JAJSRJ8B September 2019 – October 2023 BQ75614-Q1
PRODUCTION DATA
Related Pins | Components | Value | Description |
---|---|---|---|
VC0 to VC16 | Filter resistor | 100 Ω | Only differential RC filters are needed for VC channels. Besides serving for input signal filtering, these components are required to support hot-plug events during cell module insertion. Hence, it is highly recommended to use the component values as suggested. |
Filter capacitor | 0.47 μF/16 V or 1 μF/16 V |
||
CB0 to CB16 | Filter resistor | Depends on system’s balancing current requirements | The filter resistor on CB pins sets the maximum balancing current.
See Section 8.3.3 for details. Only differential RC filters are needed for CB channels. Besides serving for input signal filtering, these components are required to support hot-plug events during cell module insertion. Hence, it is highly recommended to use the component values as suggested. |
Filter capacitor | 0.47 μF/16 V or 1 μF/16 V |
Cell Connections
It is recommended to populate the battery cells from bottom channels (both VC and CB channels) and up, leaving upper channels as unused channels if cell module size is smaller than the maximum channel size of the device. Unused channel(s) will be connected as shown in Figure 9-2.
Fuse and Relay Status Detection
In the case of a system with <16S configuration, it is possible to use the upper cell sensing channel for fuse and relay detection as showed in Figure 9-3. It utilizes the differential measurement capability of the device and provide the voltage measurement across the fuse (VC15-VC14 voltage, reporting to VCELL15_HI/LO registers) and voltage measurement across the relay (VC16-VC15 voltage, reporting to VCELL16_HI/LO registers).
For example, when the fuse is intact, the differential voltage measurement (VC15-VC14) shall be close to 0V, possible within +/-300-mV given the IR increase/descrease depends on the current flow direction. When the fuse is open, the VC15 voltage is floating which result in a significant negative measurement of this differential channel. The difference in the measurement allow the host system to determine the open/close status of these component.
Fuse and Relay Diagnostic
Considering Channel 15 being used for fuse diagnostics and Channel 16 being used for Relay diagnostics.
Diagnostic | Open/Blown | Close |
---|---|---|
Fuse |
Indicated when (SW1-VC14) <<0V. Open Fuse causes SW1 to be pull down towards ground by the load. |
Indicated when (SW1-VC14) = ~0V This IR drop depends on current flow and fuse impedance (e.g. +/-0.3V) |
Relay |
Indicated when (SW2-SW1) <<0V Open Relay causes SW2 to be pull down towards ground by the load. |
Indicated when (SW2-VC1) = ~ 0V This IR drop depends on current flow and fuse impedance (e.g. +/-0.3V) |
Table above shows the expected response to different states of fuse and relay.
In addition to the 14 cell measurements, the device has 2 more differential channels that can be used for external fuse and relay diagnostics. Here channel 15 is connected across the fuse and channel 16 is connected across the relay. Table above also shows the expected response from the diagnostics. The MCU can read the ADC outputs from these channels and make a determination on the status of the fuse and the relay.