BQ24250: getting output voltage from BQ24250 after 1015 sec.

Hi Manish,

The schematic image did not come through.  Can you repost?

Regards,

Jeff

Hi Jeff,

Please see the below image for the same. I have connected battery on BAT pin.

Regards,

Manish Mistry

Hi Jeff,

Attaching herewith PDF schematic for your refs.

Regards,

Manish Mistry

3755.schematic.pdf

Hi Manish,

To what are the TS pin , EN1 and EN2 connected?  

I do not understand why SYS would not be present until 10-15 secs later.  If battery is connected, SYS should always be present.  When VBUS is attached, the buck converter turns on and provides V(SYS) = MINSYS if battery voltage is low VBAT+~100mV if charging or VBATREG if not charging.

Regards,

Jeff

Jeff,

I have not connected TS pin to the battery temp sense. Just put test point if battery temp sense is need then will hook TS test point to the battery TS pin.

EN1 & EN2 pins are directly connected to the controller.

I am also strange that what board is not working on only battery. It has to give voltage on VSYS while battery is present & charger input is absent.

Regards,

Manish Mistry

Hi Manish,

Eventually for the charger to send charge current through the internal BATFET to the battery, TS cannot be left floating.  But that should not affect SYS=BAT with no input voltage or SYS not coming up quickly (<100ms) after VIN applied.  I assume that both ENx=/=1 and that the load on SYS at startup is not too much for the input current limit as set by ENx per the table below?  If the resistive load is too much, then  SYS may not come up.  If the load is highly capacitive, then SYS may take a long time to come up.  But with a battery attached, neither of those should be a problem.  Is the buck converter working as evidenced by a squarish waveform on the SW pin?

Regards,
Jeff

Hi Jeff,

I got the answer. Actually if you look at the schematic, I missed to connect SYS pin to the output of inductor of SW.

After connecting SYS pin to the indcutor its working on battery.

But still battery is not charging. Can you guide me why its not charging. 

Do i need to introduce software for I2C line then after it will charge the battery?

Regards,

Manish Mistry

Hi Manish,

Great to hear!  I did not see that missed connection.

Regarding charging, what is connected to TS?  V(TS) must be at 1/2 * V(LDO) for normal charging.

Regards,

Jeff

Jeff,

TS is battery temperature sense input pin. We don't have temp monitor pin in our battery so I have put test point only for TS pin.

No any other connection for TS pin. 

So how it will shows the half voltage of LDO on TS pin?

I don't think so its affect the battery charging. Do you have anything on your mind to which affect the battery charging.

Regrads,

Manish Mistry

Jeff,

Thanks for the reply.

I will change the TS pin & check the battery charging circuit. If I will connect TS pin to LDO pin (5V), will it work or do i need to use voltage divider circuit.

Regards,

Manish Mistry