LTC3108IGN-1-TRPBF_技术文档

LTC3108-1

Ultralow Voltage Step-Up

Converter and Power Manager

FeaTures

DescripTion

TheLTC^®3108-1isahighlyintegratedDC/DCconverterideal

forharvestingandmanagingsurplusenergyfromextremely

low input voltage sources such as TEGs (thermoelectric

generators),thermopilesandsmallsolarcells.Thestep-up

topology operates from input voltages as low as 20mV.

n

Operates from Inputs of 20mV

n

Complete Energy Harvesting Power

Management System

- Selectable V

of 2.5V, 3V, 3.7V or 4.5V

OUT

- 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

Usingasmallstep-uptransformer,theLTC3108-1provides

acompletepowermanagementsolutionforwirelesssens-

inganddataacquisition. The2.2VLDOpowersanexternal

microprocessor, while the main output is programmed to

one of four ﬁxed voltages to power a wireless transmitter

orsensors.Thepowergoodindicatorsignalsthatthemain

outputvoltageiswithinregulation.Asecondoutputcanbe

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

n

applicaTions

n

Remote Sensors and Radio Power

n

Surplus Heat Energy Harvesting

n

HVAC Systems

n

Industrial Wireless Sensing

n

Automatic Metering

LTC3108 except for its unique ﬁxed V

options.

OUT

n

Building Automation

The LTC3108-1 is available in a small, thermally enhanced

12-lead (3mm × 4mm) DFN package and a 16-lead SSOP

package.

n

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

1nF

V_OUTCharge Time

1:100

5.25V

1000

C1

VSTORE

V

C

= 3V

= 470µF

OUT

+

0.1F

6.3V

THERMOELECTRIC

GENERATOR

LTC3108-1

220µF

330pF

100

10

1

V

OUT2

PGD

C2

PGOOD

2.2V

µP

20mV TO 500mV

VLDO

SW

2.2µF

SENSORS

RF LINK

3V

VS2

V

OUT

+

470µF

1:100 Ratio

1:50 Ratio

1:20 Ratio

VS1

V

OUT2_EN

GND

31081 TA01a

VAUX

0

100 150 200 250 300 350 400

0

50

V

(mV)

1µF

IN

31081 TA01b

31081f

ꢀ

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

VS1, VS2, VAUX, V , PGD........................–0.3V to 6V

OUT

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

V

, V

...........................................–0.3V to 6V

OUT2 OUT2_EN

VAUX....................................................15mA into VAUX

pin conFiguraTion

TOP VIEW

GND

VAUX

1

2

3

4

5

6

7

8

16

15

14

13

12

11

10

9

GND

SW

C2

VAUX

1

2

3

4

5

6

12 SW

11 C2

10 C1

VSTORE

V

13

OUT

V

C1

OUT

GND

V

9

8

7

V

OUT2_EN

OUT2

V

OUT2

OUT2_EN

VLDO

PGD

VS1

VS2

VLDO

PGD

VS1

VS2

GND

DE PACKAGE

12-LEAD (4mm s 3mm) PLASTIC DFN

GN PACKAGE

16-LEAD PLASTIC SSOP NARROW

T

= 125°C, θ = 43°C/W

JA

JMAX

EXPOSED PAD (PIN 13) IS GND, MUST BE SOLDERED TO PCB (NOTE 4)

T

= 125°C, θ = 110°C/W

JA

JMAX

orDer inForMaTion

LEAD FREE FINISH

LTC3108EDE-1#PBF

LTC3108IDE-1#PBF

LTC3108EGN-1#PBF

LTC3108IGN-1#PBF

TAPE AND REEL

PART MARKING*

31081

PACKAGE DESCRIPTION

TEMPERATURE RANGE

–40°C to 125°C

LTC3108EDE-1#TRPBF

LTC3108IDE-1#TRPBF

LTC3108EGN-1#TRPBF

LTC3108IGN-1#TRPBF

12-Lead (4mm × 3mm) Plastic DFN

16-Lead Plastic SSOP

31081

16-Lead Plastic SSOP

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 ^Thel 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.

PARAMETER

CONDITIONS

MIN

TYP

20

3

MAX

UNITS

mV

Minimum Start-Up Voltage

No-Load Input Current

Using 1:100 Transformer Turns Ratio, VAUX = 0V

50

Using 1:100 Transformer Turns Ratio; V = 20mV,

mA

IN

V

= 0V; All Outputs Charged and in Regulation

OUT2_EN

l

Input Voltage Range

Using 1:100 Transformer Turns Ratio

V

500

mV

STARTUP

31081f

ꢁ

LTC3108-1

elecTrical characTerisTics ^Thel 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.

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

l

Output Voltage

VS1 = VS2 = GND

2.45

2.94

3.626

4.41

2.50

3.00

3.70

4.50

2.55

3.06

3.774

4.59

V

VS1 = VAUX, VS2 = GND

VS1 = GND, VS2 = VAUX

VS1 = VS2 = VAUX

V

Quiescent Current

V

= 3.7V, V = 0V

OUT2_EN

0.2

6

µA

V

OUT

VAUX Quiescent Current

LDO Output Voltage

LDO Load Regulation

LDO Line Regulation

LDO Dropout Voltage

LDO Current Limit

No Load, All Outputs Charged

0.5mA Load

9

2.266

1

l

2.134

2.2

0.5

0.05

100

11

For 0mA to 2mA Load

For VAUX from 2.5V to 5V

%

0.2

200

%

l

I

= 2mA

mV

mA

V

VLDO

VLDO = 0V

= 0V

4

V

Current Limit

V

2.8

5

4.5

5.25

0.1

0.85

0.01

–7.5

–9

7

OUT

VSTORE Current Limit

VAUX Clamp Voltage

VSTORE Leakage Current

VSTORE = 0V

Current into VAUX = 5mA

VSTORE = 5V

5.55

0.3

µA

V

Leakage Current

V

= 0V, V

= 0V

OUT2_EN

OUT2

l

VS1, VS2 Threshold Voltage

VS1, VS2 Input Current

PGD Threshold (Rising)

PGD Threshold (Falling)

0.4

1.2

0.1

VS1 = VS2 = 5V

µA

%

Measured Relative to the V

Sink Current = 100µA

Source Current = 0

Voltage

OUT

%

OUT

PGD V

0.15

2.2

1

0.3

2.3

V

OL

OH

PGD V

2.1

0.4

V

PGD Pull-Up Resistance

MΩ

V

l

V

Threshold Voltage

V

Rising

OUT2_EN

1

1.3

OUT2_EN

Pull-Down Resistance

5

MΩ

µs

A

Turn-On Time

5

OUT2

Turn-Off Time

(Note 3)

= 3.7V

0.15

0.3

350

1.3

0.5

l

Current Limit

V

0.15

0.45

OUT

Current Limit Response Time

P-Channel MOSFET On-Resistance

(Note 3)

= 3.7V (Note 3)

ns

Ω

V

OUT

N-Channel MOSFET On-Resistance

C2 = 5V (Note 3)

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

environmental factors. The junction temperature (T ) is calculated from

J

the ambient temperature (T ) and power dissipation (P ) according to

A

D

the formula: T = T + (P • θ °C/W), where θ is the package thermal

J

A

D

JA

impedance.

Note 3: Speciﬁcation is guaranteed by design and not 100% tested in

production.

