DC1123A QUICK START GUIDE
1
DESCRIPTION
Demonstration circuit 1123 is a I
2
C Quad Synchro-
nous Step-Down DC/DC Regulators featuring the
LTC3562. The LTC3562 is a quad high efficiency
monolithic synchronous step-down regulator with
an I
2
C interface. Two regulators are externally ad-
justable and can have their feedback voltages pro-
grammed between 425mV and 800mV in 25mV
(Type A). The other two regulators are fixed output
regulators whose output voltages can be pro-
grammed between 600mV and 3.775V in 25mV
steps (Type B). All four regulators operate inde-
pendently and can be put into pulse skip, LDO,
Burst Mode operation or forced Burst Mode opera-
tion through I
2
C control. The Type A regulators
have separate RUN pins that can be enabled if I
2
C
control is unavailable.
The 2.85V to 5.5V input range makes the LTC-
3562 ideally suited for single Li-ion battery pow-
ered applications. At low output load conditions,
the regulators can be switched into LDO, Burst
Mode operation or forced Burst Mode operation,
extending battery life in portable systems. The qui-
escent current drops to under 100µA with all regu-
lators in LDO mode and under 0.1µA when all
regulators are shut down
Switching frequency is internally set to 2.25MHz,
allowing the use of small surface mount inductors
and capacitors. All regulators are internally com-
pensated.
The LTC3562 is offered in a low profile 3mm
3mm QFN package.
Design files for this circuit board are available.
Call the LTC factory.
L
, LTC, LTM, LT, Burst Mode, are registered trademarks of Linear Technology
Corporation.
All other trademarks are the property of their respective owners.
TABLE 1. Typical Specifications (25
°
C)
Input Voltage Range: V
CC
2.85V to 5.5V (Subject to dropout)
P600A
0.96V to 1.82V, 600mA (Max)
P600B
1.20V to 3.775V, 600mA (Max)
P400A
0.80V to 1.51V, 400mA (Max)
P400B
0.60V to 3.775V, 400mA (Max)
OPERATING PRINCIPLES
The LTC3562 is a highly integrated power man-
agement IC that contains four I
2
C controllable,
monolithic, high efficiency step-down regulators.
Two regulators provide up to 600ma of output
current and the other two regulators produce up
to 400ma. All four regulators are 2.25MHz, con-
stant-frequency, current mode switching regula-
tors that can be independently controlled through
I
2
C. All regulators are internally compensated
DC1123
QUICK START GUIDE
LTC3562
I
2
C Quad Synchronous
Step-Down DC/DC Regulators
