LTC3562 Datasheet, PDF (1/20 Pages) Linear Technology – I2C Quad Synchronous Step-Down DC/DC Regulator 2 × 600mA, 2 × 400mA

LTC3562
I²C Quad Synchronous
Step-Down DC/DC Regulator
2 × 600mA, 2 × 400mA
FEATURES
DESCRIPTION
n _{Four Independent I}²_{C Controllable Step-Down}
Regulators (2 × 600mA, 2 × 400mA)
n _{Two I}²_{C Programmable Feedback Voltage}
Regulators (R600A, R400A): V_FB 425mV to 800mV
n _{Two I}²_{C Programmable Output Voltage Regulators}
(R600B, R400B): V_OUT 600mV to 3.775V
n _{Programmable Modes: Pulse Skip, LDO, Burst Mode,}^®
Forced Burst Mode Operation
n _{Quiescent Current < 100μA (All Regulators Enabled}
in LDO Mode)
n _{Fixed 2.25MHz Switching Frequency (Pulse Skip}
Mode)
n _{Slew Limiting Reduces Switching Noise}
n _{Power-On Reset Output for Regulator R600A}
n _{Small, Thermally Enhanced, 20-Lead 3mm × 3mm}
QFN Package
APPLICATIONS
n _{Miscellaneous Handheld Applications with Multiple}
Supply Rails
n _{Personal Information Appliances}
n _{Wireless and DSL Modems}
n _{Digital Still Cameras}
n _{MP3 Players}
n _{Portable Instruments}
The LTC^®3562 is a quad high efficiency monolithic syn-
chronous step-down regulator with an I²C interface. Two
regulators are externally adjustable and can have their
feedback voltages programmed between 425mV and
800mV in 25mV steps (Type A). The other two regulators
are fixed output regulators whose output voltages can be
programmed between 600mV and 3.775V in 25mV steps
(Type B). All four regulators operate independently and
can be put into pulse skip, LDO, Burst Mode operation,
or forced Burst Mode operation through I²C control. The
Type-A regulators have separate RUN pins that can be
enabled if I²C control is unavailable.
The 2.85V to 5.5V input voltage range makes the LTC3562
ideally suited for single Li-Ion battery-powered applica-
tions. 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 quiescent current drops to under 100μA
with all regulators 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 compensated. The LTC3562 is
available in a low profile 3mm × 3mm QFN package.
L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
High Efficiency Quad Step-Down Converter with I²C
MICROPROCESSOR
Li-Ion/Polymer +
3.4V TO 4.2V
10μF
V_OUT
400A
1.5V
400mA
10μF
4.7μH
10pF 475k
V_IN SCL SDA DV_CC
RUN400A
SW400A
LTC3562
POR600A
SW600A
FB600A
100k
3.3μH
SDA
SCL
DV_CC
POR
V_OUT 600A
1.8V
600mA
634k
10pF
10μF
FB400A
RUN600A
536k
499k
V_OUT 400B
1.2V
400mA
10μF
4.7μH
SW400B
SW600B
OUT400B PGND AGND OUT600B
3562 TA01
3.3μH
V_OUT 600B
3.3V
10μF ^600mA
R600x Burst Mode Efficiency
and Power Loss vs Load Current
100
V_OUT = 3.3V
90
80
V_OUT =
2.5V
V_OUT = 1.2V
70
V_OUT =
1.8V
60
50
10000
1000
100
40
10
30
20
10
0
0.01
V_OUT = 1.2V,
1.8V, 2.5V
V_OUT = 3.3V
1
V_IN = 3.8V
0.1
0.1
1
10 100 1000
LOAD CURRENT (mA)
3562 TA01b
3562fa
1