Hardware
5
Hardware
5.1
Switches
There are 2 DIP switch packages on the bq76PL455EVM. The DIP packages provide five individual switch
levers. Configure the switch levers prior to application of bq76PL455EVM power. The switch package
designations are:
•
SW1 - OUT Filter Select
switch package
•
SW2 - COMM Mode Select
switch package
WARNING
Changing switch positions with power connected to the evaluation
module can cause damage to the bq76PL455EVM.
The operation of the switch packages are detailed in
through
.
5.1.1
SW1 - OUT Filter Select
This 4-position DIP switch is used to connect different capacitor values to OUT1/OUT2, the output of the
AFE before it enters the 14-bit ADC for conversion. This allows different single-pole low pass filters to be
used in the signal path depending on the ADC sampling configuration selected in the GUI.
NOTE:
NOTE: The current version of the GUI reads and displays the sample periods from the
appropriate registers in the bq76PL455A-Q1 devices with which it is communicating. By
default at the time of writing, bq76PL455A-Q1 devices are configured to sample the cell
channels at 60.04 µs with 8x averaging (staying on a single channel before moving on to the
next channel). For this configuration, the best external capacitor selection is 390 pF. Please
be sure to change the corresponding
SW1 - OUT Filter Select
switch if the GUI sampling
period configuration is changed.
Switch positions on the
SW1 - OUT Filter Select
switch package are marked with the numbers ‘1’ through
‘4’ on one side of the package, and marked with the word “ON” on the other side of the switch package.
To select the 390 pF recommended for the default configuration, set only switch 4 to the “ON” position.
If changing the default sampling configuration, for example to a single sample (that is, no averaging)
setting at 99.92 µs, other capacitors must be switched into the circuit.
10
bq76PL455EVM and GUI User Guide
SLUUBA7A – April 2015 – Revised July 2015
Copyright © 2015, Texas Instruments Incorporated
