Cypress CY8C29x66 - Manual (Page 11)

AN2309
November 25, 2007 Document No. 001-17394 Rev. *B - 11 -
Figure 7. Temperature Profile
T HOT_STOP
T HOT_RESTART
T COLD_STOP
T COLD_RESTART
T BATT
Charge in
process
Charge in
Process
No Charge
T DISCH_COLD_STOP
T DISCH_HOT_STOP
No Discharge
No Discharge
Two-Cell Battery Charger Firmware
The two-cell battery charger firmware is separated into
several modules that serve distinct functions, such as
performing measurements, regulating the battery charge
process and timer functions, implementing the charge and
cell-balancing algorithms, checking the charge termination
conditions, storing calibration settings into the PSoC device
Flash memory, and transmitting debugging data. Most of
these modules are described in
AN2107 , AN2258 , and
AN2294 . Therefore, in this section only the charge and cell-
balancing algorithms are described.
Two-Cell Battery Charger Algorithm
The two-cell battery charge algorithm is implemented in the
charger firmware as a state machine. The following states
are used:

Initialization: Indicates charge process initialization.

Activation: Depicts battery activation charging.

Rapid: Depicts rapid battery charging.

Charge Complete: Indicates that the battery pack is
charged completely.

Wait For Temperature: Used to depict the idle state
when the battery pack temperature is outside the
allowed temperature range.

Error: Indicates that during the charge process an error
has occurred. There are three error types: over-voltage,
over-current and stage time-out exceptions.

Discharge: Indicates that the battery pack discharge
process and the storage device state are without
external power supply.

Full Discharge: Indicates that the battery pack is
discharged completely and is not suitable for further
use.
The two-cell battery charger state diagram is shown in
Figure 8 on page 12.
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