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LOW-COST DOUBLE LI-ION BATTERY CHARGER USING ST6255C/ST6265C MCU

The core puts itself into WAIT mode during each conversion in order to gain accuracy. Preci-

sion is improved even more by using the ADC SYNC option bit.

2.4.3 State Diagrams

text

in italic is valid only for the rear slot.

Table 5. Slot States Definitions

Note that this choice of states is only one solution - among many - of implementing the re-

quired behaviour of the charger.

Here, “periodically” means “at every state update”. Therefore, the state update frequency is

equal to the PWM duty cycle increase or decrease rate in the CI, CV_D, CV_U and FAST

states. In FAIL state, the red LED flashing frequency is half of the state update frequency.

The diagram of state transitions is too complex to be described by only one figure. Hence the

performed once during a state transition.

Name

Meaning

Output configuration

Front priority

request

Slot Outputs

PWM Duty Cycle

IDLE

Slot empty

OR

Charge suspended by

front charge priority

Charge disabled,

Both LEDs off

Unchanged

No

CI

Constant current charge

Charge enabled,

Green LED off,

Red LED on

updated periodically to

Yes

CV_D

Constant voltage charge,

duty cycle down

Incremented

periodically

CV_U

Constant voltage charge,

duty cycle up

Decremented

periodically

FAST

Fast charge

Updated periodically to

TRI

Trickle charge

Unchanged

No

SAT

Battery saturated

Charge disabled,

Green LED on,

Red LED off

EXP

Charge time expired

FAIL

Battery failure

Charge disabled,

Green LED off,

Red LED flashing

(toggled periodically)

HEAT

Charge suspended

by overheat

Charge disabled,

Both LEDs on

Same as original

state