ISL78610 Datasheet, PDF (42/98 Pages) Intersil Corporation – Multi-Cell Li-Ion Battery Manager

ISL78610
Scan All Command
When a device receives the Scan All command to its stack
address (or an Address All stack address), it increments the Scan
counter (see “Scan Counter” on page 43) and begins a Scan All
operation.
The Scan All command causes the addressed device (or all
devices with an Address All stack address) to execute the Scan
Voltages, Scan Wires and Scan Temperatures commands in
sequence one time (see Figure 59 on page 44 for example timing).
Scan Continuous Command
Scan Continuous mode is used primarily for fault monitoring and
incorporates the Scan Voltages, Scan Temperatures and Scan
Wires commands. See also “Temperature Monitoring Operation”
on page 43.
The Scan Continuous command causes the addressed device (or
all devices with an Address All stack address) to set the SCAN bit
in the Device Setup register and performs a succession of scans
at a predetermined scan rate. Each device operates
asynchronously on its own clock. This is similar to the Scan All
command except that the scans are repeated at intervals
determined by the SCN0-3 bits in the Fault Setup register.
The ISL78610 provides an option that pauses cell balancing
activity while measuring cell voltages in Scan Continuous mode.
This is controlled by the BDDS bit in the Device Setup register. If
BDDS is set, then cell balancing is inhibited during cell voltage
measurement and for 10ms before the cell voltages are
scanned. Balancing is re-enabled at the end of the scan to allow
balancing to continue. This function only applies during the Scan
Continuous and the Auto Balance functions and allows the
implementation of a circuit arrangement that can be used to
diagnose the condition of external balancing components. It is up
to the host microcontroller to manually stop balancing functions
(if required) when operating a Scan or Measure command.
The Scan Continuous scan interval is set using the SCN3:0 bits
(lower nibble of the Fault Setup register.) The temperature and
wire scans occur at slower rates and depend on the value of the
scan interval selected. The scan system is synchronized such that
the wire and temperature scans always follow a voltage scan.
The three scan sequences, depending on the scans required at a
particular instance, are as follows:
• Scan Voltages
• Scan Voltages, Scan Wires
• Scan Voltages, Scan Wires, Scan Temperatures
The temperature and wire scans occur at 1/5 the voltage scan
rate for voltage scan intervals above 128ms. Below this value the
temperature scan interval is fixed at 512ms.
The behavior of the wire scan interval is determined by the WSCN
bit in the Fault Setup register. A bit value of ‘1’ causes the wire
scan to be performed at the same rate as the temperature scan.
A bit value of ‘0’ causes the wire scan rate to track the voltage
scan rate for voltage scan intervals above 512ms while at, and
below this value, the wire scan is performed at a fixed 512ms
rate. Table 11 shows the various scan rate combinations
available.
Data is not automatically returned while devices are in Scan
Continuous mode except in the case where a fault condition is
detected. The results of voltage and temperature scans are
stored in local volatile memory and may be accessed at any time
by the system host microcontroller. However, since the scan
continuous operation is running asynchronously to any
communications, it is recommended that the continuous scan be
stopped before reading the registers.
Devices may be operated in Scan Continuous mode while in
Normal mode or in Sleep mode. Devices revert to the Sleep
mode or remain in Normal mode, as applicable on completion of
each scan.
The response to a detected fault condition is to send the Fault
signal, either immediately in the case of stand-alone devices or
daisy chain devices in Normal mode, or following transmission of
the Wake-up signal if the device is being used in a daisy chain
configuration and is in Sleep mode.
To operate the “Scan Continuous” function in Sleep mode, the
host microcontroller simply configures the ISL78610, starts the
Scan Continuous mode and then sends the Sleep command. The
ISL78610 then wakes itself up each time a scan is required. Note
that for the fastest scan settings (scan interval codes 0000,
0001 and 0010) the main measurement functions do not power
down between scans, since the ISL78610 remains in Normal
mode.
TABLE 11. SCAN CONTINUOUS TIMING MODES
SCAN
INTERVAL
SCN3:0
SCAN
INTERVAL
(ms)
TEMP
SCAN
(ms)
WIRE
SCAN
WSCN = 0
(ms)
WIRE
SCAN
WSCN = 1
(ms)
0000
16
512
512
512
0001
32
512
512
512
0010
64
512
512
512
0011
128
512
512
512
0100
256
1024
512
1024
0101
512
2048
512
2048
0110
1024
4096
1024
4096
0111
2048
8192
2048
8192
1000
4096
16384
4096
16384
1001
8192
32768
8192
32768
1010
16384
65536
16384
65536
1011
32768
131072
32768 131072
1100
65536
262144
65536 262144
Scan Inhibit Command
The Scan Inhibit command is used to a Continuous scan (i.e.,
receipt of this command by the target device resets the SCAN bit
and stops the Scan Continuous function).
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FN8830.1
June 16, 2016