Maxim Releases Battery-Protection IC To Reduce BMS Cost In Hybrid & Electric VehiclesJuly 27, 2009 by Jeff Shepard
Maxim Integrated Products introduced the MAX11080, a high-voltage, 12-channel battery-protection IC for high-cell-count lithium-ion (Li+) battery stacks. The first stackable fault monitor on the market, this device provides redundant cell monitoring to prevent Li+ batteries from exploding (thermal runaway). Up to 31 MAX11080s can be daisy-chained together to monitor as many as 372 cells. This capability is said to prevent cascading electrical failures and eliminates the expensive isolation components required by discrete solutions. In a typical hybrid car, Maxim states that its solution reduces the cost of the battery-management system (BMS) by up to 80%.
Offering world-class accuracy, ultra-low power consumption, built-in safety and self-diagnostic features, and plenty of configurability, the MAX11080 solves the problems associated with safely monitoring large battery stacks. It is well suited for a spectrum of battery applications including automotive, industrial, power line, and battery backup.
Maxim claims that the MAX11080 greatly simplifies the design of high-cell-count battery packs. A 12-channel fault monitor, this device employs a proprietary capacitor-isolated daisy-chain interface to minimize component count and cost. This architecture allows up to 31 devices to be connected in a series stack to monitor as many as 372 cells. Meanwhile, the capacitor-based interface provides extremely low-cost isolation from one bank of batteries to the next, eliminating cascading electrical failures.
The company states that its high-voltage, small-geometry BiCMOS process enables the industry’s highest voltage tolerance (80V), excellent ESD performance (±2kV, Human Body Model), hot-swap capability, and reliable performance over a wide temperature range. To protect against battery thermal runaway, the MAX11080’s ultra-accurate overvoltage detection guarantees less than ±25mV error over the full AEC-Q100 Type 2 temperature range (-40 to +105°).
Additionally, the MAX11080 offers a 10x reduction in power consumption (80microamps, operating mode) to conserve battery life. A unique built-in shutdown feature reduces consumption to an ultra-low 2µA leakage, allowing the pack to be stored for many years with very little battery drain.
The MAX11080 has 16 selectable overvoltage thresholds, as well as 8 selectable undervoltage thresholds. The undervoltage-detection feature can be disabled if desired. The device includes a programmable detection-delay feature that allows the user to filter out transient events in the battery pack to eliminate false overvoltage or undervoltage alarms. The alarm line operates using a 4kHz heartbeat signal, the absence of which indicates a valid overvoltage or undervoltage event. These features are critical for discriminating between legitimate and false alarms, preventing the application from shutting down unnecessarily.
The MAX11080 has built-in self-configuration and self-diagnostic modes. On power-up the device automatically detects the presence of batteries and can be configured from 2 to 12 cells in any connection sequence or installation pattern. The device also self tests the internal comparator circuitry to ensure proper functionality on power-up. It is capable of detecting the open or short of any pin on the package and constantly monitors the pins for such a failure. FMEA reports are available upon request for the design and for the package I/Os.
The MAX11080 is packaged in a 38-pin TSSOP and is fully specified for operation over the -40 to +105°C temperature range. Prices start at $3.92 (100-up, FOB USA).