LTC3108-1
Ultralow Voltage Step-Up
Converter and Power Manager
FeaTures
n
n
DescripTion
The
LTC
®
3108-1
is a highly integrated DC/DC converter ideal
for harvesting and managing surplus energy from extremely
low input voltage sources such as TEGs (thermoelectric
generators), thermopiles and small solar cells. The step-up
topology operates from input voltages as low as 20mV.
Using a small step-up transformer, the LTC3108-1 provides
a complete power management solution for wireless sens-
ing and data acquisition. The 2.2V LDO powers an external
microprocessor, while the main output is programmed to
one of four fixed voltages to power a wireless transmitter
or sensors. The power good indicator signals that the main
output voltage is within regulation. A second output can be
enabled by the host. A storage capacitor provides power
when the input voltage source is unavailable. Extremely
low quiescent current and high efficiency design ensure
the fastest possible charge times of the output reservoir
capacitor. The LTC3108-1 is functionally equivalent to the
LTC3108 except for its unique fixed V
OUT
options.
The LTC3108-1 is available in a small, thermally enhanced
12-lead (3mm
×
4mm) DFN package and a 16-lead SSOP
package.
n
n
n
Operates from Inputs of 20mV
Complete Energy Harvesting Power
Management System
- Selectable V
OUT
of 2.5V, 3V, 3.7V or 4.5V
- LDO: 2.2V at 3mA
- Logic Controlled Output
- Reserve Energy Output
Power Good Indicator
Uses Compact Step-Up Transformers
Small 12-Lead (3mm
×
4mm) DFN or 16-Lead
SSOP Packages
applicaTions
n
n
n
n
n
n
n
Remote Sensors and Radio Power
Surplus Heat Energy Harvesting
HVAC Systems
Industrial Wireless Sensing
Automatic Metering
Building Automation
Predictive Maintenance
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Typical applicaTion
Wireless Remote Sensor Application
Powered From a Peltier Cell
1:100
+
THERMOELECTRIC
GENERATOR
20mV TO 500mV
1nF
C1
330pF
C2
SW
VSTORE
LTC3108-1
V
OUT2
PGOOD
PGD
2.2V
VLDO
5.25V
V
OUT
Charge Time
1000
0.1F
6.3V
100
TIME (sec)
µP
2.2µF SENSORS
V
OUT
= 3V
C
OUT
= 470µF
+
+
220µF
10
VS2
V
OUT
3V
+
470µF
RF LINK
1
1:100 Ratio
1:50 Ratio
1:20 Ratio
0
50
100 150 200 250 300 350 400
V
IN
(mV)
31081 TA01b
VS1 V
OUT2_EN
VAUX
GND
1µF
31081 TA01a
0
31081fb
For more information
www.linear.com/LTC3108-1
1
LTC3108-1
absoluTe MaxiMuM raTings
(Note 1)
SW Voltage ..................................................–0.3V to 2V
C1 Voltage....................................................–0.3V to 6V
C2 Voltage (Note 5).........................................–8V to 8V
V
OUT2
, V
OUT2_EN
...........................................–0.3V to 6V
VAUX....................................................15mA into VAUX
VS1, VS2, VAUX, V
OUT
, PGD ........................–0.3V to 6V
VLDO, VSTORE ............................................–0.3V to 6V
Operating Junction Temperature Range
(Note 2)................................................. –40°C to 125°C
Storage Temperature Range.................. –65°C to 125°C
pin conFiguraTion
TOP VIEW
VAUX
VSTORE
V
OUT
V
OUT2
VLDO
PGD
1
2
3
4
5
6
13
GND
12
SW
11
C2
10
C1
9
8
7
V
OUT2_EN
VS1
VS2
GND
VAUX
VSTORE
V
OUT
V
OUT2
VLDO
PGD
GND
1
2
3
4
5
6
7
8
TOP VIEW
16 GND
15 SW
14 C2
13 C1
12 V
OUT2_EN
11 VS1
10 VS2
9
GND
DE PACKAGE
12-LEAD (4mm
×
3mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 43°C/W
EXPOSED PAD (PIN 13) IS GND, MUST BE SOLDERED TO PCB (NOTE 4)
GN PACKAGE
16-LEAD PLASTIC SSOP NARROW
T
JMAX
= 125°C,
θ
JA
= 110°C/W
orDer inForMaTion
LEAD FREE FINISH
LTC3108EDE-1#PBF
LTC3108IDE-1#PBF
LTC3108EGN-1#PBF
LTC3108IGN-1#PBF
TAPE AND REEL
LTC3108EDE-1#TRPBF
LTC3108IDE-1#TRPBF
LTC3108EGN-1#TRPBF
LTC3108IGN-1#TRPBF
PART MARKING*
31081
31081
31081
31081
PACKAGE DESCRIPTION
12-Lead (4mm
×
3mm) Plastic DFN
12-Lead (4mm
×
3mm) Plastic DFN
16-Lead Plastic SSOP
16-Lead Plastic SSOP
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
Consult LTC Marketing for parts specified for other fixed output voltages or 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
PARAMETER
Minimum Start-Up Voltage
No-Load Input Current
Input Voltage Range
CONDITIONS
The
l
denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are for T
A
= 25°C (Note 2). VAUX = 5V, unless otherwise noted.
