LTC2942CDCB(RevA) View Datasheet(PDF) - Linear Technology

Part Name

Description

MFG CO.

LTC2942CDCB
(Rev.:RevA)

Battery Gas Gauge with Temperature, Voltage Measurement

Linear Technology 

LTC2942

Applications Information

The master initiates the ARA procedure with a START con-

dition and the special 7-bit ARA bus address (0001100)

followed by the read bit (R) = 1. If the LTC2942 is asserting

the AL/CC pin in alert mode, it acknowledges and responds

by sending its 7-bit bus address (1100100) and a 1. While

it is sending its address, it monitors the SDA pin to see

if another device is sending an address at the same time

using standard I2C bus arbitration. If the LTC2942 is send-

ing a 1 and reads a 0 on the SDA pin on the rising edge of

SCL, it assumes another device with a lower address is

sending and the LTC2942 immediately aborts its transfer

and waits for the next ARA cycle to try again. If transfer

is successfully completed, the LTC2942 will stop pulling

down the AL/CC pin and will not respond to further ARA

requests until a new Alert event occurs.

PC Board Layout Suggestions

Keep all traces as short as possible to minimize noise and

inaccuracy. Use a 4-wire Kelvin sense connection for the

sense resistor, locating the LTC2942 close to the resistor

with short sense traces to the SENSE+ and SENSE– pins.

Use wider traces from the resistor to the battery, load

and/or charger (see Figure 11). Put the bypass capacitor

close to SENSE+ and GND.

TO

CHARGER/LOAD

1

C2

3

RSENSE

TO BATTERY

LTC2942

6

5

4

2942 F10

Figure 11. Kelvin Connection on Sense Resistor

2942fa

15

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