Datasheet

LTC4425
3
4425fa
For more information www.linear.com/LTC4425
elecTrical characTerisTics
The l denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at T
A
= 25°C, V
IN
= 3.8V. (Note 4)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
IN
Operating Supply Range
l
2.7 5.5 V
I
Q(IN)
Quiescent Current from V
IN
V
IN
= V
OUT
20 µA
I
Q(OUT)
Quiescent Current from V
OUT
V
IN
= V
OUT
3 µA
I
SD
Quiescent Current in Shutdown EN = 0 3 µA
Ideal Diode
V
FWD
Forward Voltage 15 mV
R
FWD
Open Loop Forward On-Resistance 50 mΩ
Supercap Charger
V
FB
Feedback Voltage
l
1.18 1.2 1.22 V
I
FB
Feedback Pin Input Leakage 100 nA
I
CHG
Charge Current in LDO Mode
(FB = 0V)
R
PROG
= 0.5k
R
PROG
= 5k
2
0.2
A
A
Charge Current in Normal Mode (FB = V
IN
) R
PROG
= 0.5k, V
IN
– V
OUT
< 250mV
R
PROG
= 0.5k, V
IN
– V
OUT
> 750mV
2
0.2
A
A
R
PROG
= 5k, V
IN
– V
OUT
< 250mV
R
PROG
= 5k, V
IN
– V
OUT
> 750mV
200
20
mA
mA
V
PROG
PROG Pin Servo Voltage in LDO Mode FB < 1.2V 1.00 V
h
PROG
Ratio of Charge Current to PROG Pin Current 1000 mA/mA
V
PROG
PROG Pin Servo Voltage in Normal Mode (FB = V
IN
) V
IN
– V
OUT
< 250mV
V
IN
– V
OUT
> 750mV
1.00
0.1
V
V
I
SC
Charger Short-Circuit Current Limit PROG Pin Shorted to GND, FB = 0 2 3 4 A
t
SS
Charger Soft Start Time FB = 0 1.5 ms
T
LIM
Junction Temperature in Constant Temperature
Mode (Note 5)
V
OUT
= 0, FB = 0, R
PROG
= 0.5k 105 °C
Voltage Clamps
V
CLAMP
Maximum Voltage Across the Top Capacitor V
SEL
= Lo
V
SEL
= Hi
l
l
2.45
2.7
2.5
2.75
V
V
Maximum Voltage Across the Bottom Capacitor
V
SEL
= Lo
V
SEL
= Hi
l
l
2.45
2.7
2.5
2.75
V
V
V
RIP
V
OUT
Clamp Hysteresis If Either Capacitor Reaches Clamp
Voltage i.e. V
OUT
< V
IN
50 mV
I
SH(TOP)
Top Shunt Current R
PROG
= 1k, (V
OUT
– V
MID
) > V
CLAMP
160 mA
I
SH(BOT)
Bottom Shunt Current R
PROG
= 1k, V
MID
> V
CLAMP
140 mA
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