BQ25172: Chip application problem

Hello

Tonyx.wu said:

We set the charging time to 6 hours, but we found that the actual charging time took more than 7 hours to stop, I would like to know if there is any problem?

Bill J -- This is probably due to thermal regulation.  Power dissipation in the IC is greatest at high charge currents and low battery voltages. If the IC temperature
reaches TREG, the IC enters thermal regulation, slows the timer clock by half, and reduces the charge current as needed to keep the temperature from rising any further.

Try reducing charge current, this will reduce thermal rise and risk of thermal regulation.

What is the difference between the intermittent charging of 18K corresponding to this Vset and 24K?

What are the advantages or application scenarios of this intermittent charging method?

Hello

Intermittent charging will keep the battery topped off by restarting a short charge after the battery voltage falls below recharge voltage.  Also see section 7.3.2.1 in the data sheet.

If intermittent charging is not used then charger will only charge one cycle turn off and remain off.

We also need to confirm a few more issues with the intermittent charging mode of BQ25172

1. Does this mean that it can only be charged to the charging threshold voltage?   I read the specification sheet and the charging threshold voltage of 3 sections is about 4V

2. Does the intermittent charging mode charge to the threshold voltage for a period of time or according to the time set by the timer?Or does it judge the time it takes for the battery voltage to reach the threshold voltage (4V)?

Hello

Tonyx.wu said:

1. Does this mean that it can only be charged to the charging threshold voltage?   I read the specification sheet and the charging threshold voltage of 3 sections is about 4V

2. Does the intermittent charging mode charge to the threshold voltage for a period of time or according to the time set by the timer?Or does it judge the time it takes for the battery voltage to reach the threshold voltage (4V)?

1.) Yes --- The charge of battery will only start if it is below 4V (1.33V X 3)

2.) Intermittent charge --- will start when battery voltage drops below 4V.  After starting it will continue for 20% of the charge time, for 6hr this is 1.2 hours. 

This stat foot of BQ25172 says that it will flash when abnormality is detected.
 What does abnormality usually mean?Is there anything specific?
 Help to see why the stat foot of BQ25172 above will flash abnormally when no load is applied. According to the specification, abnormality will flash. We have designed it basically like this. Let's see what abnormalities lead to it. Is the design unreasonable or what?

Hello

With no load, no battery connected the output voltage will overshoot and trip BAT OVP fault and shut down.  Capacitors will discharge quickly, and unit will restart charge -- it will cycle from BAT OVP to Charge and STAT LED will Flash.

Tonyx.wu said:

What does abnormality usually mean?Is there anything specific?

See Table 7-3 it will list faults.  They are VIN OVP, BAT OVP, BAT OCP.  Also Open or Short on VSET, ISET, TMR Pins.