ISL78610 Datasheet, PDF (66/98 Pages) Intersil Corporation – Multi-Cell Li-Ion Battery Manager

ISL78610
System Timing Tables
Command Timing Tables
The command timing (Table 27) includes the time from the start
of the command to the start of an internal operation for each
device in a stack. Table 28 shows the time required for the
command to complete. For a stand-alone device, the two values
are the same since the internal operation starts at the end of the
command. For a daisy chain operation, the internal operation
begins before the end of the command.
When calculating overall timing for a command, start with the
time from start of the command to the start of the internal
operation for the target device. Add to this the time for the
internal operation, see “Measurement Timing Tables” on
page 67. Add to this the time it takes to read back the data. See
times shown in “Response Timing Tables” on page 68. Also
needed is a wait time between sending each command (see
Table 29).
When using the Address All option, the command timing for the
top device in the stack determines when the command ends, but
use the Time to Start of Scan for each device to determine when
that device begins its internal operation. For example, in a stack
of six devices, it takes 90.9µs for the command to complete, but
internal operations start at 13.8µs for the master, 68.7µs for
device 2, 70.9µs for device 3, etc.
In Tables 27 and 28, the calculation assumes a daisy chain (and
internal) clock that is 10% slower than the nominal and an SPI
clock that is running at the nominal speed (since the SPI clock is
normally crystal controlled.) For the 500kHz daisy setting, timing
assumes a 450kHz clock.
TABLE 27. TIME TO START OF INTERNAL OPERATION
TIME TO START OF INTERNAL OPERATION FOR TARGET DEVICE
(µs)
TARGET
DEVICE
SPI CLOCK = 2MHz
DAISY CLOCK = 500kHz
DAISY CLOCK = 250kHz
1
17.5
17.5
2
68.7
130.9
3
70.9
135.4
4
73.2
139.8
5
75.4
144.3
6
77.6
148.7
7
79.8
153.2
8
82.1
157.6
9
84.3
162.1
10
86.5
166.5
11
88.7
170.9
12
90.9
175.4
13
93.2
179.8
14
95.4
184.3
TABLE 28. COMMAND TIMING
TIME TO END OF COMMAND FOR NUMBER OF DEVICES
(µs)
NUMBER
OF DEVICES
SPI CLOCK = 2MHz
DAISY CLOCK = 500kHz DAISY CLOCK = 250kHz
1
17.5
17.5
2
82.0
157.6
3
84.2
162.0
4
86.5
166.5
5
88.7
170.9
6
90.9
175.3
7
93.1
179.8
8
95.3
184.2
9
97.6
188.7
10
99.8
193.1
11
102.0
197.6
12
104.2
202.0
13
106.5
206.5
14
108.7
210.9
SEQUENTIAL DAISY CHAIN COMMUNICATIONS
When sending a sequence of commands to the master device,
the host must allow time after each response and before sending
the next command, for the daisy chain ports of all stack devices
(other than the master) to switch to receive mode. This wait time
is equal to 8 daisy chain clock cycles and is imposed from the
time of the last edge on the master’s input daisy chain port to the
last edge of the first byte of the subsequent command on the
SPI, (see Figure 77). The minimum recommended wait time
between the host receiving the last edge of a response and
sending the first edge of the next command, is given for the
various daisy chain data rates in Table 29.
TABLE 29. MINIMUM RECOMMENDED COMMUNICATIONS WAIT TIME
MAXIMUM TIME FOR DAISY CHAIN
PORTS TO CLEAR
UNIT
DAISY CHAIN DATA RATE 500 250 125 62.5 kHz
Communications Wait Time 18
36
72 144 µs
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June 16, 2016