LTC3109IGN-PBF_技术文档

LTC3109

Auto-Polarity, Ultralow

Voltage Step-Up Converter

and Power Manager

DescripTion

TheLTC^®3109isahighlyintegratedDC/DCconverterideal

for harvesting surplus energy from extremely low input

voltage sources such as TEGs (thermoelectric genera-

tors) and thermopiles. Its unique, proprietary autopolarity

topology* allows it to operate from input voltages as low

as 30mV, regardless of polarity.

FeaTures

n

Operates from Inputs as Low as ±±3mV

n

Less Than ±ꢀ1C ꢁeeꢂeꢂ ꢃAross TEG to ꢄarvest

Energy

n

Proprietary ꢃuto-Polarity ꢃrAhiteAture

n

Complete Energy ꢄarvesting Power Management

System

– SeleAtable V

of 2.±5V, ±.±V, 4.ꢀV or 5V

OUT

Using two compact step-up transformers and external

energy storage elements, the LTC3109 provides a com-

plete power management solution for wireless sensing

and data acquisition. The 2.2V LDO can power an external

microprocessor,whilethemainoutputcanbeprogrammed

to one of four ﬁxed voltages. The power good indicator

signals that the main output is within regulation. A second

output can be enabled by the host. A storage capacitor (or

battery) can also be charged to provide power when the

input voltage source is unavailable. Extremely low quies-

cent current and high efﬁciency maximizes the harvested

energy available for the application.

– 2.2V, 5mꢃ LDO

– LogiA-Controlleꢂ Output

– Energy Storage Capability for Operation During

Power Interruption

n

Power Gooꢂ InꢂiAator

Uses Compact Step-up Transformers

Small, 20-lead (4mm × 4mm) QFN Package or

20-Lead SSOP

applicaTions

n

Remote Sensor and Radio Power

The LTC3109 is available in a small, thermally enhanced

20-lead (4mm × 4mm) QFN package and a 20-lead SSOP

package.

L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear

Technology Corporation. All other trademarks are the property of their respective owners.

*Patent pending.

n

HVAC Systems

n

Automatic Metering

n

Building Automation

n

Predictive Maintenance

n

Industrial Wireless Sensing

Typical applicaTion

TEG

(THERMOELECTRIC GENERATOR)

1nF

V_OUTCurrent vs TEG Voltage

30ꢀV TO 500ꢀV

1:100

C1A

V

OPTIONAL SWITCHED OUTPUT FOR SENSORS

OUT2

•

900

800

700

600

500

400

300

200

100

1:100 TRANSFORMERS

C1A = C1B = 1nF

470pF

3.3V

2.2V

C2A

V

47µF

OUT

V

= 3.3V

OUT

+

470µF

SWA

VLDO

2.2µF

V

LOW POWER

RADIO

INA

1nF

LTC3109

1:100

C1B

•

SENSOR(S)

µP

470pF

C2B

PG00D

SWB

V

OUT2_EN

V

INB

5.25V

VS1

VS2

VAUX

VSTORE

VAUX

0

+

–300 –200 –100

0

300

100

200

1µF

C

STORE

GND

V

(mV)

TEG

3109 TA01a

3109 TA01b

3109f

ꢀ

LTC3109

absoluTe MaxiMuM raTings ^{(ꢁote ꢀ)}

SWA, SWB, V , V Voltage .................... –0.3V to 2V

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

VAUX......................................................15mA Into V

Operating Junction Temperature Range

(Note 2).................................................. –40°C to 125°C

Storage Temperature Range .................. –65°C to 125°C

INA INB

C1A, C1B Voltage ......................................... –0.3V to 6V

AUX

C2A, C2B Voltage (Note 6).............................. –8V to 8V

V

, V

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

OUT2 OUT2_EN

VS1, VS2, V , PGOOD .............................. –0.3V to 6V

OUT

pin conFiguraTion

TOP VIEW

VS1

VS2

1

2

3

4

5

6

7

8

9

20

19

18

C1A

C2A

GND

20 19 18 17 16

VSTORE

VAUX

SWA

VSTORE

VAUX

1

2

3

4

5

15

14

13

12

11

V

17 SWA

INA

21

GND

V

16

15

14

13

12

11

V

INA

V

INB

OUT

SWB

GND

V

OUT2

V

OUT2

V

OUT2_EN

V

SWB

GND

C2B

C1B

OUT2_EN

PGOOD

6

7

8

9 10

VLDO

GND 10

UF PACKAGE

20-LEAD (4mm s 4mm) PLASTIC QFN

GN PACKAGE

20-LEAD PLASTIC SSOP

T

= 125°C, θ = 37°C/W

JA

JMAX

T

= 125°C, θ = 90°C/W

JA

JMAX

EXPOSED PAD (PIN 21) IS GND (Note 5)

orDer inForMaTion

LEꢃD FREE FIꢁISꢄ

LTC3109EUF#PBF

LTC3109IUF#PBF

LTC3109EGN#PBF

LTC3109IGN#PBF

TꢃPE ꢃꢁD REEL

PꢃRT MꢃRKIꢁG*

PꢃCKꢃGE DESCRIPTIOꢁ

TEMPERꢃTURE RꢃꢁGE

–40°C to 125°C

LTC3109EUF#TRPBF

LTC3109IUF#TRPBF

LTC3109EGN#TRPBF

LTC3109IGN#TRPBF

3109

20-Lead (4mm × 4mm) Plastic QFN

20-Lead Plastic SSOP

3109

LTC3109GN

20-Lead Plastic SSOP

Consult LTC Marketing for parts speciﬁed with wider operating temperature ranges. *The temperature grade is identiﬁed by a label on the shipping container.

Consult LTC Marketing for information on non-standard lead based ﬁnish parts.

For more information on lead free part marking, go to: http://www.linear.com/leadfree/

For more information on tape and reel speciﬁcations, go to: http://www.linear.com/tapeandreel/

3109f

ꢁ

LTC3109

elecTrical characTerisTics ^Thel ꢂenotes the speAiﬁAations whiAh apply over the full operating

junAtion temperature range, otherwise speAiﬁAations are for T_ꢃ= 251C (ꢁote 2). VꢃUX = 5V unless otherwise noteꢂ.

