ISL78610 - 12-Channel Li-ion Battery Pack Monitor
During this presentation, we’ll provide an overview of Intersil’s ISL78610, 12-channel Li-ion battery pack monitor and manager.
It can be used as a standalone battery pack monitor or manager, or used as redundant backup in a ASIL compliant battery system.
Some of its key features are:
- Full suite of integrated diagnostics as required by the automotive industry such as UV and OV, over temperature and open wire detection.
- It can be used with a range of popular cell chemistry types such as Li-ion Cobalt and Li-ion Phosphate.
- Daisy chain communications have excellent transient resistance and industry leading EMC/EMI and hot plug performance—as independently proven by multiple customers.
- When used in backup or monitoring mode, it measures absolute voltages rather than simple levels determined by a comparator – this allows customers to make informed decisions based on the voltage levels rather than immediately act on an out of range condition. This could mean giving a vehicle driver a few more miles in the tank to get home rather than stalling them at the roadside.
- Comes in a cost competitive accuracy of typically better than +/-10mV—more than adequate for redundant backup applications.
ISL78610 is a Grade 2 rated device for use in ambient temperatures from -40°C to +105°C and it comes in a space efficient quad package, 10mm x 10mm 64-lead TQFP package.
In the following slides, I will describe in more detail, the functionality provided by the ISL78610, the applications it will address and the benefits it offers these applications.
Target Markets and Applications
It can be used as a primary monitoring/management device or redundant backup device as part of a vehicle battery management system (BMS).
As a primary monitoring/management device it lends itself well to less demanding mobility programs such as electric motorcycles, low speed delivery vans and carts.
Alternatively, it has seen deployment in energy storage and backup battery systems for data centers and infrastructure support. These systems require higher quality grades than is generally offered by commercial grade parts.
As a redundant backup device, it can be used to help achieve higher automotive safety integrity levels (ASIL) ratings in hybrid electric vehicle (HEV), plug-in hybrid electric vehicle (PHEV) and electric vehicle (EV) battery packs.
ISL78610 – Backup/Redundant System Architecture
This illustration shows a standard redundant backup system configuration where the ISL78610 is connected to the same cells as the ISL78600 as a monitor; this is typical of an application you might find in an ASIL compliant HEV, EV or PHEV. The ISL78610 provides backup to the ISL78600 which is configured as the primary cell manager. The purpose of this is if the primary management device were to fail for any reason and not detect the battery or cells going out of specification, the ISL78610 would communicate this to the host microcontroller. The microcontroller can then make decisions about what action to take next. Both devices are shown configured to communicate via SPI to the host microcontroller on a common bus and are daisy chained in a stack configuration to the next board.
ISL78610 Competitive Advantage – Daisy Chain Comms.
This illustration shows a typical stacked configuration for higher overall battery voltages and is popular in automotive applications. The Daisy Chain communications uses a capacitively coupled, twisted pair for cost optimization. It’s very robust, has excellent EMC, EMI and transient immunity and can be used to string up to 14 devices together. Transients are a significant issue in ”under the hood” applications where high energy electrical noise and spikes are present and can disrupt communications.
Inter Device Communications with a Competitor Part
The alternate communication system employed by some competitors uses standard CAN bus which requires a micro to interface each node with the corresponding MCB IC. This is an expensive and complex solution and not recommended for “off board” communications between devices. This tends to limit its use to centralized battery management systems on a single PCB as opposed to distributed systems connected by wiring. The reason the competition recommends this architecture is because its own version of Daisy Chain isn't robust.
Full ISL78610 datasheets, user guides, reference designs, and FAQs are available at www.intersil.com.
Evaluation Kit – Start Designing Today!
The evaluation kit comes with three boards, cables and documentation. The boards are – the main board, containing the ISL78610; the power supply board, which when connected to a suitable power supply emulates 12 Li-ion cells; and the interface board, which provides a USB interface to a PC. Cables included are a PC USB interface cable and a twisted pair board interconnect cable for use when daisy chaining multiple boards together. If a customer wishes to daisy chain boards together then an order should be placed for evaluation kits corresponding to the number of devices to be connected together. For example, if two boards are to be daisy chained together then two evaluation kits should be ordered.
The reference designs are recommended for automotive stacked architectures and are optimized for operational and EMC compliance purposes. Reference designs, layouts and schematics are available in Altium, Protel and other popular PCB layout tool formats.
Graphical User Interface
The graphical user interface (GUI) provides an easy way to familiarize the customer with the ISL78610.
It incorporates a range of graphical tools allowing the configuration and monitoring of all key parameters, communications and fault conditions.
Also included is a useful charting feature which allows the graphing and export of data to other tools such as Excel for further analysis.
The GUI can be downloaded from the Intersil website at www.intersil.com/products/isl78610 as can the evaluation kit user manual which has a detailed description of the evaluation kit, the GUI, its setup, and operation.