LTC3108IDEPBF_技术文档

Electrical Specifications Subject to Change

LTC3108

Ultralow Voltage Step-Up

Converter and Power Manager

FEATURES

DESCRIPTION

TheLTC^®3108isahighlyintegratedDC/DCconverterideal

forharvestingandmanagingsurplusenergyfromextremely

low input voltage sources such as TEG (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 2.35V, 3.3V, 4.1V or 5V

OUT

- LDO: 2.2V at 3mA

- Logic Controlled Output

- Reserve Energy Output

Power Good Indicator

Usingasmallstep-uptransformer,theLTC3108providesa

completepowermanagementsolutionforwirelesssensing

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

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.

n

Ultralow I : 6μA

Q

Uses Compact Step-Up Transformers

Small 12-Lead (4mm × 3mm) DFN or 16-Lead

SSOP Packages

APPLICATIONS

n

Remote Sensors and Radio Power

n

Surplus Heat Energy Harvesting

n

HVAC

The LTC3108 is available in a small, thermally enhanced

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

package.

n

Industrial Wireless Sensing

n

Automatic Metering

Building Automation

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

Indoor Light Energy Harvesting

TYPICAL APPLICATION

Wireless Remote Sensor Application

Powered From a Peltier Cell

V_OUTCharge Time

1nF

1:100

1000

100

10

1

5V

C1

VSTORE

LTC3108

V

C

= 3.3V

= 470μF

OUT

+

0.1F

6.3V

TEG

220μF

330pF

V

OUT2

PGD

C2

PGOOD

2.2V

μP

20mV TO 500mV

VLDO

SW

2.2μF

SENSORS

RF LINK

3.3V

VS2

VS1

V

OUT

+

470μF

1:100 Ratio

1:50 Ratio

1:20 Ratio

V

OUT2_EN

GND

3108 TA01a

VAUX

0

100 150 200 250 300 350 400

(mV)

0

50

V

1μF

IN

3108 TA01b

3108p

1

LTC3108

ABSOLUTE MAXIMUM RATINGS ^{(Note 1)}

SW Voltage ..................................................–0.3V to 2V

C1 Voltage....................................................–0.3V to 6V

C2 Voltage.......................................................–8V to 8V

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

OUT

VLDO, VSTORE............................................–0.3V to 6V

Operating Temperature (Note 2).............. –40°C to 85°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, θ = 4.3°C/W

JA JC

JMAX

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

T

= 125°C, θ = 110°C/W, θ = 40°C/W

JA JC

JMAX

ORDER INFORMATION

LEAD FREE FINISH

LTC3108EDE#PBF

LTC3108IDE#PBF

LTC3108EGN#PBF

LTC3108IGN#PBF

TAPE AND REEL

PART MARKING*

LFJM

PACKAGE DESCRIPTION

TEMPERATURE RANGE

–40°C to 85°C

LTC3108EDE#TRPBF

LTC3108IDE#TRPBF

LTC3108EGN#TRPBF

LTC3108IGN#TRPBF

12-Lead (4mm × 3mm) Plastic DFN

16-Lead Plastic SSOP

LFJM

–40°C to 85°C

3108

–40°C to 85°C

3108

16-Lead Plastic SSOP

–40°C to 85°C

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/

3108p

2

LTC3108

ELECTRICAL CHARACTERISTICS ^Thel denotes the speciﬁcations which apply over the speciﬁed operating

junction temperature range of –40°C to 85°C, otherwise speciﬁcations are at T_A= 25°C. 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

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

Output Voltage

Using 1:100 Transformer Turns Ratio

V

500

mV

STARTUP

VS1 = VS2 = GND

2.30

3.234

4.018

4.90

2.350

3.300

4.100

5.000

2.40

3.366

4.182

5.10

V

VS1 = VAUX, VS2 = GND

VS1 = GND, VS2 = VAUX

VS1 = VS2 = VAUX

V

Quiescent Current

V

= 3.3V, V = 0V

OUT2_EN

0.4

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

l

2.156

2.2

0.5

0.01

100

4

2.244

1

For 0mA to 2mA Load

For VAUX from 2.5V to 5V

%

0.02

200

6

%

l

I

= 2mA

mV

mA

V

LDO

3

5

V

Current Limit

4.5

5.25

0.1

1

7

OUT

VSTORE Current Limit

VAUX Clamp Voltage

VSTORE Leakage Current

7

Current into VAUX = 5mA

VSTORE = 5V

5.5

μA

V

Leakage Current

V

= 0V, V

= 0V

OUT2

OUT2_EN

l

VS1, VS2 Threshold Voltage

VS1, VS2 Input Current

0.4

0.85

0.01

–7

1.2

0.1

VS1 = VS2 = 5V

μA

%

PGOOD Threshold (Rising)

