LTC2942CDCB-TRMPBF Просмотр технического описания (PDF) - Linear Technology

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LTC2942CDCB-TRMPBF

Battery Gas Gauge with Temperature, Voltage Measurement

Linear Technology 

LTC2942

OPERATION

Power-Up Sequence

When SENSE+ rises above a threshold of approximately

2.5V, the LTC2942 generates an internal power-on reset

(POR) signal and sets all registers to their default state.

In the default state, the coulomb counter is active while

the voltage and temperature ADC is switched off. The

accumulated charge register is set to mid-scale (7FFFh),

all low threshold registers are set to 0000h and all high

threshold registers are set to FFFFh. The alert mode is

enabled and the coulomb counter pre-scaling factor M

is set to 128.

APPLICATIONS INFORMATION

I2C/SMBus Interface

The LTC2942 communicates with a bus master using a

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

hard-coded I2C address of the LTC2942 is 1100100.

The LTC2942 is a slave-only device. Therefore the serial

clock line (SCL) is an input only while the serial data line

(SDA) is bidirectional. The device supports I2C standard

and fast mode. For more details refer to the I2C Protocol

section.

Internal Registers

The LTC2942 integrates current through a sense resistor,

measures battery voltage and temperature and stores the

results in internal 16-bit registers accessible via I2C. High

and low limits can be programmed for each measurement

quantity. The LTC2942 continuously monitors these limits

and sets a flag in the onboard status register when a limit

is exceeded. If the alert mode is enabled, the AL/CC pin

pulls low.

The sixteen internal 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

08h

I Voltage MSB

09h

J Voltage LSB

0Ah

K Voltage Threshold High

0Bh

L Voltage Threshold Low

0Ch

M Temperature MSB

0Dh

N Temperature LSB

0Eh

O Temperature Threshold High

0Fh

P Temperature Threshold Low

R = Read, W = Write, XX = unknown

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

R

XXh

R

XXh

R/W FFh

R/W 00h

R

XXh

R

XXh

R/W FFh

R/W 00h

2942f

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