Datasheet

LTC2942
15
2942fa
LTC2942
2942 F10
R
SENSE
TO BATTERY
TO
CHARGER/LOAD
4
5
6
3
2
C
1
Figure 11. Kelvin Connection on Sense Resistor
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 I
2
C 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.