Datasheet

LTC3556
5
3556f
ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations 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
t
HD_DAT(I)
Data Hold Time Input 0 ns
t
SU_DAT
Data Setup Time 100 ns
t
LOW
SCL Clock Low Period 1.3 µs
t
HIGH
SCL Clock High Period 0.6 µs
t
f
Clock/Data Fall Time C
B
= Capacitance of One BUS Line (pF) 20 + 0.1C
B
300 ns
t
r
Clock/Data Rise Time C
B
= Capacitance of One BUS Line (pF) 20 + 0.1C
B
300 ns
t
SP
Input Spike Suppression Pulse Width 50 ns
Switching Regulators 1, 2 and 3
V
IN1,2,3
Input Supply Voltage 2.7 5.5 V
V
OUTUVLO
V
OUT
UVLO—V
OUT
Falling
V
OUT
UVLO—V
OUT
Rising
V
IN1,2,3
Connected to V
OUT
Through Low
Impedance. Switching Regulators are
Disabled in UVLO
2.5 2.6
2.8 2.9
V
V
f
OSC
Oscillator Frequency
l
1.8 2.25 2.7 MHz
Switching Regulator 1 (Buck)
I
VIN1
Pulse Skip Mode Input Current
Burst Mode
®
Input Current
Forced Burst Mode Input Current
LDO Mode Input Current
Shutdown Input Current
I
OUT1
= 0µA (Note 6)
I
OUT1
= 0µA (Note 6)
I
OUT1
= 0µA (Note 6)
I
OUT1
= 0µA (Note 6)
I
OUT1
= 0µA, FB1 = 0V
225
35
20
20
400
60
35
35
1
µA
µA
µA
µA
µA
I
LIM1
PMOS Switch Current Limit Pulse Skip/Burst Mode Operation 600 800 1100 mA
I
OUT1
Available Output Current Pulse Skip/Burst Mode Operation (Note 9)
Forced Burst Mode Operation (Note 9)
LDO Mode (Note 9)
400
60
50
mA
mA
mA
V
FBHIGH1
Maximum Servo Voltage Full Scale (1, 1, 1, 1) (Note 7)
l
0.780 0.800 0.820 V
V
FBLOW1
Minimum Servo Voltage Zero Scale (0, 0, 0, 0) (Note 7)
l
0.405 0.425 0.445 V
V
LSB1
V
FB1
Servo Voltage Step Size 25 mV
R
P1
PMOS R
DS(ON)
0.6 
R
N1
NMOS R
DS(ON)
0.7 
R
LDO_CL1
LDO Mode Closed-Loop R
OUT
0.25 
R
LDO_OL1
LDO Mode Open-Loop R
OUT
(Note 8) 2.5 
I
FB1
FB1 Input Current V
FB1
= 0.85V –50 50 nA
D1 Maximum Duty Cycle
l
100 %
R
SW1
SW1 Pull-Down in Shutdown 10 k
Switching Regulator 2 (Buck)
I
VIN2
Pulse Skip Mode Input Current
Burst Mode Input Current
Forced Burst Mode Input Current
LDO Mode Input Current
Shutdown Input Current
I
OUT2
= 0µA (Note 6)
I
OUT2
= 0µA (Note 6)
I
OUT2
= 0µA (Note 6)
I
OUT2
= 0µA (Note 6)
I
OUT2
= 0µA, FB2 = 0V
225
35
20
20
400
60
35
35
1
µA
µA
µA
µA
µA
I
LIM2
PMOS Switch Current Limit Pulse Skip/Burst Mode Operation 600 800 1100 mA
I
OUT2
Available Output Current Pulse Skip/Burst Mode Operation (Note 9)
Forced Burst Mode Operation (Note 9)
LDO Mode (Note 9)
400
60
50
mA
mA
mA
Burst Mode is a registered trademark of Linear Technology Corporation.