12-Channel, High-Voltage Sensor, Smart Data-Acquisition Interface

 

Part Number	Replacement	Explanation

Description

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The MAX11068 is a programmable, highly integrated, high-voltage, 12-channel, battery-monitoring smart data-acquisition interface. It is optimized for use with batteries used in automotive systems, hybrid electric battery packs, electric cars, and any system that stacks long series strings of secondary metal batteries. This highly integrated battery sensor incorporates a simple state machine and a high-speed I²C bus for SMBus™-laddered serial communication.

The MAX11068 analog front-end combines a 12-channel voltage measurement data-acquisition system with a high-voltage switch bank input. All measurements are done differentially across each cell. The full-scale measurement range is from 0 to 5.0V, with full stated accuracy guaranteed from 0.5V to 4.7V. The input mux/switch bank allows for differential measurement of each cell in a series stack. A high-speed, 12-bit successive approximation (SAR) A/D converter is used to digitize the cell voltages. All 12 cells can be measured in less than 107µs. The MAX11068 uses a two-scan approach for collecting cell measurements and correcting them for errors. The first phase of the scan is the acquisition phase where the voltages of all 12 cells are acquired. The second phase is the error-cancellation phase where the ADC input is chopped to remove errors. This two-phase approach yields excellent accuracy over temperature and in the face of extreme noise in the system. The MAX11068 incorporates an internal oscillator that generates a 6.0MHz system clock with ±3.0% accuracy.

The MAX11068 consumes less than 2.0mA from the power supply while in data-acquisition modes. This current is reduced to 75µA in standby mode and less than 1µA in shutdown mode. The device is packaged in a 38-pin, 9.7mm x 4.4mm x 1.0mm TSSOP package that is lead free and RoHS compliant and is designed to operate over the AEC-Q100 Grade 2, -40°C to +105°C temperature range.

Key Features

• 12-Cell Battery Voltage Measurement with Temperature Monitoring
  • Up to 12 Lithium-Ion (Li+), NiMH, or Super-Cap Cells
  • Two Auxiliary Analog Inputs for Temperature Measurement
• High-Accuracy I/Os
  • Excellent ±0.25% Voltage-Measurement Accuracy
  • ≤ 5mV Offset Voltage
• Integrated 12-Channel Data-Acquisition System
  • 12-Channel High-Voltage Mux to ADC
  • Differential Cell-Voltage Measurement
  • 12-Bit Precision, High-Speed SAR ADC
  • 12 Cell Voltages Measured Within 107µs
• Battery-Fault Detection
  • Overvoltage and Undervoltage Digital Threshold Detection
  • Cell Sense Line Open-Circuit Detection
  • High/Low Temperature Digital Threshold Detection
• 12 Integrated Cell-Equalization Switches Support Up to 200mA
• Integrated 6V to 70V Input Linear Regulator
• Integrated 25ppm/°C, 2.5V Precision Reference
• Integrated Level-Shifted, I²C-Compliant SMBus
  • Ladder Interface
  • Supports Multiple Devices, Up to 31 SMBus-Ladder-Connected ICs
  • Communications Protocol with Autoaddressing
  • Fault-Tolerant Hardware Handshake and Data CRC Checking
• Three General-Purpose Digital I/O Lines
• Ultra-Low Power Dissipation
  • Standby Mode Quiescent Current Drain 75µA
  • Shutdown Mode Leakage Current 1µA
• Operating Temperature Range from -40°C to +105°C (AEC-Q100 Grade 2)
• 38-Pin, Lead-Free/RoHS-Compliant TSSOP Package (9.7mm x 4.4mm)

Applications/Uses

• Electric and Hybrid Electric Vehicle (HEV) Battery Packs
• Electric Bikes
• High-Power Battery Backup Systems
• High-Voltage, Multicell Series-Stacked-Battery Systems
• Power Tools
• SuperCap Backup Systems