Linear Technology 1496A-A Demo Manual

DESCRIPTION
Demonstration circuit 1496A-A (Figure 1) features the
LTC ® 2941. Demonstration circuit 1496A-B features the
LTC2942. Both devices measure battery charge state
in handheld PC and portable product applications. The
operating range is perfectly suited for single cell Li-Ion
batteries. A precision analog coulomb counter integrates
current through a sense resistor between the battery's
positive terminal and the load or charger. The LTC2942 adds
battery voltage and on-chip temperature measurement
with an internal 14-bit No Latency ΔΣ™ ADC. The three
measured quantities (charge, voltage and temperature)
are stored in internal registers accessible via the onboard
2
SMBus/I C interface.
The LTC2941 has programmable high and low thresholds
for accumulated charge. The LTC2942 has programmable
high and low thresholds for all three measured quantities.
If a programmed threshold is exceeded, the device reports
an alert using either the SMBus alert protocol or by setting
a fl ag in the internal status register.
DEMO MANUAL DC1496A-A/B
Battery Gas Gauge with I
Interface [and 14-Bit ADC
The LTC2941 and LTC2942 require only a single low value
sense resistor to set the measured current range. The
default value assembled on the DC1496 is 100mΩ for a
maximum current measurement of 500mA. Both parts
have a software-confi gurable charge complete/alert pin.
When the pin is set for charge complete, a jumper con-
nects the pushbutton which simulates a logic high input
to indicate a full battery. When the pin is confi gured for
alert, the same jumper is used to connect a red LED that
indicates an alert is present.
The DC1496A-A/B is a part of the QuikEval system for quick
evaluation with a host controller through a PC.
Design fi les for this circuit board are available at
http://www.linear.com/demo.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
No Latency ΔΣ is a trademark of Linear Technology Corporation. All other trademarks are
the property of their respective owners.
Figure 1. DC1496A-A/B
LTC2941/LTC2942:
(DC1496A-B)]
2
C
dc1496f
1