Features

• High Efficiency: Up to 96%
• 5A Output Current
• 4V to 20V V_IN Range
• Integrated Power N-Channel MOSFETs (70mΩ Top and 35mΩ Bottom)
• Adjustable Frequency 800kHz to 4MHz
• PolyPhase® Operation (Up to 12 Phases)
• Output Tracking
• 0.6V ±1% Reference Accuracy
• Current Mode Operation for Excellent Line and Load Transient Response
• Shutdown Mode Draws Less Than 15μA Supply Current
• LTC3605: 15V Absolute Maximum V_IN
• LTC3605A: 22V Absolute Maximum V_IN
• The LTC3605A Is Pin Compatible with the LTC3605
• Available in 24-Pin (4mm × 4mm) QFN Package

Typical Application

Description

The LTC®3605A is a high efficiency, monolithic synchronous buck regulator using a phase lockable controlled on-time constant frequency, current mode architecture. PolyPhase operation allows multiple LTC3605A regulators to run out of phase while using minimal input and output capacitance. The operating supply voltage range is from 20V down to 4V, making it suitable for dual, triple or quadruple lithium-ion battery inputs as well as point of load power supply applications from a 12V or 5V rail.

The operating frequency is programmable from 800kHz to 4MHz with an external resistor. The high frequency capability allows the use of small surface mount inductors. For switching noise sensitive applications, it can be externally synchronized from 800kHz to 4MHz. The PHMODE pin allows user control of the phase of the outgoing clock signal. The unique constant frequency/controlled on-time architecture is ideal for high step-down ratio applications that are operating at high frequency while demanding fast transient response. Two internal phase-lock loops synchronize the internal oscillator to the external clock and also servos the regulator on-time to lock on to either the internal clock or the external clock if it’s present.