LTC3425_15 Datasheet, PDF (5/24 Pages) Linear Technology – 5A, 8MHz, 4-Phase Synchronous Step-Up DC/DC Converter

LTC3425
TYPICAL PERFOR A CE CHARACTERISTICS
Converter Efficiency
for V_OUT = 3.3V
100
90 ^{VIN = 2.4V}
80
70
V_IN = 1.2V
V_IN = 2.4V
60
V_IN = 1.2V
50
40
30
20
10
0 ^{TA = 25°C}
0.1
1
Burst Mode OPERATION
1MHz/PHASE
10 100 1000 10000
OUTPUT CURRENT (mA)
3425 G11
Efficiency Comparison of
Discontinuous Mode and Forced
Continuous Mode at Light Loads
for V_IN = 2.4V, V_OUT = 3.3V
100
T_A = 25°C
90 1MHz/PHASE
80 ^{DISCONTINUOUS}
MODE
70
60
FORCED
CONTINUOUS
50
MODE
40
30
20
10
0
1
10
100
1000
CONVERTER OUTPUT CURRENT (mA)
3425 G14
Oscillator Frequency
10
T_A = 25°C
1
1
10
100
R_T (kΩ)
3425 G17
Converter Efficiency
for V_OUT = 5V
100
90 ^{VIN = 3.3V}
80
V_IN = 2.4V
70
V_IN = 3.3V V_IN = 2.4V
60
50
40
30
20
10
0 ^{TA = 25°C}
0.1
1
Burst Mode OPERATION
1MHz/PHASE
10 100 1000 10000
OUTPUT CURRENT (mA)
3425 G12
Efficiency Comparison of
Discontinuous Mode and Forced
Continuous Mode at Light Loads
for V_IN = 3.3V, V_OUT = 5V
100
T_A = 25°C
90 1MHz/PHASE
80
DISCONTINUOUS
70
MODE
60
FORCED
50
CONTINUOUS
MODE
40
30
20
10
0
1
10
100
1000
LOAD (mA)
3425 G15
Peak Current Limit
1.8
1.6
T_A = 25°C
1.4
1.2
1.0
0.8
Converter Efficiency for 2-, 3- and
4-Phase Operation
98
T_A = 25°C
96 ^VIN ^{= 2.4V}
V_OUT = 3.3V
94 1MHz/PHASE
92
90
4 PHASE
88
86
2 PHASE 3 PHASE
84
82
80
100
1000
LOAD (mA)
10000
3425 G13
Converter No Load Input Current
vs V_IN (Burst Mode Operation)
140
T_A = 25°C
120
100
80
V_OUT = 5V
60
V_OUT = 3.3V
40
20
0
1.5 2.0
2.5 3.0 3.5
V_IN (V)
Effective R_DS(ON)
0.065
T_A = 25°C
4.0 4.5
3425 G16
0.060
0.055
PMOS
0.050
0.045
NMOS
0.6
0.040
60 80 100 120 140 160 180 200
2.5
3
3.5
4
4.5
5
I_LIM RESISTOR (kΩ)
V_OUT (V)
3425 G18
3425 G19
3425f
5