Datasheet LT3694, LT3694-1 (Analog Devices)

LT3694/LT3694-1 36V, 2.6A Monolithic Buck Regulator With Dual LDO
FEATURES DESCRIPTION
n
Wide Input Range: 4V to 36V
The LT®3694/LT3694-1 are monolithic, current mode n
Overvoltage Shutdown Protects Circuit Through
DC/DC converters with dual, low dropout regulator con-
70V Transients
trollers. The switching converter is a step-down converter n
2.6A Output Switching Regulator with Internal
capable of generating up to 2.6A at its output. Each regu-
Power Switch
lator has independent track/soft-start circuits simplifying n
Dual, Low Dropout, Linear Regulator Controllers
power supply sequencing and interfacing with micro-
with Programmable Current Limit
controllers and DSPs. n Tracking/Soft-Start Inputs and Power Good Output The switching frequency is set with a single resistor with a Simplify Soft-Start and Supply Sequencing range of 250kHz to 2.5MHz. The high switching frequency n Uses Small Inductors and Ceramic Capacitors permits the use of small inductors and ceramic capacitors n VOUT(MIN) = 0.75V (Buck and LDOs) leading to very small triple output solutions. The constant- n Adjustable 250kHz to 2.5MHz Switching Frequency switching frequency, combined with low impedance ce- n Accurate Enable Threshold Allows User ramic capacitors, results in low, predictable output ripple. Programmable Undervoltage Lockout Protection circuitry senses the current in the power switch n Options for Clock Synchronization (LT3694) or Clock and external Schottky catch diode to protect the LT3694 Output to Enable Synchronization to Other Switching against short-circuit conditions. Frequency foldback and Regulators (LT3694-1) thermal shutdown provide additional protection. n Thermally Enhanced 28-Lead 4mm × 5mm QFN and 20-Lead TSSOP Packages With its wide input voltage range of 4V to 36V, the LT3694 regulates a broad array of power sources from 4-cell batteries
APPLICATIONS
and 5V logic rails to unregulated wall transformers, lead acid n batteries and distributed power supplies. The LT3694 can be Automotive n synchronized to an external clock with the SYNC pin while Industrial n the LT3694-1 offers a CLKOUT pin allowing other DC/DC DSL and Cable Modems n converters to synchronize to the LT3694-1 clock. Distributed Power Regulation n Wall Transformer Regulation L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
VIN
Efficiency at VOUT = 3.3V
4.5V TO 36V 4.7µF EN/UVLO VIN BIAS BST 0.22µF 100 4.7µH f OUT1 SW = 800kHz TRK/SS1 SW 3.3V VIN = 4.5V TRK/SS2 1.7A 90 1nF B340A 34k VIN = 12V TRK/SS3 DA FB1 0.1Ω LT3694 330pF 47µF 80 VIN = 36V OUT1 LIM2 41.2k V 10k C1 DRV2 OUT2 70 2.5V LIM3 OUT1 EFFICIENCY (%) 450mA 0.1Ω DRV3 24.9k OUT3 2.2µF FB2 60 1.8V SYNC 450mA 15.4k 2.2µF 10.7k 50 PGOOD FB3 0 1 2 3 51.1k RT GND 11k IOUT (A) 36941 TA01b fSW = 800kHz 36941 TA01a 36941fb 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Typical Application Related Parts