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BQ24104: Reference Design/ Design Solution to Test Battery Charger Circuit Characteristics (Not using test equipment)

Part Number: BQ24104
Other Parts Discussed in Thread: TPS54320, TPS543620, TPS543320, OPA544


We are currently planning to design a PCB test fixture for a circuit board that has BQ24104 charging circuit section on it. We would like to come up with a way of verifying/validating the charging circuit on board. This is for production testing.  We aim to have the test circuit be integrated on the design test fixture PCB. This means we cannot use an actual 4 quadrant power supply equipment as well as an actual electronic load equipment. Using an actual battery is also out of the question. We wanted to verify from TI some solutions we are thinking of for testing the charging circuit and also ask if TI also has a solution/reference design for testing charging circuits without the need to use a power supply/electronic load. 

Our design has BQ24104 configured to charge a 2S4P Battery Pack. We have configured the circuit to charge at 2A. Our ideal goal is to be able to verify that the pre-charge, fast charge and charge termination of BQ24104 circuit works. We can also limit the scope to just verifying fast charging if that would make the battery simulator/ charger tester design simpler. Can we assume that if the fast charging part of the BQ24104 is functional, that the other modes (pre-charge and charge termination) is functional as well? What is the probability of the other modes working if the fast charge part is working?

Below are out solutions that we want to verify from TI if it would work to test BQ24104 and have some questions if TI has solutions for specific circuit designs

1.  The Link below is a question regarding testing battery fuel gauge using a resistors and a voltage across the test circuit terminals (B+/B-). Can this circuit (resistor with voltage applied across it) be used to simulate a battery to test the charging circuit? Instead of using an actual power supply, we would be using a variable output buck converter to change the voltage and simulate the different levels of the battery capacity?


2. Can we use a DCDC converter (buck) with sink capability to as battery simulator? The link below suggested to use TPS54320. The current recommended part replacement for TPS54320 is TPS543320. We are thinking of using TPS543620 since is has a higher sink current limit. This post was from 10 years ago so we would want to verify if this design has been verified and will work in testing the battery charger. 


3. Battery Simulator Reference Designs. When searching TI application notes regarding battery simulation, there were 2 notes that showed up immediately in a google search result. - A Simple Battery Simulator - Building Your Own Battery Simulator

SLVA618 abstract mentions that this power amplifier circuit test single-cell Li-ion battery chargers. Can this circuit be used to test 2S battery chargers? Are there modifications to the circuit that needs to be done in order to test 2S chargers? Or is it trying to find the appropriate voltage across VIN+ and VIN- to get a voltages of a 2S Battery?

For the SLUA999 application note, it can be configured for multi-cell simulation but the note only mentions about testing fuel gauges. Can this be use to test battery charger circuits? Are there circuit design modifications needed to be done to meet the criteria?

Does TI have development boards, schematic/layout reference design for the two application notes mentioned above?

4. Reference design for a 4 quadrant power supply, electronic load with CV mode or source meter

Since we do not want to use an actual equipment to test the battery charger, does TI have a reference design for a simplified version of the test and measurement mentioned above?

Power Supply with sinking capability?

Electronic Load with CV Mode?

Source Meter?

Let us know if any of these solutions would work?

The order of solutions listed above is listed from simple to complex from our perspective.



  • Hi Deniel,

    Regarding 1, for low charge currents, a circuit as shown below is the simplest.   The resistors could be resistor boxes.

    Regarding 2, I am not familiar with the TPS54xxx family that can sink current but I suspect there will be limitations.  The e2e post is a bit incomplete.

    Regarding 3, TI's OPA power amplifiers with push pull outputs work great to simulate a battery if they are properly heat-sinked.

    Regarding 4, the best battery simulator is a Keithley sourcemeter or KEPCO 4 quadrant supply.  You can also use an electronic load in CV mode but you will also need power supply in parallel to provide a minimum start up voltage.



  •  Hello Jeff,

    Thanks for the update. It looks like we might consider either option 1 or option 3.

    For option 1, do you have the TI application note/document circuit figure is found?

    Can this be used for 2A charging testing? 

    For option 3 TI's OPA power amplifiers. 

    Can the exact  schematic in the Building Your Own Battery Simulator (slva618.pdf) be used already for testing 2S battery chargers? Or are there modifications in the circuit that needs to be done for multi-cell charger testing specifically 2S chargers ?



  • Hi Deniel,

    There is no app note for the circuit in option 1.  The power supply is prevented from sinking current by diodes.  The power supply then sinks current into the resistors until the charger replaces that current with its charge current.  Same concept for item 4 but using a e-load instead of the resistors.  If the resistors are heat sunk well enough and the diodes are rated high enough, 2A should be okay.

    The circuit in the app note should work for your application.  You would apply a voltage slightly higher than 8.4V at VIN.  The RC then slowly rises, simulating a battery that is charging. The OPA544 needs to be properly heat sunk or it might go into thermal protection.  HINT:  The input RC (stage one) is only needed for providing a ramp and the NPN and resistors (stage two) are only needed to provide a minimum voltage.  If you have a another power supply or function generator, it can drive the POS input to the opamp directly.  Also, if you don't intend to go below 2V on the output of the op amp (which you shouldn't) then the negative rail can be GND.  The positive rail needs to be at least 2.5V higher than your max output voltage (so 8.4V+2.5V = 10.9V).