT
I
C
OUT
20mA/DIV
20mA/DIV
3008 G31
3008 G32
3008 G33
500μs/DIV
500μs/DIV
1ms/DIV
3008fa
10
LT3008 Series
PIN FUNCTIONS (TSOT-23/DFN)
SHDN (Pin 1/Pin 5): Shutdown. Pulling the SHDN pin
section). TheADJpinvoltageis600mVreferencedtoGND
and the output voltage range is 600mV to 44.5V.
low puts the LT3008 into a low power state and turns the
output off. If unused, tie the SHDN pin to V . The LT3008
IN
NC (Pin 8, TSOT-23 Package Only): No Connect. Pin 8
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.
is an NC pin in the TSOT-23 package. This pin is not tied
to any internal circuitry. It may be floated, tied to V or
IN
tied to GND.
Exposed Pad (Pin 7, DFN Package Only): Ground. The
Exposed Pad (backside) of the DFN package is an electri-
cal connection to GND. To ensure optimum performance,
solder Pin 7 to the PCB and tie directly to Pin 6.
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.
SENSE (Pin 7/Pin 1): Sense. For fixed 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 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 Connec-
tion). 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 out-
put 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.
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 re-
spect 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 tran-
sients. See the Applications Information section for more
information on output capacitance and reverse-output
characteristics.
R
P
IN
OUT
LT3008
+
+
SHDN SENSE
LOAD
V
IN
GND
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
R
P
3008 F01
Figure 1. Kelvin Sense Connection
3008fa
11
LT3008 Series
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 shut-
down. The device supplies up to 20mA of output current.
Dropout voltage at 20mA is typically 300mV. The LT3008
incorporatesseveralprotectionfeatures,makingitidealfor
useinbattery-poweredsystems.Thedeviceprotectsitself
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.
current and to insure stability under minimum load condi-
tions. 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:V /0.6V.Forexample,loadregulationforanoutput
OUT
current change of 100μA to 20mA is –0.5mV typical at
V
OUT
= 0.6V. At V
= 5V, load regulation is:
OUT
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.
Adjustable Operation
The LT3008 has an output voltage range of 0.6V to 44.5V.
Figure2showsthatoutputvoltageissetbytheratiooftwo
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
Table 1. Output Voltage Resistor Divider Values
V
R1
R2
OUT
1V
1.2V
1.5V
1.8V
2.5V
3V
604k
590k
590k
590k
590k
590k
619k
590k
402k
590k
887k
1.18M
1.87M
2.37M
2.8M
4.32M
3.3V
5V
V
IN
OUT
ADJ
OUT
V
V
= 600mV • (1 + R2/R1) – (I
= 600mV
= 0.4nA at 25°C
• R2)
ADJ
OUT
ADJ
V
IN
LT3008
R2
R1
I
ADJ
OUTPUT RANGE = 0.6V to 44.5V
SHDN
GND
3008 F02
Figure 2. Adjustable Operation
3008fa
12
LT3008 Series
APPLICATIONS INFORMATION
Because the ADJ pin is relatively high impedance (de-
pendingontheresistordividerused),straycapacitances
atthispinshouldbeminimized.Specialattentionshould
be given to any stray capacitances that can couple ex-
ternal signals onto the ADJ pin, producing undesirable
output transients or ripple.
Give extra consideration to the use of ceramic capacitors.
Manufacturers make ceramic capacitors with a variety of
dielectrics,eachwithdifferentbehavioracrosstemperature
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;theX5RandX7Rcodesonlyspecifyoperating
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.
Extra care should be taken in assembly when using high
valuedresistors.Smallamountsofboardcontamination
canleadtosignificantshiftsinoutputvoltage.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
cleaningmeasurescannotbeguaranteed,consideration
shouldbegiventousingresistorsanorderofmagnitude
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 capaci-
tors.TheESRoftheoutputcapacitoraffectsstability,most
notably with small capacitors. Use a minimum output
capacitor of 2.2μF with an ESR of 3Ω or less to prevent
oscillations.TheLT3008isamicropowerdeviceandoutput
loadtransientresponseisafunctionofoutputcapacitance.
