LTC2941C(RevA) Ver la hoja de datos (PDF) - Linear Technology

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LTC2941C
(Rev.:RevA)

Battery Gas Gauge with I2C Interface

Linear Technology 

LTC2941

Applications Information

I2C/SMBus Interface

The LTC2941 communicates with a bus master using a

2-wire interface compatible with I2C and SMBus. The 7-bit

hard-coded I2C address of LTC2941 is 1100100.

The LTC2941 is a slave-only device. Therefore the serial

clock line (SCL) is input only while the data line (SDA) is

bidirectional. For more details refer to the I2C Protocol

section.

Internal Registers

The LTC2941 integrates current through a sense resistor

and stores a 16-bit result, accumulated charge, as two

bytes in registers C and D. Two byte high and low limits

programmed in registers E, F, G and H are continuously

compared against the accumulated charge. If either limit is

exceeded, a corresponding flag is set in the status register

bits A[2] or A[3]. If the alert mode is enabled, the AL/CC

pin pulls low.

The internal eight registers are organized as shown in

Table 1:

Table 1. Register Map

ADDRESS NAME REGISTER DESCRIPTION

00h

A Status

01h

B Control

02h

C Accumulated Charge MSB

03h

D Accumulated Charge LSB

04h

E Charge Threshold High MSB

05h

F Charge Threshold High LSB

06h

G Charge Threshold Low MSB

07h

H Charge Threshold Low LSB

R = Read, W = Write

R/W DEFAULT

R See Below

R/W 3Ch

R/W 7Fh

R/W FFh

R/W FFh

R/W FFh

R/W 00h

R/W 00h

Status Register (A)

Table 2 shows the details of the status register (address

00h):

Table 2. Status Register A (Read Only)

BIT NAME

OPERATION

DEFAULT

A[7] Chip Identification 1: LTC2941

1

0: LTC2942

A[6] Reserved

Not Used.

0

A[5] Accumulated Charge Indicates that the value of the

0

Overflow/Underflow accumulated charge hit either

top or bottom.

A[4] Reserved

Not used.

0

A[3] Charge Alert High Indicates that the accumulated 0

charge value exceeded the

charge threshold high limit.

A[2] Charge Alert Low Indicates that the accumulated 0

charge value dropped below

the charge threshold low limit.

A[1] VBAT Alert

A[0] Undervoltage

Lockout Alert

Indicates that the battery

0

voltage (at SENSE–) dropped

below selected VBAT threshold.

Indicates recovery from

X

undervoltage. If equal to 1,

a UVLO has occurred and

the content of registers is

uncertain.

The AL/CC pin can be configured to pull low whenever any

status register bit is set (except for bit A[7] and A[0]), us-

ing control register bits B[2] and B[1]. All status register

bits except A[7] are cleared after being read by the host

if the conditions which set these bits have been removed.

As soon as one of the measured quantities exceeds the

programmed limits, the corresponding bit A[3], A[2] or

A[1] in the status register is set.

2941fa

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