Can I use MAX17263LETD+T instead of MAX17260SETD+T?

Yes, the MAX17263 can replace the MAX17260, but the MAX17260 can’t replace the MAX17263.

Is the MAX17260's coulomb counting ineffective during short current spikes and solely rely on open circuit voltage for operation?

While the algorithm implements open circuit voltage for shorter periods than 175.8ms, the MAX17260 uses both methods to estimate the state of charge in the long term. Short pulses should not affect the long term accuracy because our sampling frequency should not coincide with their pulse frequencies. If the system frequency is not exact multiple or divider of our frequency, we can get 100mA samples as well as 100uA samples with the right ratio, given enough long sampling period as fuel-gauging is a long term behavior. Coulomb counter is similar to a long term average for days or even month.

What is the correct formula to set the shutdown time in MAX17260? The formula given in userguide doesnt seems to be correct

The formula for SHDNTIMER is 175.8ms*2^(8+THR), for THR=0, timer = 175.8m*2^8 = 45sec., for THR=7, timer=175.8ms*2^15 = 1.6hrs.

Does temperature update rate change in MAX17260 according to the power mode of the fuelgauge (hibernation, active mode )?

Yes, the IC updates the temperature every 351mS when in active mode, so the performance is optimized at that rate of update. In hibernate mode, the update is slowed down.

What is the recommended time interval in which to sample the temperature and update the MAX17260 temperature register, inorder to let the M5 algorithm work optimally?

The IC updates the temperature every 351mS when in active mode, so the performance is optimized at that rate of update. The host does not have to update Temp Register (0x08) at that same intervals, but anytime the measured temperature changes by a degree C, the temp register should be updated.

How can I verify if cell resistance (RCell register 07h) measurement of MAX17260 is accurate or not?

The RCell measurement of MAX17260 is not very accurate because it is based on signal processing of voltage and calculated OCV. But from the long term trend, the RCell value will increases over time. Typically you will see RCell value changes after about 10 charge/discharge cycle.

How does the MAX17260 determine the cell health value ? By DesignCap Register 18h) or by cell characterization information?

DesignCap is the nominal battery capacity provided by battery vendor, or measured through characterization on a new battery. As the fuel-gauge learns over time, it can update the Full capacity measured dynamically as FullCapNom. The health measurement is determined by FullCapNom/DesignCap as a ratio. Usually when battery capacity decreases to 80% of new battery capacity, it is defined as end of life (around 500 cycles ~1000 cycles for Lithium ion battery)

How often does MAX17260 poll raw coulomb count (QH register 4Dh)? 10mS or 175mS？

The update is every 175ms. But it will not frequently change the value, because it has 0.5mAhr LSB when using 10mOhm (it takes a while to discharge 0.5mAhr).

Due to current noise of ADC, MAX17260 RepSOC may increase during system standby, which will make the end user confused. How to deal with it?

RepSOC is calculated by (RepCap + RepCapL) / FullCapRep. RepCapL may increase or decrease with current ADC, so RepSOC may increase even it's not charging. However, RepCap will not increase if it's not charging. So user could use SOC=RepCap / FullCapRep as SOC display.

When the device with MAX17260 is in standby mode with very small discharge current, MAX17260 reports positive current frequently. Why?

The report current is from current ADC of MAX17260, which is actually voltage across the sense resistor. The ADC has noise in Gaussian distribution. With smaller Rsense, the output current noise will be larger. For example, Rsense=10mohm, the maximum noise current is around 6mA. However, the noise will be averaged to 0 in a long time and don't affect SOC.

I am using the MAX17260 with Panasonic NCR18650B battery with a 50mohm Rsense. Do I need to change anything in the INI file?

The following will need to be changed if they appear in the INI file Designcap fullcaprep fullcapnom dqacc ichgterm

I am using the MAX17260 with Panasonic NCR18650B battery and not getting correct hibernate threshold current, why?

The hibernate threshold current formula on the user guide is not exactly aligned with the actual threshold. This is will be updated soon. Please see the correction below For 10mOhm sense resistor: high side sensing threshold: 30mA + user guide formula low side sensing threshold: 10mA + user guide formula

Can I use the MAX17260 in a pack side battery application?

Yes, the MAX17260 can be used in a pack side application even though it does not have nonvolatile memory. To do this, you will need an application processor that can load the battery model into the MAX17260 when the power is removed.

Does the MAX17260 have a minimum supported battery capacity?

MAX17260 has no minimum battery capacity limits because unlike MAX17262 the sense resistor can be changed to accommodate any value of battery capacity.

With a FullCap Register 0X35= 0X1A7D and Rsense=10mOhm in the MAX17260, how to get the hibernate current according to the HibCfg file?

The hibernate threshold current formula on the user guide is not exactly aligned with the actual threshold. This is in our appnote update list of items. Please use the following for the actual case: In your case for 10mohm sense resistor; high side sensing threshold: 30mA + user guide formula low side sensing threshold: 10mA + user guide formula The full formula will be: For high side 300(uV)/Rsense(mOhm) + FullCap(mAh)/0.8(h)/(2^HibThreshold) For example, Rsense = 50mOhm, FullCap = 3000mAh, HibThreshold = 7, Then threshold current is 300/50 + 3000/0.8/128 = 35.29mA For low side 100(uV)/Rsense(mOhm) + FullCap(mAh)/0.8(h)/(2^HibThreshold)

In the datasheet of the MAX17260 the GND/EP Pin is connected to BATT-, but on the EVKIT to SYS-GND. Which one is correct?

The EP should be connected to the GND pin. The GND pin on the MAX17260 doesn’t need to pass current through the sense resistor, so it may be connected to the cell side. On the MAX17263, the GND pin is connected to the SYS-GND side so the LED current can be measured at startup to determine the LED count. The two kits share similarities in the layout because the MAX17260 (master EVKIT for BC21) was developed earlier. Connecting GND to Cell – has an advantage of lower offset for devices that are in idle mode longer (no I2C or AP connected for a long time). This is good for primary cell applications, or where raw coulomb counter accuracy is very important. Connecting GND to SYS side has an advantage in chatty applications where the host is always talking. The I2C sink current is not passed through the sense resistor and reduces the raw coulomb counter offset.

When the gauge is awaking from shutdown, will it continue from where it stopped (SOC, RemCap)? If not, what do I need to do to make it happen?

When the Fuel Gauge wakes up from shutdown, it will estimate the SOC and calculate remaining capacity based on this initial percentage estimate. Once the host software reloads the model data, it will update the remaining capacity and SOC based on the custom model (if used), and the battery size provide by the host I2C Master. It will then correct its current state as it has observed the battery over time and cycles. We don’t recommend putting the device in the shutdown mode frequently because of this reset behavior.

Using a small solar panel to charge a battery, it might not reach 4.2V or VEmpty for a long period of time, increasing the coulomb counter error. How to avoid this?

If your concern is that when the pack reaches 4.2V or VEmpty the RepCap will be different from what it supposed to be then rest assure that it will not happen. The RepSOC is corrected by the voltage fuel gauge, so you don't need to worry about the value when the battery hits full or empty. This is the strength of Maxim's algorithm.

Why the FullCapNom(0X23) register can be changed only through INI file and not through the App, for the MAX17260?

The FullCapNom register can be written only through dQAcc and dPAcc ratio, not directly. If you write it directly, the FG will replace it with the calculated value from dQAcc and dPAcc at the next relax event (or immediately if the battery is already relaxed). FullCap is also calculated every 175ms.