LTC3890-3 Datasheet, PDF (5/40 Pages) Linear Technology – 60V Low IQ, Dual, 2-Phase Synchronous Step-Down DC/DC Controller

Typical Performance Characteristics
Efficiency and Power Loss
vs Output Current
100 _{VIN = 12V}
BURST EFFICIENCY
90 VOUT = 3.3V
80
10000
1000
70
FCM LOSS
60
100
50
40
PULSE-SKIPPING
LOSS
BURST LOSS
10
30
20
FCM EFFICIENCY
1
10
0
0.0001
PULSE-SKIPPING
EFFICIENCY
0.001 0.01 0.1
1
OUTPUT CURRENT (A)
0.1
10
FIGURE 13 CIRCUIT
38903 G01
Efficiency vs Output Current
100
90 ^{VOUT = 8.5V}
80
V_OUT = 3.3V
70
60
50
40
30
20
Burst Mode OPERATION
10
0 ^{VIN = 12V}
0.0001 0.001 0.01 0.1
1
10
OUTPUT CURRENT (A)
FIGURE 13 CIRCUIT
38903 G02
LTC3890-3
Efficiency vs Input Voltage
100
98
96
V_OUT2 = 8.5V
94
92
90
88
V_OUT1 = 3.3V
86
84
82
80 ^{ILOAD = 2A}
0 5 10 15 20 25 30 35 40 45 50 55 60
INPUT VOLTAGE (V)
FIGURE 13 CIRCUIT
38903 G03
Load Step
Burst Mode Operation
V_OUT
100mV/DIV
AC-
COUPLED
Load Step
Pulse-Skipping Mode
V_OUT
100mV/DIV
AC-
COUPLED
Load Step
Forced Continuous Mode
V_OUT
100mV/DIV
AC-
COUPLED
I_L
2A/DIV
50µs/DIV
V_IN = 12V
V_OUT = 3.3V
FIGURE 13 CIRCUIT
38903 G04
I_L
2A/DIV
50µs/DIV
V_IN = 12V
V_OUT = 3.3V
FIGURE 13 CIRCUIT
38903 G05
I_L
2A/DIV
50µs/DIV
V_IN = 12V
V_OUT = 3.3V
FIGURE 13 CIRCUIT
38903 G06
Inductor Current at Light Load
FORCED
CONTINUOUS
MODE
Burst Mode
OPERATION
1A/DIV
PULSE-SKIPPING
MODE
V_IN = 12V
V_OUT = 3.3V
I_LOAD = 200µA
5µs/DIV
38903 G07
Soft Start-Up
V_OUT2
2V/DIV
V_OUT1
2V/DIV
2ms/DIV
FIGURE 13 CIRCUIT
38903 G08
Tracking Start-Up
V_OUT2
2V/DIV
V_OUT1
2V/DIV
2ms/DIV
FIGURE 13 CIRCUIT
38903 G09
For more information www.linear.com/3890-3
38903f
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