T ≈ T . The LTC3108-1E is guaranteed to meet speciﬁcations from

J

A

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.

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

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.

31081f

ꢂ

LTC3108-1

T_A= 25°C, unless otherwise noted.

Typical perForMance characTerisTics

I_VOUTand Efﬁciency vs V_IN,

1:20 Ratio Transformer

I_INvs V_IN, (V_OUT= 0V)

1000

100

10

4000

80

70

60

50

40

30

20

10

0

C1 = 10nF

1:50 RATIO, C1 = 4.7n

1:100 RATIO, C1 = 1n

1:20 RATIO, C1 = 10n

3500

I

VOUT

OUT

(V

= 0V)

3000

2500

I

2000 EFFICIENCY

VOUT

OUT

(V

= 4V)

(V

= 4V)

OUT

1500

1000

500

0

1

10

100

(mV)

1000

0

100

200

V

300

(mV)

400

500

V

IN

31081 G00

31081 G01

I_VOUTand Efﬁciency vs V_IN,

1:100 Ratio Transformer

I_VOUTand Efﬁciency vs V_IN,

1:50 Ratio Transformer

70

60

50

40

30

20

10

0

3200

2800

2400

2000

1600

1200

800

80

1400

1200

1000

800

600

400

200

0

C1 = 4.7nF

C1 = 1nF

I

VOUT

OUT

70

60

50

40

30

20

10

0

(V

= 0V)

I

VOUT

OUT

(V

= 0V)

EFFICIENCY

(V = 4V)

EFFICIENCY

(V = 4V)

OUT

I

VOUT

OUT

(V

= 4V)

I

VOUT

OUT

(V

= 4V)

400

0

100

200

V

300

500

0

400

100

200

V

300

(mV)

500

0

400

(mV)

IN

31081 G02

31081 G03

Input Resistance vs V_IN

(V_OUTCharging)

I_VOUTvs V_INand Source Resistance,

1:20 Ratio

10

9

8

7

6

5

4

3

2

1

0

10000

1000

100

10

C1 = 10nF

1:20 RATIO

1:50 RATIO

1Ω

2Ω

5Ω

10Ω

1:100 RATIO

400

0

100

200

V

300

(mV)

500

200 300 400 500 600 700 800

100

0

V

OPEN-CIRCUIT (mV)

IN

31081 G05

31081 G04

31081f

ꢃ

LTC3108-1

T_A= 25°C, unless otherwise noted.

Typical perForMance characTerisTics

I_VOUTvs V_INand Source Resistance,

1:50 Ratio

I_VOUTvs V_INand Source Resistance,

1:100 Ratio

1000

10000

1000

100

10

C1 = 1nF

C1 = 4.7nF

100

1Ω

2Ω

5Ω

10Ω

1Ω

2Ω

5Ω

10Ω

10

0

100

200

300

400

500

0

200 300 400 500 600 700 800

100

0

V

OPEN-CIRCUIT (mV)

V

OPEN-CIRCUIT (mV)

IN

31081 G07

31081 G06

I_VOUTvs dT and TEG Size,

1:100 Ratio

Resonant Switching Waveforms

10000

1000

100

10

V

= 0V

V

= 20mV

OUT

IN

1:100 RATIO TRANSFORMER

40mm

TEG

C1 PIN

2V/DIV

C2 PIN

2V/DIV

15mm

TEG

SW PIN

50mV/

DIV

1:50 RATIO

1:100 RATIO

1:50 RATIO

1:100 RATIO

31081 G09

10µs/DIV

0

10

1

dT ACROSS TEG (°C)

100

0.1

31081 G08

LDO Load Regulation

LDO Dropout Voltage

0.00

–0.25

–0.50

–0.75

–1.00

0.20

0.18

0.16

0.14

0.12

0.10

0.08

0.06

0.04

0.02

0.00

0

0.5

1.5

2

2.5

3

3.5

4

0

0.5

1.5

2

2.5

3

3.5

4

1

LDO LOAD (mA)

31081 G11

31081 G10

31081f

ꢄ

LTC3108-1

T_A= 25°C, unless otherwise noted.

Typical perForMance characTerisTics

V_OUTand PGD Response

During a Step Load

Start-Up Voltage Sequencing

V

= 50mV

50mA LOAD STEP

OUT

IN

1:100 RATIO TRANSFORMER

= 220µF

C

= 220µF

C

OUT

CH1

VSTORE

1V/DIV

CSTORE = 470µF

= 2.2µF

C

LDO

CH2

V

, 1V/DIV

OUT

CH2, V

1V/DIV

CH3, V

1V/DIV

OUT

CH1

PGD, 1V/DIV

LDO

31081 G12

31081 G13

10sec/DIV

5ms/DIV

V_OUTRipple

LDO Step Load Response

30µA LOAD

C

= 220µF

OUT

V

LDO

20mV/

DIV

20mV/DIV

I

LDO

5mA/DIV

31081 G14

31081 G15

100ms/DIV

200µs/DIV

0mA TO 3mA LOAD STEP

C

= 2.2µF

LDO

Enable Input and V_OUT2

Running on Storage Capacitor

CSTORE = 470µF

LOAD = 100µA

V

OUT

CH3

VSTORE

1V/DIV

CH2

OUT2

1V/DIV

V

CH2, V

OUT

1V/DIV

CH4, V

LDO

1V/DIV

CH1

OUT2_EN

1V/DIV

CH1, V

V

IN

50mV/DIV

31081 G16

31081 G17

1ms/DIV

5sec/DIV

10mA LOAD ON V

OUT

OUT2

C

= 220µF

31081f

ꢅ

LTC3108-1

pin FuncTions ^(DFN/SSOP)

VAUX (Pin 1/Pin 2): Output of the Internal Rectiﬁer Cir-

VS1 (Pin 8/Pin 11): V

Select Pin 1. Connect this pin

OUT

cuit and V for the IC. Bypass VAUX with at least 1µF of

to ground or VAUX to program the output voltage (see

CC

capacitance. An active shunt regulator clamps VAUX to

Table 1).

5.25V (typical).

V

(Pin 9/Pin 12): Enable Input for V

. V

OUT2_EN

OUT2 OUT2

VSTORE (Pin 2/Pin 3): Output for the Storage Capacitor

or Battery. A large capacitor may be connected from this

pin to GND for powering the system in the event the input

voltage is lost. It will be charged up to the maximum VAUX

clamp voltage. If not used, this pin should be left open

or tied to VAUX.

will be enabled when this pin is driven high. There is an

internal 5M pull-down resistor on this pin. If not used,

this pin can be left open or grounded.

C1(Pin10/Pin13):InputtotheChargePumpandRectiﬁer

Circuit. Connect a capacitor from this pin to the secondary

winding of the step-up transformer.

V

(Pin 3/Pin 4): Main Output of the Converter. The

OUT

C2 (Pin 11/Pin 14): Input to the N-Channel Gate Drive

Circuit. Connect a capacitor from this pin to the secondary

winding of the step-up transformer.

voltage at this pin is regulated to the voltage selected by

VS1 and VS2 (see Table 1). Connect this pin to an energy

storage capacitor or to a rechargeable battery.

SW (Pin 12/Pin 15): Drain of the Internal N-Channel

Switch. Connect this pin to the primary winding of the

transformer.

V

(Pin 4/Pin 5): Switched Output of the Converter.

