Does the configuration of TopOff timer causes a Fast-Charge_Timer_Fault on the MAX77734?

The TopOff and Fast Charge safety timers are completely separate and do not affect each other. The minimum safety timer period is 3 hours from start of entering Constant-Current state. The fast-charge safety timer is for stopping the charger if it is taking too long to charge the battery (it is spending too much time in the constant-current state. This may be a sign of a bad battery if it is taking too long to charge). Try the following to start: Read back the CNFG_CHG_C and CNFG_CHG_E registers to double check the TopOff and fast-charge safety timers were configured correctly Log the STAT_CHG_A, STAT_CHG_B, and INT_CHG registers for faults If possible, repeat the experiment with one of our EVKits charging the battery to see if the same behavior occurs.

MAX77734 built-in LDO requires to be programmed by MCU , and MCU is powered by LDO, how to solve this confilict?

You could use the OTP version of the MAX77734 IC. For these settings that have been programmed at the factory, the LDO directly provides the output voltage after the hardware is started up, without programming. For details, please refer to the yellow part in the table below.

What is Fast-Charge Safety Timer accuracy if tFC=7hours? (not 3hours)

Q : What is Fast-Charge Safety Timer Accuracy if tFC=7hours? (not 3hours) A : The same 10% applies to all timer settings within the specified range, not just tFC = 3 hours.

What is MAX77734 Fast-Charge current accuracy if Ta=0 to +40degC? (not Ta=-40 to+85degC)

Q : What is MAX77734Fast-Charge current accuracy if Ta=0~40degC? (not Ta=-40~+85degC) A : The accuracies in the specs that is whole temperature range, so it would be the same for Ta=0C to 40C.

What happens if Safety Timer register is changed during charging on MAX77734?

Question: Fast-Charge Safety Timer can be set T_FAST_ CHG (0x24h). If this register is changed during fast charging, existing timer count will be reset to zero and restart counting? Or timer count will not be changed (keep counting) even though T_FAST_ CHG is changed? Answer : If the timer already started, then changing T_FAST_CHG does not do anything (including T_FAST_CHG = 0x0). If the timer needs to be changed, the host can disable the charger, change T_FAST_CHG, and then reenable the charger. Once charge timer is started, changing T_FAST_CHG register will be ignored. It means customer cannot disable timer by T_FAST_CHG=0b00. So customer needs to disable charger (CHG_EN=0) before T_FAST_CHG register change.

Please advise MAX77734 pre-charge current variation when fast-charge=300mA.

Question: Please advise MAX77734 pre-charge current variation when fast-charge=300mA. Answer : For I FAST-CC = 300mA: PQ [% of I FAST-CC ] Min. Typ. Max. 10% 28.5mA 30mA 35.3mA 20% 58.0mA 60mA 66.0mA

Can MAX77734 SCL accept a signal from a push-pull output?

Question: Can MAX77734 SCL accept a signal from a push-pull output? Answer : Yes it can. There is only an input buffer at SCL.

MAX77734 ship mode application circuit recommendations

Figure 1, if MCU send the ship mode CMD to MAX77734, the MAX77734 can enter into the ship mode, but it will re-power on, what's the issue happened? Figure 1 is the initial application schematic. When MCU send ship mode CMD to MAX77734 through I2C, MAX77734 open the Switch betweeen Vbatt and Vsys, so the Vsys will drop to "0", then the Vbuck drop to "0", so the nEnLdo voltage is about Vbatt*4.7k/(200k+4.7k), (Vccint =Vbatt), the nEnLdo voltage is less than the nEnLdo falling threshold voltage, so the MAX77734 think the onkey is active, then MAX77734 exit the ship mode and re-power on. Figure 2 Adds a Diode between MCU's GPIO_turnon and MAX77734's nEnLdo, the issue was fixed

if MCU send the ship mode CMD to MAX77734, the MAX77734 can enter into the ship mode, but it will re-power on, what's the issue happened?

According to below test schematics. When MCU send ship mode CMD to MAX77734 through I2C, MAX77734 open the Switch betweeen Vbatt and Vsys, so the Vsys will drop to "0", then the Vbuck drop to "0", so the nEnLdo voltage is about Vbatt*4.7k/(200k+4.7k), (Vccint =Vbatt), the nEnLdo voltage is less than the nEnLdo falling threshold voltage, so the MAX77734 judged that onkey is active, then MAX77734 exit the ship mode and re-power on. Adding a Diode between MCU's GPIO_turnon and MAX77734's nEnLdo, the issue was fixed.

From the max77734 datasheet, the Vrestart =Vfast_chg-150mV, this mean that only the VBATT voltage < Vfast_chg-150mV, the MAX77734 can start up charge? If the Vbatt< Vfast_chg-100mV but Vbatt> Vfast_chg-150mV, the MAX77734 cannot restart the charg

Yes, you are right. When the Vbatt< Vfast_chg-100mV but Vbatt> Vfast_chg-150mV, the MAX77734 cannot restart the charge. Another side, the 150mV setting cannot be modified, MAX77734 has no register for this setting. If you want to restart the charge when Vfast_chg-100mV >Vbatt> Vfast_chg-150mV, you can change the Vfast_chg(for example, increase the Vfast_chg from 4.2V to 4.25V), when the Charger state machine enter the CC mode, you can decreaset the Vfast_chg(from 4.25V to 4.2V)

What is JEITA in battery charging?

JEITA stands for Japan Electronics and Information Technology Industries Association. JEITA's mission is to foster a digital network society for the 21st century, in which IT advancement brings fulfillment and a higher quality of life to everyone. The Association is also actively promoting environmental preservation countermeasures, including those to combat global warming. Maxim implements the JEITA standards for safe charging over temperature in some of their battery charger ICs. In JEITA modes, when the IC hits its upper or lower temperature limit, the charging current, the charging voltage or both are automatically decreased to ensure safe charging.