PꢃRꢃMETER

COꢁDITIOꢁS

MIꢁ

TYP

30

6

MꢃX

UꢁITS

mV

Minimum Start-Up Voltage

No-Load Input Current

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

50

Using 1:100 Transformer Turns Ratios,

mA

V

= 30mV, V

= 0V, All Outputs Charged

OUT2_EN

IN

and in Regulation

l

Input Voltage Range

Output Voltage

Using 1:100 Transformer Turns Ratios

V

500

mV

STARTUP

l

VS1 = VS2 = GND

2.30

3.234

4.018

4.875

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

VAUX Quiescent Current

VAUX Clamp Voltage

No Load, All Outputs Charged

Current Into VAUX = 5mA

7

10

µA

V

l

5.0

6

5.25

0.2

15

5.55

V

OUT

V

OUT

Quiescent Current

Current Limit

V

OUT

V

OUT

= 3.3V, V

= 0V

OUT2_EN

µA

mA

Ω

26

N-Channel MOSFET On-Resistance

C2B = C2A = 5V (Note 3) Measured from V or

0.35

INA

SWA, V or SWB to GND

INB

l

LDO Output Voltage

LDO Load Regulation

LDO Line Regulation

LDO Dropout Voltage

LDO Current Limit

0.5mA Load On V

2.134

2.2

0.5

0.05

100

12

2.30

1

V

%

LDO

For 0mA to 2mA Load

For V from 2.5V to 5V

0.2

200

%

AUX

l

I

= 2mA

= 0V

mV

mA

µA

mA

nA

V

LDO

V

5

6

LDO

VSTORE Leakage Current

VSTORE Current Limit

VSTORE = 5V

VSTORE = 0V

0.1

15

0.3

26

l

V

OUT2

Leakage Current

V

OUT2

= 0V, V = 0V

OUT2_EN

50

VS1, VS2 Threshold Voltage

VS1, VS2 Input Current

0.4

0.85

1

1.2

50

V

= V = 5V

nA

%

S1

S2

PGOOD Threshold (Rising)

PGOOD Threshold (Falling)

Measured Relative to the V

Sink Current = 100µA

Source Current = 0

Voltage

–7.5

–9

OUT

%

PGOOD V

0.12

2.2

1

0.3

2.3

V

OL

OH

2.1

0.4

V

PGOOD Pull-Up Resistance

MΩ

V

l

V

Threshold Voltage

V

Rising

OUT2_EN

1.0

100

5

1.3

OUT2_EN

Threshold Hysteresis

Pull-Down Resistance

mV

MΩ

µs

A

Turn-On Time

0.5

0.15

0.3

350

1.0

OUT2

Turn-Off Time

(Note 3)

= 3.3V

l

Current Limit

V

OUT

0.2

0.5

Current Limit Response Time

P-Channel MOSFET On-Resistance

(Note 3)

= 5V (Note 3)

ns

Ω

V

OUT

ꢁote ꢀ: 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.

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

LTC3109I 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

ꢁote 2: The LTC3109 is tested under pulsed load conditions such that

T ≈ T . The LTC3109E is guaranteed to meet speciﬁcations from

J

A

3109f

ꢂ

LTC3109

elecTrical characTerisTics

board layout, the rated thermal package thermal resistance and other

ꢁote 5: Failure to solder the exposed backside of the QFN package to the

PC board ground plane will result in a thermal resistance much higher

than 37°C/W.

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

ꢁote 6: The Absolute Maximum Rating is a DC rating. Under certain

conditions in the applications shown, the peak AC voltage on the C2A and

C2B pins may exceed 8V. This behavior is normal and acceptable because

the current into the pin is limited by the impedance of the coupling

capacitor.

impedance.

ꢁote ±: Speciﬁcation is guaranteed by design and not 100% tested in

production.

ꢁote 4: Current measurements are made when the output is not switching.

Typical perForMance characTerisTics ^T_ꢃ^{= 251C, unless otherwise noteꢂ.}

I_Iꢁvs V_Iꢁ

I_VOUTvs V_Iꢁ

P_VOUTvs V_Iꢁ

10000

1000

100

10

1

1000

100

10

V

= 0V

1:100 RATIO, C1 = 1nF

1:50 RATIO, C1 = 4.7nF

1:20 RATIO, C1 = 10nF

1:50 RATIO

C1 = 4.7nF

OUT

V

= 3.3V

OUT

V

= 5V

OUT

NO LOAD ON VLDO

V

OUT

= 3.3V

1:100 RATIO, C1 = 1nF

1:50 RATIO, C1 = 4.7nF

1:20 RATIO, C1 = 10nF

10

0.1

1

10

100

(mV)

1000

10

100

V (mV)

IN

1000

10

100

(mV)

1000

V

IN

3109 G02

3109 G18

3109 G01

Open-CirAuit Start-Up Voltage

vs SourAe ResistanAe

Input ResistanAe vs V_Iꢁ

EfﬁAienAy vs V_Iꢁ

50

45

40

35

30

25

20

15

10

5

90

80

70

60

50

40

30

20

10

0

7.0

6.5

6.0

5.5

5.0

4.5

4.0

3.5

3.0

2.5

2.0

V

= 0V

OUT

1:100 RATIO, C1 = 1nF

1:50 RATIO, C1 = 4.7nF

1:20 RATIO, C1 = 10nF

V

= 0V

OUT

1:100 RATIO, C1 = 1nF

1:50 RATIO, C1 = 4.7nF

1:20 RATIO, C1 = 10nF

0

10

100

(mV)

1000

10

100

1000

0

1

2

3

4

5

10

6

7

8

9

V

(mV)

SOURCE RESISTANCE (Ω)

IN

3109 G04

3109 G03

3109 G05

3109f

ꢃ

LTC3109

Typical perForMance characTerisTics _{T = 251C, unless otherwise noteꢂ.}

ꢃ

VꢃUX Clamp Voltage

vs Shunt Current

P_VOUTvs ꢂT anꢂ TEG Size,

ꢀ:ꢀ33 Ratio, V_OUT= 5V

V

_OUTanꢂ VLDO vs Temperature

5.5

5.4

5.3

5.2

5.1

5.0

1.00

3.0

2.5

0.75

0.50

FERROTEC 9500/127/100B

40mm

VLDO

2.0

1.5

0.25

0

V

OUT

–0.25

–0.50

–0.75

1.0

0.5

0

FERROTEC 9501/071/040B

22mm

–1.00

0

3

6

9

12

15

–25

0

50

75 100 125

0

1

2

3

4

5

6

7

8

9

10

–50

25

dT (°K)

VAUX SHUNT CURRENT (mA)

TEMPERATURE (°C)

3109 G07

3109 G06

3109 G08

Resonant SwitAhing Waveforms

LDO Loaꢂ 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

C1 A OR B

2V/DIV

C2 A OR B

2V/DIV

3109 G9

20µs/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)

3109 G10

3109 G11

V

_OUTanꢂ PGOOD Response

Start-Up Voltage SequenAing

During a Step Loaꢂ

V_OUTRipple

V

= 50mV

50mA LOAD STEP

OUT

30µA LOAD

OUT

IN

1:100 RATIO TRANSFORMER

C

= 220µF

C

= 220µF

C

= 220µF

OUT

STORE

CH1

VSTORE

1V/DIV

= 470µF

= 2.2µF

LDO

CH2

OUT

1V/DIV

20mV/

DIV

V

CH2, V

OUT

1V/DIV

CH3, V

1V/DIV

CH1

PGD

1V/DIV

LDO

3109 G12

3109 G13

3109 G14

10SEC/DIV

5ms/DIV

100ms/DIV

3109f

ꢄ

LTC3109

Typical perForMance characTerisTics _{T = 251C, unless otherwise noteꢂ.}

ꢃ

LDO Step Loaꢂ Response

Enable Input anꢂ V_OUT2

Running on Storage CapaAitor

C

V

= 470µF

STORE

OUT

LOAD = 100µA

CH3

VSTORE

1V/DIV

V

LDO

CH2

OUT2

1V/DIV

20mV/DIV

V

CH2, V

OUT

1V/DIV

CH4, V

LDO

1V/DIV

I

CH1

OUT2_EN

1V/DIV

LDO

CH1, V

5mA/DIV

V

IN

50mV/DIV

3109 G16

3109 G17

3109 G15

200µs/DIV

1ms/DIV

5SEC/DIV

10mA LOAD ON V

OUT2

OUT

0mA TO 3mA LOAD STEP

LDO

C

= 220µF

C

= 2.2µF

pin FuncTions ^(QFꢁ/SSOP)

VSTORE(Pinꢀ/Pin±):OutputfortheStorageCapacitoror

Battery. A large storage 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.

