LTC2943
APPLICATIONS INFORMATION
All status register bits are cleared after being read by the
host, but might be reasserted after the next temperature,
voltage or current conversion or charge integration, if the
corresponding alert condition is still fulfilled.
BIT
NAME
OPERATION
DEFAULT
B[2:1]
ALCC
Configure
Configures the ALCC pin.
[10] Alert Mode.
[10]
Alert functionality enabled. Pin
becomes logic output.
[01] Charge Complete Mode. Pin
becomes logic input and accepts
charge complete inverted signal
(e.g., from a charger) to set
accumulated charge register (C,D)
to FFFFh.
Control Register (B)
The operation of the LTC2943 is controlled by program-
ming the control register. Table 3 shows the organization
of the 8-bit control register B[7:0].
[00] ALCC pin disabled.
[11] Not allowed.
Table 3. Control Register B
BIT
NAME
OPERATION
DEFAULT
B[0]
Shutdown
Shut down analog section to
[0]
B[7:6]
ADC Mode
[11] Automatic Mode:
continuously performing
voltage, current and temperature
conversions
[00]
reduce I
.
SUPPLY
Power Down B[0]
[10] Scan Mode: performing
voltage, current and temperature
conversion every 10s
Setting B[0] to 1 shuts down the analog parts of the
LTC2943, reducing the current consumption to less than
1±μA (typical). The circuitry managing I C communica-
tion remains operating and the values in the registers are
retained. Note that any charge flowing while B[0] is 1 is
not measured and any charge information below 1LSB of
the accumulated charge register is lost.
2
[01] Manual Mode: performing
single conversions of voltage,
current and temperature then
sleep
[00] Sleep
B[±:3]
Prescaler M
Sets coulomb counter prescaling
factor M between 1 and 4096.
Default is 4096.
[111]
Alert/Charge Complete Configuration B[2:1]
Maximum value is limited to 4096
The ALCC pin is a dual function pin configured by the
control register. By setting bits B[2:1] to [10] (default),
the ALCC pin is configured as an alert pin following the
SMBus protocol. In this configuration, the ALCC is pulled
lowifoneofthefourmeasuredquantities(charge,voltage,
current, temperature) exceeds its high or low threshold or
if the value of the accumulated charge register overflows
or underflows. An alert response procedure started by the
master resets the alert at the ALCC pin. If the configura-
tion of the ALCC pin is changed while it is pulled low due
to an alert condition, the part will continue to pull ALCC
low until a successful alert response procedure (ARA) has
been issued by the master. For further information see the
Alert Response Protocol section.
B[±:3]
000
001
010
011
100
101
110
111
M
1
4
16
64
2±6
1024
4096
4096
Setting the control bits B[2:1] to [01] configures the
ALCC pin as a digital input. In this mode, a low input on
the ALCC pin indicates to the LTC2943 that the battery
is full and the accumulated charge register is set to its
maximum, value FFFFh.
2943fa
10
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