ISL78610 Datasheet, PDF (72/98 Pages) Intersil Corporation – Multi-Cell Li-Ion Battery Manager

ISL78610
System Diagnostics Functions
There are four types of faults that the system uses to determine
the overall health of the system. These are:
1. Automatic Fault detection within the IC.
2. Fault detection that is automatic, but requires the host
microcontroller to initiate an operation.
3. Faults that are detected by the host microcontroller during
normal communication. This includes lack of response or
responses that indicate a fault condition.
4. Faults that are detected by the host microcontroller following
a series of commands and responses that check various
internal and external circuits.
Hardware Fault Detection
The ISL78610 is always checking the internal V3P3, V2P5 and
VREF power supplies using window comparators. If any of these
voltages exceed a programmed limit (either too high or too low),
then a REG fault exists. This immediately starts an alarm
response. See “Alarm Response” on page 75.
The ISL78610 also checks the two oscillators continually. The
high speed and low speed oscillators are compared against
limits and against each other. If there is a deviation greater than
programmed, then an OSC fault exists. This immediately starts
an alarm response. See “Alarm Response” on page 75.
System Out of Limit Detection
Bits are set in the fault data registers for detection of:
• Overvoltage
• Undervoltage
• Open-wires
• Over-temperature
• Open VBAT
• Open VSS
The Overvoltage, undervoltage, over-temperature, and open-wire
conditions have individual fault bits for each cell input. These bits
are OR’d and reflected to bits in the Fault Status register (one bit
per data register). The Open VBAT and Open VSS have one bit
each in the Fault Status register.
These conditions are not detected unless the host initiates a scan
operation. The cell overvoltage, cell undervoltage, VBAT open and
VSS open faults are sampled at the same time at the end of a
Scan Voltages command. The cell undervoltage and cell
overvoltage signals are also checked following a Measure Cell
Voltage command. These conditions are also checked during a
Scan Continuous operation. If the host initiates a Scan
Continuous operation, then the status is checked automatically
every scan cycle, without further host involvement. For any other
Scan command, the host needs to periodically send the
command to perform another check of the system.
FAULT SIGNAL FILTERING
Filtering is provided for the cell overvoltage, cell undervoltage,
VBAT open and VSS open tests. These fault signals use a
totalizing method in which an unbroken sequence of positive
results is required to validate a fault condition. The sequence
length (number of sequential positive samples) is set by the
[TOT2:0] bits in the Fault Setup register. See Table 43 on
page 73.
If the host sends a Scan Continuous command, then the Scan
Interval and the Totalizer value set the Fault Detection time. See
Table 42.
Each cell input, VBAT and VSS open circuits have separate filter
functions. The filter is reset whenever a test results in a negative
result (no fault). All filters are reset when the Fault Status register
bits are changed. When a fault is detected, the bits must be
rewritten.
Any out of limit condition generates an Alarm response. See
“Alarm Response” on page 75.
TABLE 42. FAULT DETECTION TIME AS A FUNCTION OF SCAN INTERVAL AND NUMBER OF TOTALIZED SAMPLES
FAULT DETECTION TIME
SCAN SCAN
INTERVAL INTERVAL ⁰⁰⁰
001
010
011
100
101
110
111 FAULT SETUP REGISTER
CODE
(ms)
1
2
4
8
16
32
64
128
TOTALIZER VALUE
0000
16
16
32
64
128
256
512
1024
2048
0001
32
32
64
128
256
512
1024
2048
4096
0010
64
64
128
256
512
1024
2048
4096
8192
0011
128
128
256
512
1024
2048
4096
8192
16384
0100
256
256
512
1024
2048
4096
8192
16384
32768
0101
512
512
1024
2048
4096
8192
16384
32768
65536
0110
1024
1024
2048
4096
8192
16384
32768
65536 131072
0111
2048
2048
4096
8192
16384
32768
65536 131072 262144
1000
4096
4096
8192
16384
32768
65536 131072 262144 524288
1001
8192
8192
16384
32768
65536 131072 262144 524288 1048576
1010 16384 16384
32768
65536 131072 262144 524288 1048576 2097152
1011 32768 32768
65536 131072 262144 524288 1048576 2097152 4194304
1100 65536 65536 131072 262144 524288 1048576 2097152 4194304 8388608
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June 16, 2016