PGOOD (Pin 6/Pin 8): Power Good Output. When V

OUT

is within 7.5% of its programmed value, this pin will be

pulled up to the LDO voltage through a 1M resistor. If

V

drops 9% below its programmed value PGOOD will

OUT

go low. This pin can sink up to 100µA.

VLDO (Pin 7/Pin 9): 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.

VꢃUX (Pin 2/Pin 4): Output of the Internal Rectiﬁer Cir-

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

CC

capacitance to ground. An active shunt regulator clamps

GꢁD (Pins 8, ꢀꢀ, ꢀ6, Exposeꢂ Paꢂ Pin 2ꢀ/Pins ꢀ3, ꢀ±,

ꢀ8):GroundPins.Connectthesepinsdirectlytotheground

plane.Theexposedpadservesasagroundconnectionand

as a means of conducting heat away from the die.

VAUX to 5.25V (typical).

V

OUT

(Pin ±/Pin 5): Main Output of the Converter. The

voltage at this pin is regulated to the voltage selected by

VS1 and VS2 (see Table 1). Connect this pin to a reservoir

capacitor or to a rechargeable battery. Any high current

pulse loads must be fed by the reservoir capacitor on

this pin.

VS2 (Pin 23/Pin 2): V

Select Pin 2. Connect this

OUT

pin to ground or VAUX to program the output voltage

(see Table 1).

VSꢀ (Pin ꢀ9/Pin ꢀ): V

Select Pin 1. Connect this

OUT

V

(Pin 4/ Pin 6): Switched Output of the Converter.

OUT2

pin to ground or VAUX to program the output voltage

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

(see Table 1).

until V is driven high, then it is connected to V

OUT_EN

OUT

Table ꢀ. Regulateꢂ Output Voltage Using Pins VSꢀ anꢂ VS2

through a 1Ω PMOS switch. If not used, this pin should

VS2

GND

VAUX

VSꢀ

GND

VAUX

GND

VAUX

V

OUT

be left open or tied to V

.

OUT

2.35V

3.3V

4.1V

5.0V

V

(Pin 5/Pin 7): Enable Input for V

. V

OUT2 OUT2

OUT2_Eꢁ

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.

3109f

ꢅ

LTC3109

pin FuncTions ^(DFꢁ/SSOP)

CꢀB(Pin9/Pinꢀꢀ):InputtotheChargePumpandRectiﬁer

Circuit for Channel B. Connect a capacitor from this pin

to the secondary winding of the “B” step-up transformer.

SeetheApplicationsInformationsectionforrecommended

capacitor values.

SWꢃ (Pin ꢀ5/Pin ꢀ7): Connection to the Internal N-Chan-

nel Switch for Channel A. Connect this pin to the primary

winding of the “A” transformer.

SWB (Pin ꢀ2/Pin ꢀ4): Connection to the Internal N-Chan-

nel Switch for Channel B. Connect this pin to the primary

winding of the “B” transformer.

Cꢀꢃ (Pin ꢀ8/Pin 23): Input to the Charge Pump and Recti-

ﬁerCircuitforChannelA. Connectacapacitorfromthispin

to the secondary winding of the “A” step-up transformer.

SeetheApplicationsInformationsectionforrecommended

capacitor values.

V

(Pinꢀ4/Pinꢀ6):ConnectiontotheInternalN-Channel

Iꢁꢃ

Switch for Channel A. Connect this pin to one side of the

input voltage source (see Typical Applications).

V

(Pinꢀ±/Pinꢀ5):ConnectiontotheInternalN-Channel

IꢁB

C2B (Pin ꢀ3/Pin ꢀ2): Input to the Gate Drive Circuit for

SWB. Connect a capacitor from this pin to the secondary

windingofthe“B”step-uptransformer.SeetheApplications

Information section for recommended capacitor values.

Switch for Channel B. Connect this pin to the other side of

the input voltage source (see Typical Applications).

C2ꢃ (Pin ꢀ7/Pin ꢀ9): Input to the Gate Drive Circuit for

SWA. Connect a capacitor from this pin to the secondary

windingofthe“A”step-uptransformer.SeetheApplications

Information section for recommended capacitor values.

3109f

ꢆ

LTC3109

block DiagraM

SYNC

RECTIFY

C1B

V

REF

1.2V

REFERENCE

V

OUT2

1Ω

V

OUT2

SYNC

RECTIFY

V

OUT2_EN

V

OUT

C1A

V

OUT

•

+

5.25V

C

OUT

VS1

VS2

+

–

C2A

V

OUT

V

IN

PROGRAM

CHARGE

CONTROL

C2B

V

OUT

V

LDO

V

SWA

STORE

V

1M

INA

POWER

SWITCHES

V

REF

+

–

PG00D

•

SWB

PG00D

VSTORE

V

INB

+

V

OUT

C

STORE

LDO

V

REF

GND

VAUX

VLDO

2.2V

LDO

2.2µF

3109 BD

C

AUX

1µF

C

3109f

ꢇ

LTC3109

operaTion ^{(Refer to the BloAk Diagram)}

The LTC3109 is designed to use two small external

step-up transformers to create an ultralow input voltage

step-up DC/DC converter and power manager that can

operate from input voltages of either polarity. This unique

capability enables energy harvesting from thermoelectric

generators (TEGs) in applications where the temperature

differential across the TEG may be of either (or unknown)

polarity. It can also operate from low level AC sources. It

is ideally suited for low power wireless sensors and other

applications in which surplus energy harvesting is used to

generate system power because traditional battery power

is inconvenient or impractical.

Charge Pump anꢂ ReAtiﬁer

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 C1A or C1B) and the rectiﬁers internal to the LTC3109.

The rectiﬁer circuit feeds current into the V

ing charge to the external VAUX capacitor and the other

outputs.

pin, provid-

AUX

VꢃUX

The active circuits within the LTC3109 are powered from

VAUX, which should be bypassed with a 1µF minimum

capacitor. Once VAUX exceeds 2.5V, the main V

lowed to start charging.

The LTC3109 is designed to manage the charging and

regulation of multiple outputs in a system in which the

average power draw is very low, but where periodic pulses

of higher load current may be required. This is typical of

wireless sensor applications, where the quiescent power

drawisextremelylowmostofthetime,exceptfortransmit

pulses when circuitry is powered up to make measure-

ments and transmit data.

is al-

OUT

An internal shunt regulator limits the maximum voltage

on VAUX to 5.25V typical. It shunts to ground 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. This current should be limited to

15mA max.

