MAX11068,pdf (battery-monitoring smart data acquisition)

The MAX11068 is a programmable, highly integrated,
high-voltage, 12-channel, battery-monitoring smart dataacquisition
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 SMBusK-laddered
serial communication.
The MAX11068 analog front-end combines a 12-channel
voltage measurement data-acquisition system with a highvoltage
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 107Fs. 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 Q3.0% accuracy.
The MAX11068 consumes less than 2.0mA from the power
supply while in data-acquisition modes. This current is
reduced to 75FA in standby mode and less than 1FA 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, -40NC to +105NC temperature range.
Applications
High-Voltage, Multicell Series-Stacked-Battery
Systems
Electric and Hybrid Electric Vehicle (HEV)
Battery Packs
Electric Bikes
High-Power Battery Backup Systems
SuperCap Backup Systems
Power Tools