Datasheet

LTC3677-3
7
36773f
elecTrical characTerisTics
Step-Down Switching Regulators. The l denotes the specifications
which apply over the full operating junction temperature range, otherwise specifications are at T
J
= 25°C. V
OUT
= V
IN12
= V
IN3
= 3.8V,
all regulators enabled unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Step-Down Switching Regulators (Buck1, Buck2 and Buck3)
V
IN12
, V
IN3
Input Supply Voltage (Note 9)
l
2.7 5.5 V
V
OUT
UVLO V
OUT
Falling
V
OUT
Rising
V
IN12
and V
IN3
Connected to V
OUT
Through
Low Impedance. Switching Regulators Are
Disabled Below V
OUT
UVLO
2.5 2.7
2.8 2.9
V
V
f
OSC
Oscillator Frequency 1.91 2.25 2.59 MHz
800mA Step-Down Switching Regulator 3 (Buck3-Enabled via EN3, Disabled in PDN and POFF States)
I
VIN3Q
Pulse-Skipping Mode Input Current (Note 10) 100 µA
Burst Mode Operation Input Current (Note 10) 20 35 µA
Shutdown Input Current EN3 = 0 0.01 1 µA
I
LIM3
Peak P-Channel MOSFET Current Limit (Note 7) 1000 1400 1700 mA
V
FB3
Feedback Voltage Pulse-Skipping Mode
Burst Mode Operation
l
l
0.78
0.78
0.8
0.8
0.82
0.824
V
V
I
FB3
FB3 Input Current (Note 10) –0.05 0.05 µA
D3 Max Duty Cycle FB3 = 0V 100 %
R
P3
R
DS(ON)
of P-Channel MOSFET 0.3 Ω
R
N3
R
DS(ON)
of N-Channel MOSFET 0.4 Ω
R
SW3_PD
SW3 Pull-Down in Shutdown EN3 = 0 10 kΩ
V
IL,EN3
EN3 Input Low Voltage 0.4 V
V
IH,EN3
EN3 Input High Voltage 1.2 V
500mA Step-Down Switching Regulator 2 (Buck2-Pushbutton Enabled, Third in Sequence)
I
VIN12Q
Pulse-Skipping Mode Input Current (Note 10) 100 µA
Burst Mode Operation Input Current (Note 10) 20 µA
Shutdown Input Current POFF State 0.01 1 µA
I
LIM2
Peak P-Channel MOSFET Current Limit (Note 7) 650 900 1200 mA
V
FB2
Feedback Voltage Pulse-Skipping Mode
Burst Mode Operation
l
l
0.78
0.78
0.8
0.8
0.82
0.824
V
V
I
FB2
FB2 Input Current (Note 10) –0.05 0.05 µA
D2 Max Duty Cycle FB2 = 0V 100 %
R
P2
R
DS(ON)
of P-Channel MOSFET I
SW2
= 100mA 0.6 Ω
R
N2
R
DS(ON)
of N-Channel MOSFET I
SW2
= –100mA 0.6 Ω
R
SW2_PD
SW2 Pull-Down in Shutdown POFF State 10 kΩ
500mA Step-Down Switching Regulator 1 (Buck1-Pushbutton Enabled, Second in Sequence)
I
VIN12Q
Pulse-Skipping Mode Input Current (Note 10) 100 µA
Burst Mode Operation Input Current (Note 10) 20 µA
Shutdown Input Current 0.01 1 µA
I
LIM1
Peak P-Channel MOSFET Current Limit (Note 7) 650 900 1200 mA
V
FB1
Feedback Voltage Pulse-Skipping Mode
Burst Mode Operation
l
l
0.78
0.78
0.8
0.8
0.82
0.824
V
V
I
FB1
FB1 Input Current (Note 10) –0.05 0.05 µA
D1 Max Duty Cycle FB1 = 0V 100 %
R
P1
R
DS(ON)
of P-Channel MOSFET I
SW1
= 100mA 0.6 Ω
R
N1
R
DS(ON)
of N-Channel MOSFET I
SW1
= –100mA 0.6 Ω
R
SW1_PD
SW1 Pull-Down in Shutdown POFF State 10 kΩ