LTC3649
TA = 25°C, unless otherwise noted.
TYPICAL PERFORMANCE CHARACTERISTICS
Start-up Waveform
VIMON vs Load (Temperature)
VIMON Error vs Frequency
1.2
1.0
0.8
0.6
0.4
0.2
0
0.5
–45°C
25°C
130°C
V
V
= 24V
OUT
IN
= 5V
V
RUN
2V/DIV
0
–0.5
–1.0
–1.5
I
L
2A/DIV
V
OUT
2V/DIV
V
PGOOD
2V/DIV
V
V
SW
R
= 24V
IN
= 5V
OUT
3649 G16
1ms/DIV
f
= 1MHz
I
= 4A
800
= 10kΩ
OUT
IMON
V
R
R
= 24V, R
LOAD
= 100kΩ
IN
ISET
–2.0
300
= 120Ω, L = 2.2µH, f = 1MHz
SW
ITHP
0
0.5
1
1.5
2
2.5
3
3.5
4
1300 1800 2300 2800
FREQUENCY (kHz)
3649 G18
= 4kΩ, C = 2.2nF, C
= 47pF
ITH
ITH
BURST MODE, C
= 2× 47µF
I
(A)
OUT
OUT
3649 G17
Efficiency vs Load Current at
5VOUT
Efficiency vs Load Current at
3.3VOUT
100
100
95
90
85
80
75
70
65
60
55
50
95
90
85
80
75
70
65
60
55
50
f
= 500kHz
f
= 500kHz
SW
SW
L = 6.8µH
L = 4.7µH
V
V
V
V
= 12V
= 24V
= 48V
= 60V
V
V
V
V
= 12V
IN
IN
IN
IN
IN
IN
IN
IN
= 24V
= 48V
= 60V
0
0.5
1
1.5
2
2.5
3
3.5
4
0
0.5
1
1.5
2
2.5
3
3.5
4
LOAD (A)
LOAD (A)
3649 G19
3649 G20
Output Capacitor Charging with
Fixed Average Current Limit
Load Step with Cable Drop
Compensation
V
V
IMON
1V/DIV
RUN
2V/DIV
V
I
OUT
L
500mV/DIV
2A/DIV
I
V
L
OUT
2A/DIV
2V/DIV
3649 G21
3649 G22
20ms/DIV
= 100kΩ
50ms/DIV
CABLE DROP RESISTANCE OF 200mΩ
V
= 24V, R
ISET
IN
R
= 10Ω, L = 2.2µH R = 4kΩ,
ITH
LOAD
C
C
= 2.2nF, C
= 47pF, R
= 40kΩ,
IMON
ITH
ITHP
= 0.47nF, C
= 2× 47µF + 36mF
OUT
IMON
3649fb
6
For more information www.linear.com/LTC3649
Linear [ Linear ]
