LTC4020_15 Datasheet, PDF (35/42 Pages) Linear Technology – 55V Buck-Boost Multi-Chemistry Battery Charger

APPLICATIONS INFORMATION
LTC4020 Lead-Acid Charging Diagram
START
INDICATE NOT
CHARGING
NO
POWER
AVAILABLE?
YES
BGATE PULLED
LOW
SET ABSORPTION
REFERENCE (2.5V)
LTC4020
CLEAR LOW BATTERY
AND SAFETY TIMERS
INDICATE BULK
CHARGING
NO
V_FB < 1.75?
YES
TRICKLE
CHARGE (7%)
NO
TIMER ACTIVE?
YES
RUN LOW
BATTERY TIMER
NO
TIMER AT 1/8
EOC?
YES
STOP CHARGING
NTC
YES
OUT-OF-RANGE?
NO
BGATE PULLED LOW
SET ABSORPTION ^YES
REFERENCE (2.5V)
V_FB < 2.125?
NO
FLOAT
YES
REFERENCE SET
(2.3125)?
NO
YES
V_FB < 2.5 – ε?
NO
INDICATE BULK
CHARGING
CHARGE AT
CONSTANT-CURRENT
NO
V_FB = 2.4375V
YES
STOP CHARGING
INDICATE NOT
CHARGING
ENABLE IDEAL
DIODE FUNCTION
NO
TIMERS ACTIVE?
YES
PAUSE TIMERS
INDICATE
ABSORPTION
CHARGING
NO
I_BAT < C/10?
YES
CHARGE TO FIXED
VOLTAGE
NO
TIMER ACTIVE?
YES
RUN SAFETY TIMER
YES
I_BAT < C/10?
NO
YES _{SAFETY TIMER} NO
AT EOC?
BGATE PULLED HIGH
INDICATE NOT
CHARGING
NO
V_FB > 1.75?
YES
SET FLOAT
REFERENCE
(2.3125V)
INDICATE FLOAT
CHARGING
For more information www.linear.com/LTC4020
4020 CD02
4020fb
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