OUT2

Connect this pin to a switched load. This output is open

until V is driven high, then it is connected to

OUT2_EN

GND (Pins 1, 8, 9, 16) SSOP Only: Ground

V

through a 1.3Ω P-channel switch. If not used, this

OUT

pin should be left open or tied to V . The peak current

OUT

GND (Exposed Pad Pin 13) DFN Only: Ground. The DFN

exposed pad must be soldered to the PCB ground plane.

It serves as the ground connection, and as a means of

conducting heat away from the die.

in this output is limited to 0.3A typical.

VLDO (Pin 5/Pin 6): Output of the 2.2V LDO. Connect a

2.2µF or larger ceramic capacitor from this pin to GND.

If not used, this pin should be tied to VAUX.

Table 1. Regulated Voltage Using Pins VS1 and VS2

VS2

GND

VAUX

VS1

GND

VAUX

GND

VAUX

V

OUT

PGD (Pin 6/Pin 7): Power Good Output. When V

is

OUT

2.5V

3V

within 7.5% of its programmed value, PGD will be pulled

up to VLDO through a 1MΩ resistor. If V drops 9%

OUT

3.7V

4.5V

below its programmed value PGD will go low. This pin

can sink up to 100µA.

VS2 (Pin 7/Pin 10): V

Select Pin 2. Connect this pin

OUT

to ground or VAUX to program the output voltage (see

Table 1).

31081f

ꢆ

LTC3108-1

block DiagraM

LTC3108-1

V

OUT2

1.3Ω

V

OUT2

ILIM

V

OUT2_EN

OFF ON

1.2V

REF

SYNC RECTIFY

REFERENCE

V

5M

C1

V

OUT

1:100

C1

V

OUT

IN

C

OUT

IN

5.25V

C2

+

C2

VS1

VS2

–

V

SW

OUT

CHARGE

CONTROL

V

OUT

PROGRAM

VSTORE

0.5Ω

V

REF

VLDO

1M

PGD

–

+

PGOOD

VAUX

VSTORE

V

LDO

BEST

V

REF

OUT

C

1µF

STORE

VLDO

GND (SSOP)

EXPOSED PAD (DFN)

31081 BD

2.2V

2.2µF

operaTion ^{(Refer to the Block Diagram)}

TheLTC3108-1 isdesigned touse a small externalstep-up

transformer to create an ultralow input voltage step-up

DC/DC converter and power manager. It is ideally suited

for low power wireless sensors and other applications in

whichsurplusenergyharvestingisusedtogeneratesystem

power because traditional battery power is inconvenient

or impractical.

average power draw is very low, but there may be periodic

pulses of higher load current required. This is typical of

wireless sensor applications, where the quiescent power

drawisextremelylowmostofthetime,exceptfortransmit

bursts when circuitry is powered up to make measure-

ments and transmit data.

TheLTC3108-1canalsobeusedtotricklechargeastandard

capacitor, supercapacitor or rechargeable battery, using

energy harvested from a Peltier or photovoltaic cell.

The LTC3108-1 is designed to manage the charging and

regulation of multiple outputs in a system in which the

31081f

ꢇ

LTC3108-1

operaTion

Oscillator

Synchronous Rectiﬁers

TheLTC3108-1utilizesaMOSFETswitchtoformaresonant

step-up oscillator using an external step-up transformer

andasmallcouplingcapacitor.Thisallowsittoboostinput

voltages as low as 20mV high enough to provide multiple

regulated output voltages for powering other circuits. The

frequencyofoscillationisdeterminedbytheinductanceof

the transformer secondary winding and is typically in the

range of 10kHz to 100kHz. For input voltages as low as

20mV, a primary-secondary turns ratio of about 1:100 is

recommended. For higher input voltages, this ratio can be

lower. See the Applications Information section for more

information on selecting the transformer.

Once VAUX exceeds 2V, synchronous rectiﬁers in parallel

with each of the internal diodes take over the job of rectify-

ing the input voltage, improving efﬁciency.

Low Dropout Linear Regulator (LDO)

The LTC3108-1 includes a low current LDO to provide a

regulated 2.2V output for powering low power processors

or other low power ICs. The LDO is powered by the higher

of VAUX or V . This enables it to become active as soon

OUT

as VAUX has charged to 2.3V, while the V

storage

OUT

capacitor is still charging. In the event of a step load on

the LDO output, current can come from the main V

OUT

capacitor if VAUX drops below V . The LDO requires

OUT

Charge Pump and Rectiﬁer

a 2.2µF ceramic capacitor for stability. Larger capacitor

values can be used without limitation, but will increase

the time it takes for all the outputs to charge up. The LDO

output is current limited to 4mA minimum.

The AC voltage produced on the secondary winding of

the transformer is boosted and rectiﬁed using an external

charge pump capacitor (from the secondary winding to

pin C1) and the rectiﬁers internal to the LTC3108-1. The

rectiﬁer circuit feeds current into the VAUX pin, provid-

ing charge to the external VAUX capacitor and the other

outputs.

V

OUT

ThemainoutputvoltageonV

ischargedfromtheVAUX

OUT

supply, and is user programmed to one of four regulated

voltages using the voltage select pins VS1 and VS2, ac-

cording to Table 2. Although the logic threshold voltage

for VS1 and VS2 is 0.85V typical, it is recommended that

they be tied to ground or VAUX.

VAUX

TheactivecircuitswithintheLTC3108-1arepoweredfrom

VAUX, which should be bypassed with a 1µF capacitor.

Larger capacitor values are recommended when using

turns ratios of 1:50 or 1:20 (refer to the Typical Applica-

Table 2. Regulated Voltage Using Pins VS1 and VS2

VS2

GND

VAUX

VS1

GND

VAUX

GND

VAUX

V

OUT

2.5V

3V

tion examples). Once VAUX exceeds 2.5V, the main V

is allowed to start charging.

OUT

3.7V

4.5V

An internal shunt regulator limits the maximum voltage

on VAUX to 5.25V typical. It shunts to GND any excess

current into VAUX when there is no load on the converter

or the input source is generating more power than is

required by the load.

Whentheoutputvoltagedropsslightlybelowtheregulated

value,thechargingcurrentwillbeenabledaslongasVAUX

is greater than 2.5V. Once V

has reached the proper

OUT

value, the charging current is turned off.

Voltage Reference

The internal programmable resistor divider sets V

,

OUT

The LTC3108-1 includes a precision, micropower refer-

ence,foraccurateregulatedoutputvoltages.Thisreference

becomes active as soon as VAUX exceeds 2V.

eliminating the need for very high value external resistors

that are susceptible to board leakage.

31081f

ꢈ

LTC3108-1

operaTion

In a typical application, a storage capacitor (typically a few

The V

enable input has a typical threshold of 1V

OUT2

hundred microfarads) is connected to V . As soon as

with 100mV of hysteresis, making it logic-compatible. If

(which has an internal pull-down resistor) is

OUT

V

VAUX exceeds 2.5V, the V

capacitor will be allowed to

OUT2_EN

OUT

low, V

the V

will be off. Driving V

output.

high will turn on

charge up to its regulated voltage. The current available

to charge the capacitor will depend on the input voltage

and transformer turns ratio, but is limited to about 4.5mA

typical.