The LTC3109 can also be used to trickle charge a standard

capacitor, super capacitor or rechargeable battery, using

energy harvested from a TEG or low level AC source.

Voltage ReferenAe

The LTC3109 includes a precision, micropower reference,

for accurate regulated output voltages. This reference

becomes active as soon as VAUX exceeds 2V.

Resonant OsAillator

The LTC3109 utilizes MOSFET switches to form a reso-

nant step-up oscillator that can operate from an input of

either polarity using external step-up transformers and

small coupling capacitors. This allows it to boost input

voltages as low as 30mV high enough to provide multiple

regulated output voltages for powering other circuits. The

frequency of oscillation is determined by the inductance

of the transformer secondary winding, and is typically

in the range of 10kHz to 100kHz. For input voltages as

low as 30mV, transformers with a turns ratio of about

1:100 is recommended. For operation from higher input

voltages, this ratio can be lower. See the Applications

Information section for more information on selecting

the transformers.

SynAhronous ReAtiﬁers

Once VAUX exceeds 2V, synchronous rectiﬁers in paral-

lel with each of the internal rectiﬁer diodes take over the

job of rectifying the input voltage at pins C1A and C1B,

improving efﬁciency.

Low Dropout Linear Regulator (LDO)

The LTC3109 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 as soon as VAUX has charged to 2.3V, while the

OUT

3109f

ꢈ

LTC3109

operaTion ^{(Refer to the BloAk Diagram)}

V

storage capacitor is still charging. In the event of a

PGOOD

OUT

step load on the LDO output, current can come from the

main V reservoir capacitor. The LDO requires 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 5mA minimum.

A power good comparator monitors the V

voltage.

OUT

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

up (1MΩ) to the LDO voltage. Once V

has charged

OUT

to within 7.5% of its programmed voltage, the PGOOD

output will go high. If V drops more than 9% from its

OUT

programmed voltage, PGOOD will go low. The PGOOD

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. The PGOOD pin can also be pulled low in

a wire-OR conﬁguration with other circuitry.

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.

V

OUT2

V

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

OUT2

host using the V

pin. When enabled, V

is con-

OUT2_EN

OUT2

nected to V

through a 1Ω P-channel MOSFET switch.

Table 2

OUT

This output, controlled by a host processor, can be used

to power external circuits such as sensors and ampliﬁers,

that don’t have a low power “sleep” or shutdown capabil-

OUT2

they are needed.

VS2

GND

VAUX

VSꢀ

GND

VAUX

GND

VAUX

V

OUT

2.35V

3.3V

4.1V

5V

ity. V

can be used to power these circuits only when

Minimizing the amount of decoupling capacitance on

OUT2

Whentheoutputvoltagedropsslightlybelowtheregulated

value,thechargingcurrentwillbeenabledaslongasVAUX

V

enables it to be switched on and off faster, allow-

ing shorter pulse times and therefore smaller duty cycles

is greater than 2.5V. Once V

has reached the proper

OUT

in applications such as a wireless sensor/transmitter. A

value, the charging current is turned off. The resulting

ripple on V is typically less than 20mV peak to peak.

small V

capacitor will also minimize the energy that

OUT2

OUT

will be wasted in charging the capacitor every time V

is enabled.

OUT2

The internal programmable resistor divider, controlled by

VS1 and VS2, sets V , eliminating the need for very

OUT

V

has a current limiting circuit that limits the peak

OUT2

high value external resistors that are susceptible to noise

current to 0.3A typical.

pickup and board leakages.

The V enable input has a typical threshold of 1V

OUT2

In a typical application, a reservoir capacitor (typically a

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

few hundred microfarads) is connected to V . As soon

OUT

V

(which has an internal 5M pull-down resistor)

OUT2_EN

is low, V

as VAUX exceeds 2.5V, the V

capacitor will begin to

OUT

will be off. Driving V

high will turn

OUT2_EN

OUT2

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 15mA

typical. Note that for very low input voltages, this current

may be in the range of 1µA to 1000µA.

on the V

output.

Note that while V

is high, the current limiting cir-

OUT2_EN

cuitry for V

draws an extra 8µA of quiescent current

OUT2

from V . This added current draw has a negligible effect

OUT

3109f

ꢀ0

LTC3109

operaTion ^{(Refer to the BloAk Diagram)}

on the application and capacitor sizing, since the load on

Since the maximum charging current available at the

VSTORE output is limited to about 15mA, it can safely be

used to trickle charge NiCd or NiMH batteries for energy

storage when the input voltage is lost.

the V

output, when enabled, is likely to be orders of

OUT2

magnitude higher than 8µA.

VSTORE

Note that VSTORE is not intended to supply high pulse

The VSTORE output can be used to charge a large storage

load currents to V . Any pulse load on V

must be

OUT

capacitor or rechargeable battery. Once V

has reached

handled by the V

reservoir capacitor.

OUT

regulation, the VSTORE output will be allowed to charge

up to the clamped VAUX voltage (5.25V typical). The

storage element on VSTORE can then be used to power

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

Short-CirAuit ProteAtion

All outputs of the LTC3109 are current limited to protect

against short circuits to ground.

is unable to provide the current demanded by the V

,

OUT

V

OUT2

and LDO outputs.

Output Voltage SequenAing

If VAUX drops below VSTORE, the LTC3109 will automati-

cally draw current from the storage element. Note that it

may take a long time to charge a large storage capacitor,

depending on the input energy available and the loading

Atimingdiagramshowingthetypicalchargingandvoltage

sequencing of the outputs is shown in Figure 1. Note that

the horizontal (time) axis is not to scale, and is used for

illustration purposes to show the relative order in which

the output voltages come up.

on V

and VLDO.

OUT

5.0

2.5

0

3.0

2.0

1.0

0

VSTORE

PGOOD

5.0

2.5

0

V

OUT

3.0

2.0

1.0

0

VLDO

VAUX

5.0

2.5

0

10

20

30

40

50

60

70

80

TIME (ms)

3109 F01

Figure ꢀ. Output Voltage SequenAing

(with V_OUTProgrammeꢂ for ±.±V). Time ꢁot to SAale

3109f

ꢀꢀ

LTC3109

applicaTions inForMaTion

IꢁTRODUCTIOꢁ

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

switchingcurrent(whichcanreachhundredsofmilliamps).

Since the input voltage may be of either polarity, a ceramic

capacitor is recommended.

The LTC3109 is designed to gather energy from very low

input voltage sources and convert it to usable output

voltages to power microprocessors, wireless transmit-

ters and analog sensors. Its architecture is speciﬁcally

tailored to applications where the input voltage polarity is

unknown, or can change. This “auto-polarity” capability

makes it ideally suited to energy harvesting applications

using a TEG whose temperature differential may be of

either polarity.

PELTIER CELL (TꢄERMOELECTRIC GEꢁERꢃTOR)

A Peltier cell is made up of a large number of series-con-

nected P-N junctions, sandwiched between two parallel

ceramic plates. Although Peltier cells are often used as

coolers by applying a DC voltage to their inputs, they will

alsogenerateaDCoutputvoltage,usingtheSeebeckeffect,

when the two plates are at different temperatures.

