ISL78610 Datasheet, PDF (27/98 Pages) Intersil Corporation – Multi-Cell Li-Ion Battery Manager

ISL78610
ISL78610
COMMS SELECT2
SPI
COMMS SELECT1
VSS
FIGURE 46. NON-DAISY CHAIN COMMUNICATIONS CONNECTIONS
AND SELECTION
.
V3P3
ISL78610
COMMS SELECT2
COMMS SELECT1
VSS
Daisy Down
V3P3
ISL78610
COMMS SELECT2
COMMS SELECT1
VSS
Daisy Up
Daisy Down
V3P3
ISL78610
COMMS SELECT2
COMMS SELECT1
VSS
Daisy Up
SPI
FIGURE 47. DAISY CHAIN COMMUNICATIONS CONNECTIONS AND
SELECTION
Four daisy chain data rates are available and are configurable by
pin selection using the COMMS RATE 0 and COMMS RATE 1 pins
(see Table 4).
TABLE 4. DAISY CHAIN COMMUNICATIONS DATA RATE SELECTION
COMMS RATE 0 COMMS RATE 1
DATA RATE
(kHz)
0
0
62
0
1
125
1
0
250
1
1
500
Daisy Chain Circuits
The ISL78610 daisy chain communications system external
circuit arrangement is symmetrical to provide the bidirectional
communications function. The performance of the system under
transient voltage and EMI conditions is enhanced by the use of a
capacitive load. A schematic of the daisy chain circuit for board
to board connection is shown in Figure 48 on page 28.
The basic circuit elements are the series resistor and capacitor
elements R₁ and C₁, which provide the transient current limit
and AC coupling functions, and the line termination components
C₂, which provide the capacitive load. Capacitors C₁ and C₂
should be located as closely as possible to the board connector.
The AC coupling capacitors C₁ need to be rated for the maximum
voltage, including transients, that will be applied to the interface.
Specific component values are needed for correct operation with
each daisy chain data rate and are given in Table 5 on page 28.
The daisy chain operates with standard unshielded twisted pair
wiring. The component values given in Table 5 will accommodate
cable capacitance values from 0pF to 50pF when operating at
the 500kHz data rate. Higher cable capacitance values may be
accommodated by either reducing the value of C₂ or operating at
lower data rates.
The values of components in Figure 48 are given in Table 5 for
various Daisy chain operating data rates.
The circuit and component values of Figure 48 and Table 5 will
accommodate cables with differential capacitance values in the
ranges given. This allows a range of cable lengths to be
accommodated through careful selection of cable properties.
The circuit of Figure 48 provides full isolation when used with off
board wiring. The daisy chain external circuit can be simplified in
cases where the daisy chain system is contained within a single
board. Figure 49 on page 28 and Table 6 on page 29 show the
circuit arrangement and component values for single board use.
In this case the AC coupling capacitors C₁ need only be rated for
the maximum transient voltage expected from device to device.
Submit Document Feedback ₂₇
FN8830.1
June 16, 2016