Datasheet

LTC3809
4
3809fc
TYPICAL PERFORMANCE CHARACTERISTICS
Effi ciency vs Load Current
Maximum Current Sense Voltage
vs I
TH
Pin Voltage
Load Step
(Burst Mode Operation)
Load Step (Pulse-Skipping Mode) Start-Up with Internal Soft-Start
T
A
= 25°C unless otherwise noted.
LOAD CURRENT (mA)
EFFICIENCY (%)
100
90
80
70
95
85
75
65
60
1 100 1k 10k
3809 G01
10
V
OUT
= 3.3V
V
OUT
= 2.5V
V
OUT
= 1.8V
V
OUT
= 1.2V
FIGURE 10 CIRCUIT
SYNC/MODE = V
IN
V
IN
= 5V
LOAD CURRENT (mA)
EFFICIENCY (%)
100
90
80
70
95
85
75
65
50
55
60
3809 G02
1 100 1k 10k10
FIGURE 10 CIRCUIT
V
IN
= 5V, V
OUT
= 2.5V
FORCED
CONTINUOUS
(SYNC/MODE = 0V)
PULSE SKIPPING
(SYNC/MODE = 0.6V)
BURST MODE
(SYNC/MODE =
V
IN
)
I
TH
VOLTAGE (V)
0.5
–20
CURRENT LIMIT (%)
0
20
40
60
100
1 1.5
3809 G03
2
80
Burst Mode OPERATION
(I
TH
RISING)
Burst Mode OPERATION
(I
TH
FALLING)
FORCED CONTINUOUS
MODE
PULSE SKIPPING
MODE
Effi ciency vs Load Current
V
OUT
200mV/DIV
AC COUPLED
I
L
2A/DIV
100μs/DIV
V
IN
= 3.3V
V
OUT
= 1.8V
I
LOAD
= 300mA TO 3A
SYNC/MODE = V
IN
FIGURE 10 CIRCUIT
3809 G04
V
OUT
200mV/DIV
AC COUPLED
I
L
2A/DIV
100μs/DIV
V
IN
= 3.3V
V
OUT
= 1.8V
I
LOAD
= 300mA TO 3A
SYNC/MODE = 0V
FIGURE 10 CIRCUIT
3809 G05
Load Step
(Forced Continuous Mode)
V
OUT
200mV/DIV
AC COUPLED
I
L
2A/DIV
100μs/DIV
V
IN
= 3.3V
V
OUT
= 1.8V
I
LOAD
= 300mA TO 3A
SYNC/MODE = V
FB
FIGURE 10 CIRCUIT
3809 G06
V
OUT
1.8V
500mV/DIV
200μs/DIV
V
IN
= 4.2V
R
LOAD
= 1Ω
FIGURE 10 CIRCUIT
3809 G07