Applications such as wireless sensors typically require

much more peak power, and at higher voltages, than

the input voltage source can produce. The LTC3109 is

designed to accumulate and manage energy over a long

period of time to enable short power pulses for acquiring

and transmitting data. The pulses must occur at a low

enough duty cycle that the total output energy during the

pulsedoesnotexceedtheaveragesourcepowerintegrated

over the accumulation time between pulses. For many

applications, this time between pulses could be seconds,

minutes or hours.

When used in this manner, they are referred to as thermo-

electricgenerators(TEGs).Thepolarityoftheoutputvoltage

will depend on the polarity of the temperature differential

between the TEG plates. The magnitude of the output volt-

age is proportional to the magnitude of the temperature

differential between the plates.

The low voltage capability of the LTC3109 design allows it

tooperatefromatypicalTEGwithtemperaturedifferentials

as low as 1°C of either polarity, making it ideal for harvest-

ing energy in applications where a temperature difference

exists between two surfaces or between a surface and

the ambient temperature. The internal resistance (ESR)

of most TEGs is in the range of 1Ω to 5Ω, allowing for

reasonablepowertransfer.ThecurvesinFigure2showthe

open-circuit output voltage and maximum power transfer

for a typical TEG with an ESR of 2Ω, over a 20°C range of

temperature differential (of either polarity).

The PGOOD signal can be used to enable a sleeping

microprocessor or other circuitry when V

reaches

OUT

regulation, indicating that enough energy is available for

a transmit pulse.

IꢁPUT VOLTꢃGE SOURCES

The LTC3109 can operate from a number of low input

voltage sources, such as Peltier cells (thermoelectric

generators), or low level AC sources. The minimum input

voltage required for a given application will depend on the

transformer turns ratios, the load power required, and the

internal DC resistance (ESR) of the voltage source. Lower

ESRsourceswillallowoperationfromlowerinputvoltages,

and provide higher output power capability.

1000

100

10

100

10

1

TEG: 30mm SQUARE

127 COUPLES

R = 2Ω

V

OC

MAX P

OUT

(IDEAL)

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.

1

0.1

1

10

dT (°C)

100

3109 F02

Note that a low ESR decoupling capacitor may be required

acrossaDCinputsourcetopreventlargevoltagedroopand

Figure 2. TypiAal PerformanAe of a Peltier Cell

ꢃAting as a Power Generator (TEG)

3109f

ꢀꢁ

LTC3109

applicaTions inForMaTion

TEG LOꢃD MꢃTCꢄIꢁG

UꢁIPOLꢃR ꢃPPLICꢃTIOꢁS

The LTC3109 was designed to present an input resistance

(load) in the range of 2Ω to 10Ω, depending on input volt-

age,transformerturnsratioandtheC1AandC2Acapacitor

values (as shown in the Typical Performance curves). For

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

resistance increases. This feature allows the LTC3109 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.

The LTC3109 can also be conﬁgured to operate from two

independent unipolar voltage sources, such as two TEGs

in different locations. In this conﬁguration, energy can be

harvestedfromeitherorbothsourcessimultaneously.See

the Typical Applications for an example.

The LTC3109 can also be conﬁgured to operate from a

singleunipolarsource,usingasinglestep-uptransformer,

by ganging its V and SW pins together. In this manner,

IN

it can extract the most energy from very low resistance

sources. See Figure 3 for an example of this conﬁguration,

along with the performance curves.

Table ±. Peltier Cell ManufaAturers

PELTIER CELL (TEG) SUPPLIERS

CUI Inc

www.cui.com

Peltiercellsareavailableinawiderangeofsizesandpower

capabilities, from less than 10mm square to over 50mm

square. They are typically 2mm to 5mm in height. A list

of some Peltier cell manufacturers is given in Table 3 and

some recommended part numbers in Table 4.

Ferrotec

www.ferrotec.com/products/thermal/modules/

Fujitaka

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

Hi-Z Technology

www.hi-z.com

Kryotherm

COMPOꢁEꢁT SELECTIOꢁ

Step-Up Transformer

www.kryotherm

Laird Technologies

www.lairdtech.com

Micropelt

www.micropelt.com

The turns ratio of the step-up transformers will determine

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

Duetotheauto-polarityarchitecture,twoidenticalstep-up

transformersshouldbeused,unlessthetemperaturedrop

across the TEG is signiﬁcantly different in one polarity, in

which case the ratios may be different.

Nextreme

www.nextreme.com

TE Technology

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

Tellurex

www.tellurex.com/

Table 4. ReAommenꢂeꢂ TEG Part ꢁumbers by Size

MꢃꢁUFꢃCTURER

CUI Inc. (Distributor)

Ferrotec

ꢀ5mm

23mm

±3mm

43mm

CP85438

CP60133

CP60233

CP60333

9501/031/030 B

FPH13106NC

9501/071/040 B

FPH17106NC

9500/097/090 B

FPH17108AC

TGM-127-1.0-0.8

PT6.7.F2.3030.W6

RC6-6-01

9500/127/100 B

FPH112708AC

LCB-127-1.4-1.15

PT8.12.F2.4040.TA.W6

RC12-8-01LS

Fujitaka

Kryotherm

Laird Technology

Marlow Industries

Tellurex

RC3-8-01

C2-20-0409

C2-15-0405

C2-30-1505

C2-40-1509

TE Technology

TE-31-1.0-1.3

TE-31-1.4-1.15

TE-71-1.4-1.15

TE-127-1.4-1.05

3109f

ꢀꢂ

LTC3109

applicaTions inForMaTion

C1

T1

V

C1A

C2A

V

OUT2

IN

OUT2

•

+

1nF

LTC3109

V

C

IN

V

OUT

330k

+

C

OUT

SWA

VLDO

2.2µF

V

INA

C1B

C2B

SWB

PG00D

OUT2_EN

V

INB

OUT2_ENABLE

VS1

VS2

V

VSTORE

VAUX

OUT

SET

10µF

GND

NOTE: VALUES FOR C , T1, C1 AND C

3109 F03a

IN

OUT

ARE DETERMINED BY THE APPLICATION

Figure ±. Unipolar ꢃppliAation

TypiAal EfﬁAienAy vs V_Iꢁfor

Unipolar Conﬁguration

TypiAal P_VOUTvs ꢂT for Unipolar

Conﬁguration

TypiAal I_VOUTvs V_Iꢁfor Unipolar

Conﬁguration

10000

1000

100

60

55

50

45

40

35

30

25

20

15

10

5

10

V

= 3.3V

FERROTEC 9500/127/100B, 40mm TEG

C1 = 33nF,

T1 = COILCRAFT LPR6235-123QML

1:50 RATIO

OUT

V

= 5V

OUT

V

= 3.3V

OUT

1

1:100, C1 = 6.8nF

1:50, C1 = 33nF

1:20, C1 = 68nF

1:100, C1 = 6.8nF

1:50, C1 = 33nF

1:20, C1 = 68nF

0

0.1

100

10

100

1000

10

100

V (mV)

IN

1000

dT (°K)

V

(mV)

IN

3109 F03f

3109 F03b

3109 F03c

TypiAal R_Iꢁvs V_Iꢁfor Unipolar

Conﬁguration

TypiAal Input Current vs V_Iꢁfor

Unipolar Conﬁguration

600

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

1:100, C1 = 6.8nF

1:50, C1 = 33nF

1:20, C1 = 68nF

550

500

450

400

350

300

250

200

150

100

50

1:100, C1 = 6.8nF

1:50, C1 = 33nF

1:20, C1 = 68nF

0

10

100

1000

10

100

V (mV)

IN

1000

V

(mV)

IN

3109 F03d

3109 F03e

3109f

ꢀꢃ

LTC3109

applicaTions inForMaTion

Using a 1:100 primary-secondary ratio yields start-up

voltages as low as 30mV. Other factors that affect per-

formance are the resistance of the transformer windings

and the inductance of the windings. Higher DC resistance

will result in lower efﬁciency and higher start-up volt-

ages. The secondary winding inductance will determine

the resonant frequency of the oscillator, according to the

formula below.

