LTC3556_15 Datasheet, PDF (6/36 Pages) Linear Technology – High Effi ciency USB Power Manager with Dual Buck and Buck-Boost DC/DCs

LTC3556
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, V_IN1 = V_IN2 = V_IN3 = V_OUT3 = 3.8V, BAT = 3.8V, DV_CC = 3.3V,
R_PROG = 1k, R_CLPROG = 3.01k, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
V_FB2
R_P2
R_N2
R_{LDO_CL2}
R_{LDO_OL2}
I_FB2
D2
V_FB2 Servo Voltage
PMOS R_DS(ON)
NMOS R_DS(ON)
LDO Mode Closed-Loop R_OUT
LDO Mode Open-Loop R_OUT
FB2 Input Current
Maximum Duty Cycle
(Note 7)
(Note 8)
V_FB2 = 0.85V
l 0.780 0.800 0.820
V
0.6
Ω
0.7
Ω
0.25
Ω
2.5
Ω
–50
50
nA
l 100
%
R_SW2
SW2 Pull-Down in Shutdown
Switching Regulator 3 (Buck-Boost)
10
kΩ
I_VIN3
Input Current
PWM Mode, I_OUT3 = 0μA
Burst Mode Operation, I_OUT3 = 0μA
Shutdown
220 400
μA
13
20
μA
0
1
μA
V_OUT3(LOW)
Minimum Regulated Output Voltage For Burst Mode Operation or Synchronous
PWM Operation
2.65 2.75
V
V_OUT3(HIGH)
Maximum Regulated Output Voltage
5.50 5.60
V
I_LIMF3
Forward Current Limit (Switch A)
PWM Mode
l
2
2.5
3
A
I_PEAK3(BURST)
Forward Burst Current Limit (Switch A) Burst Mode Operation
l 200
275 350
mA
I_ZERO3(BURST)
Reverse Burst Current Limit (Switch D) Burst Mode Operation
l –30
0
30
mA
I_MAX3(BURST)
Maximum Deliverable Output Current 2.7V ≤ V_IN3 ≤ 5.5V, 2.75V ≤ V_OUT3 ≤ 5.5V
50
mA
in Burst Mode Operation
(Note 9)
V_FBHIGH3
V_FBLOW3
V_LSB3
I_FB3
R_DS(ON)P
R_DS(ON)N
I_LEAK(P)
I_LEAK(N)
R_VOUT3
D_BUCK(MAX)
D_BOOST(MAX)
t_SS3
Maximum Servo Voltage
Minimum Servo Voltage
V_FB3 Servo Voltage Step Size
FB3 Input Current
PMOS R_DS(ON)
NMOS R_DS(ON)
PMOS Switch Leakage
NMOS Switch Leakage
V_OUT3 Pull-Down in Shutdown
Maximum Buck Duty Cycle
Maximum Boost Duty Cycle
Soft-Start Time
Full Scale (1, 1, 1, 1)
Zero Scale (0, 0, 0, 0)
V_FB3 = 0.8V
Switches A, D
Switches B, C
Switches A, D
Switches B, C
PWM Mode
PWM Mode
l 0.780 0.800 0.820
V
l 0.405 0.425 0.445
V
25
mV
–50
50
nA
0.22
Ω
0.17
Ω
–1
1
μA
–1
1
μA
10
kΩ
l 100
%
75
%
0.5
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 LTC3556E is 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.
Note 3: The LTC3556E includes 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: Applies to Pulse Skip, Burst Mode operation and Forced Burst
Mode operation only.
Note 8: Inductor series resistance adds to open-loop R_OUT.
Note 9: Guaranteed by design.
3556f
6