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EM1402EVM: Differences Between EM1401EVM (Obsolete) and EM1402EVM

ti_0090
Prodigy 40 points
Part Number: EM1402EVM
Other Parts Discussed in Thread: BQ76PL455A

We have been using the EM1401EVM for active balancing on 14S2P battery packs for the past 9 months. We only needed to purchase one additional EM1401EVM to finish our current project, but we just found out the 1401 is now obsolete (the product page status was shown as "Active" until we submitted an inquiry a day ago, and there was no indication that it had been superseded by the 1402).

We are now in a difficult situation where we cannot purchase the 1401 and have very little time or budget to learn how to switch to the 1402. I would like a summary of the differences between the two versions so we can assess the best path forward to finish our current project. After a quick glance, the main differences I have identified are the communication protocol (1401 used CAN) and the external isolated balance source (not present in the 1401).

I would greatly appreciate a timely follow up so we can move quickly in mitigating the 1401's unforeseen obsolescence.

  • 0
    TI__Guru 54715 points

    Hi Jacob,

    The EM1401EVM is an older design with a number of parts which are no longer available.  The EM1402EVM is a newer design.  Both use the EM1428Q and EM1499Q active cell balance components to demonstrate a system.

    Feature EM1401EVM EM1402EVM
    Documentation TI Design TIDA-00239 TIDA-00817
    Max cells on EVM 14 16
    Converters 2 1
    Balances to Module voltage External isolated 12V for module to module balancing
    MCU on board Yes No
    Monitor EMB1432 bq76PL455A
    Communication CAN bus UART
    Software reference No Sample code; TIDM-TMS570BMS
  • 0 in reply to WM5295
    Prodigy 40 points
    Thank you for the comparison. Since we are using a single module for this application, what is the purpose of the external isolated 12 V balance source?
  • 0 in reply to ti_0090
    TI__Guru 54715 points
    Hi ti,
    The external isolate 12V source in EM1402EVM provides a method to balance between cells in different modules in a stacked module system. The EM1401EVM did not allow balancing between modules and the alternative was to balance higher modules down using additional dissipative methods or running the high module active circuit to cause dissipation. For a single module 14S system the external 12V does not seem beneficial.
  • 0 in reply to WM5295
    Prodigy 40 points
    So for our application with a 14S single module, would you recommend leaving the external 12V source disconnected?
  • 0 in reply to ti_0090
    TI__Guru 54715 points
    Hi ti,
    The EM1402EVM will not run with the external isolated 12V source disconnected. The operation of the design is to transfer energy from a cell to the external 12V or from the external 12V to a cell.
    The EM1401EVM was designed to transfer energy from a cell to the module, or from the module to a cell. Since there were 2 converters it was conceptually possible to operate 2 cells at once, I don't know what the algorithm supported.
    Since the EM1401 fit your system well, but with its obsolecence and the limitations in the EVM notices, it seems your mitigation plan may be to design a switch matrix and converter topology much like the TIDA-00239 (EM1401EVM). The bq76PL455A can provide measurement as shown on the EM1402EVM with control by a MCU such as TMS570 and your choice of support components. The software noted may be helpful but is not a drop in for your system.