MIN
TYP
20
3
l
MAX
50
UNITS
mV
mA
Using 1:100 Transformer Turns Ratio, VAUX = 0V
Using 1:100 Transformer Turns Ratio; V
IN
= 20mV,
V
OUT2_EN
= 0V; All Outputs Charged and in Regulation
Using 1:100 Transformer Turns Ratio
V
STARTUP
500
mV
31081fb
2
For more information
www.linear.com/LTC3108-1
LTC3108-1
elecTrical characTerisTics
PARAMETER
Output Voltage
CONDITIONS
VS1 = VS2 = GND
VS1 = VAUX, VS2 = GND
VS1 = GND, VS2 = VAUX
VS1 = VS2 = VAUX
V
OUT
= 3.7V, V
OUT2_EN
= 0V
No Load, All Outputs Charged
0.5mA Load
For 0mA to 2mA Load
For VAUX from 2.5V to 5V
I
VLDO
= 2mA
VLDO = 0V
V
OUT
= 0V
VSTORE = 0V
Current into VAUX = 5mA
VSTORE = 5V
V
OUT2
= 0V, V
OUT2_EN
= 0V
l
l
l
l
l
l
l
l
l
l
l
The
l
denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are for T
A
= 25°C (Note 2). VAUX = 5V, unless otherwise noted.
MIN
2.45
2.94
3.626
4.41
TYP
2.50
3.00
3.70
4.50
0.2
6
2.134
2.2
0.5
0.05
100
4
2.8
2.8
5
11
4.5
4.5
5.25
0.1
0.1
0.4
0.85
0.01
–7.5
–9
0.15
2.1
l
MAX
2.55
3.06
3.774
4.59
9
2.266
1
0.2
200
7
7
5.55
0.3
1.2
0.1
UNITS
V
V
V
V
µA
µA
V
%
%
mV
mA
mA
mA
V
µA
µA
V
µA
%
%
V
OUT
Quiescent Current
VAUX Quiescent Current
LDO Output Voltage
LDO Load Regulation
LDO Line Regulation
LDO Dropout Voltage
LDO Current Limit
V
OUT
Current Limit
VSTORE Current Limit
VAUX Clamp Voltage
VSTORE Leakage Current
V
OUT2
Leakage Current
VS1, VS2 Threshold Voltage
VS1, VS2 Input Current
PGD Threshold (Rising)
PGD Threshold (Falling)
PGD V
OL
PGD V
OH
PGD Pull-Up Resistance
V
OUT2_EN
Threshold Voltage
V
OUT2_EN
Pull-Down Resistance
V
OUT2
Turn-On Time
V
OUT2
Turn-Off Time
V
OUT2
Current Limit
V
OUT2
Current Limit Response Time
V
OUT2
P-Channel MOSFET On-Resistance
N-Channel MOSFET On-Resistance
VS1 = VS2 = 5V
Measured Relative to the V
OUT
Voltage
Measured Relative to the V
OUT
Voltage
Sink Current = 100µA
Source Current = 0
V
OUT2_EN
Rising
0.3
2.3
1.3
V
V
MΩ
V
MΩ
µs
µs
2.2
1
1
5
5
0.4
(Note 3)
V
OUT
= 3.7V
(Note 3)
V
OUT
= 3.7V (Note 3)
C2 = 5V (Note 3)
l
0.15
0.15
0.3
350
1.3
0.5
0.45
A
ns
Ω
Ω
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 LTC3108-1 is tested under pulsed load conditions such that
T
J
≈ T
A
. The LTC3108-1E is guaranteed to meet specifications from
0°C to 85°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
LTC3108-1I is guaranteed over the full –40°C to 125°C operating junction
temperature range. Note that the maximum ambient temperature
is determined by specific operating conditions in conjunction with
board layout, the rated thermal package thermal resistance and other
environmental factors. The junction temperature (T
J
) is calculated from
the ambient temperature (T
A
) and power dissipation (P
D
) according to
the formula: T
J
= T
A
+ (P
D
•
θ
JA
°C/W), where
θ
JA
is the package thermal
impedance.
Note 3:
Specification is guaranteed by design and not 100% tested in
production.
Note 4:
Failure to solder the exposed backside of the package to the PC
board ground plane will result in a thermal resistance much higher than
43°C/W.
