LT3048-15
Low Noise Bias Generator
in 2mm
×
2mm DFN
FEATURES
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DESCRIPTION
The
LT
®
3048-15
generates a low noise, low ripple bias
supply from an input voltage of 2.7V to 4.8V.
The LT3048-15 includes a boost regulator and a LDO
linear regulator. The boost regulator provides power to
the linear regulator.
The boost regulator output voltage is regulated to 1.1V
above the LDO output, optimizing LDO ripple rejection and
transient response. Fixed frequency operation and current
mode control allow the use of very small inductors and
results in low, predictable output ripple.
The linear regulator in the LT3048-15 generates a fixed
15V output. High power supply ripple rejection combined
with a low noise internal reference results in less than
500µV
P-P
output ripple and noise.
The LT3048-15 is available in a 8-lead 2mm
×
2mm DFN
package.
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.
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Generates Low Noise Bias Voltage from Single Cell
Li-Ion Battery
Output Current: Up to 40mA
Low Output Ripple and Noise: <500µV
P-P
Boost Regulator
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2.2MHz Operation
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300mA Power Switch
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Integrated Schottky Diode
Low Dropout Linear Regulator
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Low Noise: <120µV
RMS
(10Hz to 100kHz)
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0.1% Load Regulation
Short-Circuit and Thermal Protection
Load Disconnect in Shutdown
Available in 2mm
×
2mm DFN Package
APPLICATIONS
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Sensor Bias
Op Amp Supply
TYPICAL APPLICATION
Efficiency
IN
2.7V TO 4.8V
10µH
SW
1µF
V
IN
BSTOUT
LDOIN
EFFICIENCY (%)
LT3048-15
LDOOUT
OFF ON
EN
GND
BYP
1nF
1µF
OUT
15V
V
IN
(V) I
OUT
(mA)
2.7
19
3.3
22
3.6
24
4.7µF
80
70
60
50
40
30
20
10
0
0
5
10
LDOOUT = 15V
L = 10µH
DCR = 650m
V
IN
= 2.7V
V
IN
= 3.3V
V
IN
= 3.6V
20
15
LOAD CURRENT (mA)
25
3048 TA01b
3048 TA01a
304815f
For more information
www.linear.com/LT3048-15
1
LT3048-15
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
SW 1
V
IN
2
GND 3
BYP 4
9
GND
8 BSTOUT
7 EN
6 LDOIN
5 LDOOUT
V
IN
..............................................................................6V
SW ............................................................................25V
BSTOUT ....................................................................23V
LDOIN .......................................................................22V
LDOOUT ....................................................................22V
BYP ........................................................................±0.3V
EN ...............................................................................6V
Operating Junction Temperature Range (Note 2)
LT3048E-15........................................ –40°C to 125°C
LT3048I-15......................................... –40°C to 125°C
Maximum Junction Temperature .......................... 125°C
Storage Temperature Range .................. –65°C to 150°C
DC PACKAGE
8-LEAD (2mm
×
2mm) PLASTIC DFN
θ
JA
= 102°C/W
EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LT3048EDC-15#PBF
LT3048IDC-15#PBF
TAPE AND REEL
LT3048EDC-15#TRPBF
LT3048IDC-15#TRPBF
PART MARKING
LGKK
LGKK
PACKAGE DESCRIPTION
8-Lead (2mm
×
2mm) Plastic DFN
8-Lead (2mm
×
2mm) Plastic DFN
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on nonstandard lead based finish parts.
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/
304815f
2
For more information
www.linear.com/LT3048-15
LT3048-15
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3.6V, EN/UVLO = 3V, unless otherwise noted.
