Datasheet
LTC4081
3
4081f
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
I
BAT_SD
Battery Current in Shutdown (Both
Battery Charger and Switching
Regulator Off)
V
⎯
E
⎯
⎯
N
⎯
_
⎯
C
⎯
H
⎯
R
⎯
G
= 5V, V
EN_BUCK
= 0, V
CC
> V
BAT
V
⎯
E
⎯
⎯
N
⎯
_
⎯
C
⎯
H
⎯
R
⎯
G
= 4V, V
EN_BUCK
= 0, V
CC
(3.5V) <
V
BAT
(4V)
●
0.6
2
5μA
μA
Battery Charger
V
FLOAT
V
BAT
Regulated Output Voltage I
BAT
= 2mA
I
BAT
= 2mA, 4.3V < V
CC
< 5.5V
●
4.179
4.158
4.2
4.2
4.221
4.242
V
V
I
BAT
Current Mode Charge Current R
PROG
= 4k; Current Mode; V
EN_BUCK
= 0
R
PROG
= 0.8k; Current Mode; V
EN_BUCK
= 0
●
●
90
475
100
500
110
525
mA
mA
V
UVLO_CHRG
V
CC
Undervoltage Lockout Voltage V
CC
Rising
V
CC
Falling
●
●
3.5
2.8
3.6
3.0
3.7
3.2
V
V
V
PROG
PROG Pin Servo Voltage 0.8k ≤ R
PROG
≤ 4k
●
0.98 1.0 1.02 V
V
ASD
Automatic Shutdown Threshold Voltage (V
CC
– V
BAT
), V
CC
Low to High
(V
CC
– V
BAT
), V
CC
High to Low
60
15
82
32
100
45
mV
mV
t
SS_CHRG
Battery Charger Soft-Start Time 180 μs
I
TRKL
Trickle Charge Current V
BAT
= 2V, R
PROG
= 0.8k
35 50 65 mA
V
TRKL
Trickle Charge Threshold Voltage V
BAT
Rising
●
2.75 2.9 3.05 V
V
TRHYS
Trickle Charge Threshold Voltage
Hysteresis
100 150 350 mV
ΔV
RECHRG
Recharge Battery Threshold Voltage V
FLOAT
– V
BAT
, 0°C < T
A
< 85°C 70 100 130 mV
ΔV
UVCL1,
ΔV
UVCL2
(V
CC
– V
BAT
) Undervoltage Current
Limit Threshold Voltage
I
BAT
= 0.9 I
CHG
I
BAT
= 0.1 I
CHG
180
90
300
130
mV
mV
t
TIMER
Charge Termination Timer
●
3 4.5 6 hrs
Recharge Time
●
1.5 2.25 3 hrs
Low-Battery Charge Time V
BAT
= 2.5V
●
0.75 1.125 1.5 hrs
I
C/10
End of Charge Indication Current Level R
PROG
= 2k (Note 6)
●
0.085 0.1 0.115 mA/mA
T
LIM
Junction Temperature in Constant-
Temperature Mode
115 °C
R
ON_CHRG
Power FET On-Resistance (Between
V
CC
and BAT)
I
BAT
= 350mA, V
CC
= 4V 700 mΩ
f
BADBAT
Defective Battery Detection
⎯
C
⎯
H
⎯
R
⎯
G Pulse
Frequency
V
BAT
= 2V 2 Hz
D
BADBAT
Defective Battery Detection
⎯
C
⎯
H
⎯
R
⎯
G Pulse
Frequency Duty Ratio
V
BAT
= 2V 75 %
I
NTC
NTC Pin Current V
NTC
= 2.5V 1 μA
V
COLD
Cold Temperature Fault Threshold
Voltage
Rising Voltage Threshold
Hysteresis
0.76 • V
CC
0.015 • V
CC
V
V
V
HOT
Hot Temperature Fault Threshold
Voltage
Falling Voltage Threshold
Hysteresis
0.35 • V
CC
0.017 • V
CC
V
V
V
DIS
NTC Disable Threshold Voltage Falling Threshold; V
CC
= 5V
Hysteresis
82
50
mV
mV
f
NTC
Fault Temperature
⎯
C
⎯
H
⎯
R
⎯
G Pulse
Frequency
2Hz
D
NTC
Fault Temperature
⎯
C
⎯
H
⎯
R
⎯
G Pulse
Frequency Duty Ratio
25 %
The ● denotes specifi cations which apply over the full operating tempera-
ture range, otherwise specifi cations are at T
A
= 25°C, V
CC
= 5V, V
BAT
= 3.8V, V
⎯
E
⎯
N
⎯
_
⎯
C
⎯
H
⎯
R
⎯
G
= 0V, V
NTC
= 0V, V
EN_BUCK
= V
BAT
, V
MODE
= 0V.
(Note 2)
ELECTRICAL CHARACTERISTICS