ISL9217
8 to 12 Cell Li-Ion Battery Overcurrent Protection and Analog Front End Chip Set

Key Features

• Software selectable overcurrent protection levels and variable protect detection/release times
• 4 Discharge overcurrent thresholds
• 4 Short circuit thresholds
• 4 Charge overcurrent thresholds
• 8 Overcurrent delay times (Charge)
• 8 Overcurrent delay times (Discharge)
• 2 Short circuit delay times (Discharge)
• Automatic FET turn-off and cell balance disable on reaching external (battery) or internal (IC) temperature limit
• Automatic over-ride of cell balance on reaching internal (IC) temperature limit
• Fast short circuit pack shutdown
• Can use current sense resistor, FET r_DS(ON), or Sense FET for overcurrent detection
• Four battery backed software controlled flags
• Allows three different FET controls:
• Back-to-back N-Channel FETs for charge and discharge control
• Single N-Channel FET for discharge control
• N-Channel FET for discharge, with separate, optional (smaller) back-to-back FET for charge
• Chips cascade for packs of 8 to 12 cells
• Integrated charge/discharge FET drive circuitry with 200µA (typ) turn on current and 150mA (typ) discharge FET turn off current
• 10% accurate 3.3V voltage regulator (35mA out with external NPN transistor having current gain of 70)
• Cell voltage monitor accurate to within 25mV
• Monitored cell voltage output stable in 100µs
• Internal cell balancing FETs handle up to 200mA of balancing current for each cell (with the number of cells being balanced limited by the maximum power dissipation of 400mW)
• Simple I²C host interface
• Sleep operation with programmable negative edge or positive edge wake-up

Description

The ISL9216 and ISL9217 chipset provides overcurrent protection and voltage monitoring for multi-cell li-ion battery packs consisting of 8 to 12 cells. When used together, these devices provide integrated overcurrent protection circuitry, short circuit protection, an internal voltage regulator, internal cell balancing switches, cell voltage level shifters, and drive circuitry for external FET devices that control pack charge and discharge. Level shifting of the analog output voltage from the upper cells and communication between the chips is handled automatically.

Overcurrent and short circuit thresholds reside in internal RAM registers and are selected independently via software using an I²C serial interface. Detection and time-out delays can be individually varied using internal registers. Using an internal analog multiplexer, the device provides monitoring of cell voltage by a separate microcontroller with A/D converter. Software on this microcontroller implements all battery control functionality, except for overcurrent and short circuit shutdown.

Applications

• Power Tools
• Battery Backup Systems
• E-bikes
• Portable Test Equipment
• Medical Systems
• Hybrid Vehicle
• Military Electronics