LTC4070

1

4070f

TYPICAL APPLICATION

DESCRIPTION

Li-Ion/Polymer Shunt

Battery Charger System

batteries from very low current, intermittent or continuous

charging sources. The 450nA to 50mA operating cur-

rent makes charging possible from previously unusable

sources. With the addition of an external pass device,

shunt current may be boosted to 500mA. Stacked cell high

voltage battery packs are inherently balanced with shunt

charging. With its low operating current, the LTC4070 is

well suited to charge thin film batteries in energy harvesting

applications where charging sources may be intermittent

or very low power. The unique architecture of the LTC4070

allows for an extremely simple battery charger solution;

requiring just one external resistor.

The LTC4070 offers a pin selectable float voltage with 1%

accuracy across the full range of operating temperature

and shunt current. The integrated thermal battery quali-

fier extends battery lifetime and improves reliability by

automatically reducing the battery float voltage at NTC

thermistor temperatures above 40°C. The LTC4070 also

provides both low and high battery status outputs. With

the addition of an external PFET, the low-battery output

pin can implement a latch-off function that automatically

disconnects the system load from the battery to protect

the battery from deep discharge.

The device is offered in two thermally enhanced packages,

a compact low profile (0.75mm) 8-lead (2mm

× 3mm)

DFN and an 8-lead MSOP package.

FEATURES

APPLICATIONS

and Shunt Current Range

(500mA with External PFET)

4.0V, 4.1V, 4.2V

Li-Ion/Polymer Protection

Power Charging Sources

8-Lead (2mm

× 3mm) DFN and MSOP Packages

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..

NTC Overtemperature Battery Float Voltage Qualifying

Simple Shunt Charger with Load

Disconnect and NTC Conditioning

TEMPERATURE (°C)

4.3

4.2

4.0

4.1

3.9

3.8

3.7

40

20

0

60

4070 TA01b

80

100

ADJ = FLOAT

ADJ = GND

4070 TA01a

LTC4070

ADJ

GND

T

10k

Li-Ion

NTCBIAS

LBO

NTC

+

NTHS0805E3103LT

Q1:FDR8508