LTC3555 Datasheet, PDF (6/32 Pages) Linear Technology – High Effi ciency USB Power Manager + Triple Step-Down DC/DC

LTC3555/LTC3555-X
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T_A = 25°C. V_BUS = 5V, BAT = 3.8V, DV_CC = 3.3V, R_PROG = 1k, R_CLPROG = 3k,
unless otherwise noted.
SYMBOL
PARAMETER
V_FBHIGH2
Maximum Servo Voltage
V_FBLOW2
Minimum Servo Voltage
V_LSB2
V_FB2 Servo Voltage Step Size
R_P2
PMOS R_DS(ON)
R_N2
NMOS R_DS(ON)
R_{LDO_CL2}
LDO Mode Closed-Loop R_OUT
R_{LDO_OL2}
LDO Mode Open-Loop R_OUT
General Purpose Switching Regulator 3
I_VIN3
I_LIMSW3
I_OUT3
Pulse Skip Mode Input Current
Burst Mode Input Current
Forced Burst Mode Input Current
LDO Mode Input Current
Shutdown Input Current
PMOS Switch Current Limit
Available Output Current
V_FBHIGH3
V_FBLOW3
V_LSB3
R_P3
R_N3
R_LDOCL3
R_LDOOL3
t_RST3
Maximum Servo Voltage
Minimum Servo Voltage
V_FB Servo Voltage Step Size
PMOS R_DS(ON)
NMOS R_DS(ON)
LDO Mode Closed Loop R_OUT
LDO Mode Open Loop R_OUT
Power On Reset Time for Switching
Regulator
CONDITIONS
Full Scale (1, 1, 1, 1) (Note 8)
Zero Scale (0, 0, 0, 0) (Note 8)
(Note 9)
I_OUT3 = 0μA (Note 6)
I_OUT3 = 0μA (Note 6)
I_OUT3 = 0μA (Note 6)
I_OUT3 = 0μA (Note 6)
I_OUT3 = 0μA, FB3 = 0V
Pulse Skip/Burst Mode Operation
Pulse Skip/Burst Mode Operation (Note 7)
Forced Burst Mode Operation (Note 7)
LDO Mode (Note 7)
Full Scale (1, 1, 1, 1) (Note 8)
Zero Scale (0, 0, 0, 0) (Note 8)
(Note 9)
V_FB3 Within 92% of Final Value to RST3 Hi-Z
MIN
l 0.78
0.405
TYP
0.80
0.425
25
0.6
0.7
0.25
2.5
MAX
0.82
0.445
UNITS
V
V
mV
Ω
Ω
Ω
Ω
225
μA
35
60
μA
20
35
μA
20
35
μA
1
μA
1500 2000 2800
mA
1000
mA
150
mA
50
mA
l 0.78 0.80
0.82
V
0.405 0.425 0.445
V
25
mV
0.18
Ω
0.30
Ω
0.25
Ω
2.5
Ω
230
ms
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LTC3555E/LTC3555E-X are guaranteed to meet performance
specifications from 0°C to 85°C. Specifications over the – 40°C to 85°C
operating temperature range are assured by design, characterization and
correlation with statistical process controls. The LTC3555I/LTC3555I-X are
guaranteed to meet performance specifications over the full –40°C to 85°C
operating temperature range.
Note 3: The LTC3555/LTC3555-X include overtemperature protection that
is intended to protect the device during momentary overload conditions.
Junction temperature will exceed 125°C when overtemperature protection
is active. Continuous operation above the specified maximum operating
junction temperature may impair device reliability.
Note 4: Total input current is the sum of quiescent current, I_VBUSQ, and
measured current given by:
V_CLPROG/R_CLPROG • (h_CLPROG +1)
Note 5: h_C/10 is expressed as a fraction of measured full charge current
with indicated PROG resistor.
Note 6: FBx above regulation such that regulator is in sleep. Specification
does not include resistive divider current reflected back to V_INx.
Note 7: Guaranteed by design but not explicitly tested.
Note 8: Applies to pulse skip, Burst Mode operation and forced Burst
Mode operation only.
Note 9: Inductor series resistance adds to open-loop R_OUT.
3555fd
6