Test Summary
Figure 2. BAT_Load (PR1010) Schematic
2.2.3
Load #2 Between SYS and GND
Although not required, a resistive load in the form of a decade box or electronic load capable of sinking up
to 3 A can be used.
2.2.4
Meters
There are four equivalent voltage meters (VM#) and two equivalent current meters (CM#). The current
meters must be configured to measure 4-A current.
2.2.5
Computer
A computer with at least one USB port and a USB cable is required. The bq2427x evaluation software
must be properly installed.
2.2.6
HPA172 Communication Kit (USB to GPIO)
A HPA172 USB-to-I
2
C communication kit.
2.2.7
Software
Download the BQ2427xSW.zip file from the charger's product folder, unzip the file, and double-click on the
SETUP.EXE file. Follow the installation steps.
Because the watchdog timer is enabled, it is recommended that you set the software's Reset Watchdog
Timer to reset every 5 seconds. Otherwise, after 30 seconds of operation, the integrated circuit (IC) enters
Default mode. Note that the 27-minute safety timer is not reset by this function and eventually times out if
charging does not complete, unless the Safety Timer Time Limit is expanded or disabled via the GUI.
One way to reset the safety timer is to allow the 30-second watchdog timer to expire. See Figure 3 in the
data sheet for more information about the timers.
Also, it is generally helpful to set the AutoRead and Write On Change functions, in the upper left of the
GUI window, to ON. The AutoRead function periodically updates the GUI with the IC status. The Write On
Change function writes any changes to the GUI check boxes, drop-down boxes, and registers to the IC.
Otherwise, the user is responsible for periodically pressing the READ button to find the IC instantaneous
status and WRITE button to write changes to the IC.
2.3
Recommended Test Equipment Setup
1. For all power connections, use short, twisted-pair wires of appropriate gauge wire for the maximum
current amount.
7
SLUU924 – April 2012
QFN-Packaged bq24270/271 Evaluation Modules
Copyright © 2012, Texas Instruments Incorporated