Note 5:
The absolute maximum rating is a DC rating. Under certain
conditions in the applications shown, the peak AC voltage on the C2 pin
may exceed ±8V. This behavior is normal and acceptable because the
current into the pin is limited by the impedance of the coupling capacitor.
31081fb
For more information
www.linear.com/LTC3108-1
3
LTC3108-1
Typical perForMance characTerisTics
1000
T
A
= 25°C, unless otherwise noted.
I
IN
vs V
IN
, (V
OUT
= 0V)
1:50 RATIO, C1 = 4.7n
1:100 RATIO, C1 = 1n
1:20 RATIO, C1 = 10n
I
VOUT
and Efficiency vs V
IN
,
1:20 Ratio Transformer
4000
3500
3000
C1 = 10nF
I
VOUT
(V
OUT
= 0V)
80
70
60
EFFICIENCY (%)
50
EFFICIENCY
(V
OUT
= 4V)
I
VOUT
(V
OUT
= 4V)
40
30
20
10
0
100
200
300
400
0
500
31081 G01
100
I
VOUT
(µA)
10
1
10
100
V
IN
(mV)
1000
31081 G00
2500
2000
1500
1000
500
0
I
IN
(mA)
V
IN
(mV)
I
VOUT
and Efficiency vs V
IN
,
1:50 Ratio Transformer
3200
2800
2400
I
VOUT
(µA)
2000
1600
1200
800
400
0
0
100
200
300
400
EFFICIENCY
(V
OUT
= 4V)
I
VOUT
(V
OUT
= 4V)
C1 = 4.7nF
80
I
VOUT
(V
OUT
= 0V)
70
60
EFFICIENCY (%)
50
40
30
20
10
0
500
31081 G02
I
VOUT
and Efficiency vs V
IN
,
1:100 Ratio Transformer
1400
1200
1000
I
VOUT
(µA)
800
600
400
200
0
0
100
200
300
400
EFFICIENCY
(V
OUT
= 4V)
C1 = 1nF
I
VOUT
(V
OUT
= 0V)
70
60
50
EFFICIENCY (%)
40
I
VOUT
(V
OUT
= 4V)
30
20
10
0
500
31081 G03
V
IN
(mV)
V
IN
(mV)
Input Resistance vs V
IN
(V
OUT
Charging)
10
9
8
INPUT RESISTANCE ( )
7
6
5
4
3
2
1
0
0
100
200
300
400
500
31081 G04
I
VOUT
vs V
IN
and Source Resistance,
1:20 Ratio
10000
C1 = 10nF
1:20 RATIO
1000
I
VOUT
(µA)
1:50 RATIO
100
1:100 RATIO
10
0
1
2
5
10
0
100 200 300 400 500 600 700 800
V
IN
OPEN-CIRCUIT (mV)
31081 G05
V
IN
(mV)
4
31081fb
For more information
www.linear.com/LTC3108-1
LTC3108-1
Typical perForMance characTerisTics
I
VOUT
vs V
IN
and Source Resistance,
1:50 Ratio
10000
C1 = 4.7nF
1000
T
A
= 25°C, unless otherwise noted.
I
VOUT
vs V
IN
and Source Resistance,
1:100 Ratio
C1 = 1nF
1000
I
VOUT
(µA)
I
VOUT
(µA)
100
100
10
0
1
2
5
10
0
100 200 300 400 500 600 700 800
V
IN
OPEN-CIRCUIT (mV)
31081 G06
10
1
2
5
10
0
100
200
300
400
V
IN
OPEN-CIRCUIT (mV)
500
31081 G07
I
VOUT
vs dT and TEG Size,
1:100 Ratio
10000
V
OUT
= 0V
40mm
TEG
15mm
TEG
100
C1 PIN
2V/DIV
C2 PIN
2V/DIV
SW PIN
50mV/
DIV
Resonant Switching Waveforms
V
IN
= 20mV
1:100 RATIO TRANSFORMER
1000
I
VOUT
(µA)
10
0
0.1
1:50 RATIO
1:100 RATIO
1:50 RATIO
1:100 RATIO
10
1
dT ACROSS TEG (°C)
100
31081 G08
10µs/DIV
31081 G09
LDO Load Regulation
0.00
0.20
0.18
DROPOUT VOLTAGE (V)
–0.25
DROP IN VLDO (%)
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
–1.00
0
0.5
1
1.5 2 2.5
LDO LOAD (mA)
3
3.5
4
0.00
LDO Dropout Voltage
–0.50
–0.75
0
0.5
1
31081 G10
1.5 2 2.5
LDO LOAD (mA)
3
3.5
4
31081 G11
31081fb
For more information
www.linear.com/LTC3108-1
5
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