PGOOD Threshold (Falling)

Measured Relative to the V

Sink Current = 100μA

Source Current = 0

Voltage

OUT

–9

%

PGOOD V

0.3

2.2

1

0.5

2.3

V

OL

OH

2.1

0.4

V

PGOOD 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)

0.15

0.3

350

1.3

0.5

l

Current Limit

0.2

0.5

Current Limit Response Time

P-Channel MOSFET On-Resistance

ns

Ω

V

= 3.3V (Note 3)

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.

with statistical process controls. The LTC3108I is guaranteed to meet

speciﬁcations over the full –40°C to 85°C operating temperature range.

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

production.

Note 2: The LTC3108E is guaranteed to meet performance speciﬁcations

from 0°C to 85°C. Speciﬁcations over the –40°C to 85°C operating

temperature range are assured by design, characterization and correlation

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.

3108p

3

LTC3108

T_A= 25°C, unless otherwise noted.

TYPICAL PERFORMANCE CHARACTERISTICS

I_OUTand Efﬁciency vs V_IN,

1:20 Ratio Transformer

I_OUTand Efﬁciency vs V_IN,

1:50 Ratio Transformer

3000

2500

2000

1500

1000

500

60

50

40

30

20

10

0

1800

1500

1200

900

600

300

0

60

50

40

30

20

10

0

EFFICIENCY

I

OUT

I

OUT

0

200

(mV)

300

400

0

100

200

(mV)

300

400

0

100

V

IN

3108 G01

3108 G02

I

_OUTand Efﬁciency vs V_IN,

I_OUTvs V_INand Source Resistance,

1:20 Ratio

Input Resistance vs V_IN

(V_OUTShorted)

1:100 Ratio Transformer

12

10

8

10000

1000

100

1200

1000

800

600

400

200

0

60

50

40

30

20

10

0

1Ω

I

OUT

2Ω

3Ω

5Ω

10Ω

15Ω

1:50 RATIO

EFFICIENCY

1:20 RATIO

6

4

1:100 RATIO

2

0

10

60 80 100 120 140 160

200

150

200

250

300

200

(mV)

300

400

20 40

180

50

100

0

100

V

(mV)

V

IN

OPEN CIRCUIT (mV)

V

IN

3108 G04

3108 G05

3108 G03

I_OUTvs V_INand Source Resistance,

1:100 Ratio

I_OUTvs dT and TEG Size,

1:100 Ratio

I_OUTvs V_INand Source Resistance,

1:50 Ratio

1000

100

10

1000

100

10

1000

100

10

1Ω

2Ω

3Ω

5Ω

1.5" SQUARE

10Ω

15Ω

0.625" SQUARE

1Ω

2Ω

3Ω

5Ω

10Ω

15Ω

1

60 80 100 120 140 160

200

180

20 40

0.1

1

10

100

60 80 100 120 140 160

200

180

20 40

dT ACROSS TEG (°C)

V

OPEN CIRCUIT (mV)

IN

V

OPEN CIRCUIT (mV)

3108 G08

IN

3108 G07

3108 G06

3108p

4

LTC3108

T_A= 25°C, unless otherwise noted.

