introducing the ltc4071 shunt battery charger system with low battery disconnect

Introducing the LTC4071Shunt Battery Charger System

with Low Battery Disconnect

© 2006 Linear Technology

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Emerging Markets

• Power management for nontraditional energy sources

Micro Fuel Cell

SuperCaps Organic Solar Cell Thin film battery

Piezo-Electric

Elements

Thermo-Electric Generator


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LTC4071: What is It? Shunt Battery Charger + Integrated Pack Protection

Shunt Battery

Charger System

With Low Battery

Disconnect

• Low Operating Current: 550nA• 1% Float Voltage Accuracy Over Full Temperature and

Shunt Current Range• 50mA Maximum Internal Shunt Current• Pin Selectable Float Voltage Options: 4.0V, 4.1V. 4.2V


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LTC4071: Key Technical Features • Integrated Pack Protection in One IC

• Overvoltage (zener) and Undervoltage (Low Battery Disconnect)

• Low Operating Current: 550nA• Pin Selectable Low Battery Disconnect Level: 2.7V or

3.2V• 1% Float Voltage Accuracy Over Full Temperature and

Shunt Current Range• 50mA Maximum Internal Shunt Current • Pin Selectable Float Voltage Options: 4.0V, 4.1V. 4.2V• Ultralow Power NTC Float Voltage Conditioning for Li-

Ion/Polymer Protection• Suitable for Very Low Power (Intermittent or

Continuous) Charging Sources• High Battery Status Output• Thermally Enhanced, Low Profile 8-Lead DFN (2mm x

3mm x 0.75mm) and MSOP Packages


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LTC4071: Features and Benefits


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LTC4071: Features and Benefits - NTC (cont.)


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LTC4071: Features and Benefits – NanoPower (cont.)

When the input supply is removed and the battery

voltage is below the high battery output

threshold, the LTC4071 consumes just 550nA

from the battery.

This enables the device to draw or harvest

power from previously unusable low current,

intermittent or continuous power

sources.


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LTC4071: Packaging

* not to scale


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LTC4071: Typical Application Circuits

Simple Single Cell

Li Charger


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LTC4071: Typical Application Circuits (cont.)

Photovoltaic (Solar) Charger

2-Cell Stacked Battery Charger


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LTC4071: PositioningLinear Tech Linear Tech Linear Tech

Part # LTC4071 LTC4070 LTC4065L

TopologyShunt-based

ChargerShunt-based

ChargerLinear Charger -

current-limited LDO

Battery Chemistry Li-Ion/Polymer Li-Ion/Polymer Li-Ion/Polymer

Shunt/Float Voltage 4.0V, 4.1V, 4.2V 4.0V, 4.1V, 4.2V 4.2V

Maximum Shunt Current 50mA (10uA min)50mA (10uA min)

(500mA w/ ext PFET)Charge Current

250mA max

Quiescent Current550nA (TYP)1.2uA (max)

450nA (TYP)1.04uA (max)

120uA (TYP)250uA (max)

Over-voltage Protection (zener) Yes Yes No

Under-voltage Protection(Low Battery Disconnect)

Yes, internal & programmable

Yes, fixed,ext PFET + R + 2 inverters No

Load Disconnect Yes, load & batt ext PFET (load only) No

Battery Stack Compatible Yes Yes No

Status Indicators HBO LBO, HBO /CHRG

Thermal Battery Qualifier/NTC Yes Yes No (thermal reg)

Package2mmx3mm DFN-8,

MSOP-82mmx3mm DFN-8,

MSOP-82mmx2mm DFN-6

1k Price $2.20 $2.06 $1.10


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LTC4071: CompetitionLinear Tech National, etc. Various

Part # LTC4071 LM431 Various

TopologyShunt-based

ChargerShunt reference

(adjustable)Linear Charger

Battery Chemistry Li-Ion/Polymer none Li-Ion/Polymer

Shunt/Float Voltage 4.0V, 4.1V, 4.2V 2.5V to 36V various

Maximum Shunt Current 50mA (10uA min) 10mACharge Current

1A max

Quiescent Current550nA (TYP)1.2uA (max)

0.4mA (TYP)1mA (max)

>100uA (TYP)

Over-voltage Protection (zener) Yes No some

Under-voltage Protection(Low Battery Disconnect)

Yes, internal & programmable No No

Load Disconnect Yes, load & batt No No

Battery Stack Compatible Yes Yes No

Status Indicators HBO No various

Thermal Battery Qualifier/NTC Yes No Yes

Package2mmx3mm DFN-8,

MSOP-8TO-92, SOT-23, SOIC-8, SMD-4

various

1k Price $2.20 $0.23 cheap


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LTC4071: End Markets/Applications

• Low Power Li-Ion/Polymer Battery Back-Up• Energy Scavenging/Harvesting• Solar Power Systems with Back-Up• Memory Back-Up• Embedded Automotive• Thin Film Batteries

introducing the ltc4071 shunt battery charger system with low battery disconnect

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