IC Does Management for 14 Series-Connected Li-ion Battery Cells

Renesas Electronics has announced its fourth-generation lithium-ion (Li-ion) battery management IC that offers unmatched lifetime accuracy. The ISL78714 provides accurate cell voltage and temperature monitoring, along with cell balancing and extensive system diagnostics to protect 14-cell Li-ion battery packs while maximizing driving time and range for hybrid and electric vehicles (HEV/MHEV/PHEV/BEV).

The feature-rich ISL78714 monitors and balances up to 14 series connected cells with ±2mV accuracy across automotive temperature ranges, letting system designers make informed decisions based on absolute voltage levels. The ISL78714 includes a precision 14-bit analog-to-digital converter and associated data acquisition circuitry. The device also offers up to six external temperature inputs (two available from GPIOs) and includes fault detection and diagnostics for all key internal functions.

The ISL78714 meets the stringent reliability and performance requirements of battery pack systems for all EV variants including HEV/PHEV, with safety features enabling automotive manufacturers to achieve the ISO 26262 automotive safety integrity level (ASIL D). In addition, the ISL78714 monitors and reads back over/under voltage, temperature, open wire conditions, and fault status for 112 cells in less than 10 ms, or 70 cells in 6.5 ms.

Multiple ISL78714’s can be connected together via a proprietary daisy chain that supports systems up to 420 cells (30 ICs) that provide industry-leading transient and EMC/EMI immunity, exceeding automotive requirements. The ISL78714’s daisy-chain architecture uses low-cost capacitive or transformer isolation, or a combination of both, with twisted pair wiring to stack multiple battery packs together while protecting against hot plug and high voltage transients. A watchdog timer automatically shuts down a daisy-chained IC if communications is lost with the master MCU.

Key Features:

  • Monitors and manages up to 14 cell voltages with ±2mV measurement accuracy
  • Robust two-wire daisy chain communications system using capacitor or transformer coupling up to 1 Mbps
  • Fully differential cell input range of ±5V accommodates fuel cell and bus bar measurement requirements for aging battery packs
  • 15-year board level accuracy (long term drift) of ±6mV at ±6σ
  • High diagnostic coverage for cell voltage and temperature measurements
  • AEC-Q100 Grade-2 qualified and specified for operation from -40°C to +105°C

A battery management system (BMS) reference design is available, which includes five ISL78714 ICs and a RH850/P1M MCU to form a complete 70-cell evaluation platform for external balancing. The reference design kit provides setup and data logging via CAN and UART. Also provided is a GUI, Altium layout files and low-level drivers for the RH850 peripherals and ISL78714. Hardware, software, and interface reference manuals are included, along with an EMC report.

Mass production quantities of the ISL78714 Li-ion battery management IC are available now in a 64-lead TQFP package.

Renesas Electronics | www.renesas.com

 

Reference Designs and Analog ICs Target Hybrid and Electric Vehicles

Texas Instruments (TI) has introduced fully tested reference designs for battery management and traction inverter systems, along with new analog circuits with advanced monitoring and protection features to help reduce carbon dioxide emissions and enable hybrid electric vehicles and electric vehicles (HEV/EVs) to drive farther and longer.
Scalable across six to 96-series cell supervision circuits, TI’s new battery management system (BMS) reference design (shown) features the advanced BQ79606A-Q1 precision battery monitor and balancer. Engineers can get their automotive designs to market quickly using the reference design, which implements the battery monitor in a daisy chain configuration to create a highly accurate and reliable system design for three- to 378-series, 12-V up to 1.5 kV lithium-ion battery packs.

The highly integrated BQ79606A-Q1 accurately monitors temperature and voltage levels and helps maximize battery life and time on the road. Additionally, the BQ79606A-Q1 battery monitor features safe-state communication that helps system designers meet requirements up to Automotive Safety Integrity Level D (ASIL D), which is the highest functional safety goal defined by the ISO 26262 road vehicles standard.

With so many kilowatts of power filtering through an electric vehicle’s traction inverter and batteries, high temperatures could potentially damage expensive and sensitive powertrain elements. Excellent thermal management of the system is crucial to vehicle performance, as well as protecting drivers and passengers.

To protect powertrain systems such as a 48-V starter generator from overheating, TI introduced the TMP235-Q1 precision analog output temperature sensors. This low-power, low-quiescent-current (9-µA) device provides high accuracy (±0.5°C typical and ±2.5°C maximum accuracy across the full operating temperature from -40°C to 150°C) to help traction inverter systems react to temperature surges and apply appropriate thermal management techniques.

The TMP235-Q1 temperature sensing device joins the recently released UCC21710-Q1 and UCC21732-Q1 gate drivers in helping designers create smaller, more efficient traction-inverter designs. These devices are the first isolated gate drivers to integrate sensing features for insulated-gate bipolar transistors (IGBTs) and silicon carbide (SiC) field-effect transistors, enabling greater system reliability in applications operating up to 1.5 kVRMS and with superior isolation surge protection exceeding 12.8 kV with a specified isolation voltage of 5.7 kV. The devices also provide fast detection times to protect against overcurrent events while ensuring safe system shutdown.

