Datasheet

LTC4425
6
4425fa
For more information www.linear.com/LTC4425
Typical perForMance characTerisTics
Charge Current vs Voltage Across
Top Capacitor (V
OUT
– V
MID
)
Charge Current vs Voltage Across
Bottom Capacitor (V
MID
)
Output Voltage Transient Step
Response Waveform (LDO Mode)
Output Voltage Waveform When
V
MID
is Shorted to GND
Output Voltage Waveform When
V
MID
is Shorted to V
OUT
PROG Pin Soft-Start Waveform
(Normal Mode)
Logic Inputs (EN and SEL)
Threshold Voltage vs Temperature
Open Drain Outputs
(PFI_RET and PFO)
FET On-Resistance vs Temperature
PROG Pin Short Circuit Charge
Current vs Temperature
TEMPERATURE (°C)
–45
0
VOLTAGE (V)
0.4
0.5
0.6
0.7
0.8
0.3
0.1
0.2
0.9
–25 55 75 90–5 15 35
4425 G10
V
IN
= 3.8V
TEMPERATURE (°C)
–45
0
RESISTANCE (Ω)
8
10
12
14
16
6
2
4
–25 55 75–5 15 35
4425 G11
V
IN
= 3.8V
90
V
OUT
TO V
MID
DIFFERENTIAL (V)
1.6
0
CHARGE CURRENT (mA)
2000
2500
3000
1500
500
1000
3500
1.7 2.1 2.2 2.3 2.4 2.51.8 1.9 2
4425 G12
PROG PIN GROUNDED
R
PROG
= 1k
SEL = 0
V
MID
(V)
1.6
0
CHARGE CURRENT (mA)
2000
2500
3000
1500
500
1000
3500
1.7 2.1 2.2 2.3 2.4 2.51.8 1.9 2
4425 G13
SEL = 0
PROG PIN GROUNDED
R
PROG
= 1k
TEMPERATURE (°C)
–45 –25 –5 15 35 55 75
2.70
CHARGE CURRENT (A)
2.90
2.95
2.85
2.80
2.75
3.00
4425 G011a
V
IN
= 3.8V
V
OUT
= 3.3V
PROG PIN SHORTED TO GND
90
100ms/DIV
SUPERCAP VALUE = 0.55F
V
OUT
(DC) = 2.45V
4425 G16
V
IN
= 3.8V
R
PROG
= 1k
SEL = 0
V
OUT
20mV/DIV
AC-COUPLED
250ms/DIV
SUPERCAP VALUE = 0.55F
V
OUT
(DC) = 2.45V
4425 G15
V
IN
= 3.8V
R
PROG
= 1k
V
IN
= 3.8V
R
PROG
= 1k
SEL = 0
V
OUT
20mV/DIV
AC-COUPLED
500µs/DIV
4425 G14
V
OUT
20mV/DIV
(AC-COUPLED)
V
IN =
3.8V
R
PROG
= 500Ω
SUPERCAP VALUE = 0.55F
V
OUT
(DC) = 3.3V
I
LOAD
800mA
100mA
500µs/DIV
4425 G18
V
OUT
(1V/DIV)
V
IN
= 5V
R
PROG
= 1k
EN
T
A
= 25°C, unless otherwise noted.
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