Cꢀ CꢃPꢃCITOR

The charge pump capacitor that is connected from each

transformer’s secondary winding to the corresponding

C1A and C1B pins has an effect on converter input resis-

tance and maximum output current capability. Generally

a minimum value of 1nF is recommended when operating

from very low input voltages using a transformer with

a ratio of 1:100. Capacitor values of 2.2nF to 10nF will

provide higher output current at higher input voltages,

however larger capacitor values can compromise perfor-

mance 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 examples for the recommended value for a

given turns ratio.

1

Freq=

Hz

2•π • L_SEC•C

where L

is the inductance of one of the secondary

SEC

windings and C is the load capacitance on the second-

ary winding. This is comprised of the input capacitance

at pin C2A or C2B, typically 70pF each, in parallel with

the transformer secondary winding’s shunt capacitance.

The recommended resonant frequency is in the range of

10kHz to 100kHz. Note that loading will also affect the

resonant frequency. See Table 5 for some recommended

transformers.

C2 CꢃPꢃCITOR

The C2 capacitors connect pins C2A and C2B to their

respective transformer secondary windings. For most

applications a capacitor value of 470pF is recommended.

Smaller capacitor values tend to raise the minimum

start-up voltage, and larger capacitor values can lower

efﬁciency.

Table 5. ReAommenꢂeꢂ Transformers

TYPICꢃL STꢃRT-

VEꢁDOR

UP VOLTꢃGE

PꢃRT ꢁUMBER

Coilcraft

www.coilcraft.com

25mV

35mV

85mV

LPR6235-752SML (1:100 ratio)

LPR6235-123QML (1:50 ratio)

LPR6235-253PML (1:20 ratio)

Note that the C1 and C2 capacitors must have a voltage

rating greater than the maximum input voltage times the

transformer turns ratio.

USIꢁG EXTERꢁꢃL CꢄꢃRGE PUMP RECTIFIERS

The synchronous rectiﬁers in the LTC3109 have been

optimizedforlowfrequency,lowcurrentoperation,typical

of low input voltage applications. For applications where

the resonant oscillator frequency exceeds 100kHz, or a

transformer turns ratio of less than 1:20 is used, or the

C1A and C1B capacitor values are greater than 68nF, the

use of external charge pump rectiﬁers (1N4148 or 1N914

orequivalent)isrecommended.SeetheTypicalApplication

circuits for an example. Avoid the use of Schottky recti-

ﬁers, as their low forward voltage increases the minimum

start-up voltage.

V

ꢃꢁD VSTORE CꢃPꢃCITOR

OUT

For pulsed load applications, the V

be sized to provide the necessary current when the load

is pulsed on. The capacitor value required will be dictated

capacitor should

OUT

by the load current (I

PULSE

), the duration of the load pulse

LOAD

(t

), and the amount of V

voltage droop the ap-

OUT

plication can tolerate (∆V ). The capacitor must be

OUT

rated for whatever voltage has been selected for V

by

OUT

VS1 and VS2:

I

_LOAD(mA)• t_PULSE(ms)

C_OUT(µF)≥

∆V_OUT(V)

3109f

ꢀꢄ

LTC3109

applicaTions inForMaTion

Note that there must be enough energy available from the

Note that storage capacitors requiring voltage balancing

resistors are not recommended due to the steady-state

current draw of the resistors.

input voltage source for V

to recharge the capacitor

OUT

during the interval between load pulses (as discussed in

Design Example 1). Reducing the duty cycle of the load

pulse will allow operation with less input energy.

PCB LꢃYOUT GUIDELIꢁES

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

sands of microfarads or even Farads), to provide energy

storage at times when the input voltage is lost. Note that

this capacitor can charge all the way to the VAUX clamp

voltage of 5.25V typical (regardless of the settings for

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.

Duetotheverylowinputvoltagesthecircuitoperatesfrom,

V

), so be sure that the holdup capacitor has a work-

OUT

the connections to V , the primary of the transformers

IN

ing voltage rating of at least 5.5V at the temperature that

it will be used.

and the SW, V and GND pins of the LTC3109 should be

IN

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 start-up voltage and capaci-

tor charge time.

The VSTORE input is not designed to provide high pulse

load currents to V . The current path from VSTORE to

OUT

V

OUT

is limited to about 26mA max.

The VSTORE capacitor can be sized using the following

formula:

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

puts of the LTC3109, any sources of leakage current on

the output voltage pins must be minimized. An example

board layout is shown in Figure 4.

7µA +I +I + I_PULSE• t_PULSE• f • t

(

)

(

)

Q

LDO

STORE

C_STORE

≥

5.25– V_OUT

where 7µA is the quiescent current of the LTC3109, I is

Q

the load on V

in between pulses, I

is the load on

is the total load during the

OUT

LDO

the LDO between pulses, I

PULSE

pulse, t

is the duration of the pulse, f is the frequency

PULSE

of the pulses, t

is the total storage time required

STORE

and V

is the output voltage required. Note that for a

OUT

programmed output voltage of 5V, the VSTORE capacitor

cannot provide any beneﬁcial storage time to V

.

OUT

To minimize losses and capacitor charge time, all capaci-

tors used for V

and VSTORE should be low leakage.

OUT

See Table 6 for recommended storage capacitors.

Table 6. ReAommenꢂeꢂ Storage CapaAitors

VEꢁDOR

PꢃRT ꢁUMBER/SERIES

AVX

BestCap Series

Figure 4. Example Component PlaAement for 2-Layer PC Boarꢂ

(QFꢁ PaAkage). ꢁote That VSTORE anꢂ VOUT CapaAitor Sizes

are ꢃppliAation Depenꢂent

www.avx.com

TAJ and TPS Series Tantalum

Cap-XX

www.cap-xx.com

GZ Series

Cooper/Bussman

KR Series

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

Vishay/Sprague

www.vishay.com/capacitors

Tantamount 592D

595D Tantalum

3109f

ꢀꢅ

LTC3109

applicaTions inForMaTion

DESIGꢁ EXꢃMPLE ꢀ

To calculate the maximum rate at which load pulses can

occur, you must know how much charge current is avail-

This design example will explain how to calculate the

able from the LTC3109 V

pin given the input voltage

OUT

necessary reservoir capacitor value for V

in pulsed-

OUT

source being used. This number is best found empirically,

since there are many factors affecting the efﬁciency of the

converter. You must also know what the total load cur-

load applications, such as a wireless sensor/transmitter.

