LTC1980 Ver la hoja de datos (PDF) - Linear Technology

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LTC1980

Combination Battery Charger and DC/DC Converter

Linear Technology 

U

OPERATIO

The LTC1980 is an IC designed to provide a regulated

voltage to a system load from an unregulated or regulated

wall adapter, or from a battery and also charge a battery,

thereby providing an uninterruptable power source for the

system. When the wall adapter is present it provides

power to the system load and, if needed, a portion of the

power can be used to simultaneously charge the battery.

If the wall adapter is removed, the LTC1980 uses the

battery as a power source to continue providing a regu-

lated output voltage to power the system.

Combining these two functions into a single IC reduces

circuit area compared to presently available solutions

LTC1980

(Figure 1). The unique bidirectional power converter to-

pology (Figure 2) accounts for much of the area savings.

A transformer based design allows the wall adapter volt-

age to be less than or greater than the battery voltage.

The LTC1980 includes a 300kHz DC/DC PWM converter

that operates in two modes. The first mode is when the wall

adapter is present and the LTC1980 is used to charge the

battery using a constant-current/constant-voltage charge

scheme. The second mode is when the wall adapter is

removed and the battery powers the LTC1980 and the

DC/DC converter generates a regulated output voltage.

Existing Methods

CHARGE

TERMINATION

BATTERY

CHARGER

PWM

REGULATOR

POWER ROUTING

LOW DROPOUT

REGULATOR

FROM

WALL ADAPTER

TO SYSTEM LOAD

DC/DC CONVERTERS

Using the LTC1980

LTC1980-BASED

POWER DESIGN

1980 F01

FROM WALL ADAPTER

TO SYSTEM LOAD

DC/DC CONVERTERS

Figure 1. Portable Power Systems

T1

Li-Ion

•

BATTERY

BAT-FET • REG-FET

RS

ISENSE

WALL

ADAPTER

SYSTEM LOAD

DC/DC

CONVERTERS

T1

Li-Ion

•

BATTERY

BAT-FET • REG-FET

RS

ISENSE

SYSTEM LOAD

DC/DC

CONVERTERS

LTC1980

1980 F02a

(a) Battery Charger Mode

LTC1980

1980 F02a

(b) DC/DC Converter Mode (Wall Adapter Removed)

Figure 2. LTC1980 Bidirectional Power Conversion

1980f

9

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