Larger values of output capacitance decrease the peak
deviations and provide improved transient response for
larger load current changes.
Voltage and temperature coefficients are not the only
sources of problems. Some ceramic capacitors have a
40
20
20
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10μF
0
X5R
X5R
0
–20
–20
–40
–40
Y5V
–60
–60
Y5V
–80
–80
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10μF
–100
–100
0
8
12 14
–50
25
50
75
100 125
2
4
6
10
16
–25
0
DC BIAS VOLTAGE (V)
TEMPERATURE (°C)
3008 F03
3008 F04
Figure 3. Ceramic Capacitor DC Bias Characteristics
Figure 4. Ceramic Capacitor Temperature Characteristics
3008fa
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 micro-
phone 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.
GND pin current is found by examining the GND Pin Cur-
rent curves in the Typical Performance Characteristics
section. Power dissipation is equal to the sum of the two
components listed prior.
TheLT3008regulatorhasinternalthermallimitingdesigned
to protect the device during overload conditions. For con-
tinuous normal conditions, do not exceed the maximum
junction temperature rating of 125°C. Carefully consider
all sources of thermal resistance from junction to ambi-
ent 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 stiffen-
ers and plated through-holes can also be used to spread
the heat generated by power devices.
V
C
LOAD
= 0.6V
= 22μF
= 10μA
OUT
OUT
I
V
OUT
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.
500μV/DIV
3008 F05
100ms/DIV
PCB layers, copper weight, board layout and thermal vias
affect the resultant thermal resistance. Although Tables 2
and3providethermalresistancenumbersfor2-layerboards
with 1 ounce copper, modern multilayer PCBs provide bet-
ter performance than found in these tables. For example,
Figure 5. Noise Resulting from Tapping
on a Ceramic Capacitor
Thermal Considerations
Table 2: Measured Thermal Resistance for DC Package
COPPER AREA
The LT3008’s maximum rated junction temperature of
125°Climitsitspower-handlingcapability.Twocomponents
comprise the power dissipated by the device:
BOARD
AREA
THERMAL RESISTANCE
TOPSIDE*
BACKSIDE
(JUNCTION-TO-AMBIENT)
2
2
2
2
2
2
2
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
65°C/W
70°C/W
75°C/W
80°C/W
85°C/W
1. Output current multiplied by the input/output voltage
2
2
1000mm
2500mm
differential: I
• (V – V
)
OUT
IN
OUT
2
2
225mm
2500mm
2. GND pin current multiplied by the input voltage:
• V
2
2
100mm
2500mm
I
GND
IN
2
2
50mm
2500mm
*Device is mounted on the topside.
3008fa
14
LT3008 Series
APPLICATIONS INFORMATION
So,
Table 3: Measured Thermal Resistance for TSOT-23 Package
COPPER AREA
P = 20mA(12.6V – 3.3V) + 0.3mA(12.6V) = 189.8mW
BOARD
AREA
THERMAL RESISTANCE
(JUNCTION-TO-AMBIENT)
TOPSIDE*
BACKSIDE
The thermal resistance ranges from 65°C/W to 85°C/W
dependingonthecopperarea.So,thejunctiontemperature
rise above ambient approximately equals:
2
2
2
2
2
2
2
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
65°C/W
67°C/W
70°C/W
75°C/W
85°C/W
2
2
1000mm
2500mm
2
2
225mm
2500mm
0.1898W(75°C/W) = 14.2°C
2
2
100mm
2500mm
2
2
50mm
2500mm
The maximum junction temperature equals the maximum
junctiontemperatureriseaboveambientplusthemaximum
ambient temperature or:
*Device is mounted on the topside.
