• State Resolved
  • Locked Locked
  • Replies 6 replies
  • Subscribers 64 subscribers
  • Views 731 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ24617 Battery charger information & query

vengadesh uthirapathy
Intellectual 770 points
Other Parts Discussed in Thread: BQ24617, BQ20Z70, BQ29330

We are using BQ24617 battery charger in our project. can  you help us on the following issues.

1. We have connected the thermal shutdown pin of the battery to the TS pin of the charger. At certain temperature (example 45˚ C)

a. How will the charger suspends the charging of the battery

b. Does it indicate through the status signals to shut down the system.

2. When the DC adaptor is not connected and only battery connected, how can we shut down the system below certain voltage level.

3. When the DC adaptor is removed, How can we use the STAT 1, STAT 2, PG signals to identify the DC adaptor present.

4. One more issue we are facing in the battery controller is in reading the charge units. The VFB pin is connected to an ADC and it’s output is read through SPI of the Microcontroller. The value read from the SPI is 0 or greater than 3000 sometimes. The reasonable working ADC values range between 1500(low charge condition) and 2100(full charge condition) approximately. Also we would like to know the cut off voltage at which the software should put the system off for the battery to come longer.

Regards/

Vengat

 

  • 0
    TI__Guru 56650 points

    1. If it is on certain temperature, please measure the TS pin voltage. So, you can compare it with the spec table (VLTF; VHTF...).

    a.  In suspend mode, the HIDRV and LODRV will keep the FETs off to suspend the charger.

    b. bq24617 can not shut down the system. It  turns on either ACFETs or BATFET to support a system load.

    2. When the DC adaptor is not connected; only battery connected and the system below certain voltage level (UVLO),.the body diode of BATFET can still connect batery to system. If you want to disconnect system load from battery, you have to add two BATFET FETs and an extra controller to control them. In bq20z70 application, it uses bq29330 to protects the battery charging and discharging.

    3. The PG signal can identify the DC adaptor present.

    4. I want to understand what does "cut off voltage" mean?

  • 0 in reply to Wang5577
    Intellectual 770 points

    Hi Wang,

    Thanks for your input.

    We are using ADS7843E ADC chip from Texas Instrument  to read the touch screen data through differential interface of touch screen (X+, X-, Y+, Y-). The same device is used to read the battery feedback voltage (VFB, Charge Voltage) through single ended interface to IN4. We are reading the values using SPI interface from Atmel MCU . We are getting correct values of touch screen interface. But we have issue with battery feedback voltage. Occasionally we are getting Overflow error in SPI Bus and also we are getting wrong values.

    Can you please go through & advice to us .

    Regards/

    Vengat

  • 0 in reply to vengadesh uthirapathy
    Intellectual 770 points

    Hi,

    Any update for above mail.

    Can you share your information with me to resolve the issue.

    Regards/

    Vengat

     

  • 0 in reply to vengadesh uthirapathy
    TI__Guru 56650 points

    If VFB voltage is correct, it means that the charger circuit is good. You can monitor it on the scope or votlage meter. If the reading value of SPI interface is wrong, we have to investigate the SPI interface circuit.

    I am not familiar with Atmel SPI interface circuit. I think you may find the root cause with Atmel customer support team.

  • 0 in reply to Wang5577
    Intellectual 770 points

    Hi ,

    Thanks for your support.

    We got the samples from TI  &  have started using the ADS7846E  to measure the Battery voltage instead of ADS7843E.

    We connected the Battery voltage (‘+’ wire of Battery) to the 7th Pin (VBAT) of ADS7846E. Please Clarify the following points.

    1.       Whether Battery voltage can be connected to 7th pin ADC directly?.

    2.        

    a.       Case 1: The Battery voltage range is 0V (min), 8.4V (max). Since the ADC has the internal ¼ divider circuit, we connected the 8.4V battery voltage. Shall We connect like this or not?

    b.      Case 2: The Battery voltage is divided by 2 and the resistor divider output (1/2 of the Battery voltage) is given to the 7th pin of ADC.

     

    In both cases, We are able to measure the correct voltages at the 7th pin of ADC. But the ADC digital output values are wrong (Reading through the SPI). Very much irrelevant values. What will be the issue.

    Can you please help me out ...

    Regards/

    Vengat

     

  • 0 in reply to vengadesh uthirapathy
    Intellectual 930 points
    May be you might be reading the data register before conversion completes / or properly configuring the ADC