Features

• Wide Input Range: 4V to 36V
• Overvoltage Shutdown Protects Circuit Through 70V Transients
• 2.6A Output Switching Regulator with Internal Power Switch
• Dual, Low Dropout, Linear Regulator Controllers with Programmable Current Limit
• Tracking/Soft-Start Inputs and Power Good Output Simplify Soft-Start and Supply Sequencing
• Uses Small Inductors and Ceramic Capacitors
• V_OUT(MIN) = 0.75V (Buck and LDOs)
• Adjustable 250kHz to 2.5MHz Switching Frequency
• Accurate Enable Threshold Allows User Programmable Undervoltage Lockout
• Options for Clock Synchronization (LT3694) or Clock Output to Enable Synchronization to Other Switching Regulators (LT3694-1)
• Thermally Enhanced 28-Lead 4mm × 5mm QFN and 20-Lead TSSOP Packages

Typical Application

Description

The LT3694/LT3694-1 are monolithic, current mode DC/DC converters with dual, low dropout regulator controllers. The switching converter is a step-down converter capable of generating up to 2.6A at its output. Each regulator has independent track/soft-start circuits simplifying power supply sequencing and interfacing with microcontrollers and DSPs.

The switching frequency is set with a single resistor with a range of 250kHz to 2.5MHz. The high switching frequency permits the use of small inductors and ceramic capacitors leading to very small triple output solutions. The constant switching frequency, combined with low impedance ceramic capacitors, results in low, predictable output ripple. Protection circuitry senses the current in the power switch and external Schottky catch diode to protect the LT3694 against short-circuit conditions. Frequency foldback and thermal shutdown provide additional protection.

With its wide input voltage range of 4V to 36V, the LT3694 regulates a broad array of power sources from 4-cell batteries and 5V logic rails to unregulated wall transformers, lead acid batteries and distributed power supplies. The LT3694 can be synchronized to an external clock with the SYNC pin while the LT3694-1 offers a CLKOUT pin allowing other DC/DC converters to synchronize to the LT3694-1 clock.