OUT2

OUT2_EN

Note that while V

cuitry for V

is high, the current limiting cir-

OUT2_EN

draws an extra 8µA of quiescent current

OUT2

from V . This added current draw has a negligible effect

OUT

PGOOD

on the application and capacitor sizing, since the load on

A power good comparator monitors the V

voltage.

the V

output, when enabled, is likely to be orders of

OUT

OUT2

The PGD pin is an open-drain output with a weak pull-up

magnitude higher than 8µA.

(1MΩ)totheLDOvoltage.OnceV haschargedtowithin

OUT

VSTORE

7.5% of its regulated voltage, the PGD output will go high.

If V

drops more than 9% from its regulated voltage,

OUT

The VSTORE output can be used to charge a large storage

PGD will go low. The PGD output is designed to drive a

microprocessor or other chip I/O and is not intended to

drive a higher current load such as an LED. Pulling PGD

up externally to a voltage greater than VLDO will cause a

small current to be sourced into VLDO. PGD can be pulled

low in a wire-OR conﬁguration with other circuitry.

capacitor or rechargeable battery after V

has reached

OUT

regulation.OnceV hasreachedregulation,theVSTORE

OUT

output will be allowed to charge up to the VAUX voltage.

The storage element on VSTORE can be used to power

the system in the event that the input source is lost, or

is unable to provide the current demanded by the V

,

OUT

V

and LDO outputs. If VAUX drops below VSTORE,

OUT2

V

OUT2

the LTC3108-1 will automatically draw current from the

storageelement.Notethatitmaytakealongtimetocharge

a large capacitor, depending on the input energy available

V

is an output that can be turned on and off by the

OUT2

host, using the V

connected to V

pin. When enabled, V

is

OUT2_EN

OUT2

and the loading on V

and VLDO.

through a 1.3Ω P-channel MOSFET

OUT

switch. This output, controlled by a host processor, can

be used to power external circuits such as sensors and

ampliﬁers,thatdonothavealowpowersleeporshutdown

Since the maximum current from VSTORE is limited to a

few milliamps, it can safely be used to trickle-charge NiCd

or NiMH rechargeable batteries for energy storage when

the input voltage is lost. Note that the VSTORE capacitor

capability. V

can be used to power these circuits only

OUT2

when they are needed.

cannotsupplylargepulsecurrentstoV . Anypulseload

OUT

on V

must be handled by the V

capacitor.

Minimizing the amount of decoupling capacitance on

OUT

V

willallowittobeswitchedonandofffaster, allowing

OUT2

Short-Circuit Protection

shorter burst times and, therefore, smaller duty cycles in

pulsed applications such as a wireless sensor/transmit-

All outputs of the LTC3108-1 are current limited to protect

against short-circuits to ground.

ter. A small V

capacitor will also minimize the energy

OUT2

that will be wasted in charging the capacitor every time

V

is enabled.

Output Voltage Sequencing

OUT2

V

has a soft-start time of about 5µs to limit capacitor

A timing diagram showing the typical charging and

voltage sequencing of the outputs is shown in Figure 1.

Note: time not to scale.

OUT2

chargingcurrentandminimizeglitchingofthemainoutput

whenV

isenabled. Italsohasacurrentlimitingcircuit

OUT2

that limits the peak current to 0.3A typical.

31081f

ꢀ0

LTC3108-1

operaTion

5.0

2.5

0

VSTORE (V)

PGD (V)

3.0

2.0

1.0

0

5.0

2.5

0

V

(V)

OUT

3.0

2.0

1.0

0

VLDO (V)

VAUX (V)

5.0

2.5

0

50

60

80

10

20

30

40

TIME (ms)

70

31081 F01a

Figure 1. Output Voltage Sequencing with V_OUTProgrammed for 3V (Time Not to Scale)

31081f

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LTC3108-1

applicaTions inForMaTion

Introduction

Refer to the I vs V curves in the Typical Performance

IN IN

Characteristicssectiontoseewhatinputcurrentisrequired

for the source for a given input voltage.

The LTC3108-1 is designed to gather energy from very

low input voltage sources and convert it to usable output

voltagestopowermicroprocessors, wirelesstransmitters

and analog sensors. Such applications typically require

much more peak power, and at higher voltages, than

the input voltage source can produce. The LTC3108-1 is

designed to accumulate and manage energy over a long

period of time to enable short power bursts for acquiring

and transmitting data. The bursts must occur at a low

enough duty cycle such that the total output energy dur-

ing the burst does not exceed the average source power

integrated over the accumulation time between bursts.

For many applications, this time between bursts could

be seconds, minutes or hours.

For a given transformer turns ratio, there is a maximum

recommended input voltage to avoid excessively high

secondary voltages and power dissipation in the shunt

regulator. It is recommended that the maximum input

voltage times the turns ratio be less than 50.

Note that a low ESR bulk decoupling capacitor will usually

berequiredacrosstheinputsourcetopreventlargevoltage

droop and ripple caused by the source’s ESR and the peak

primary switching current (which can reach hundreds of

milliamps). The time constant of the ﬁlter capacitor and

the ESR of the voltage source should be much longer than

the period of the resonant switching frequency.

The PGD signal can be used to enable a sleeping micro-

Peltier Cell (Thermoelectric Generator)

processororothercircuitrywhenV reachesregulation,

OUT

indicating that enough energy is available for a burst.

A Peltier cell (also known as a thermoelectric cooler) is

made up of a large number of series-connected P-N junc-

tions, sandwiched between two parallel ceramic plates.

Although Peltier cells are often used as coolers by apply-

ing a DC voltage to their inputs, they will also generate

a DC output voltage, using the Seebeck effect, when the

two plates are at different temperatures. The polarity of

the output voltage will depend on the polarity of the tem-

perature differential between the plates. The magnitude of

the output voltage is proportional to the magnitude of the

temperature differential between the plates. When used in

Input Voltage Sources

The LTC3108-1 can operate from a number of low input

voltagesources, suchasPeltiercells, photovoltaiccellsor

thermopilegenerators.Theminimuminputvoltagerequired

for a given application will depend on the transformer

turns ratio, the load power required, and the internal DC

resistance (ESR) of the voltage source. Lower ESR will

allow the use of lower input voltages, and provide higher

output power capability.

1000

100

10

1

TEG: 30mm

127 COUPLES

R = 2Ω

V

OC

100

MAX P

(IDEAL)

OUT

10

1

0.1

100

1

10

dT (°C)

31081 F02

Figure 2. Typical Performance of a Peltier Cell Acting as a Thermoelectric Generator

31081f

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LTC3108-1

applicaTions inForMaTion

this manner, a Peltier cell is referred to as a thermoelectric

generator (TEG).

current capability by providing a higher input voltage

under load.

The low voltage capability of the LTC3108-1 design allows

it to operate from a TEG with temperature differentials

as low as 1°C, making it ideal for harvesting energy in

applications in which a temperature difference exists

between two surfaces or between a surface and the am-

bient temperature. The internal resistance (ESR) of most

cells is in the range of 1Ω to 5Ω, allowing for reasonable

power transfer. The curves in Figure 2 show the open-

circuit output voltage and maximum power transfer for a

typical Peltier cell (with an ESR of 2Ω) over a 20°C range

of temperature differential.

Peltier Cell (TEG) Suppliers

Peltier cells are available in a wide range of sizes and

power capabilities, from less than 10mm square to over

50mm square. They are typically 2mm to 5mm in height.

