Texas Instruments bq77905, User Manual, Page: 3 / 21

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bq77905EVM Quick Start Guide
3 SLVUAN2A – May 2016 – Revised July 2016
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Copyright © 2016, Texas Instruments Incorporated
bq77905 3-5S Low Power Protector Evaluation Module
Figure 1. bq77905 Circuit Module Connection for Simple Demonstration
• Supply terminal block (J2)
These are the supply terminals for the board. BATT+ or CELL5 is the positive terminal of the power
supply and BATT– is the negative terminal of the power supply. The inputs CELL1 through CELL4 are
divided between the BATT+ and BATT- voltages. When using a power supply for evaluation, be sure
the power supply can accept or is protected from any reverse current such as with a blocking diode if
another supply is used in the system.
• Pack terminals (J6)
PACK+ and PACK– terminals are for attachment for the load or charger. If using a power supply to
simulate a charger, be sure it can accept or is protected from any reverse current.
• "H" shunt (J3)
This shunt shorts J3 pins 1 and 2 connecting the IC VTB pin to the temperature measurement path. A
hot temperature is simulated when the shunt is removed.
• "L" shunt (J3)
This shunt shorts J3 pins 3 and 4 connecting the IC TS pin to the thermistor. A cold temperature is
simulated when the shunt is removed.
2.4 Quick Start Sequence
These steps describe a simple demonstration or check of the operation of the bq77905EVM in a 5S
configuration with a typical 18-V stack voltage.
1. Connect 5 200- Ω resistors between the cell terminals of J2.
2. Confirm the "H" and "L" shunts are in place on J3.
3. Connect an 18-V adjustable DC power supply across the BATT+ and BATT– terminals of J2.
4. Enable the supply.
5. Measure the voltage on the pack terminals. Observe that this is the same voltage as the supply
because both charge and discharge FETs are on, approximately 18 V.
6. Connect a load such as a 5-k Ω resistor across the PACK terminals
7. Adjust the supply voltage to 23 V to simulate an overvoltage condition. Observe that the voltage on the
PACK terminals is approximately 600 mV below the supply voltage because the charge FET is off.
8. Adjust the supply voltage to 18 V to cause recovery from the overvoltage condition. Observe that the
voltage on the PACK terminals is the supply voltage.
9. Remove the shunt at the J3 H position to simulate a hot condition. Observe that the pack voltage drops
to approximately 0 V, and returns to normal when the shunt is re-installed.