Datasheet

LTC3557/LTC3557-1
5
35571fc
SWITCHING REGULATOR ELECTRICAL CHARACTERISTICS
The denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at T
A
= 25°C.
V
OUT
= V
IN1
= V
IN2
= 3.8V, MODE = EN1 = EN2 = EN3 = 0V.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Step-Down Switching Regulator 2
I
VIN2
Pulse-Skip Mode Input Current (Note 10) I
OUT
= 0, EN2 = 3.8V, MODE = 0V 220 µA
Burst Mode Input Current (Note 10) I
OUT
= 0, EN2 = MODE = 3.8V 35 50 µA
Shutdown Input Current I
OUT
= 0, EN2 = 0V, FB2 = 0V 0.01 1 µA
I
LIM2
Peak PMOS Current Limit EN2 = 3.8V, MODE = 0V or 3.8V (Note 7) 600 800 1000 mA
V
FB2
Feedback Voltage EN2 = 3.8V, MODE = 0V
EN2 = MODE = 3.8V
0.78
0.78
0.8
0.8
0.82
0.824
V
V
I
FB2
FB2 Input Current (Note 10) EN2 = 3.8V
0.05
0.05 µA
D2 Maximum Duty Cycle FB2 = 0V, EN2 = 3.8V 100 %
R
P2
R
DS(ON)
of PMOS EN2 = 3.8V 0.6
Ω
R
N2
R
DS(0N)
of NMOS EN2 = 3.8V 0.6
Ω
R
SW2(PD)
SW2 Pull-Down in Shutdown EN2 = 0V 10
kΩ
V
RST2
Power-On RST2 Pin Output Low Voltage I
RST2
= 1mA, FB2 = 0V, EN2 = 3.8V 0.1 0.35 V
I
RST2
Power-On RST2 Pin Input Current (Note 10) V
RST2
= 5.5V, EN2 = 3.8V 1 µA
V
TH(RST2)
Power-On RST2 Pin Threshold (Note 8)
8
%
t
RST2
Power-On RST2 Pin Delay From RST2 Threshold to RST2 Hi-Z 230 ms
Step-Down Switching Regulator 3
I
VIN2
Pulse-Skip Mode Input Current (Note 10) I
OUT
= 0, EN3 = 3.8V, MODE = 0V 220 µA
Burst Mode Input Current (Note 10) I
OUT
= 0, EN3 = MODE = 3.8V 35 50 µA
Shutdown Input current I
OUT
= 0, EN3 = 0V, FB3 = 0V 0.01 1 µA
I
LIM3
Peak PMOS Current Limt EN3 = 3.8V, MODE = 0V or 3.8V (Note 7) 600 800 1000 mA
V
FB3
Feedback Voltage EN3 = 3.8V, MODE = 0V
EN3 = MODE = 3.8V
0.78
0.78
0.8
0.8
0.82
0.824
V
V
I
FB3
FB3 Input Current (Note 10) EN3 = 3.8V
0.05
0.05 µA
D3 Maximum Duty Cycle FB3 = 0V, EN3 = 3.8V 100 %
R
P3
R
DS(ON)
of PMOS EN3 = 3.8V 0.6
R
N3
R
DS(ON)
of NMOS EN3 = 3.8V 0.6
R
SW3(PD)
SW3 Pull-Down in Shutdown EN3 = 0V 10 k
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 LTC3557/LTC3557-1 is guaranteed to meet performance
specifi cations from 0°C to 85°C. Specifi cations over the 40°C to 85°C
operating temperature range are assured by design, characterization and
correlation with statistical process controls.
Note 3. This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperatures will exceed 110°C when overtemperature protection is
active. Continuous operation above the specifi ed maximum operating
junction temperature may result in device degradation or failure.
Note 4. V
CC
is the greater of V
BUS
, V
OUT
or BAT.
Note 5. Total input current is the sum of quiescent current, I
BUSQ
, and
measured current given by V
CLPROG
/R
CLPROG
• (h
CLPROG
+ 1)
Note 6. h
C/10
is expressed as a fraction of measured full charge current
with indicated PROG resistor.
Note 7. The current limit features of this part are intended to protect the
IC from short term or intermittent fault conditions. Continuous operation
above the maximum specifi ed pin current rating may result in device
degradation or failure.
Note 8. RST2 threshold is expressed as a percentage difference from the
FB2 regulation voltage. The threshold is measured for FB2 rising.
Note 9. V
OUT
not in UVLO.
Note 10. FB high, not switching.