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
thermalresistance. Democircuit DC1388A’sboardlayout
achieves this 45°C/W performance. This is approximately
a 30% improvement over the lowest numbers shown in
Tables 2 and 3.
T
= 85°C + 14.2°C = 99.2°C
J(MAX)
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
monolithicregulators,suchascurrentlimitingandthermal
limiting, the device also protects against reverse-input
voltages, reverse-output voltages and reverse output-to-
input voltages.
Calculating Junction Temperature
Example: Given an output voltage of 3.3V, an input volt-
age 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?
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
typicalthermalshutdowncircuitrytemperaturethreshold
is 160°C.
The power dissipated by the device is equal to:
I
(V
– V ) + I
(V
)
OUT(MAX) IN(MAX)
OUT
GND IN(MAX)
where,
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.
I
= 20mA
= 12.6V
OUT(MAX)
V
IN(MAX)
I
at (I = 20mA, V = 12.6V) = 0.3mA
OUT IN
GND
3008fa
15
LT3008 Series
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.
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.
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 neces-
sary. In this case, grounding the SHDN pin turns off the
LT3008 and stops OUT from sourcing current.
100
90
80
70
60
50
40
30
20
10
0
ADJ 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.
OUT CURRENT
0
1
2
3
4
5
6
7
8
9
10
OUTPUT AND ADJ VOLTAGE (V)
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
3008 F06
Figure 6. Reverse-Output Current
3008fa
16
LT3008 Series
TYPICAL APPLICATIONS
Keep-Alive Power Supply
NO PROTECTION
DIODES NEEDED!
3.3V
V
IN
IN
OUT
LT3008-3.3
12V
1μF
2.2μF
LOAD:
SHDN SENSE
SYSTEM MONITOR,
VOLATILE MEMORY, ETC.
GND
3009 TA02
Last-Gasp Circuit
LINE POWER
V
LINE
SENSE
12V TO 15V
D
CHARGE
LINE
INTERRUPT
DETECT
R
LIMIT
TO
5V
PWR
FAULT
MONITORING
CENTER
IN
OUT
LT3008-5
GND
SUPERCAP
1μF
2.2μF
3008 TA03
SHDN SENSE
GND
3008fa
17
LT3008 Series
PACKAGE DESCRIPTION
DC Package
6-Lead Plastic DFN (2mm × 2mm)
(Reference LTC DWG # 05-08-1703)
R = 0.115
TYP
0.56 p 0.05
(2 SIDES)
0.38 p 0.05
4
6
0.675 p 0.05
2.50 p 0.05
0.61 p 0.05
(2 SIDES)
2.00 p 0.10
(4 SIDES)
1.15 p 0.05
PIN 1 BAR
TOP MARK
(SEE NOTE 6)
PIN 1
PACKAGE
OUTLINE
CHAMFER OF
EXPOSED PAD
(DC6) DFN 1103
3
1
0.25 p 0.05
0.25 p 0.05
0.50 BSC
0.50 BSC
0.75 p 0.05
0.200 REF
1.37 p 0.05
(2 SIDES)
1.42 p 0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
0.00 – 0.05
BOTTOM VIEW—EXPOSED PAD
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WCCD-2)
2. DRAWING NOT TO SCALE
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
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
3008fa
18
LT3008 Series
PACKAGE DESCRIPTION
TS8 Package
8-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1639 Rev Ø)
2.90 BSC
(NOTE 4)
0.52
MAX
0.65
REF
1.22 REF
1.50 – 1.75
(NOTE 4)
2.80 BSC
1.4 MIN
3.85 MAX 2.62 REF
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
DATUM ‘A’
0.01 – 0.10
1.00 MAX
0.30 – 0.50 REF
1.95 BSC
0.09 – 0.20
(NOTE 3)
TS8 TSOT-23 0802
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
3008fa
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.
