November 1, 2012 – Linear Technology Korea (CEO Hong Sa-kwak) announced the launch of the High Voltage Battery Monitor (Product Name: LTC®6804), suitable for hybrid and electric vehicles, as well as other high-voltage battery stack systems. The LTC6804 can measure voltages up to 4.2V for up to 12 battery cells connected in series with 16-bit resolution. High precision is maintained over time, temperature, and operating conditions using a subsurface Zener voltage reference similar to references used in precision instruments. The LTC6804 can measure the voltage of all battery cells in large-scale high-voltage systems connected in series. Six operating modes are available to optimize update rate, resolution, and the low-pass response of the built-in third-order noise filter. In the fastest mode, all cells can be measured within 290µsec.

Multiple LTC6804s can be interconnected over very long distances and operate simultaneously using Linear Technology's proprietary 2-wire isoSPI™ interface. The isoSPI interface built into all LTC6804s provides high RF noise immunity of up to 1 Mbps and a cable transmission distance of up to 100 m using only twisted-pair cables. It is available in two communication options as follows: For the LTC6804-1 product, multiple devices are connected in a daisy-chain using a single host processor for all devices. For the LTC6804-2, multiple devices are connected in parallel to a host processor, with each device individually addressed.

The LTC6804 is designed to minimize power consumption, especially under long-term storage conditions where battery depletion is not permitted. In standby mode, the LTC6804 consumes less than 4µA from the battery. General-purpose I/O pins can be used to monitor analog signals such as current and temperature, and can simultaneously perform cell voltage measurements. Additional features include manual balancing that is programmable for up to two hours, even when the LTC6804 is in standby mode. The LTC6804 can be connected to external temperature sensors, ADCs, DACs, and EEPROMs via an I2C interface. The local EEPROM can be used to store serialization and calibration data, enabling a modular system.

The LTC6804 is designed to exceed the environmental, reliability, and safety requirements of automotive and industrial applications. The LTC6804 is fully standardized to operate from -40°C to 125°C. Designed for ISO 26262 (ASIL) compliant systems, it features a complete set of self-tests to ensure the absence of potential failure situations. To complete these advantages, the LTC6804 includes a redundant voltage reference, extensive logic test circuitry, open-wire detection capabilities, a watchdog timer, and packet error checking for the serial interface.
"The LTC6804 combines hard-earned technical knowledge and 30 years of analog experience in automotive battery management," said Mike Kultgen, Design Manager at Linear Technology. "Whether in the laboratory or in a real-vehicle environment, this component delivers excellent performance."

Along with the LTC6804, Linear Technology also released the LTC6820 isoSPI transceiver. The LTC6820 enables bidirectional transmission of SPI (Serial Peripheral Interface) over isolated barriers up to 100m. When using the LTC6820, SPI data is converted into differential signals and transmitted via twisted-pair cables and simple, inexpensive Ethernet transformers. The LTC6820 supports SPI data transmission up to 1 MHz, matches source and sink currents to eliminate the need for a transformer center tap, and reduces EMI. Drive current and comparator thresholds are set using two registers, enabling systems that optimize cable length and signal-to-noise performance. The LTC6820 features a built-in isoSPI interface, allowing it to be used in conjunction with the LTC6804 high-voltage battery monitor. Battery management systems utilizing the LTC6804 interface with external components, such as microcontrollers, via the LTC6820.

The LTC6804 is available as a small 8mm x 12mm surface mount device. It is offered at $10.95 in 1,000-unit quantities, and samples, demo boards, and datasheets are available at www.linear.com/product/LTC6804 . The LTC6804 is scheduled to be available in production quantities in January 2013. The LTC6820 is available in MSOP and small QFN packages and is priced at $2.29 per unit in 1,000-unit quantities. Samples, demo boards, and data sheets are available at www.linear.com/product/LTC6820 .

Photo Caption: High-precision, high-voltage multi-cell battery stack monitor & high-noise immunity, isolated, bidirectional SPI communication up to 100M

Product Features: LTC6804 & LTC6820

LTC6804
• Measures up to 12 battery cells connected in series
• Stackable architecture supports over 100 cells
• Built-in isoSPI interface
o 1MB isolated serial communication
o Single, twisted pair use, up to 100M
o Low EMI acceptance & emissions
• 1.2mV maximum total measurement error
• Measure all cells in the system within 290µs
• Synchronized Voltage & Current Measurement
• Delta-Sigma converter with built-in noise filter
• Designed for ISO26262 compliant systems
• Passive cell balancing with programmable timer
• 5 general-purpose digital I/O or analog inputs
o Temperature or other sensor input
o Configurable via I2C interface
• 4μA standby mode current consumption
• 48-pin SSOP package

LTC6820
• 1Mbps Isolated SPI Data Communication
• Simple galvanic isolation using a standard transformer
• Bidirectional interface with a single twisted-pair cable
•; Supports cable lengths up to 100M
• Very low EMI acceptance & emissions
• Configurable for high noise immunity or low power
• No software changes are required in most systems
• Ultra-low, 2μA idle current
• Automatic: Wake-up detection
• Operating temperature range: –40°C to 125°C
• 2.7V ~ 5.5V power supply
• Interface for all logic from 1.7V to 5.5V
• Available in 16-pin QFN & MSOP packages