LTC3555 Datasheet, PDF (9/32 Pages) Linear Technology – High Effi ciency USB Power Manager + Triple Step-Down DC/DC

LTC3555/LTC3555-X
TYPICAL PERFORMANCE CHARACTERISTICS
RST3, CHRG Pin Current vs
Voltage (Pull-Down State)
100 _{VBUS = 5V}
BAT = 3.8V
80
3.3V LDO Step Response
(5mA to 15mA)
I_LDO3V3
5mA/DIV
Battery Drain Current vs
Temperature
50
BAT = 3.8V
V_BUS = 0V
BUCK REGULATORS OFF
40
60
0mA
V_LDO3V3
40
20mV/DIV
AC COUPLED
20
BAT = 3.8V
20μs/DIV
3555 G20
0
0
1
2
3
4
5
RST3, CHRG PIN VOLTAGE (V)
3555 G19
R_DS(ON) for Switching Regulator
Power Switches vs Temperature
1.0
REGULATORS 1, 2
0.8
NMOS SWITCH
0.6
PMOS SWITCH
0.4
REGULATOR 3
Switching Regulator Current Limit
vs Temperature
2.0
REGULATOR 3
1.5
1.0
REGULATORS 1, 2
0.2
NMOS SWITCH
PMOS SWITCH
0
–40 –15 10
35
60
85
TEMPERATURE (°C)
3555 G22
0.5
V_IN1,2,3 = 3.8V
0
–40 –15 10
35
60
85
TEMPERATURE (°C)
3555 G23
30
20
10
0
–40 –15 10
35
60
85
TEMPERATURE (°C)
3555 G21
Switching Regulator Low Power
Mode Quiescent Currents
50
V_IN1,2,3 = 3.8V
V_OUT1,2,3 = 2.5V
40
30
FORCED
Burst Mode
OPERATION
20
Burst Mode
OPERATION
LDO MODE
10
0
–40 –15 10
35
60
85
TEMPERATURE (°C)
3555 G24
Switching Regulators 1, 2 Pulse
Skip Mode Quiescent Currents
325
1.95
V_IN1,2 = 3.8V
300
1.90
V_OUT1,2 = 2.5V
(CONSTANT FREQUENCY)
275
1.85
250
1.80
225
200
–40
1.75
V_OUT1,2 = 1.25V
(PULSE SKIPPING)
1.70
–15 10
35
60
85
TEMPERATURE (°C)
3555 G25
Switching Regulator 3 Pulse Skip
Mode Quiescent Currents
400
11
V_OUT3 = 2.5V
350
10
V_IN3 = 3.5V
(CONSTANT FREQUENCY)
300
9
250
200
–40
8
–15 10
V_IN3 = 3.8V
(PULSE
SKIPPING)
7
35
60
85
TEMPERATURE (°C)
3555 G26
Switching Regulator Soft-Start
Waveform
50μs/DIV
3555 G27
3555fd
9