19
LT3008 Series
TYPICAL APPLICATION
Low Duty Cycle Applications
Average Power Savings for Low Duty Cycle Applications
0mA to 10mA Pulsed Load, IN = 12V
100
90
80
70
60
3.3V
V
IN
IN
OUT
LT3008-3.3
12V
1μF
2.2μF
LOW DUTY CYCLE
PULSED LOAD
0mA TO 10mA
SHDN SENSE
GND
100μA I
Q
50
40
30
20
10
0
3008 TA04a
30μA I
Q
10μA I
Q
1
10
0.1
DUTY CYCLE (%)
3008 TA04b
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT1761
100mA, Low Noise Micropower LDO V : 1.8V to 20V, V
= 1.22V, V = 0.3V, I = 20μA, I < 1μA, Low Noise: < 20μV
,
,
,
IN
OUT
DO
Q
SD
RMS
RMS
RMS
Stable with 1μF Ceramic Capacitors, ThinSOTTM Package
LT1762
LT1763
150mA, Low Noise Micropower LDO V : 1.8V to 20V, V
= 1.22V, V = 0.3V, I = 25μA, I < 1μA, Low Noise: < 20μV
DO Q SD
IN
OUT
OUT
OUT
MS8 Package
500mA, Low Noise Micropower LDO V : 1.8V to 20V, V
= 1.22V, V = 0.3V, I = 30μA, I < 1μA, Low Noise: < 20μV
DO Q SD
IN
S8 Package
LT1764/LT1764A 3A, Low Noise, Fast Transient
Response LDOs
V : 2.7V to 20V, V
= 1.21V, V = 0.34V, I = 1mA, I < 1μA, Low Noise: < 40μV
,
IN
DO
Q
SD
RMS
LT1764A Version Stable with Ceramic Capacitors, DD and TO220-5 Packages
LT1962
300mA, Low Noise Micropower LDO V : 1.8V to 20V, V
= 1.22V, V = 0.27V, I = 30μA, I < 1μA,
OUT(MIN) DO Q SD
RMS
IN
Low Noise: < 20μV
, MS8 Package
LT1963/LT1963A 1.5A, Low Noise, Fast Transient
Response LDOs
V : 2.1V to 20V, V
= 1.21V, V = 0.34V, I = 1mA, I < 1μA,
OUT(MIN) DO Q SD
RMS
IN
Low Noise: < 40μV
, LT1963A Version Stable with Ceramic Capacitors, DD, TO220-5,
SOT223 and S8 Packages
LT3009
LT3020
20mA, 3μA I Micropower LDO
V : 1.6V to 20V, Low I : 3μA, V = 0.28V, 2mm × 2mm DFN and SC70-8 Packages
Q
IN
Q
DO
100mA, Low Voltage VLDO
V : 0.9V to 10V, V
= 0.20V, V = 0.15V, I = 120μA, I < 1μA, 3mm × 3mm DFN
DO Q SD
IN
OUT(MIN)
and MS8 Packages
LT3021
500mA, Low Voltage VLDO
V : 0.9V to 10V, V
= 0.20V, V = 0.16V, I = 120μA, I < 3μA, 5mm × 5mm DFN
DO Q SD
IN
OUT(MIN)
and SO8 Packages
LT3080/ LT3080-1 1.1A, Parallelable, Low Noise,
Low Dropout Linear Regulator
300mV Dropout Voltage (2-Supply Operation), Low Noise: 40μV
, V : 1.2V to 36V,
RMS IN
V
: 0V to 35.7V, Current-Based Reference with 1-Resistor V
Set; Directly Parallelable
OUT
OUT
(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: 40μV
, V : 1.2V to 36V,
RMS IN
V
: 0V to 35.7V, Current-Based Reference with 1-Resistor V
Set; Directly Parallelable
OUT
OUT
(No Op Amp Required), Stable with Ceramic Caps, MSOP-8 and 2mm × 3mm DFN Packages
ThinSOT is a trademark of Linear Technology Corporation.
3008fa
LT 0509 REV A • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
20
●
●
© LINEAR TECHNOLOGY CORPORATION 2007
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
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