Datasheet

LTC4020
34
4020fd
For more information www.linear.com/LTC4020
applicaTions inForMaTion
LTC4020 Constant-Current/Constant-Voltage (CC/CV) Charging Diagram
POWER
AVAILABLE?
INDICATE NOT
CHARGING
BGATE PULLED
LOW
V
FB
> 2.5 – ε?
V
FB
> 1.75?
YES
NO
NO
NO NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
YES
4020 CD01
YES
YES
YESYES
YES
YES
V
FB
< 1.75?
V
FB
= 2.4375V
NTC
OUT-OF-RANGE?
CHARGE AT
CONSTANT-CURRENT
INDICATE CHARGING
TRICKLE CHARGE
(7%)
TIMER ACTIVE?
BGATE PULLED HIGH
INDICATE BAD
BATTERY FAULT
INDICATE NTC
FAULT
ENABLE IDEAL
DIODE FUNCTION
TIMERS ACTIVE?
PAUSE TIMERS
CHARGE TO FIXED
VOLTAGE
TIMER ACTIVE?
RUN SAFETY TIMER
SAFETY TIMER
AT EOC?
STOP CHARGING
INDICATE NOT
CHARGING
STOP CHARGING
I
BAT
< C/10?
I
BAT
< C/10?
START
CLEAR LOW BATTERY
AND SAFETY TIMERS
RUN LOW BATTERY
TIMER
BGATE PULLED LOW
INDICATE NOT
CHARGING
INDICATE CHARGING
TERMINATED
V
FB
< 2.5 – ε?
INDICATE NOT
CHARGING
ENABLE IDEAL DIODE
FUNCTION
YES
YES
YES
YES
YES
STOP CHARGING
NO
TIMER AT 1/8
EOC?
YES
V
FB
= 2.4375?
NO
YES
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