LTC4425 Linear Technology, LTC4425 Datasheet - Page 6

• Manufacturer Part Number: LTC4425
• Description: Linear SuperCap Charger
• Manufacturer: Linear Technology

LTC4425
TYPICAL PERFORMANCE CHARACTERISTICS
AC-COUPLED
6
20mV/DIV
3500
3000
2500
2000
1500
1000
500
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
–45
0
V
1.6
Logic Inputs (EN and SEL)
Threshold Voltage vs Temperature
Charge Current vs Voltage Across
Top Capacitor (V
OUT
V
V
SEL = 0
V
IN
IN
OUT
1.7
Output Voltage Waveform When
V
V
R
= 3.8V
= 3.8V
–25
IN
V
R
PROG
= 3.4V
MID
IN
PROG
= 3.8V
1.8 1.9
= 3.8V
is Shorted to GND
= 1k
–5
= 1k
TEMPERATURE (°C)
V
OUT
PROG PIN GROUNDED
15
2
TO V
RPROG = 1k
250ms/DIV
SUPERCAP VALUE = 0.55F
OUT
2.1 2.2 2.3 2.4 2.5
MID
35
– V
(V)
MID
55
)
75
4425 G10
4425 G12
4425 G16
AC-COUPLED
3500
3000
2500
2000
1500
1000
500
18
16
14
12
10
20mV/DIV
8
6
4
2
0
–45
0
1.6
Open Drain Outputs
(PFI_RET and PFO)
FET On-Resistance vs Temperature
Charge Current vs Voltage Across
Bottom Capacitor (V
V
V
SEL = 0
V
V
IN
IN
OUT
OUT
1.7
= 3.8V
= 3.8V
–25
= 3.4V
Output Voltage Waveform When
V
V
R
1.8 1.9
IN
PROG
MID
= 3.8V
–5
TEMPERATURE (°C)
is Shorted to V
= 1k
PROG PIN GROUNDED
V
15
2
MID
2.1 2.2 2.3 2.4 2.5
(V)
100ms/DIV
SUPERCAP VALUE = 0.55F
35
MID
)
55
OUT
75
4425 G11
4425 G13
4425 G15
(AC-COUPLED)
20mV/DIV
(1V/DIV)
800mA
100mA
I
V
V
LOAD
3.00
2.95
2.90
2.85
2.80
2.75
2.70
OUT
OUT
EN
–45
PROG Pin Short Circuit Charge
Current vs Temperature
Output Voltage Transient Step
Response Waveform (LDO Mode)
PROG Pin Soft-Start Waveform
(Normal Mode)
V
R
SUPERCAP VALUE = 0.55F
V
R
IN =
PROG
IN
PROG
= 5V
–25
3.8V
= 500Ω
= 1k
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–5
TEMPERATURE (°C)
PROG PIN SHORTED TO GND
500μs/DIV
500μs/DIV
15
35
55
V
OUT
V
IN
= 3.8V
= 3.3V
4425 G011a
75
4425 G14
4425 G18
4425p