PARAMETER
V
IN
Operating Range
Boost Regulator
BSTOUT-LDOOUT Regulation Voltage
BSTOUT-V
IN
Regulation Voltage
V
IN
Quiescent Current
Switching Frequency
l
l
ELECTRICAL CHARACTERISTICS
CONDITIONS
MIN
2.7
1
TYP
MAX
4.8
UNITS
V
V
V
µA
µA
MHz
MHz
%
mA
mV
V
V
1.1
1
475
0.1
1.2
600
1
2.7
2.8
500
LDOOUT = 0V
Not Switching
EN ≤ 0.4V
1.7
1.6
86
300
I
SW
= 200mA
I
DIODE
= 100mA
1.25
2.2
2.2
90
400
220
0.84
Maximum Duty Cycle
Switch Current Limit
Switch V
CESAT
Diode Forward Drop
EN Voltage High
EN Voltage Low
LDO Linear Regulator
LDOIN Quiescent Current
LDOOUT Regulation Voltage
LDOOUT Load Regulation
LDOOUT Voltage Noise
Ripple Rejection
Current Limit
I
LOAD
= 100µA
I
LOAD
= 100µA to 40mA
∆I
LOAD
= 1mA to 40mA
C
OUT
= 1µF, C
BYP
= 0nF, BW = 10Hz to 100kHz
C
OUT
= 1µF, C
BYP
= 1nF, BW = 10Hz to 100kHz
f
RIPPLE
= 2.2MHz
LDOOUT = 15V
l
l
0.4
14
14.775
14.625
15
15
10
450
120
20
45
80
20
15.225
15.375
30
V
µA
V
V
mV
µV
RMS
µV
RMS
dB
mA
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 LT3048E-15 is guaranteed to meet performance specifications
from 0°C to 125°C 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
LT3048I-15 is guaranteed over the full –40°C to 125°C operating junction
temperature range. High junction temperatures degrade operating
lifetimes. Operating lifetime is derated at junction temperatures greater
than 125°C.
304815f
For more information
www.linear.com/LT3048-15
3
LT3048-15
TYPICAL PERFORMANCE CHARACTERISTICS
Efficiency (10µH)
80
70
60
EFFICIENCY (%)
50
40
30
20
10
0
0
5
10
V
IN
= 3.6V
LDOOUT = 15V
L = 10µH
DCR = 650m
20
15
LOAD CURRENT (mA)
25
3048 G01
Efficiency (2.2µH)
70
60
50
EFFICIENCY (%)
40
30
20
10
0
V
IN
= 3.6V
LDOOUT = 15V
L = 2.2µH
DCR = 175m
0
1
4
3
5
2
LOAD CURRENT (mA)
6
7
3048 G02
LDOOUT Load Regulation
15.5
15.4
15.3
LDOOUT VOLTAGE (V)
15.2
15.0
14.9
14.8
14.7
14.6
14.5
0
5
10
15 20 25
LOAD (mA)
30
35
40
15.1
3048 G03
LDOOUT Voltage
15.100
15.075
LDOOUT VOLTAGE (V)
15.050
15.025
15.000
14.975
14.950
14.925
14.000
–50 –25
0
75
50
25
TEMPERATURE (°C)
100
125
I
L
100mA/DIV
V
SW
5V/DIV
Operating Waveforms: DCM
Operating Waveforms: CCM
V
SW
5V/DIV
I
L
100mA/DIV
3048 G04
V
IN
= 3.6V
V
OUT
= 15V
L = 2.2µH
I
LOAD
= 15mA
500ns/DIV
3048 G05
V
IN
= 3.6V
V
OUT
= 15V
L = 10µH
I
LOAD
= 20mA
500ns/DIV
3048 G06
Transient Response
50
OUTPUT VOLTAGE DEVIATION (mV)
0
–50
V
OUT
70
60
50
40
30
I
LOAD
20
10
3048 G07
LDOOUT Noise
10µV/√Hz
LOAD CURRENT (mA)
0.1µV/√Hz
–100
–150
–200
–250
–300
1nV/√Hz
100kHz
10Hz
1kHz
L = 10µH
V
IN
= 3.6V
C
BYP
= 1nF
V
OUT
= 15V
I
LOAD
= 40mA C
OUT
= 1µF
10MHz
V
IN
= 3.6V
10µs/DIV
V
OUT
= 15V
L = 10µH
C
LDOOUT
= 1µF
C
BYP
= 1nF
I
LOAD
= 4mA TO 20mA
0
304815f
4
For more information
www.linear.com/LT3048-15
LT3048-15
TYPICAL PERFORMANCE CHARACTERISTICS
LDOOUT Current Limit
90
80
SWITCH CURRENT LIMIT (mA)
70
CURRENT LIMIT (mA)
60
50
40
30
20
10
0
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
125
500
450
400
350
300
250
200
150
100
50
0
0
20
60
40
DUTY CYCLE (%)
80
100
3048 G10
Boost Switch Current Limit
3048 G09
Boost Switch Current Limit
500
450
SWITCH CURRENT LIMIT (mA)
400
FREQUENCY (MHz)
350
300
250
200
150
100
50
0
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
3048 G11
Switching Frequency
2.5
2.0
1.5
1.0
0.5
0
–50 –25
0
25 50
75 100 125 150
TEMPERATURE (°C)
3048 G12
304815f
For more information
www.linear.com/LT3048-15
5
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