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 pulses of load current occurring periodi-

cally during a transmit burst.

rent is on V

during the sleep state (between pulses).

OUT

Note that this must include any losses, such as storage

capacitor leakage.

The reservoir capacitor on V

supports the load during

OUT

Let’s assume that the charge current available from the

the transmit pulse; the long sleep time between pulses

allows the LTC3109 to accumulate energy and recharge

the capacitor (either from the input voltage source or the

storagecapacitor).Amethodforcalculatingthemaximum

rate at which the load pulses can occur for a given output

current from the LTC3109 will also be shown.

LTC3109 is 150µA and the total current draw on V

and

OUT

VLDOinthesleepstateis17µA,includingcapacitorleakage.

We’ll also use the value of 330µF for the V capacitor.

OUT

The maximum transmit rate (neglecting the duration of

the transmit pulse, which is very short compared to the

period) is then given by:

In this example, V

is set to 3.3V, and the maximum

OUT

330µF •0.33V

150µA –17µA

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

0.33V. The duration of a transmit pulse is 5ms, with a total

average current requirement of 20mA during the pulse.

Given these factors, the minimum required capacitance

T =

= 0.82sec or f_MAX=1.2Hz

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

port a 5ms transmit pulse of 20mA every 0.82 seconds.

on V

is:

OUT

It can be seen 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 or standby current is low. Even if the available

charge current in the example above was only 21µA, if the

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

every seven seconds.

20mA •5ms

0.33V

C_OUTµF ≥

( )

= 303µF

NotethatthisequationneglectstheeffectofcapacitorESR

on output voltage droop. For ceramic capacitors and low

ESR tantalum capacitors, the ESR will have a negligible

effectattheseloadcurrents.However,bewareofthevoltage

coefﬁcientofceramiccapacitors, especiallythoseinsmall

case sizes. This greatly reduces the effective capacitance

when a DC bias is applied.

The following formula will allow you to calculate the time

it will take to charge the LDO output capacitor and the

V

capacitor the ﬁrst time, from zero volts. Here again,

OUT

the charge current available from the LTC3109 must be

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

output capacitor is 2.2µF:

A standard value of 330µF could be used for C

in

OUT

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

draw on V , V and VLDO, since the current for all

OUT OUT2

of these outputs must come from V

during a pulse.

OUT

2.2V •2.2µF

I_CHG– I_LDO

t_LDO

=

Current contribution from the capacitor on VSTORE is not

considered, since it may not be able to recharge between

pulses. Also, it is assumed that the harvested charge

current from the LTC3109 is negligible compared to the

magnitude of the load current during the pulse.

If there was 150µA of charge current available and a 5µA

loadontheLDO(whentheprocessorissleeping), thetime

for the LDO to reach regulation would be only 33ms.

3109f

ꢀꢆ

LTC3109

applicaTions inForMaTion

The time for V

to charge and reach regulation can be

In this example, I is 5µA, I

and T is one hour. The average charge current required

from the LTC3109 would be:

is 100mA, t

is 5ms

OUT

Q

PULSE

calculated by the formula below, which assumes V

is

OUT

programmed to 3.3V and C

is 330µF:

OUT

3.3V •330µF

I_CHG–I_VOUT–I_LDO

100mA •0.005sec

t_VOUT

=

+ t_LDO

I_CHG≥5µA +

= 5.14µA

3600sec

Therefore, if the LTC3109 has an input voltage that allows

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

application can support 100mA pulses lasting 5ms every

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

dominant factor in this example, because the transmit

With 150µA of charge current available and 5µA of load on

both V and VLDO, the time for V to reach regula-

OUT

tion after the initial application of power would be 7.81

seconds.

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

OUT

DESIGꢁ EXꢃMPLE 2

of 3.3V, the average power required by this application is

only 17µW (not including converter losses).

Inmostpulsed-loadapplications, theduration, magnitude

and frequency of the load current pulses are known and

ﬁxed. In these cases, the average charge current required

from the LTC3109 to support the average load must be

calculated, which can be easily done by the following:

Keep in mind that the charge current available from the

LTC3109 has no effect on the sizing of the V

capacitor,

OUT

and the V

capacitor has no effect on the maximum

OUT

allowed pulse rate.

I_PULSE• t_PULSE

I_CHG≥I_Q+

T

where I is the sleep current supplied by V

and V

LDO

Q

OUT

to the external circuitry in-between load pulses, including

output capacitor leakage, I is the total load current

PULSE

during the pulse, t

is the duration of the load pulse

and T is the pulse period (essentially the time between

PULSE

load pulses).

3109f

ꢀꢇ

LTC3109

Typical applicaTions

Energy ꢄarvester Operates from Small Temperature Differentials of Either Polarity

TEG

(THERMOELECTRIC GENERATOR)

30ꢀV TO 500ꢀV

T1

1:100

1nF

C1A

V

OPTIONAL SWITCHED OUTPUT FOR SENSORS

3.3V

OUT2

•

470pF

C2A

V

OUT

+

2.2V

470µF

SWA

VLDO

2.2µF

V

LOW POWER

RADIO

INA

T2

1:100

1nF

LTC3109

C1B

SENSOR(S)

µP

470pF

C2B

PG00D

SWB

INB

V

OUT2_EN

V

5.25V

VS1

VS2

VSTORE

VAUX

+

1µF

C

STORE

GND

3109 TA02

T1, T2: COILCRAFT LPR6235-752SML

3109f

ꢀꢈ

LTC3109

Typical applicaTions

Li-Ion Battery Charger anꢂ LDO Operates from a Low Level ꢃC Input

50mV TO

300mV RMS

T1

1:100

1nF

C1A

V

OUT2

•

470pF

60Hz

AC

C2A

V

TO LOAD

OUT

2.2V

SWA

VLDO

2.2µF

LTC4070*

FAIRCHILD

FDG328P

V

LBO

HBO

NC

INA

T2

1:100

1nF

LTC3109

NTC

DRV

4.1V

C1B

V

NTCBIAS

•

CC

470pF

+

NC

ADJ

Li-Ion

BATTERY

GND

C2B

PG00D

SWB

INB

VS1

VS2

V

OUT2_EN

V

*THE LTC4070 IS A PRECISION BATTERY

CHARGER OFFERING UNDERVOLTAGE

PROTECTION, WITH A TYPICAL SUPPLY

CURRENT OF ONLY 0.45µA

T1, T2: COILCRAFT

LPR6235-752SML

VSTORE

VAUX

1µF

GND

3109 TA03

Unipolar Energy ꢄarvester Charges Battery BaAkup

THERMOELECTIC

GENERATOR

T1

1:50

33nF

1nF

FERROTEC 9500/127/100B

+

C1A

C2A

V

OUT2

•

47µF

–

V

OUT

V

OUT

3.3V

+

330µF

4V

330k

LTC3109

2.2V

SWA

VLDO

V

2.2µF

INA

T1: COILCRAFT

LPR6235-123QML

C1B

C2B

SWB

PGOOD

PG00D

V

OUT2_EN

V

INB

VS1

VS2

VSTORE

VAUX

FAIRCHILD

FDG328P

LTC4070

LBO HBO

NTC

NC

1µF

GND

DRV

TypiAal P_VOUTvs ꢂT for Unipolar

Conﬁguration

4.1V

V

NTCBIAS

CC

+

NC

ADJ

5.0

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

Li-Ion

BATTERY

GND

FERROTEC 9500/127/100B

C1 = 33nF

T1 = COILCRAFT LPR6235-123QML

1:50 RATIO

OUT

3109 TA06a

V

= 3.3V

0

1

2

3

4

5

6

7

8

9

10

dT (°K)

