Datasheet LTC3562 (Analog Devices)

LTC3562 I2C Quad Synchronous Step-Down DC/DC Regulator 2 × 600mA, 2 × 400mA
FEATURES DESCRIPTION
n
Four Independent I2C Controllable Step-Down
The LTC®3562 is a quad high effi ciency monolithic syn-
Regulators (2
×
600mA, 2
×
400mA)
chronous step-down regulator with an I2C interface. Two n
Two I2C Programmable Feedback Voltage
regulators are externally adjustable and can have their
Regulators (R600A, R400A): VFB 425mV to 800mV
feedback voltages programmed between 425mV and n
Two I2C Programmable Output Voltage Regulators
800mV in 25mV steps (Type A). The other two regulators
(R600B, R400B): VOUT 600mV to 3.775V
are fi xed output regulators whose output voltages can be n
Programmable Modes: Pulse Skip, LDO, Burst Mode,
® programmed between 600mV and 3.775V in 25mV steps
Forced Burst Mode Operation
(Type B). All four regulators operate independently and n Quiescent Current < 100μA (All Regulators Enabled can be put into pulse skip, LDO, Burst Mode operation, in LDO Mode) or forced Burst Mode operation through I2C control. The n Fixed 2.25MHz Switching Frequency (Pulse Skip Type-A regulators have separate RUN pins that can be Mode) enabled if I2C control is unavailable. n Slew Limiting Reduces Switching Noise The 2.85V to 5.5V input voltage range makes the LTC3562 n Power-On Reset Output for Regulator R600A ideally suited for single Li-Ion battery-powered applica- n Small, Thermally Enhanced, 20-Lead 3mm × 3mm tions. At low output load conditions, the regulators can QFN Package be switched into LDO, Burst Mode operation, or forced
APPLICATIONS
Burst Mode operation, extending battery life in portable systems. The quiescent current drops to under 100μA n with all regulators in LDO mode, and under 0.1μA when Miscellaneous Handheld Applications with Multiple all regulators are shut down. Supply Rails n Personal Information Appliances Switching frequency is internally set to 2.25MHz, allowing n Wireless and DSL Modems the use of small surface mount inductors and capacitors. n Digital Still Cameras All regulators are internally compensated. The LTC3562 is n MP3 Players available in a low profi le 3mm × 3mm QFN package. n Portable Instruments 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 R600x Burst Mode Effi ciency High Effi ciency Quad Step-Down Converter with I2C and Power Loss vs Load Current
MICROPROCESSOR 100 10000 SDA VOUT = 3.3V Li-Ion/Polymer + SCL 90 3.4V TO 4.2V 10μF DVCC VOUT = V POR 80 OUT = 1.2V 1000 V 2.5V IN SCL SDA DVCC 100k V POWER LOSS (mW) OUT 600A 70 VOUT = V 1.8V OUT RUN400A 4.7μH POR600A 3.3μH 1.8V 400A 600mA 60 100 SW400A SW600A 1.5V LTC3562 50 400mA 10μF 10pF 475k FB600A 634k 10pF 10μF 40 10 FB400A RUN600A EFFICIENCY (%) 30 536k 499k V V OUT = 1.2V, OUT = 3.3V 20 1.8V, 2.5V 1 4.7μH V 3.3μH OUT 400B VOUT 600B 10 SW400B SW600B 1.2V 3.3V VIN = 3.8V 400mA 0 0.1 OUT400B PGND AGND OUT600B 10μF 600mA 10μF 0.01 0.1 1 10 100 1000 3562 TA01 LOAD CURRENT (mA) 3562 TA01b 3562fa 1