LTC3555/LTC3555-X
6
3555fe
For more information www.linear.com/LTC3555
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 CONDITIONS MIN TYP MAX UNITS
V
FBHIGH2
Maximum Servo Voltage Full Scale (1, 1, 1, 1) (Note 8)
l
0.78 0.80 0.82 V
V
FBLOW2
Minimum Servo Voltage Zero Scale (0, 0, 0, 0) (Note 8) 0.405 0.425 0.445 V
V
LSB2
V
FB2
Servo Voltage Step Size 25 mV
R
P2
PMOS R
DS(ON)
0.6 Ω
R
N2
NMOS R
DS(ON)
0.7 Ω
R
LDO_CL2
LDO Mode Closed-Loop R
OUT
0.25 Ω
R
LDO_OL2
LDO Mode Open-Loop R
OUT
(Note 9) 2.5 Ω
General Purpose Switching Regulator 3
I
VIN3
Pulse Skip Mode Input Current
Burst Mode Input Current
Forced Burst Mode Input Current
LDO Mode Input Current
Shutdown Input Current
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
225
35
20
20
60
35
35
1
µA
µA
µA
µA
µA
I
LIMSW3
PMOS Switch Current Limit Pulse Skip/Burst Mode Operation 1500 2000 2800 mA
I
OUT3
Available Output Current Pulse Skip/Burst Mode Operation (Note 7)
Forced Burst Mode Operation (Note 7)
LDO Mode (Note 7)
1000
150
50
mA
mA
mA
V
FBHIGH3
Maximum Servo Voltage Full Scale (1, 1, 1, 1) (Note 8)
l
0.78 0.80 0.82 V
V
FBLOW3
Minimum Servo Voltage Zero Scale (0, 0, 0, 0) (Note 8) 0.405 0.425 0.445 V
V
LSB3
V
FB
Servo Voltage Step Size 25 mV
R
P3
PMOS R
DS(ON)
0.18 Ω
R
N3
NMOS R
DS(ON)
0.30 Ω
R
LDOCL3
LDO Mode Closed Loop R
OUT
0.25 Ω
R
LDOOL3
LDO Mode Open Loop R
OUT
(Note 9) 2.5 Ω
t
RST3
Power On Reset Time for Switching
Regulator
V
FB3
Within 92% of Final Value to RST3 Hi-Z 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
.
