Texas Instruments BQ79631EVM, User Manual

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Table 4-7. Resistors (continued)
Resistor # on EVM Switch Being Bypassed Network
R40 Q3 HV_Fuse
R17 Q1 Charge_Plus
R73 Q5 Charge_Neg
R113 Q6 Insulation Detection
4.3.5 Buffers
Just prior to the VC measurements in the positive side of each high voltage network (not HV_Extra1_Plus or
HV_Extra2_Plus), there is a buffer present to prevent leakage current from flowing back into VC pins. This
leakage current would create inaccuracy in the measurements made by the VC pins. While it is recommended
that these buffers are implemented in the user’s final design for accuracy, if one wishes to assess impact on
accuracy without the buffer, the user may connect to the first pin of the jumper associated with each buffer as
shown below. Simply compare the measurement obtained by connecting a DMM to the desired jumper and
GNDHV with the measurement seen on the VC pin associated with that network to calculate the percent error
that would be introduced if a buffer were not to be included in the user’s final design.
Figure 4-6. Buffer Bypass Jumpers
Table 4-8. Bypass Jumpers
Jumper Network
J35 HV_Plus
J33 HV_Fuse
J34 LINK_Plus
J4 Charge_Plus
4.3.6 Insulation Detection Network
The insulation detection network on the BQ79631EVM located around HV_plus allows the user to ensure that all
high voltage networks within their design are properly insulated from low voltage ground. To utilize this feature,
first ensure that GPIO2, and GPIO3 are both configured as “output high” and that GPIO1 is set to ADC only
input. Next, connect the desired high voltage at either HV_Plus or at VCC40V. If the user is utilizing the VCC40V
supply method, be sure to place a shunt on the J7 jumper in the same method as mentioned in
Section 4.3.3 to
connect the network to the 40-V supply. Additionally, for 40-V connection ensure that the J24 jumper is
depopulated. This will add increased resistance to the bottom side of the network that will ensure the
measurement stays accurate.
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16 BQ79631EVM Evaluation Module SLUUCC3 – FEBRUARY 2021
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