Datasheet

PowerLAN Communications
Operation Modes
COMPLEMENTARY PRODUCTS
PowerLAN Master Gateway Battery Controller
bq76PL102
www.ti.com .......................................................................................................................................... SLUS887A – DECEMBER 2008 – REVISED OCTOBER 2009
PowerLAN communications technology is a patented serial network and protocol designed specifically for battery
management in a multicell environment. PowerLAN is used to initiate and report measurements of cell voltage
and temperature, as well as control cell balancing. Using only a capacitor, PowerLAN isolates voltages from
adjacent bq76PL102 parts to permit high-voltage stack assemblies without compromising precision and
accuracy. PowerLAN is expandable to support up to 12 cells in series, with each bq76PL102 handling two series
cells. PowerLAN provides high ESD standoff and high immunity to noise generated by nearby digital circuitry or
switching currents. Each bq76PL102 has both a PowerLAN serial input and serial output pin. Received data is
buffered and retransmitted, permitting high numbers of nodes without loss of signal fidelity. Signals are
capacitor-coupled between nodes to provide high dc isolation.
The bq76PL102 normally operates in one of two modes: active or standby. The bq76PL102 is normally in
standby mode and consumes typically less than 50 µ A. The low-dropout regulator output is still functional in this
mode, as are internal system protection functions (undervoltage, communications timeout, etc.)
When a PowerLAN communications event occurs, then the bq76PL102 transitions to active mode and current
drain increases to 250 µ A typically. The bq76PL102 stays in this mode to complete any measurements or
cell-balancing pumping operations. Once activity in this mode ceases, the return to standby is automatic, thus
reducing overall power consumption.
An undervoltage ultralow-current mode is also available when initiated by the bq78PL114 master-gateway battery
controller and when the cell voltages drop below a preset threshold. This mode is used to preserve battery
capacity during long periods of non-use and therefore has a current drain of approximately 1 µ A.
Note that cell balancing currents are external to the bq76PL102 and may be sized according to the needs of the
application (typically 10 mA to 1 A). These currents are fixed by the cell-balancing circuitry and only enabled or
disabled by the bq76PL102 (under control of the bq78PL114) to achieve the necessary cell-balance operations.
The bq78PL114 master-gateway battery-management controller with PowerPump cell balancing from Texas
Instruments is the central controller for a complete multicell battery system.
This advanced master-gateway battery controller works with up to 12 series cells monitored by bq76PL102 cell
monitors to provide battery voltage, temperature, current and safety monitoring; state-of-charge and
state-of-health information; system-wide internal PowerLAN communications; as well as external communications
of battery parameters via the industry-standard SMBus interface.
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