LTC3556_15 Datasheet, PDF (10/36 Pages) Linear Technology – High Effi ciency USB Power Manager with Dual Buck and Buck-Boost DC/DCs

LTC3556
TYPICAL PERFORMANCE CHARACTERISTICS
Switching Regulators 1, 2 Load
Regulation at V_OUT1,2 = 2.5V
2.56
V_BUS = 3.8V
2.53 ^{Burst Mode OPERATION}
PULSE SKIP MODE
2.50
FORCED
Burst Mode
OPERATION
2.47
Switching Regulator 3 Burst Mode
Operation Input Quiescent Current
14.0
V_OUT3 = 3.3V
T_A = 27°C
13.5
V_IN3 = 4.5V
13.0 V_IN3 = 3.6V
V_IN3 = 3V
12.5
12.0
11.5
Switching Regulator 3 Forward
Current Limit vs Temperature
2600
V_IN3 = 3V
2550
2500
2450
V_IN3 = 3.6V
V_IN3 = 4.5V
2400
2350
2.44
0.1
1
10
100
LOAD CURRENT (mA)
1000
3556 G28
11.0
–55 –35 –15 5 25 45 65 85 105 125
TEMPERATURE (°C)
3556 G29
2300
–55 –35 –15 5 25 45 65 85 105 125
TEMPERATURE (°C)
3556 G30
R_DS(ON)’s for Switching Regulator 3
vs Temperature
0.30
0.40
0.25
0.35
PMOS
0.20
V_IN3 = V_OUT3 = 3V 0.30
V_IN3 = V_OUT3 = 3.6V
0.15
V_IN3 = V_OUT3 = 4.5V
0.25
0.10
0.20
NMOS
V_IN3 = 3V
0.05
V_IN3 = 3.6V
0.15
V_IN3 = 4.5V
0
0.10
–55 –35 –15 5 25 45 65 85 105 125
TEMPERATURE (°C)
3556 G31
Switching Regulator 3 Efficiency
vs Load Current
100
90
80 _{Burst Mode}
70
OPERATION
CURVES
60
50
PWM MODE
CURVES
40
V_OUT3 = 3.3V
30
T_A = 27°C
20
10
0
0.1
V_IN3 = 3V
V_IN3 = 3.6V
V_IN3 = 4.5V
1
10
100
LOAD CURRENT (mA)
1000
3556 G32
10
Switching Regulator 3 PWM Mode
Efficiency vs Input Voltage
100
I_OUT3 = 50mA
90
80 _{IOUT3 = 200mA}
70
I_OUT3 = 1000mA
60
50
40
30
20
10 ^{VOUT3 = 3.3V}
T_A = 27°C
0
2.7 3.1 3.5 3.9 4.3
V_IN3 (V)
4.7
3556 G33
Switching Regulator 3 Reduction in
Current Deliverability at Low V_IN3
300
V_OUT3 = 3.3V
T_A = 27°C
250
200
150
100
50
0
2.7
STEADY STATE LOAD
START-UP WITH A
RESISTIVE LOAD
START-UP WITH A
CURRENT SOURCE LOAD
3.1 3.5 3.9 4.3
V_IN3 (V)
4.7
3556 G34
3556f