TYPICAL PERFORMANCE CHARACTERISTICS

Resonant Switching Waveforms

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

V

= 20mV

IN

1:100 RATIO TRANSFORMER

C1 PIN

2V/DIV

C2 PIN

2V/DIV

SW PIN

50mV/DIV

3108 G09

10μs/DIV

0

0.5

1.5

2

2.5

3

3.5

4

1

0

0.5

1.5

2

2.5

3

3.5

4

1

LDO LOAD (mA)

3108 G11

3108 G10

V_OUTand PGD Response

During a Step Load

V_OUTRipple

Start-Up Voltage Sequencing

V

= 50mV

50mA LOAD STEP

OUT

30μA LOAD

OUT

IN

CH1

1:100 RATIO TRANSFORMER

= 220μF

C

= 220μF

C

= 220μF

VSTORE

C

OUT

1V/DIV

CSTORE = 470μF

= 2.2μF

C

CH2

OUT

1V/DIV

LDO

CH2, V

1V/DIV

20mV/

DIV

OUT

V

CH3, V

1V/DIV

LDO

CH1

PGD

1V/DIV

3108 G12

3108 G13

3108 G14

10sec/DIV

5ms/DIV

100ms/DIV

LDO Step Load Response

Enable Input and V_OUT2

Running on Storage Capacitor

CSTORE = 470μF

LOAD = 100μA

CH3

VSTORE

1V/DIV

V

OUT

CH2, V

OUT

CH2, V

OUT2

1V/DIV

CH4, V

LDO

1V/DIV

CH1, V

CH1

OUT2_EN

1V/DIV

IN

50mV/DIV

V

3108 G16

3108 G17

1ms/DIV

5sec/DIV

10mA LOAD ON V

OUT

OUT2

C

= 220μF

3108p

5

LTC3108

PIN FUNCTIONS ^(DFN/SSOP)

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

VS1 (Pin 8/Pin 11): V

to ground or VAUX to program the output voltage (see

Table 1).

Select Pin 1. Connect this pin

OUT

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

CC

capacitance. An active shunt regulator clamps VAUX to

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 1.3ꢀ P-channel switch. If not used, this

OUT

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

OUT

ExposedPad(Pin13)DFNOnly:Ground.TheDFNExposed

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

2.35V

3.3V

4.1V

5V

within 7% of its programmed value, PGD will be pulled

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

OUT

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).

3108p

6

LTC3108

BLOCK DIAGRAM ^{(DFN Package Shown)}

LTC3108

1.2V

V

OUT2

1.3Ω

V

ILIM

OUT2

V

OUT2_EN

OFF ON

SYNC RECTIFY

REFERENCE

V

REF

5M

C1

V

OUT

1:100

C1

V

OUT

IN

C

IN

5.25V

OUT

C2

+

C2

VS1

VS2

–

V

SW

OUT

CHARGE

CONTROL

V

OUT

PROGRAM

VHOLD

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)

3108 BD

2.2V

2.2μF

OPERATION ^{(Refer to the Block Diagram)}

The LTC3108 is designed to use a small external step-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.

The LTC3108 can also be used to trickle charge a standard

capacitor, supercapacitor or rechargeable battery, using

energy harvested from a Peltier or photovoltaic cell.

The LTC3108 is designed to manage the charging and

regulation of multiple outputs in a system in which the

3108p

7

LTC3108

OPERATION

Oscillator

Synchronous Rectiﬁers

The LTC3108 utilizes a MOSFET switch to form a resonant

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 20kHz to 200kHz. 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 includes a low current LDO to provide a

regulated 2.2V output for powering low power proces-

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

higher of VAUX or V . This enables it to become active

OUT

as soon as VAUX has charged to 2.3V, while the V

stor-

OUT

age 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 typical.

The AC voltage produced on the secondary winding of

the transformer is boosted and rectiﬁed using an external

chargepumpcapacitor(fromthesecondarywindingtopin

C1) and the rectiﬁers internal to the LTC3108. The rectiﬁer

circuit feeds current into the VAUX pin, providing 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

The active circuits within the LTC3108 are powered from

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

Larger capacitor values will reduce the ripple on VAUX but

increase the time it takes for VAUX to rise and the other

outputs to become active. Once VAUX exceeds 2.5V, the

Table 2. Regulated Voltage Using Pins VS1 and VS2

VS2

GND

VAUX

VS1

GND

VAUX

GND

VAUX

V

OUT

2.35V

3.3V

4.1V

5V

main V

is allowed to start charging.

OUT

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

Voltage Reference

value, the charging current is turned off.

The LTC3108 includes a precision, micropower reference,

for accurate regulated output voltages. This reference

becomes active as soon as VAUX exceeds 2V.

The internal programmable resistor divider sets V

eliminating the need for very high value external resistors

that are susceptible to board leakage.

