LTC4100

1

sn4100 4100is

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 represen-

tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.

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Single Chip Smart Battery Charger Controller

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100% Compliant (Rev. 1.1) SMBus Support allows

for Operation with or without Host

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SMBus Accelerator Improves SMBus Timing*

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Wide Output Voltage Range: 6.4V to 26V

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Hardware Interrupt and SMBAlert Response

Eliminate Interrupt Polling

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High Efficiency Synchronous Buck Charger

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0.5V Dropout Voltage; Maximum Duty Cycle > 98%

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AC Adapter Current Limit Maximizes Charge Rate

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±0.8% Voltage Accuracy; ±5% Current Accuracy

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Up to 4A Charging Current Capability

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10-Bit DAC for Charge Current Programming

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11-Bit DAC for Charger Voltage Programming

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User-Selectable Overvoltage and Overcurrent Limits

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High Noise Immunity SafetySignal Sensor

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Small 24-Pin Narrow (0.209") SSOP Package

APPLICATIO S

FEATURES

DESCRIPTIO

TYPICAL APPLICATIO

Smart Battery

Charger Controller

July 2003

The LTC

charging solution that dramatically simplifies construc-

tion of an SBS compliant system. The LTC4100 imple-

ments a Level 2 charger function whereby the charger can

be programmed by the battery or by the host. A SafetySignal

on the battery being charged is monitored for tempera-

ture, connectivity and battery type information. The SMBus

interface remains alive when the AC power adapter is

removed and responds to all SMBus activity directed to

it, including SafetySignal status (via the ChargerStatus

command). The charger also provides an interrupt to the

host whenever a status change is detected (e.g., battery

removal, AC adapter connection).

Charging current and voltage are restricted to chemistry

specific limits for improved system safety and reliability.

Limits are programmable by two external resistors. Addi-

tionally, the maximum average current from the AC adapter

is programmable to avoid overloading the adapter when

simultaneously supplying load current and charging

current. When supplying system load current, charging

current is automatically reduced to prevent adapter over-

load.**

, LTC and LT are registered trademarks of Linear Technology Corporation.

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Portable Instruments and Computers

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Data Storage Systems and Battery Backup Servers

Figure 1. 4A Smart Battery Charger

DCDIV

CHGEN

ACP

SMBALERT

SCL

SDA

THB

THA

DCIN

INFET

CLP

CLN

TGATE

BGATE

PGND

CSP

BAT

GND

17

11

6

10

7

9

8

15

16

13

14

20

5

4

24

23

1

3

2

21

22

18

19

12

LTC4100

3V

TO 5.5V

0.12

µF

0.1

µF

0.082

µF

0.1

µF

0.01

µF

0.0015

µF

6.04k

10k

54.9k

100

Ω

0.033

Ω

20

µF

20

µF

0.1

µF

10

µH

0.025

Ω

SMBCLK

5k

SMBDAT

SMBCLK

SMBDAT

DCIN

4100 TA01

CHGEN

SMBALERT#

ACP

SMART BATTERY

1.13k

1.21k

13.7k

SafetySignal

*U.S. Patent No. 6,650,174 **U.S. Patent No. 5,723,970