A list of Peltier cell manufacturers is given in Table 3.

Table 3. Peltier Cell Manufacturers

Fujitaka

www.fujitaka.com/pub/peltier/english/thermoelectric_power.html

FerroTec

www.ferrotec.com/products/thermal/modules

Laird Technologies

www.lairdtech.com

Marlow Industries

www.marlow.com

Micropelt

www.micropelt.com

Nextreme

www.nextreme.com

TE Technology

www.tetech.com/Peltier-Thermoelectric-Cooler-Modules.html

Tellurex

www.tellurex.com

Kryotherm

www.kryothermusa.com

TEG Load Matching

The LTC3108-1 was designed to present a minimum input

resistance (load) in the range of 2Ω to 10Ω, depending

on input voltage and transformer turns ratio (as shown

in the Typical Performance Characteristics curves). For

a given turns ratio, as the input voltage drops, the input

resistance increases. This feature allows the LTC3108-1

to optimize power transfer from sources with a few ohms

of source resistance, such as a typical TEG. Note that a

lower source resistance will always provide more output

Table 4. Recommended TEG Part Numbers by Size

MANUFACTURER

CUI Inc. (Distributor)

Ferrotec

15mm × 15mm

CP60133

20mm × 20mm

CP60233

30mm × 30mm

CP60333

40mm × 40mm

CP85438

9501/031/030 B

FPH13106NC

9501/071/040 B

FPH17106NC

9500/097/090 B

FPH17108AC

9500/127/100 B

FPH112708AC

Fujitaka

Kryotherm

TGM-127-1.0-0.8

PT6.7.F2.3030.W6

RC6-6-01

LCB-127-1.4-1.15

PT8.12.F2.4040.TA.W6

RC12-8-01LS

Laird Technology

Marlow Industries

Tellurex

RC3-8-01

C2-15-0405

C2-20-0409

TE-31-1.4-1.15

C2-30-1505

C2-40-1509

TE Technology

TE-31-1.0-1.3

TE-71-1.4-1.15

TE-127-1.4-1.05

31081f

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LTC3108-1

applicaTions inForMaTion

Thermopile Generator

these applications the C2 and SW pins are not used and

can be grounded or left open.

Thermopile generators (also called powerpile generators)

are made up of a number of series-connected thermo-

couples enclosed in a metal tube. They are commonly

used in gas burner applications to generate a DC output

of hundreds of millivolts when exposed to the high tem-

perature of a ﬂame. Typical examples are the Honeywell

CQ200 and Q313. These devices have an internal series

resistance of less than 3Ω, and can generate as much as

750mVopen-circuitattheirhighestratedtemperature.For

applications in which the temperature rise is too high for

a solid-state thermoelectric device, a thermopile can be

usedasanenergysourcetopowertheLTC3108-1.Because

of the higher output voltages possible with a thermopile

generator, a lower transformer turns ratio can be used

(typically 1:20, depending on the application).

Examples of such input sources would be piezoelectric

transducers, vibration energy harvesters, low current

generators, a stack of low current solar cells or a 60Hz

AC input.

A series resistance of at least 100Ω/V should be used

to limit the maximum current into the VAUX shunt

regulator.

COMPONENT SELECTION

Step-Up Transformer

The step-up transformer turns ratio will determine how

low the input voltage can be for the converter to start.

Using a 1:100 ratio can yield start-up voltages as low as

20mV. Other factors that affect performance are the DC

resistanceofthetransformerwindingsandtheinductance

of the windings. Higher DC resistance will result in lower

efﬁciency. The secondary winding inductance will deter-

mine the resonant frequency of the oscillator, according

to the following formula.

Photovoltaic Cell

The LTC3108-1 converter can also operate from a single

photovoltaic cell (also known as a PV or solar cell) at light

levels too low for other low input voltage boost convert-

ers to operate. However, many variables will affect the

performance in these applications. Light levels can vary

over several orders of magnitude and depend on light-

ing conditions (the type of lighting and indoor versus

outdoor). Different types of light (sunlight, incandescent,

ﬂuorescent) also have different color spectra, and will

producedifferentoutputpowerlevelsdependingonwhich

type of photovoltaic cell is being used (monocrystalline,

polycrystalline or thin-ﬁlm). Therefore, the photovoltaic

cell must be chosen for the type and amount of light avail-

able. Note that the short-circuit output current from the

cell must be at least a few milliamps in order to power the

LTC3108-1 converter

1

Frequency =

Hz

2 • π • L(sec)• C

Where L is the inductance of the transformer secondary

winding and C is the load capacitance on the secondary

winding. This is comprised of the input capacitance at pin

C2,typically30pF,inparallelwiththetransformersecondary

winding’s shunt capacitance. The recommended resonant

frequency is in the range of 10kHz to 100kHz. See Table 5

for some recommended transformers.

Table 5. Recommended Transformers

VENDOR

PART NUMBER

Non-Boost Applications

Coilcraft

www.coilcraft.com

LPR6235-752SML (1:100 Ratio)

LPR6235-253PML (1:20 Ratio)

LPR6235-123QML (1:50 Ratio)

The LTC3108-1 can also be used as an energy harvester

and power manager for input sources that do not require

boosting. In these applications the step-up transformer

can be eliminated.

Any source whose peak voltage exceeds 2.5V AC or 5V

DC can be connected to the C1 input through a current-

limiting resistor where it will be rectiﬁed/peak detected. In

31081f

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LTC3108-1

applicaTions inForMaTion

C1 Capacitor

Using External Charge Pump Rectiﬁers

The charge pump capacitor that is connected from the

transformer’s secondary winding to the C1 pin has an ef-

fect on converter input resistance and maximum output

current capability. Generally, a minimum value of 1nF is

recommended when operating from very low input volt-

ages using a transformer with a ratio of 1:100. Too large

a capacitor value can compromise performance when

operating at low input voltage or with high resistance

sources. For higher input voltages and lower turns ratios,

the value of the C1 capacitor can be increased for higher

output current capability. Refer to the Typical Applications

schematic examples for the recommended value for a

given turns ratio.

ThesynchronouschargepumprectiﬁersintheLTC3108-1

(connectedtotheC1pin)areoptimizedforoperationfrom

very low input voltage sources, using typical transformer

step-up ratios between 1:100 and 1:50, and typical C1

charge pump capacitor values less than 10nF.

Operation from higher input voltage sources (typically

250mV or greater, under load), allows the use of lower

transformer step-up ratios (such as 1:20 and 1:10) and

larger C1 capacitor values to provide higher output cur-

rent capability from the LTC3108. However, due to the

resulting increase in rectiﬁer currents and resonant oscil-

lator frequency in these applications, the use of external

charge pump rectiﬁers is recommended for optimal

performance.

Squegging

In applications where the step-up ratio is 1:20 or less, and

the C1 capacitor is 10nF or greater, the C1 pin should be

grounded and two external rectiﬁers (such as 1N4148 or

1N914 diodes) should be used. These are available as

dual diodes in a single package. Avoid the use of Schottky

rectiﬁers, as their lower forward-voltage drop increases

theminimumstartupvoltage. SeetheTypicalApplications

schematics for an example.