,

OUT

3108p

8

LTC3108

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

OUT

V

(which has an internal pull-down resistor) is

VAUX exceeds 2.5V, the V

capacitor will be allowed to

OUT2_EN

OUT

low, V

will be off. Driving V

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 4mA.

OUT2

OUT2_EN

the V

output.

OUT2

Note that while V

cuitry for V

is high, the current limiting cir-

OUT2_EN

draws an extra 8μA of quiescent current

OUT2

PGOOD

from V . This added current draw has a negligible effect

OUT

A power good comparator monitors the V

voltage.

on the application and capacitor sizing, since the load on

OUT

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

the V

output, when enabled, is likely to be orders of

OUT2

(1MΩ)totheLDOvoltage.OnceV haschargedtowithin

magnitude higher than 8μA.

OUT

7% of its regulated voltage, the PGD output will go high.

VSTORE

If V

drops more than 9% from its regulated voltage,

OUT

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.

The VSTORE output can be used to charge a large storage

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

OUT2

,

OUT

V

OUT2

V

and LDO outputs. If VAUX drops below VSTORE,

V

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

the LTC3108 will automatically draw current from the stor-

age element. Note that it may take a long time to charge

a large capacitor, depending on the input energy available

OUT2

host, using the V

pin. When enabled, V

is

OUT2_EN

OUT2

connected to V

through a 1.3ꢀ P-channel MOSFET

OUT

and the loading on V

and VLDO.

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

be used to power external circuits such as sensors and

ampliﬁers,thatdonothavealowpowersleeporshutdown

OUT

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

Minimizing the amount of decoupling capacitance on

OUT

on V

must be handled by the V

capacitor.

V

willallowittobeswitchedonandofffaster, allowing

OUT

OUT2

shorter burst times and, therefore, smaller duty cycles in

Short-Circuit Protection

pulsed applications such as a wireless sensor/transmit-

ter. A small V

capacitor will also minimize the energy

OUT2

All outputs of the LTC3108 are current limited to protect

against short-circuits to ground.

that will be wasted in charging the capacitor every time

V

is enabled.

OUT2

Output Voltage Sequencing

V

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

OUT2

chargingcurrentandminimizeglitchingofthemainoutput

A timing diagram showing the typical charging and

voltage sequencing of the outputs is shown in Figure 1.

Note: time not to scale.

whenV

isenabled. Italsohasacurrentlimitingcircuit

OUT2

that limits the peak current to 0.3A typical.

3108p

9

LTC3108

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

3108 F01a

Figure 1. Output Voltage Sequencing (with V_OUTProgrammed for 3.3V)

3108p

10

LTC3108

APPLICATIONS INFORMATION

Introduction

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.

The LTC3108 is designed to gather energy from very low

input voltage sources and convert it to usable output volt-

agestopowermicroprocessors,wirelesstransmittersand

analog sensors. Such applications typically require much

more peak power, and at higher voltages, than the input

voltage source can produce. The LTC3108 is designed to

accumulate and manage energy over a long period of time

to enable short power bursts for acquiring and transmit-

ting data. The bursts must occur at a low enough duty

cycle such that the total output energy during 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.

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.

Peltier Cell (Thermoelectric Generator)

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

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

generator (TEG).

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

processororothercircuitrywhenV reachesregulation,

OUT

indicating that enough energy is available for a burst.

Input Voltage Sources

The LTC3108 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.

0.3

10

R

= 2Ω

S

MAX P

OUT

0.2

0.1

0

1

V

OC

0.1

0.01

0

5

10

15

20

25

ΔT (°C)

3108 F02

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

3108p

11

LTC3108

APPLICATIONS INFORMATION

The low voltage capability of the LTC3108 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.

Thermopile Generator

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

used as an energy source to power the LTC3108. Because

of the higher output voltages possible with a thermopile

generator, a much lower transformer turns ratio can be

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

TEG Load Matching

The LTC3108 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 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

current capability by providing a higher input voltage

under load.

Photovoltaic Cell

The LTC3108 converter can also operate from a single

photovoltaic(solar)celloperatinginindoorlighting,where

the available power is orders of magnitude less than in

directsunlight.ThiscapabilityallowstheLTC3108topower

circuits at light levels far too low for even very low input

voltage boost converters.

