BQ76PL455A-Q1 Datasheet, PDF (104/130 Pages) Texas Instruments – 16-Cell EV/HEV Integrated Battery Monitor and Protector

bq76PL455A-Q1
SLUSC51B – APRIL 2015 – REVISED DECEMBER 2015
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Application Information (continued)
8.1.2.2 Daisy-Chain Communication Differential Communications
For applications that require multiple bq76PL455A-Q1 devices, a back-side differential communication bus is
provided that allows the host controller to interface with up to 16 devices, while utilizing only one UART interface.
In this configuration, the bq76PL455A-Q1 devices are daisy-chained. For the devices that are higher in the stack
(not using the UART interface, differential communications only), the following is the required configuration.
1. FAULT_N has a 50-kΩ pull-down resistor to make sure a fault is generated when VIO is not present.
2. TX and RX should be pulled-up to VIO via a 100-kΩ resistor. Do not leave TX and RX unconnected.
8.1.2.2.1 Stacked Devices on Same PCB
When multiple, daisy-chained bq76PL455A-Q1 devices are located on the same PCB, use the circuit in
Figure 32 to ensure best performance of the backside communication.
COMMH+
TVS Diode (2)
10 Ÿ
1 nF 10 Ÿ
COMML+
TVS Diode (2)
COMMH-
10 Ÿ
1 nF 10 Ÿ
UP-STACK, HIGHER VOLTAGE
COMML-
Figure 32. Components Required for Daisy-Chain Communication between Devices on Same PCB
8.1.2.2.2 Stacked Devices Separated by Cables
Many applications require multiple, daisy-chained bq76PL455A-Q1 devices that are separated by cables. The
cable introduces additional challenges to the application. The recommended circuit is as defined in Figure 33 and
Figure 34.
COMMH+
TVS Diode(2)
PCB#1
Common-mode
Choke
10 Ÿ
Tw. Pair Cable
1 nF
1 nF
PCB#2
Common-mode
Choke
10 Ÿ
COMML+
TVS Diode(2)
COMMH-
10 Ÿ
100 µH
~100 Ÿ
1 nF
1 nF
UP- STACK, HIGHER VOLTAGE
100 µH
10 Ÿ
COMML-
Figure 33. Components Required for Daisy-Chain Communication between PCBs
COMMH+
TVS Diode(2)
10 Ÿ
PCB#1
Common-mode
Choke
Tw. Pair Cable
1 nF
1 nF
PCB#2
Common-mode
Choke
10 Ÿ
COMML+
TVS Diode(2)
COMMH-
10 Ÿ
470 µH
100 µH
~100 Ÿ
1 nF
UP-STACK, HIGHER VOLTAGE
1 nF
100 µH
470 µH
10 Ÿ
COMML-
Figure 34. Components Required for Daisy-Chain Communication between PCBs in Noisy Environments
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