Dear Forum
I built my own designed 5-cell pack utilizing '77915-01 device. I experienced the unusal balance operation:
staring conditions: cells are: 3,58 ; 3,58 ; 3,58 ;3,58 ;3,72V (lowest cell in the string)
The balance started only tandem with Overvoltage (4,25V) event and did not start if no longer OV occured but a lower Vfc threshold reached despite the charge current developed enough voltage for Vstate_comp (>1,875mV) (on the shunt).
Therefore the balance worked only partially: altough it could eliminate the Overvoltage apperence, it was not able to effectively balance the cells even not if multiply cycles applied.
The '77915 shall balance any time if full charge voltage reached (Vfc) regardless of cell relationships (>Vstep etc). I think for -01 variant the Vfc = 4,15V (=Vov-Vhyst=4,25-100mV). This is confirmed by balance off: at 4,15V occured prior to turning ON the CFET (ca 4,05 which is OK because Hyst_ov=200mV). Because in case of OV-trigged balance, it Will be OFF when dropping cell voltage below Vfc or Vov-HYST_ov which reached earlier.
Note, I use external balance NFETs. Balance ON/OFF info taken by VC1-GND measurement.
I have graphical data: there were many chg/dchg cycles but I show the last one when balance was estabilished. /*Unfortunately the current curve inverted because I tied the shunt voltage with opposite directon to the recorder input :( */
CBI pulled down by 10K. I use series diode at LD pin (and JP8 shorted):
Joseph