LTC3808 Datasheet, PDF (4/28 Pages) Linear Technology – No RSENSE TM, Low EMI, Synchronous DC/DC Controller with Output Tracking

LTC3808
TYPICAL PERFOR A CE CHARACTERISTICS T_A = 25°C unless otherwise noted.
Efficiency vs Load Current
100 _{FIGURE 11 CIRCUIT}
95
V_OUT = 2.5V
90 ^{VOUT = 3.3V}
85
V_OUT = 1.2V
80
75
V_OUT = 1.8V
70
65
SYNC/MODE = V_IN
60
V_IN = 5V
1
10
100
1k
10k
LOAD CURRENT (mA)
3808 G01
Load Step (Burst Mode
Operation)
Efficiency vs Load Current
100 _{FIGURE 11 CIRCUIT}
95 V_IN = 5V, V_OUT = 2.5V
90
85
BURST MODE
80
(SYNC/MODE =
75
V_IN)
FORCED
70
CONTINUOUS
(SYNC/MODE = 0V)
65
60
55
50
1
PULSE SKIPPING
(SYNC/MODE = 0.6V)
10
100
1k
10k
LOAD CURRENT (mA)
3808 G02
Load Step (Forced Continuous
Mode)
Maximum Current Sense Voltage
vs I_TH Pin Voltage
100
Burst Mode OPERATION
(I_TH RISING)
80
Burst Mode OPERATION
(I_TH FALLING)
FORCED CONTINUOUS
60
MODE
PULSE SKIPPING
40
MODE
20
0
–20
0.5
1
1.5
I_TH VOLTAGE (V)
2
3808 G03
Load Step (Pulse Skipping Mode)
V_OUT
200mV/DIV
AC COUPLED
I_L
2A/DIV
V_OUT
200mV/DIV
AC COUPLED
I_L
2A/DIV
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 11 CIRCUIT
3808 G04
100µs/DIV
V_IN = 3.3V
V_OUT = 1.8V
I_LOAD = 300mA TO 3A
SYNC/MODE = 0V
FIGURE 11 CIRCUIT
3808 G05
100µs/DIV
V_IN = 3.3V
V_OUT = 1.8V
I_LOAD = 300mA TO 3A
SYNC/MODE = V_FB
FIGURE 11 CIRCUIT
Start-Up with Internal Soft-Start
(TRACK/SS = V_IN)
Start-Up with External Soft-Start
(C_SS = 10nF)
V_OUT
1.8V
500mV/DIV
V_OUT
1.8V
500mV/DIV
3808 G06
4
200µs/DIV
V_IN = 4.2V
R_LOAD = 1Ω
FIGURE 11 CIRCUIT
3808 G07
1ms/DIV
V_IN = 4.2V
R_LOAD = 1Ω
FIGURE 11 CIRCUIT
3808 G08
3808f