Peltier Cell (TEG) Suppliers

Non-Boost Applications

Peltiercellsareavailableinawiderangeofsizesandpower

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.

The LTC3108 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.

Table 3. Peltier Cell Manufacturers

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

these applications the C2 and SW pins are not used and

can be grounded or left open.

Fujitaka

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

FerroTec

www.ferrotec.com/products/thermal/modules

Melcor

www.melcor.com/tec.html

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.

Micropelt

www.micropelt.com

Nextreme

www.nextreme.com

TE Technology

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

to limit the maximum current into the VAUX shunt

regulator.

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

Tellurex

www.tellurex.com

3108p

12

LTC3108

APPLICATIONS INFORMATION

COMPONENT SELECTION

output current capability. Refer to the Typical Applications

schematic examples for the recommended value for a

given turns ratio.

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.

V

and VSTORE Capacitor

OUT

For pulsed load applications, the V

capacitor should

OUT

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

1

I_LOAD(mA) • t_PULSE(sec)

Frequency =

Hz

C_OUT(mF) ≥

2 • π • L(sec)• C

ΔV_OUT

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 20kHz to 200kHz. See Table 4

for some recommended transformers.

Note that there must be enough energy available from

theinputvoltagesourceforV torechargethecapacitor

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.

OUT

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

sands of microfarads or even Farads), to provide holdup

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

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

Table 4. Recommended Transformers

VENDOR

PART NUMBER

Coilcraft

www.coilcraft.com

LPR6235-752SML (1:100 Ratio)

LPR6235-253PML (1:20 Ratio)

LPR6235-123QML (1:50 Ratio)

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:

C1 Capacitor

⎡

⎤

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

⎣

⎦

C_STORE

≥

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

5.25 − V_OUT

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

Q

the load on V

in between bursts, I

is the load on the

is the total load during the

OUT

LDO

LDO between bursts, I

BURST

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

the bursts, TSTORE is the storage time required and V

OUT

istheoutputvoltagerequired. Notethatforaprogrammed

outputvoltageof5V,theVSTOREcapacitorcannotprovide

any beneﬁcial storage time.

3108p

13

LTC3108

APPLICATIONS INFORMATION

To minimize losses and capacitor charge time, all capaci-

Due to the very low input voltage the circuit may operate

tors used for V

and VSTORE should be low leakage.

from, the connections to V , the primary of the trans-

OUT

IN

See Table 5 for recommended storage capacitors.

former and the SW and GND pins of the LTC3108 should

bedesignedtominimizevoltagedropfromstrayresistance

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.

Table 5. Recommended Storage Capacitors

VENDOR

PART NUMBER/SERIES

AVX

www.avx.com

BestCap Series

TAJ and TPS Series Tantalum

Cap-XX

GZ Series

KR Series

Also, due to the low charge currents available at the out-

puts of the LTC3108, any sources of leakage current on

the output voltage pins must be minimized. An example

board layout is shown in Figure 3.

www.cap-xx.com

Cooper/Bussman

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

Vishay/Sprague

www.vishay.com/capacitors

Tantamount 592D

595D Tantalum

150CRZ/153CRV Aluminum

013 RLC (Low Leakage)

Design Example 1

This design example will explain how to calculate the

Storage capacitors requiring voltage balancing are not

recommended due to the current draw of the balancing

resistors.

necessary storage capacitor value for V

in pulsed load

OUT

applications,suchasawirelesssensor/transmitter.Inthese

types of applications, the load is very small for a major-

ity of the time (while the circuitry is in a low power sleep

state), with bursts of load current occurring periodically

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.

during a transmit burst. The storage capacitor on V

OUT

supports the load during the transmit burst, and the long

sleeptimebetweenburstsallowstheLTC3108torecharge

V

IN

SW

C2

VAUX

1

2

3

4

5

6

12

11

10

9

VSTORE

V

C1

V

OUT

V

OUT2

VLDO

PGD

OUT2_EN

V

OUT2

VS1

VS2

8

VLDO

PGOOD

7

GND

3108 FO3

VIAS TO GROUND PLANE

Figure 3. Example Component Placement for Two-Layer PC Board (DFN Package)

3108p

14

LTC3108

APPLICATIONS INFORMATION

the capacitor. A method for calculating the maximum rate

at which the load pulses can occur for a given output cur-

rent from the LTC3108 will also be shown.

addition, use the value of 150μF for the V

capacitor.

