Dual 3A synchronous voltage regulation technology based on LTC3615 design - Power Circuit - Circuit Diagram

The LTC3615 is a dual 3A synchronous buck regulator with a current mode fixed frequency architecture. The input voltage is 2.25V-5.5V, the output current is 2x3A, the efficiency is up to 94%, the output voltage is as low as 0.6V, and the output voltage accuracy is ±1%. Adjustable switching frequency up to 4MHz, mainly used as point load power supply, distributed power supply, laptop power supply, DDR memory power supply and handheld devices. This paper introduces the main features of LTC3615, block diagram and various typical application circuits.

The LTC®3615 is a dual 3A synchronous step-down regulator using a current mode, constant-frequency architecture. The DC supply current is only 130μA (Burst Mode operation at no-load) while maintaining the output voltages, dropping to zero current in The 2.25V to 5.5V input supply range makes the LTC3615 ideally suited for single Li-Ion applications. 100% duty cycle capability provides low dropout operation, which extends operating time in battery-operated systems.

The operating frequency is externally programmable up to 4MHz, allowing the use of small surface mount inductors. 0°, 90°, or 180° of phase shift between the two channels can be selected to minimize input current ripple and output voltage ripple in a single 6A output configuration. Programmable slew rate limiting reduces EMI, and external synchronization can be applied up to 4MHz.

The internal synchronous switches increase efficiency and eliminate the need for external catch diodes, saving external components and board space.

The LTC3615 is offered in leadless 24-pin 4mm × 4mm QFN and thermally enhanced 24-pin TSSOP packages.

Main features of LTC3615:

High Efficiency: Up to 94%

Dual Outputs with 2 × 3A Output Current Capability

Low Output Ripple Burst Mode® Operation: IQ = 130μA

2.25V to 5.5V Input Voltage Range

±1% Output Voltage Accuracy

Output Voltages Down to 0.6V

Programmable Slew Rate at Switch Pins

Low Dropout Operation: 100% Duty Cycle

Shutdown Current ≤1μA

Adjustable Switching Frequency Up to 4MHz

Internal or External Compensation

Selectable Pulse-Skipping/Forced Continuous/Burst Mode Operation with Adjustable Burst Clamp

Optional Active Voltage Positioning (AVP) with Internal Compensation

Selectable 0°/90°/180° Phase Shift Between Channels

Fixed Internal and Programmable External Soft-Start

Accurate Start-Up Tracking Capability

DDR Memory Mode IOUT = ±1.5A

Available in 4mm × 4mm QFN-24 and TSSOP-24 Packages

LTC3615 application:

Point-of-Load Supplies

Distributed Power Supplies

Portable Computer Systems

DDR Memory Termination

Handheld Devices

Figure 1. Block diagram of the LTC3615

Figure 2. Typical Application Circuit for the LTC3615

Figure 3. LTC3615 Application Circuit: Path 1 Soft Start and Compensation by External Programming, Path Soft Start and Compensation by Internal Programming