To power the new gate drivers directly from a car’s 12-V battery, TI has released a new reference design demonstrating three types of IGBT/SiC bias-supply options for traction inverter power stages. The design consists of reverse-polarity protection, electric-transient clamping and over- and under-voltage protection circuits. The compact design includes the new LM5180-Q1, which is a 65-V primary-side regulation flyback converter with a 100-V, 1.5-A integrated power MOSFET.

Texas Instruments | www.ti.com

 

Maxim’s Battery Monitoring IC Selected for New Nissan LEAF

Maxim Integrated Products has announced that its single-chip, ASIL D-rated battery monitoring IC is being integrated into the new Nissan LEAF, the next evolution of its zero-emission electric vehicle. The battery monitoring IC meets the highest safety standards, supporting ISO 26262 and ASIL D requirements (also applicable for ASIL C). Its differential universal asynchronous receiver/transmitter (UART) using capacitive isolation reduces BOM costs and failure in time (FIT) rates. The flexible UART enables robust communications in noisy environments.
Using Maxim’s proprietary daisy-chain architecture and successive-approximation-register (SAR) ADC, the battery monitoring IC captures fast, accurate voltage measurements and delivers high electromagnetic capability (EMC) performance. The chip also offers a comprehensive diagnostic feature that complies with bulk current injection (BCI) requirements that are designed to promote safe and smart future vehicles.

The chip supports ISO 26262 and single-chip ASIL D standards, meets various BCI requirements and offers comprehensive diagnostics. It also provides a reliable distributive and centralized cell-monitoring controller (CMC) architecture with UART. It supports 100 m daisy-chain segments and high noise immunity; supports emission, electrostatic discharge (ESD) and hot plugging requirements. Internal cell balancing and UART reduce BOM costs compared to competitive solutions. Maxim claims it as the only IC proven to enable capacitive or transformer isolation.

Maxim Integrated | www.maximintegrated.com

MCU/MPUs Target Next-Gen Electric and Autonomous Vehicles

NXP Semiconductors  has announced a new family of high-performance safe microprocessors to control vehicle dynamics in next-generation electric and autonomous vehicles. The new NXP S32S microprocessors will manage the systems that accelerate, brake and steer vehicles safely, whether under the direct control of a driver or an autonomous vehicle’s control.

NXP is addressing the needs of carmakers developing future autonomous and hybrid electric vehicles with newly available 800 MHz MCU/MPUs. The first of the new S32 product lines, the S32S microprocessor offers the highest performance ASIL D capability available today, according to NXP.
The NXP S32S processors use an array of the new Arm Cortex-R52 cores, which integrate the highest level of safety features of any Arm processor. The array offers four fully independent ASIL D capable processing paths to support parallel safe computing. In addition, the S32S architecture supports a new “fail availability” capability allowing the device to continue to operate after detecting and isolating a failure—a critical capability for future autonomous applications.

NXP has partnered with OpenSynergy to develop a fully featured, real-time hypervisor supporting the NXP S32S products. OpenSynergy’s COQOS Micro SDK is one of the first hypervisor platforms that takes advantage of the Arm Cortex-R52’s special hardware features. It enables the integration of multiple real-time operating systems onto microcontrollers requiring high levels of safety (up to ISO26262 ASIL D). Multiple vendor independent OS/stacks can also run on a single microcontroller. COQOS Micro SDK provides secure, safe and fast context switching ahead of today’s software-only solutions in traditional microcontrollers.

NXP Seimconductors | www.nxp.com

Single-Chip Battery Management System for Cars

Maxim Integrated Products has announced MAX17843 battery management system (BMS). The MAX17843 is 12-channel, high-voltage smart sensor data-acquisition device. Electric vehicles (EVs), hybrid EVs, and plug-in hybrids rely on large lithium-ion battery packs filled with hundreds or even thousands of individual battery cells. With industry experts predicting that 25% of cars sold by 2025 will have electric engines, automotive OEMs and Tier 1s need an intelligent battery management system to enable safe, low cost solutions with robust communications.

MAX17843 meets the highest safety standards, adhering to ISO 26262 and ASIL D requirements (also applicable for ASIL C). Its differential universal asynchronous receiver/transmitter (UART) using capacitive isolation reduces bill of materials (BOM) costs and failure in time (FIT) rates. With this, designers can save up to 90% of their isolation BOM cost. The UART, with ultimate flexibility, enables robust communications in noisy environments. Using Maxim’s unique proprietary daisy-chain architecture and successive-approximation-register (SAR) analog-to-digital converter (ADC), the MAX17843 captures fast, accurate voltage measurements and delivers high EMC performance. It is applicable for a variety of automotive and EV powertrain applications.

Key advantages:

  • Safety: ISO 26262 and ASIL D certification, as well as TUV certification in design and management process; meets various BCI requirements; comprehensive diagnostics
  • Low System Cost: Internal cell balancing and UART reduces BOM costs compared to competitive solutions; only IC to allow capacitive or transformer isolation
  • Robust Communications: Reliable distributive and centralized CMC architecture with UART; Supports 100m daisy-chain segments and high noise immunity; Supports emission, ESD, and hot plug

The MAX17843 is available at Maxim’s website for $7.61 (1,000), The MAX17843EVKIT# evaluation kit is available for $1,000. The device operates over the -40°C to +125°C temperature range and is available in a 64-pin LQFP package (10mm x 10mm).

Maxim Integrated Products | www.maximintegrated.com