4
dc1496fa
DEMO MANUAL DC1496B
QuikEval INTERFACE
Address/I
2
C Status
The write address for the LTC2941/LTC2942/LTC2941-1/
LTC2942-1 is C8h and the read address is C9h. The
alert response address (ARA) is 19h. If an error occurs
while reading from the LTC2941/LTC2942/LTC2941-1/
LTC2942-1, the I
2
C status will read as an error. Otherwise,
the status is good. If the LTC2941/LTC2942/LTC2941-1/
LTC2942-1
AL
/CC pin is set for alert mode and an alert
has been latched, the device will pull down this pin. Click
on ARA to send out an ARA on to the bus lines and the
device will respond with its address. The Alert pin will then
be cleared if the alert is no longer present.
Status
The individual status bits A[0:7] and their states are shown
here. A red indicator next to bits A[0:5] indicates the re-
spective alert is currently present and will latch the Alert
pin if confi gured for alert. Bit A[7] shows if an LTC2941,
LTC2942, LTC2941-1 or LTC2942-1 is detected.
Sense Resistor
Enter here the sense resistor value used in the application.
The default for the DC1496B is a 100mΩ sense resistor.
Check LTC2941-1/LTC2942-1 if one of these devices is
used in place of the default IC. This sets the sense resistor
value to 50mΩ, the value of the internal sense resistor
in these devices. The sense resistor can only be changed
when not polling. The software only accepts sense resis-
tors between 0.1mΩ to 5Ω.
Battery Gas Gauge
The battery capacity in the application is entered here. The
ACR full scale (FFFFh) is set to this value and affects the
two Gas Gauge ACR display options. Instead of counting
up from 0 as in the Coulomb Counters, the Gas Gauge
is used to count down from a full battery. The battery
capacity can only be entered when not polling. The data
in the ACR when a battery should be empty is calculated
based off of R
SENSE
, and pre-scaler M, and displayed in
hexadecimal below the ACR full scale.
Control
Confi gurations done in the Control section write to the
Control register (register B). For the LTC2941, the Control
bits B[7:6] enables a battery monitor to one of three set
voltage thresholds (2.8V, 2.9V, or 3V) or disables this
battery voltage alert. The ADC mode with the LTC2942 is
default to Sleep where both Voltage and Temperature ADCs
(LTC2942) are disabled. Setting ADC Mode to Automatic
Mode enables full-time the Voltage and Temperature ADC.
Selecting Manual Voltage or Temperature mode enables
the respective ADC once and returns the ADC to Sleep
mode.
Select a pre-scaler M value to scale the ACR according
to battery capacity and maximum current. Changing the
pre-scaler will halt the poll. A calculator tool is provided
in the tool bar under Tools to assist in calculating a pre-
scaler value and sense resistor (Figure 4).
The AL#/CC pin can be confi gured for Alert mode, Charge
Complete mode, or disabled. Select the corresponding
settings on the DC1496B jumper J2.
The Shutdown Analog Section is checked to disable the
Analog portion of the LTC2941/42/41-1/42-1 and set the
device in a low current state.
Register Read/Write
Data in the internal registers of the LTC2941/LTC2942/
LTC2941-1/LTC2942-1 is displayed here in hexadecimal
or appropriate units. Data can also be entered and written
to the write registers. Enter data to be written in hexa-
decimal, or select Unit and enter data in decimal form.
Data in decimal scale is auto corrected if the maximum
or minimum full scale is exceeded. Select the ACR display
in Counter (Coulombs) to be able to write to the ACR and
charge thresholds in Coulombs, or select Counter (mAh)
to be able to write to the ACR and charge thresholds in
mA • hour. Voltage and Temperature High thresholds are
rounded down in the calculations to the nearest lower
Downloaded from
Downloaded from
Downloaded from
Downloaded from