Certaintypesofoscillators,includingtransformer-coupled

oscillatorssuchastheresonantoscillatoroftheLTC3108-1,

can exhibit a phenomenon called squegging. This term

refers to a condition that can occur which blocks or stops

the oscillation for a period of time much longer than the

period of oscillation, resulting in bursts of oscillation. An

exampleofthisistheblockingoscillator,whichisdesigned

to squegg to produce bursts of oscillation. Squegging

is also encountered in RF oscillators and regenerative

receivers.

V

and VSTORE Capacitor

OUT

For pulsed load applications, the V

capacitor should

OUT

In the case of the LTC3108-1, squegging can occur when

a charge builds up on the C2 gate coupling capacitor, such

thattheDCbiaspointshiftsandoscillationisextinguished

foracertainperiodoftime,untilthechargeonthecapacitor

bleeds off, allowing oscillation to resume. It is difﬁcult to

predict when and if squegging will occur in a given ap-

plication. While squegging is not harmful, it reduces the

average output current capability of the LTC3108-1.

be sized to provide the necessary current when the load

is pulsed on. The capacitor value required will be dictated

by the load current, the duration of the load pulse, and

the amount of voltage droop the circuit can tolerate. The

capacitor must be rated for whatever voltage has been

selected for V

by VS1 and VS2.

OUT

I_LOAD(mA) • t_PULSE(ms)

C_OUT(µF) ≥

∆V_OUT(V)

Squegging can easily be avoided by the addition of a

bleeder resistor in parallel with the coupling capacitor on

the C2 pin. Resistor values in the range of 100k to 1MΩ

are sufﬁcient to eliminate squegging without having any

negative impact on performance. For the 330pF capacitor

used for C2 in most applications, a 499k bleeder resistor

isrecommended. SeetheTypicalApplicationsschematics

for an example.

Note that there must be enough energy available from

theinputvoltagesourceforV torechargethecapacitor

OUT

during the interval between load pulses (to be discussed

in the next example). Reducing the duty cycle of the load

pulse will allow operation with less input energy.

The VSTORE capacitor may be of very large value (thou-

sands of microfarads or even Farads), to provide holdup

31081f

ꢀꢄ

LTC3108-1

applicaTions inForMaTion

at times when the input power may be lost. Note that this

capacitor can charge all the way to 5.25V (regardless of

PCB Layout Guidelines

Due to the rather low switching frequency of the resonant

converter and the low power levels involved, PCB layout

is not as critical as with many other DC/DC converters.

There are, however, a number of things to consider.

the settings for V ), so ensure that the holdup capacitor

OUT

has a working voltage rating of at least 5.5V at the tem-

perature for which it will be used. The VSTORE capacitor

can be sized using the following:

Due to the very low input voltage the circuit may operate

from,theconnectionstoV ,theprimaryofthetransformer





6µA +I_Q+I_LDO+ (I_BURST• t • f) • TSTORE





IN

C_STORE

≥

and the SW and GND pins of the LTC3108-1 should be

designed to minimize voltage drop from stray resistance

and able to carry currents as high as 500mA. Any small

voltage drop in the primary winding conduction path will

lower efﬁciency and increase capacitor charge time.

5.25 − V_OUT

Where 6µA is the quiescent current of the LTC3108-1, I

Q

is the load on V

in between bursts, I

is the load on

OUT

LDO

the LDO between bursts, I

is the total load during

BURST

the burst, t is the duration of the burst, f is the frequency

of the bursts, TSTORE is the storage time required and

Also,duetothelowchargecurrentsavailableattheoutputs

of the LTC3108-1, any sources of leakage current on the

outputvoltagepinsmustbeminimized. Anexampleboard

layout is shown in Figure 3.

V

is the output voltage required.

OUT

To minimize losses and capacitor charge time, all capaci-

tors used for V

and VSTORE should be low leakage.

OUT

V

IN

See Table 6 for recommended storage capacitors.

Table 6. Recommended Storage Capacitors

VENDOR

PART NUMBER/SERIES

AVX

www.avx.com

BestCap Series

TAJ and TPS Series Tantalum

Cap-XX

www.cap-xx.com

GZ Series

SW

C2

VAUX

Cooper/Bussmann

KR Series

1

2

3

4

5

6

12

11

10

9

VSTORE

www.bussmann.com/3/PowerStor.html P Series

V

C1

V

OUT

Vishay/Sprague

www.vishay.com/capacitors

Tantamount 592D

595D Tantalum

150CRZ/153CRV Aluminum

013 RLC (Low Leakage)

V

OUT2

OUT2_EN

V

OUT2

VLDO

PGD

VS1

VS2

8

VLDO

PGOOD

7

Storage capacitors requiring voltage balancing are not

recommended due to the current draw of the balancing

resistors.

GND

VIAS TO GROUND PLANE

31081 FO3

Figure 3. Example Component Placement for

Two-Layer PC Board (DFN Package)

31081f

ꢀꢅ

LTC3108-1

applicaTions inForMaTion

Design Example 1

since there are many factors affecting the efﬁciency of

the converter. Also determine what the total load cur-

This design example will explain how to calculate the

rent is on V

during the sleep state (between bursts).

OUT

necessary storage capacitor value for V

in pulsed

OUT

Note that this must include any losses, such as storage

capacitor leakage.

load applications, such as a wireless sensor/transmit-

ter. In these types of applications, the load is very small

for a majority of the time (while the circuitry is in a low

power sleep state), with bursts of load current occur-

ring periodically during a transmit burst. The storage

Assume, for instance, that the charge current from the

LTC3108-1 is 50µA and the total current drawn on V

OUT

in the sleep state is 17µA, including capacitor leakage. In

capacitor on V

supports the load during the transmit

addition, use the value of 150µF for the V capacitor.

OUT

burst, and the long sleep time between bursts allows

the LTC3108-1 to recharge the capacitor. A method for

calculating the maximum rate at which the load pulses

can occur for a given output current from the LTC3108-1

will also be shown.

The maximum transmit rate (neglecting the duration of

the transmit burst, which is typically very short) is then

given by:

150µF • 0.3V

(50µA − 17µA)

t =

= 1.36sec or f_MAX= 0.73Hz

In this example, V

is set to 3V, and the maximum al-

OUT

Therefore, in this application example, the circuit can sup-

port a 1ms transmit burst every 1.3 seconds.

lowed voltage droop during a transmit burst is 10%, or

0.3V. The duration of a transmit burst is 1ms, with a total

average current requirement of 40mA during the burst.

Given these factors, the minimum required capacitance

It can be determined that for systems that only need to

transmit every few seconds (or minutes or hours), the

average charge current required is extremely small, as

long as the sleep current is low. Even if the available

charge current in the example above was only 10µA and

the sleep current was only 5µA, it could still transmit a

burst every 9 seconds.

on V

is:

OUT

40mA • 1ms

0.3V

C_OUT(µF) ≥

= 133µF

Note that this equation neglects the effect of capacitor

ESR on output voltage droop. For most ceramic or low

ESR tantalum capacitors, the ESR will have a negligible

effect at these load currents.

The following formula enables the user to calculate the

time it will take to charge the LDO output capacitor and

the V

capacitor the ﬁrst time, from 0V. Here again, the

OUT

A standard value of 150µF or larger could be used for C

charge current available from the LTC3108-1 must be

known. For this calculation, it is assumed that the LDO

output capacitor is 2.2µF.