OUT

The maximum transmit rate (neglecting the duration of

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

given by:

In this example, V

is set to 3.3V, and the maximum

OUT

150µF • 0.33V

(50µA − 17µA)

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

0.33V. 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

t =

= 1.5sec or f_MAX= 0.666Hz

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

port a 1ms transmit burst every 1.5 seconds.

on V

is:

OUT

40mA • 1ms

0.33V

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 ten seconds.

C_OUT(µF) ≥

= 121µF

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.

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

OUT

The following formula enables the user to calculate the

time it will take to charge the LDO output capacitor and

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

the V

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

OUT

theseoutputsmustcomefromV duringaburst.Current

OUT

the charge current available from the LTC3108 must be

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

output capacitor is 2.2μF.

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 is negligible compared to the magnitude of

the load current during the burst.

2.2V • 2.2µF

I_CHG−I_LDO

t_LDO

=

To calculate the maximum rate at which load bursts can

occur, determine how much charge current is available

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

loadontheLDO(whentheprocessorissleeping), thetime

for the LDO to reach regulation would be 107ms.

fromtheLTC3108V

pingiventheinputvoltagesource

OUT

being used. This number is best found empirically, since

there are many factors affecting the efﬁciency of the

converter. Also determine what the total load current is

If V

were programmed to 3.3V and the V

capacitor

OUT

was 150μF, the time for V

to reach regulation would be:

OUT

on V

during the sleep state (between bursts). Note

OUT

3.3V • 150µF

I_CHG−I_VOUT

t_VOUT

=

+ t_LDO

that this must include any losses, such as storage ca-

pacitor leakage.

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

load on V , the time for V to reach regulation after

the initial application of power would be 11.1 seconds.

Assume, for instance, that the charge current from the

LTC3108 is 50μA and the total current drawn on V

in

OUT

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

3108p

15

LTC3108

APPLICATIONS INFORMATION

Design Example 2

Therefore, if the LTC3108 has an input voltage that allows

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

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 to support the average load must be

calculated, which can be easily done by the following:

so small (0.00014%). Note that for a V

of 3.3V, the

OUT

average power required by this application is only 17μW

(not including converter losses).

I_BURST• t

I_CHG≥ I_Q+

T

Note that the charge current available from the LTC3108

Where I is the sleep current on V

required by the ex-

has no effect on the sizing of the V

capacitor (if it is

Q

OUT

ternal circuitry in between bursts (including cap leakage),

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

assumedthattheloadcurrentduringaburstismuchlarger

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

I

BURST

OUT

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

burst rate (essentially the time between bursts).

effect on the maximum allowed burst rate.

In this example, I = 5μA, I

= 100mA, t = 5ms and

BURST

Q

T = one hour. The average charge current required from

the LTC3108 would be:

