BQ25886: technical questions about operation

ajayt

Part Number: BQ25886
Other Parts Discussed in Thread: BQ25883,

Queries:
1. With no battery connected, input @ 5V:
Some input sources cause the SYS output to pulse on and off.
I thought it could be due to missing data lines but have tested some USB cables without D-/D+ lines which performed fine.
Specifically I have tested 3 adjustable bench power supplies with no current limit set (up to 4A capable) which, when connected to evaluation board @ 5V all cause this SYS pulsing.
Standard USB (PC/DCP) chargers have not shown this behaviour.
Is this the behaviour what FIGURE 25 of the device datasheet is demonstrating?

2. USB OnTheGo functionality/intelligence:
Is there any intelligence to how USB on the go is enabled/managed?
I know that it is enabled by pulling the OTG pin high BUT what happens if this happens when a charge source is already connected?
Does the device only output 5V if it detects there is not a charger present?

3. Do TI have any solutions to managing the audible noise generated when the device switches to PFM mode when under LOW load conditions?#

4. Are there any higher resolution images for the PCB artwork present in the evaluation board user guide (OR design files/gerbers)
These would be very useful for cross checking suggested layout guidelines from datasheet/user guide.

over 6 years ago

0 Angelo Zhang87 over 6 years ago

TI__Genius 11850 points

Hi,

1) Figure 25 in the datasheet shows float charge behavior (without a battery connected). The device continuously enters charge and recharge cycles as the small capacitor on BAT charges and discharges. VSYS follows VBAT up to BATREG and then drops only to SYSMIN. If charging is disabled, then you will not see these float charge cycles. Can you send a waveform showing VBUS, VSYS, and VBAT so I can see the pulses you're describing?

2) Please take a look at Section 8.3.5 of the BQ25883 datasheet for a list of conditions that must be met in order to enable OTG operation. We're working on adding a similar section to the BQ25886 datasheet.

http://www.ti.com/lit/ds/symlink/bq25883.pdf

3) PFM OOA (out of audio) is enabled by default. Are you experiencing audible noise when the device is operating in PFM? If so, can you send a waveform showing SW during this time?

4) If you give me your email address, I can send you the PCB files.

Best regards,
Angelo

0 ajayt over 6 years ago in reply to Angelo Zhang87

TI__Genius 9555 points

Hi Can you send the files to Alan.thomsonti.com.peter

0 ajayt over 6 years ago in reply to ajayt

TI__Genius 9555 points

sorry that did not come out right alan.thomson@ti.com

0 Angelo Zhang87 over 6 years ago in reply to ajayt

TI__Genius 11850 points

Hi,

I've just emailed you the PCB files.

Best regards,
Angelo

0 user6063195 over 6 years ago in reply to Angelo Zhang87

Prodigy 110 points

I have some questions about BQ25883.

1）What is the relationship between “D+/D– Detection Sets Input Current Limit” and “The ILIM resistor”?

if I set the ILIM resistor,and I have no"D+/D–",What about the input current limit?

If I set "the ILIM resistor" and "D+/D -" at the same time ,What about the result?

0 Angelo Zhang87 over 6 years ago in reply to user6063195

TI__Genius 11850 points

Hi,

The actual input current limit is set by the lower value between the ILIM pin setting, the IINDPM register setting, and the ICO setting.

When D+/D- are open, the BQ25883 will detect an unknown adapter and set the IINDPM register to 500 mA.

Please note that the host can still overwrite the IINDPM register setting and set a different input current limit after D+/D- detection is complete.

Best regards,

Angelo

0 user6063195 over 6 years ago in reply to Angelo Zhang87

Prodigy 110 points

For example, I use a fast charging head, which can output “5V/3A” power.And I short-circuit BQ25886's "D+/D-" to enter DCP mode. The ILIM pin grounding is set to the maximum. Can I get the maximum charging current?

0 Angelo Zhang87 over 6 years ago in reply to user6063195

TI__Genius 11850 points

Hi,

In the case you're describing (D+/D- shorted and the ILIM pin shorted to GND), the input current limit will be set to 3 A.

Best regards,

Angelo

0 user6063195 over 6 years ago in reply to Angelo Zhang87

Prodigy 110 points

Hi,

I had some trouble.When I connected the ILIM pin to GND, the module entered the wrong mode. STAT started flickering at 1Hz. How to deal with this situation? Or can we only change modules?

0 Angelo Zhang87 over 6 years ago in reply to user6063195

TI__Genius 11850 points

Hi,

Since we're discussing the BQ25886 now, can you please create a new thread with the BQ25886 in the title? I can continue supporting your questions on the new thread.

Best regards,

Angelo

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BQ25886: technical questions about operation