OUT

in this case. Note that the load current is the total current

draw on V , V

and VLDO, since the current for all of

OUT OUT2

theseoutputsmustcomefromV duringaburst.Current

OUT

2.2V • 2.2µF

I_CHG−I_LDO

t_LDO

=

contribution from the holdup capacitor on VSTORE is not

considered, since it may not be able to recharge between

bursts. Also, it is assumed that the charge current from

the LTC3108-1 is negligible compared to the magnitude

of the load current during the burst.

If there were 50µA of charge current available and a 5µA

loadontheLDO(whentheprocessorissleeping), thetime

for the LDO to reach regulation would be 107ms.

To calculate the maximum rate at which load bursts can

occur, determine how much charge current is available

If V

were programmed to 3V and the V

capacitor

OUT

was 150µF, the time for V

to reach regulation would be:

OUT

from the LTC3108-1 V

pin given the input voltage

OUT

3V • 150µF

I_CHG−I_VOUT−I_LDO

sourcebeingused.Thisnumberisbestfoundempirically,

t_VOUT

=

+ t_LDO

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LTC3108-1

applicaTions inForMaTion

If there were 50µA of charge current available and 5µA of

In this example, I = 5µA, I

T = one hour. The average charge current required from

the LTC3108-1 would be:

= 100mA, t = 5ms and

Q

BURST

load on V , the time for V

to reach regulation after

OUT

the initial application of power would be 11.35 seconds.

100mA • 0.005sec

Design Example 2

I_CHG≥ 5µA +

= 5.14µA

3600sec

Inmanypulsedloadapplications, theduration, magnitude

and frequency of the load current bursts are known and

ﬁxed. In these cases, the average charge current required

from the LTC3108-1 to support the average load must be

calculated, which can be easily done by the following:

Therefore, if the LTC3108-1 has an input voltage that al-

lows it to supply a charge current greater than 5.14µA, the

application can support 100mA bursts lasting 5ms every

hour. It can be determined that the sleep current of 5µA is

the dominant factor because the transmit duty cycle is so

I_BURST• t

small (0.00014%). Note that for a V

of 3V, the average

I_CHG≥ I_Q+

OUT

T

power required by this application is only 15.4µW (not

including converter losses).

Where I is the sleep current on V

required by the ex-

OUT

Q

ternal circuitry in between bursts (including cap leakage),

Note that the charge current available from the LTC3108-1

I

is the total load current during the burst, t is the

has no effect on the sizing of the V

capacitor (if it is

BURST

OUT

duration of the burst and T is the period of the transmit

burst rate (essentially the time between bursts).

assumedthattheloadcurrentduringaburstismuchlarger

than the charge current), and the V capacitor has no

OUT

effect on the maximum allowed burst rate.

Typical applicaTions

Peltier-Powered Energy Harvester for Remote Sensor Applications

COOPER BUSSMAN PB-5ROH104-R

OR KR-5R5H104-R

5.25V

1nF

1:100

T1

VSTORE

C

0.1F

6.3V

+

STORE

C1

C2

3V

+

THERMOELECTRIC

GENERATOR

V

OUT2

µP

V

C

OUT2

IN

330pF

499k

PGOOD

2.2V

PGD

SENSORS

XMTR

LTC3108-1

∆T = 1°C TO 20°C

VLDO

2.2µF

3V

V

SW

OUT

+

VS2

C

*

OUT

VS1

V

OUT2_EN

VAUX

GND

OFF ON

T1: COILCRAFT LPR6235-752SML

*C VALUE DEPENDENT ON

THE MAGNITUDE AND DURATION

OF THE LOAD PULSE

OUT

1µF

31081 TA02

31081f

ꢀꢇ

LTC3108-1

Typical applicaTions

Supercapacitor Charger and LDO Powered by a Solar Cell

(Uses External Charge Pump Rectiﬁers)

BAS31

I_VOUTvs Illuminance

0.022µF

(2 Diameter Monocrystalline Cell)

"

VAUX

10,000

1000

100

INCANDESCENT LIGHT

T1

1:20

C1

C2

VSTORE

+

–

+

SOLAR

CELL*

V

OUT2

220µF

OUTDOOR

LIGHT (CLOUDY)

330pF

499k

LTC3108-1

PGD

2.2V

VLDO

3.0V

V

OUT

+

2.2µF

SW

VS2

4F*

FLOURESCENT LIGHT

* 2 DIAMETER MONOCRYSTALLINE CELL

"

V

VS1

10

OUT2_EN

GND

LIGHT LEVEL ≥ 900 LUX

100

1000

10,000

10,0000

VAUX

ILLUMINANCE (LUX)

T1: COILCRAFT LPR6235-253PML

31081 TA03b

*TAIYO YUDEN

PAS1020LA3R0405

VAUX

4.7µF

31081 TA03

Dual Output Converter and LDO Powered by a Thermopile Generator

HONEYWELL

Q313

THERMOPILE

T1

1:50

4.7nF

C1

C2

VSTORE

+

V

OUT2

PGD

220µF

330pF

499k

LTC3108-1

PGOOD

2.2V

VLDO

2.2µF

4.5V

SW

V

OUT

V

OUT

+

VS2

VS1

150µF

6.3V

T1: COILCRAFT LPR6235-123QML

V

OUT2_EN

VAUX

GND

2.2µF

31081 TA04

31081f

ꢀꢈ

LTC3108-1

Typical applicaTions

DC Input Energy Harvester and Power Manager

R

IN

R

IN

> 100Ω/V

5.25V

OUT2

C1

VSTORE

+

C

STORE

V

+

IN

V

OUT2

PGD

–

> 5V

PGOOD

C2

LTC3108-1

2.2V

SW

VS2

VLDO

2.2µF

3V

V

OUT

+

C

OUT

VS1

V

OUT2_ENABLE

V

OUT2_EN

GND

VAUX

31081 TA05

2.2µF

AC Input Energy Harvester and Power Manager

R

C

IN

R

IN

> 100Ω/V

5.25V

C1

VSTORE

+

C

STORE

V

IN

AC

V

OUT2

PGD

> 5V

P-P

- PIEZO

- 60Hz

PGOOD

LTC3108-1

2.2V

C2

VLDO

2.2µF

4.5V

V

SW

OUT

+

C

OUT

VS2

VS1

V

OUT2_ENABLE

OUT2_EN

GND

VAUX

31081 TA06

2.2µF

31081f

ꢁ0

LTC3108-1

Typical applicaTions

Low Proﬁle (1.5mm) Step-Up Converter/Harvester Using 1:10 Transformer

VSTORE

3V AT 20mA

V

OUT2

T1

1:10

499k

0.1µF

V

10ms

IN

150mV TO 600mV

PGD

C1

C2

PGOOD

2.2V

C

*

IN

RES

LTC3108-1

330pF

390pF

VLDO

2.2µF

VLDO

3V

V

SW

OUT

+

330µF

s 3

VS2

0.068µF

BAS31

AVX TPSX337M004R0100

2.2V

VS1

V

GND

OUT2_EN

ENABLE

OFF ON

VAUX

T1: COILCRAFT LPR4012-202LML

10ms

VAUX

*C

LOWERS START-UP VOLTAGE

RES

TO 135mV TYPICAL

10µF

OUTPUT CAN SUPPORT A 20mA,

10ms LOAD PULSE EVERY 0.4s

AT V = 150mV

IN

31081 TA07

I_VOUTvs V_IN(Steady State)