100mA • 0.005sec

I_CHG≥ 5µA +

= 5.14µA

3600sec

TYPICAL APPLICATIONS

Peltier-Powered Energy Harvester for Remote Sensor Applications

COOPER BUSSMAN PB-5ROH104-R

OR KR-5R5H104-R

5V

1nF

1:100

T1

VSTORE

C

0.1F

6.3V

+

STORE

C1

3.3V

+

V

OUT2

μP

V

OUT2

C

IN

TEG

330pF

PGOOD

PGD

SENSORS

XMTR

C2

LTC3108

2.2V

ΔT = 1°C TO 20°C

VLDO

SW

2.2μF

3.3V

+

V

OUT

VS2

VS1

C

OUT

V

OUT2_EN

VAUX

GND

OFF ON

T1: COILCRAFT LPR6235-752SML

1μF

3108 TA02

3108p

16

LTC3108

TYPICAL APPLICATIONS

Li-Ion Battery Charger and LDO Powered by a Solar Cell with Indoor Lighting

T1

1:20

0.047μF

C1

VSTORE

+

–

+

V

SOLAR CELL

OUT2

220μF

330pF

LTC3108

PGD

C2

2.2V

OUT

SW

VLDO

2.2μF

4.1V

V

OUT

T1: COILCRAFT LPR6235-253PML

VS2

VS1

Li-Ion

V

GND

OUT2_EN

VAUX

1μF

3108 TA03

Supercapacitor Charger and LDO Powered by a Thermopile Generator

HONEYWELL

CQ200

THERMOPILE

0.047μF

1:20

C1

VSTORE

+

V

OUT2

220μF

330pF

LTC3108

PGD

PGOOD

C2

2.2V

SW

VLDO

2.2μF

2.35V

V

OUT

+

VS2

VS1

150mF

2.5V

V

OUT2_EN

VAUX

GND

CAP-XX GZ115F

1μF

3108 TA04

DC Input Energy Havester and Power Manager

AC Input Energy Havester and Power Manager

R

IN

C

IN

R

> 100Ω/V

R

> 100Ω/V

IN

5V

C1

VSTORE

C1

VSTORE

+

C

STORE

V

+

IN

AC

V

OUT2

V

OUT2

V

OUT2

–

> 5V

V

> 5V

IN

P-P

- PIEZO

- 60Hz

PGD

PGOOD

PGD

PGOOD

C2

LTC3108

2.2V

SW

VS2

VLDO

C2

VLDO

2.2μF

VLDO

2.2μF

3.3V

5V

+

V

SW

OUT

+

C

OUT

VS2

VS1

V

OUT2_EN

OUT2_ENABLE

OUT2_EN

VAUX

GND

VAUX

GND

3108 TA05

3108 TA06

1μF

3108p

17

LTC3108

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

3108p

18

LTC3108

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

3108p

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

LTC3108

TYPICAL APPLICATION

Dual TEG Energy Harvester Operates from Temperature Differentials of Either Polarity

1nF

1:100

5V

C1

HOT

VSTORE

+

C

STORE

V

OUT2

TEG

TEC

330pF

LTC3108

PGD

PGOOD

3.3V

C2

COLD

2.2V

VLDO

SW

VS2

VS1

VLDO

2.2μF

V

OUT

+

LPR6235-752SML

V

OUT2_EN

C

OUT

VAUX

GND

OFF

ON

1μF

VAUX

1nF

1:100

C1

C2

VSTORE

COLD

HOT

+

V

OUT2

PGD

TEC

TEG

330pF

LTC3108

SW

VLDO

V

VS2

VS1

OUT

V

LPR6235-752SML

OUT2_EN

VAUX

GND

3108 TA07

RELATED PARTS

PART NUMBER

LTC1041

DESCRIPTION

Bang-Bang Controller

Nanopower Precision Shunt Voltage Reference

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

COMMENTS

V : 2.8V to 16V; V

IN

= Adj; I = 1.2mA; I < 1μA; SO-8 Package

OUT(MIN)

Q

SD

LTC1389

V

= 1.25V; I = 0.8μA; SO-8 Package

OUT(MIN) Q

LT1672/LT1673/

LT1674

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,

OUT(MIN)

Q

IN

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

LTC3631

LTC3632

LTC3642

Piezoelectric Energy Generator with Integrated High

Efﬁciency Buck Converter

V : 2.6V to 19.2V; V

: Fixed to 2.5V, 3V, 3.3V, 3.6V; I = 0.95μA;

IN

OUT(MIN) Q

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

45V, 100mA Synchronous MicroPower Buck Converter V : 4.5V to 45V, 60V

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

MAX OUT(MIN)

IN

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

Q

SD

45V, 20mA Synchronous MicroPower Buck Converter

45V, 50mA Synchronous MicroPower Buck Converter

V : 4.5V to 45V, 60V

; V

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

MAX OUT(MIN)

IN

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

Q

SD

V : 4.5V to 45V, 60V

; V

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

MAX OUT(MIN)

IN

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;

MAX Q SD

IN

OUT(MIN)

2mm × 2mm DFN-8 Package

3108p

LT 1109 • PRINTED IN USA

LinearTechnology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

20

●

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


型号：	LTC3108IDEPBF
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20页 (文件大小：252K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

LTC3108IDEPBF [Linear]

相关型号：

SI9130DB

SI9135LG-T1

SI9135LG-T1-E3

SI9135_11

SI9136_11

SI9130CG-T1-E3

SI9130LG-T1-E3

SI9130_11

SI9137

SI9137DB

SI9137LG

SI9122E