3109 TA06b

3109f

ꢁ0

LTC3109

Typical applicaTions

Dual-Input Energy ꢄarvester Generates 5V anꢂ 2.2V from Either or Both TEGs,

Operating at Different Temperatures of Fixeꢂ Polarity

COILCRAFT

LPR6235-752SML

1:100

1nF

C1A

C2A

V

OUT2

+

–

•

THERMOELECTRIC

GENERATOR

25mV TO 500mV

470pF

LTC3109

V

5V

V

OUT

+

SWA

C

*

OUT

V

INA

COILCRAFT

LPR6235-123QML

1:50

2.2V

4.7nF

VLDO

2.2µF

C1B

+

–

•

THERMOELECTRIC

GENERATOR OR

THERMOPILE

470pF

C2B

SWB

PG00D

OUT2_EN

PG00D

1µF

35mV TO 1000mV

V

INB

VS1

VS2

VSTORE

VAUX

GND

3109 TA04

*THE VALUE OF THE C

CAPACITOR IS

OUT

DETEMINED BY THE LOAD CHARACTERISTICS

3109f

ꢁꢀ

LTC3109

package DescripTion

UF PaAkage

23-Leaꢂ PlastiA QFꢁ (4mm × 4mm)

(Reference LTC DWG # 05-08-1710 Rev A)

0.70 p0.05

4.50 p 0.05

3.10 p 0.05

2.45 p 0.05

2.00 REF

2.45 p 0.05

PACKAGE OUTLINE

0.25 p0.05

0.50 BSC

PIN 1 NOTCH

R = 0.20 TYP

OR 0.35 s 45o

CHAMFER

RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS

APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED

BOTTOM VIEW—EXPOSED PAD

R = 0.05

TYP

R = 0.115

0.75 p 0.05

TYP

4.00 p 0.10

19 20

0.40 p 0.10

PIN 1

TOP MARK

(NOTE 6)

1

2

2.45 p 0.10

2.00 REF

4.00 p 0.10

2.45 p 0.10

(UF20) QFN 01-07 REV A

0.200 REF

0.25 p 0.05

0.50 BSC

0.00 – 0.05

NOTE:

1. DRAWING IS PROPOSED TO BE MADE A JEDEC PACKAGE OUTLINE MO-220

VARIATION (WGGD-1)—TO BE APPROVED

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

3109f

ꢁꢁ

LTC3109

package DescripTion

Gꢁ PaAkage

23-Leaꢂ PlastiA SSOP (ꢁarrow .ꢀ53 InAh)

(Reference LTC DWG # 05-08-1641)

.337 – .344*

(8.560 – 8.738)

.058

(1.473)

REF

.045 p.005

20 19 18 17 16 15 14 13 12 11

.254 MIN

.150 – .165

.229 – .244

.150 – .157**

(5.817 – 6.198)

(3.810 – 3.988)

.0165 p.0015

.0250 BSC

1

2

3

4

5

6

7

8

9 10

RECOMMENDED SOLDER PAD LAYOUT

.015 p .004

(0.38 p 0.10)

.0532 – .0688

(1.35 – 1.75)

s 45o

.004 – .0098

(0.102 – 0.249)

.0075 – .0098

(0.19 – 0.25)

0o – 8o TYP

.016 – .050

(0.406 – 1.270)

.008 – .012

.0250

(0.635)

BSC

(0.203 – 0.305)

TYP

NOTE:

1. CONTROLLING DIMENSION: INCHES

INCHES

(MILLIMETERS)

2. DIMENSIONS ARE IN

GN20 (SSOP) 0204

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

3109f

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

LTC3109

Typical applicaTion

I_VOUTvs V_Iꢁ

16

14

12

10

8

1:20 RATIO

C1 = 1µF

TYPICAL

EXTERNAL DIODES

Unipolar TEG Energy ꢄarvester for Low ResistanAe/ꢄigh Current Inputs,

Using External Charge Pump ReAtiﬁers

VAUX

COILCRAFT

LPR6235-253PML

1:20

1.0µF

6

BAS31

SWITCHED V

GOES HIGH

OUT

+

4

WHEN PGOOD IS HIGH

C1A

C2A

V

OUT2

2

•

0.1µF

1nF

LTC3109

V

70mV TO 1V

0

3.3V

2.2V

V

0

100

400 500

200 300

600 700

800

OUT

+

SWA

V

(mV)

IN

C

OUT

V

INA

3109 TA05b

VLDO

C1B

EfﬁAienAy vs V_Iꢁ

2.2µF

50

45

40

35

30

25

20

15

10

5

C2B

PG00D

SWB

V

OUT2_EN

V

INB

VS1

VS2

VAUX

VSTORE

VAUX

+

10µF

C

STORE

GND

3109 TA05

0

10

100

1000

V

(mV)

IN

3109 TA05c

relaTeD parTs

PꢃRT ꢁUMBER

DESCRIPTIOꢁ

COMMEꢁTS

V : 0.02V to 1V, V

LTC3108/

LTC3108-1

Ultralow Voltage Step-Up Converter and

Power Manager

= 2.2V, 2.35V, 3.3V, 4.1V, 5V, I = 6µA,

OUT Q

IN

4mm × 3mm DFN-12, SSOP-16; LTC3108-1 V

= 2.2V, 2.5V, 3V, 3.7V, 4.5V

OUT

LTC4070

Micropower Shunt Battery Charger

1% Float Voltage Accuracy, 50mA Max Shunt Current, V

Q

= 4.0V, 4.1V, 4.2V,

OUT

I = 450nA, 2mm × 3mm DFN-8, MSOP-8

LTC1041

LTC1389

Bang-Bang Controller

V : 2.8V to 16V; V

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

OUT(MIN) Q SD

IN

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

LTC3588-1

LT8410/LT8410-1

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

Micropower 25mA/8mA Low Noise Boost Converter V : 2.6V to 16V; V

with Integrated Schottky Diode and Output

Disconnect

= 40V

; I = 8.5µA; I < 1µA;

MAX Q SD

IN

OUT(MIN)

2mm × 2mm DFN-8 Package

3109f

LT 0610 • 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：	LTC3109IGN-PBF
厂家：	Linear
描述：	Auto-Polarity, Ultralow Voltage Step-Up Converter and Power Manager 自动极性，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：329K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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