ACT8847
Rev 5, 15-Nov-12
FUNCTIONAL DESCRIPTION
I2C Interface
Table 4:
BATLEV Falling Threshold
The ACT8847 features an I2C interface that allows
advanced programming capability to enhance overall
system performance. To ensure compatibility with a
wide range of system processors, the I2C interface
supports clock speeds of up to 400kHz (“Fast-Mode”
operation) and uses standard I2C commands. I2C
write-byte commands are used to program the
ACT8847, and I2C read-byte commands are used to
read the ACT8847’s internal registers. The ACT8847
always operates as a slave device, and is addressed
using a 7-bit slave address followed by an eighth bit,
which indicates whether the transaction is a read-
operation or a write-operation, [1011010x].
BATLEV[3:0]
BATLEV Falling
Threshold
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
2.5
2.6
2.7
2.8
2.9
3.0
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9
4.0
SDA is a bi-directional data line and SCL is a clock
input. The master device initiates a transaction by
issuing a START condition, defined by SDA
transitioning from high to low while SCL is high. Data
is transferred in 8-bit packets, beginning with the
MSB, and is clocked-in on the rising edge of SCL.
Each packet of data is followed by an “Acknowledge”
(ACK) bit, used to confirm that the data was
transmitted successfully.
For more information regarding the I2C 2-wire serial
interface, go to the NXP website: http://www.nxp.com.
Housekeeping Functions
Programmable battery Voltage Monitor
The ACT8847 features a programmable battery-
voltage monitor, which monitors the voltage at INL2
(which should be connected directly to the battery)
and compares it to a programmable threshold
voltage. The VBATMON comparator is designed to
be immune to noise resulting from switching, load
transients, etc. The BATMON comparator is disable
by default; to enable it, set the BATLEV[3:0] register
to one of the value in Table 4. Note that there is a
200mV hysteresis between the rising and falling
threshold for the comparator. The VBATDAT [-] bit
reflects the output of the BATMON comparator. The
value of VBATDAT[ ] is 1 when VINL2 < BATLEV;
value is 0 otherwise.
Thermal Protection
The ACT8847 integrates thermal shutdown
protection circuitry to prevent damage resulting
from excessive thermal stress, as may be
encountered under fault conditions.
Thermal Interrupt
If the thermal interrupt is unmasked (by setting
nTMSK[ ] to 1), ACT8847 can generate an interrupt
when the die temperature reaches 120°C (typ).
The VBATMON comparator can generate an
interrupt when VINL2 is lower than BATLEV[ ] voltage.
The interrupt is masked by default by can be
unmasked by setting VBATMSK[ ] = 1.
Thermal Protection
If the ACT8847 die temperature exceeds 160°C, the
thermal protection circuitry disables all regulators
and prevents the regulators from being enabled until
the IC temperature drops by 20°C (typ).
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