Linear Technology DC1496C Demo Manual

DESCRIPTION
Demonstration circuit 1496C-A (Figure 1) features the
LTC 2941. Demonstration circuit 1496C-B features the
®
LTC2942. Demonstration circuit 1496C-C features the
LTC2941-1. Demonstration circuit 1496C-D features the
LTC2942-1. The C, D options have parts that use an internal
sense resistor while the A, B options rely on an external
precision sense resistor. All four devices measure battery
charge state in handheld PC and portable product applica-
tions. 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 ∆Σ™
ADC. The three measured quantities (charge, voltage and
temperature) are stored in internal registers accessible via
the onboard SMBus/I
The LTC2941/LTC2941-1 has programmable high and
low thresholds for accumulated charge. The LTC2942/
LTC2942-1 has programmable high and low thresholds for
all three measured quantities. If a programmed threshold
Arrow.com.
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C interface.
DEMO MANUAL DC1496C
Battery Gas Gauge with I
Interface and 14-Bit ADC
is exceeded, the device reports an alert using either the
SMBus alert protocol or by setting a flag in the internal
status register.
The LTC2941 and LTC2942 require only a single low
value sense resistor to set the measured current range.
The LTC2941-1 and the LTC2942-1 have their own 50mΩ
internal resistor. The default value assembled on the
DC1496 is 100mΩ for a maximum current measurement
of 500mA. Both parts have a software-configurable charge
complete/alert pin. When the pin is set for charge com-
plete, a jumper connects the pushbutton which simulates
a logic high input to indicate a full battery. When the pin is
configured for alert, the same jumper is used to connect
a red LED that indicates an alert is present.
The DC1496C is a part of the QuikEval™ system for quick
evaluation with a host controller through a PC.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1496C.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
No Latency ∆Σ and QuikEval are trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
Figure 1. DC1496C
LTC2941/LTC2942:
2
C
dc1496cfb
1