fs3862 Fortune Semiconductor Corporation, fs3862 Datasheet - Page 10

• Manufacturer Part Number: fs3862
• Description: 8-bit Mcu With 1k Program Eprom, 64-byte Sram, 5-bit I/o Port, Intelligent Charger Management Controller
• Manufacturer: Fortune Semiconductor Corporation

FS3862
˙Constant current charge (as Phase-1, referred as C-C stage): where the programmable constant current
ranging from typical 250mA to 1,050mA is applied to the battery, until the battery voltage reaches to the full-level
at 4.2v or similar value such as 4.1v or even 4.0v. Some applications require the constant current charge at
USB current of 500mA when its power line at 5v is applied, and such charge stage can be implemented with
selection of the current regulation at 500mA by setting the corresponding C-C reference bit and current select
values at the specified control registers, as explained in details descriptions in later section.
˙Constant voltage charge (shown as Phase-2, referred as C-V stage): using the regulated voltage at 4.2v
reached at the constant current charge stage until the termination condition is met at the final low termination
top-off current at smaller amount (such as 100mA which can be programmable to select), and then charges to
the full capacity when termination occurs. Selections of the C-V charge’s voltage level can be made with
corresponding C-V enable and voltage select values at the individual specified control registers.
˙Maintenance re-charge (shown as Phase-3 stage): can be called Post-charge stage, which is to resume
charges to the battery when the battery’s voltage drops is more than 0.1v (i.e. The battery terminal voltage
becomes 4.10v or less from its full voltage at 4.20v) as a result of the internal resistor during its idle state
through some time. If the battery has been taken off for use on its portable device, there is no re-charge check
to conduct since the state transitions to the initial state without the battery itself.
In some other cases, the preliminary charge stage which can be conducted as one step prior to the phase-0 to
assure the battery to be through the charge sequences has working functions to perform. This stage would
involve in applying constant-voltage charge pulses at defined level of 4.0v or so to the battery, which was
examined to determine if it’s at low voltage of 2.5v or less. The charge pulses applied to the battery for a short
period of 15 intervals with 10 seconds high (at 4.0v voltage beats) and 5 seconds low (ground) each to examine
if the battery voltage still remain low at 2.5v or less, which is then considered as defective and should be
discarded.
Sometimes another additional check-up procedure follows the termination of the C-V stage to assure the
battery in proper waiting stage for operation. That is to have the battery stay idle from its charge termination at
full voltage of 4.20v (or 4.1v, depending on the battery’s manufacturer’s parameters). Then the battery stays in
for additional 10 (or 15, also an adjustable parameter) minutes, and then its voltage is examined to assure the
terminal voltage won’t be decreased to lower than 4.05v (or 3.95v if the situation prevails), then the battery is
also determined as a defective one without reliable performance since it could be losing more than 0.15v within
a short period of just 10 (or 15) minutes. These check-up procedures are optional.
In brief summary, the typical Li+ battery charger’s procedures could be summarized in the following few steps:
pre-charge conditioning, constant-current (C-C), constant voltage (C-V) stage, charge termination and monitor
to re-charge, etc. There might have some individual charge’s current- or voltage-control schemes within the
designated step to perform.
Rev. 1.3
10/32