Each of these high voltage supply connections supports 400-V inputs. This voltage is then divided across a
series of 330-kΩ resistors so that high voltages do not come into contact with any amplifiers or pins on the
BQ79631-Q1 device.
Note
The BQ79631EVM is rated for 800 V but the resistor values in the divider networks have been
selected for 400-V application. To use this EVM for 800-V testing, swap out each of the 330-kΩ
resistors for 660-kΩ resistors.
WARNING
Again, please ensure that extreme care is taken around these networks.
4.3.3 High Voltage Alternatives
If the user does not have access to a high voltage lab and proper high voltage lab equipment, it is possible to
use a 40-V supply and the EVMs 40-V network in order to provide voltage to the various parameters one wishes
to measure. To utilize this 40-V supply option, connect a power supply set to 40 V to the VCC40V connector
located near the bottom of the board. To use this feature, the user must also populate jumpers J7, J8, J29, J1,
J30, and J2 with shunts in order to connect VCC40V to the desired network. The blue regions in the figure above
show the jumpers that must be populated in order to connect each network to the VCC40V supply.
4.3.4 Switches
In each of the high voltage networks on the BQ79631EVM, there are MOSFET switches controlled by GPIO pins
that may disconnect the high voltage inputs from the rest of the network. These switches should always remain
on while measurement is taking place but may be off to block any leakage current from escaping the battery
pack while not in use. These switches are controlled by the GPIO2 pin by default but those connected to the
HV_Plus and HV_Fuse network may be controlled by GPIO4 instead by moving the shunt from pins 1-2 over to
pins 2-3 on jumpers J9 and J12 respectively.
Figure 4-5. GPIO4 Control Option
To close the switch and enable current to flow through each network, the user must set the associated GPIO pin
to “output high” from within the GUI.
If one wishes to use the EVM to test without use of the included switches, simply populate the following resistor
slots with a 0-Ω resistor.
Table 4-7. Resistors
Resistor # on EVM
Switch Being Bypassed
Network
R39
Q2
HV_Plus
Connectors
SLUUCC3 – FEBRUARY 2021
BQ79631EVM Evaluation Module
15
Copyright © 2021 Texas Instruments Incorporated