6

5

4

3

2

1

0

V

≤ 3V

OUT

TYPICAL

MINIMUM LIMIT

250 300 350 400 450 500

600

550

150 200

V

(mV)

IN

31081 TA07b

31081f

ꢁꢀ

LTC3108-1

package DescripTion

UE/DE Package

12-Lead Plastic DFN (4mm × 3mm)

(Reference LTC DWG # 05-08-1695)

0.70 p0.05

3.30 p0.05

3.60 p0.05

2.20 p0.05

1.70 p 0.05

PACKAGE OUTLINE

0.25 p 0.05

0.50 BSC

2.50 REF

RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS

APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED

0.40 p 0.10

4.00 p0.10

(2 SIDES)

R = 0.115

TYP

7

12

R = 0.05

TYP

3.30 p0.10

3.00 p0.10

(2 SIDES)

1.70 p 0.10

PIN 1

TOP MARK

(NOTE 6)

PIN 1 NOTCH

R = 0.20 OR

0.35 s 45o

CHAMFER

(UE12/DE12) DFN 0806 REV D

6

1

0.25 p 0.05

0.75 p0.05

0.200 REF

0.50 BSC

2.50 REF

BOTTOM VIEW—EXPOSED PAD

0.00 – 0.05

NOTE:

1. DRAWING PROPOSED TO BE A VARIATION OF VERSION

(WGED) IN JEDEC PACKAGE OUTLINE M0-229

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

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

31081f

ꢁꢁ

LTC3108-1

package DescripTion

GN Package

16-Lead Plastic SSOP (Narrow .150 Inch)

(Reference LTC DWG # 05-08-1641)

.189 – .196*

(4.801 – 4.978)

.045 ±.005

.009

(0.229)

REF

16 15 14 13 12 11 10 9

.254 MIN

.150 – .165

.229 – .244

.150 – .157**

(5.817 – 6.198)

(3.810 – 3.988)

.0165 ±.0015

.0250 BSC

RECOMMENDED SOLDER PAD LAYOUT

1

2

3

4

5

6

7

8

.015 ± .004

(0.38 ± 0.10)

× 45°

.0532 – .0688

(1.35 – 1.75)

.004 – .0098

(0.102 – 0.249)

.007 – .0098

(0.178 – 0.249)

0° – 8° TYP

.016 – .050

(0.406 – 1.270)

.0250

(0.635)

BSC

.008 – .012

GN16 (SSOP) 0204

(0.203 – 0.305)

TYP

NOTE:

1. CONTROLLING DIMENSION: INCHES

INCHES

2. DIMENSIONS ARE IN

(MILLIMETERS)

3. DRAWING NOT TO SCALE

*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH

SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE

**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD

FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE

31081f

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.

ꢁꢂ

LTC3108-1

Typical applicaTion

Dual TEG Energy Harvester Operates from Temperature Differentials of Either Polarity

1nF

1:100

C1

HOT

5.25V

+

VSTORE

+

THERMOELECTRIC

GENERATOR

TEC

C

330pF

499k

STORE

V

OUT2

C2

COLD

LTC3108-1

PGD

PGOOD

3V

2.2V

VLDO

2.2µF

SW

VS2

VS1

V

OUT

LPR6235-752SML

V

OUT2_EN

C

OUT

VAUX

GND

OFF

ON

1µF

VAUX

1nF

1:100

C1

C2

VSTORE

COLD

HOT

+

THERMOELECTRIC

GENERATOR

V

OUT2

PGD

TEC

330pF

499k

LTC3108-1

VLDO

SW

V

VS2

VS1

OUT

LPR6235-752SML

V

OUT2_EN

GND

VAUX

31081 TA08

relaTeD parTs

PART NUMBER

DESCRIPTION

COMMENTS

LTC3108

Ultralow Voltage Step-Up Converter and Power Manager V : 0.02V to 1V; V

= 2.35V, 3.3V, 4.1V, 5V Fixed; I = 6µA; I <1µA;

OUT Q SD

IN

3mm × 4mm DFN-12 and SSOP-16 Packages

LTC4070

Li-Ion/Polymer Low Current Shunt Battery

Charger System

V : 450nA to 50mA; V : V + 4V, 4.1V, 4.2V; I = 300nA;

IN

OUT(MIN) FLOAT

Q

2mm × 3mm DFN-8 and MSOP-8 Packages

LTC1041

LTC1389

Bang-Bang Controller

V : 2.8V to 16V; V = Adj; I = 1.2mA; I < 1µA; SO-8 Package

IN

OUT(MIN)

Q

SD

Nanopower Precision Shunt Voltage Reference

V

= 1.25V; I = 0.8µA; SO-8 Package

OUT(MIN) Q

LT1672/LT1673/

LT1674

Single-/Dual-/Quad-Precision 2µA Rail-to-Rail Op Amps SO-8, SO-14 and MSOP-8 Packages

LT3009

3µA I , 20mA Linear Regulator V : 1.6V to 20V; V : 0.6V to Adj, 1.2V, 1.5V, 1.8V, 2.5V, 3.3V,

Q

IN

OUT(MIN)

5V to Fixed; I = 3µA; I < 1µA; 2mm × 2mm DFN-8 and SC70 Packages

Q

SD

LTC3525L-3/

LTC3525L-3.3/

LTC3525L-5

400mA (I ), Synchronous Step-Up DC/DC Converter

V : 0.7V to 4V; V

IN

= 5V ; I = 7µA; I < 1µA; SC70 Package

MAX Q SD

SW

OUT(MIN)

with Output Disconnect

LTC3588-1

LTC3632

LTC3642

Piezoelectric Energy Generator with Integrated High

Efﬁciency Buck Converter

V : 2.7V to 20V; V

: Fixed to 1.8V, 2.5V, 3.3V, 3.6V; I = 0.95µA;

OUT(MIN) Q

IN

3mm × 3mm DFN-10 and MSOP-10E Packages

45V, 20mA Synchronous MicroPower Buck Converter

V : 4.5V to 45V, 60V ; V : 0.8V to Adj, 3.3V Fixed, 5V Fixed;

IN

MAX OUT(MIN)

I = 12µA; I < 1µA; 3mm × 3mm DFN-8 and MSOP-8E Packages

Q

SD

45V, 50mA Synchronous MicroPower Buck Converter

V : 4.5V to 45V, 60V

; V

: 0.8V to Adj, 3.3V Fixed, 5V Fixed;

IN

MAX OUT(MIN)

I = 12µA; I < 1µA; 3mm × 3mm DFN-8 and MSOP-8E Packages

Q

SD

LT8410/ LT8410-1 MicroPower 25mA/8mA Low Noise Boost Converter

with Integrated Schottky Diode and Output Disconnect

V : 2.6V to 16V; V

= 40V

; I = 8.5µA; I < 1µA;

IN

OUT(MIN)

MAX Q SD

2mm × 2mm DFN-8 Package

31081f

LT 0410 • PRINTED IN USA

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

ꢁꢃ

●

 LINEAR TECHNOLOGY CORPORATION 2010

(408) 432-1900 FAX: (408) 434-0507 www.linear.com


型号：	LTC3108IGN-1-TRPBF
厂家：	Linear
描述：	Ultralow Voltage Step-Up Converter and Power Manager 超低电压，升压型转换器和电源管理器转换器
文件：	总24页 (文件大小：1508K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

LTC3108IGN-1-TRPBF [Linear]

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