Hardware
shows how to set switches for the various selectable sample rates. An ‘x’ means set the indicated
switch(es) toward the “ON” side of the switch package. All table values are provided for a “no averaging”
configuration.
Table 1. Switch Settings for Sample Rates
SW1 - OUT Filter Select
99.92 µs
60.04 µs
40.10 µs
30.02 µs
24.98 µs
Switch 1
x
x
Switch 2
x
x
x
x
Switch 3
x
x
Switch 4
x
x
By setting the switch package switches as indicated above, the capacitor values associated with each
sample rate are as follows:
•
99.92 µs
xxxx
4850 pF
•
60.04 µs
xxxx
2700 pF
•
40.10 µs
xxxx
1760 pF
•
30.02 µs
xxxx
1590 pF
•
24.98 µs
xxxx
1200 pF - Not recommended (see note)
NOTE:
Although selectable in the current version of the GUI, selection of sample rates faster than
24.98 µs (19.94 µs, 17.42 µs, 14.90 µs, 12.60 µs, 10.08 µs, 8.02 µs, 5.96 µs, or 4.13 µs) are
not recommended at this time due to potential loss in accuracy at those sample rates.
Recommended sample rates when not using averaging are 99.92 µs, 60.04 µs, 40.10 µs,
30.02 µs, and in some cases 24.98 µs.
5.1.2
SW2 - COMM Mode Select
This switch package has a single lever to control multiple connections. The purpose of the ganged
switches controlled by the switch lever is to configure the low-side interface of the bq76PL455A-Q1
between single-ended and differential modes. There are two labels, one on either side of the
SW2 -
COMM Mode Select
switch: “SINGLE” and “DIFF”. When the bq76PL455EVM is connected directly to a
PC, set the
SW2 - COMM Mode Select
switch so the lever is in the SINGLE mode position. On the other
hand, if the bq76PL455EVM occupies the second or higher position in a stack of evaluation modules, then
set the
SW2 - COMM Mode Select
switch lever to the DIFF mode position.
For Differential Mode, move the switch lever toward the DIFF label.
For Single-Ended Mode, move the switch lever toward the SINGLE label.
WARNING
Differential mode is the only allowed position when using the
differential
daisy-chain
communication
interface
on
stacked
bq76PL455EVMs.
WARNING
Single-Ended
mode
is
an
unisolated
connection
for
PC
communication
and
should
not
be
used
on
stacked
bq76PL455EVMs occupying positions 2 or higher in the stack.
11
SLUUBA7A – April 2015 – Revised July 2015
bq76PL455EVM and GUI User Guide
Copyright © 2015, Texas Instruments Incorporated
