Datasheet

6
LTC3727/LTC3727-1
3727fc
Soft-Start Up (Figure 12)
I
OUT
*
5A/DIV
V
OUT
5V/DIV
V
RUN/SS
5V/DIV
V
IN
= 20V 50ms/DIV 3727 G16
V
OUT
= 12V
Load Step (Figure 12)
V
OUT
200mV/DIV
I
OUT
*
2A/DIV
V
IN
= 15V 50μs/DIV 3727 G17
V
OUT
= 12V
LOAD STEP = 0A TO 3A
Burst Mode OPERATION
Load Step (Figure 12)
V
OUT
200mV/DIV
I
OUT
*
2A/DIV
V
IN
= 15V 50μs/DIV 3727 G18
V
OUT
= 12V
LOAD STEP = 0A TO 3A
CONTINUOUS MODE
Input Source/Capacitor
Instantaneous Current (Figure 12)
V
SW1
20V/DIV
V
IN
= 15V 1μs/DIV 3727 G19
V
OUT1
= 12V
V
OUT2
= 5V
I
OUT1
= I
OUT2
= 2A
Burst Mode Operation (Figure 12)
V
OUT
20mV/DIV
I
OUT
*
0.5A/DIV
V
IN
= 15V 50μs/DIV 3727 G20
V
OUT
= 12V
V
FCB
= OPEN
I
OUT
= 20mA
Constant Frequency (Burst Inhibit)
Operation (Figure 12)
V
OUT
20mV/DIV
I
OUT
*
0.5A/DIV
V
IN
= 15V 5μs/DIV 3727 G21
V
OUT
= 12V
V
FCB
= 7.5V
I
OUT
= 20mA
V
SW2
20V/DIV
TYPICAL PERFOR A CE CHARACTERISTICS
UW
I
IN
1A/DIV
SENSE Pins Total Source Current
V
SENSE
COMMON MODE VOLTAGE (V)
0
–400
I
SENSE
(μA)
–300
–250
–200
–150
–100
–50
5
10
3727 G13
0
50
100
–350
15
Dropout Voltage vs Output Current
(Figure 13)
RUN/SS Current vs Temperature
OUTPUT CURRENT (A)
0
1.0
1.2
1.4
4
3727 G14
0.8
0.6
123 5
0.4
0.2
0
DROPOUT VOLTAGE (V)
V
OUT
= 5V
R
SENSE
= 0.015Ω
R
SENSE
= 0.010Ω
TEMPERATURE (°C)
–50 –25
0
RUN/SS CURRENT (μA)
0.2
0.6
0.8
1.0
75 10050
1.8
3727 G15
0.4
0 25 125
1.2
1.4
1.6
*I
OUT
⇒ INDUCTOR CURRENT