Features

• V_IN Range: 2.25V to 5.5V
• V_OUT Range: 0.6V to 5V
• Programmable Frequency Operation; 2.25MHz, or Adjustable Between 0.75MHz to 4MHz
• Low R_DS(ON) Internal Switches
• High Efficiency: Up to 96%
• No Schottky Diodes Required
• Short-Circuit Protected
• Current Mode Operation for Excellent Line and Load Transient Response
• Low Ripple Burst Mode Operation (30mV_P-P), I_Q = 160μA
• Ultralow Shutdown Current: I_Q < 1μA
• Low Dropout Operation: 100% Duty Cycle
• Power Good Output For Each Channel
• Externally or Internally Programmable Burst Level
• External or Internal Soft-Start or Supply Tracking
• Available in Thermally Enhanced 28-Lead (4mm × 5mm) QFN and TSSOP Packages

Typical Application

Description

The LTC®3546 is a dual, constant-frequency, synchronous step down DC/DC converter for medium power applications. The design consists of 2A and 1A primary output switches. In addition to the 2A/1A capability, a 1A dependant output switch can be externally connected to either of the primary outputs to produce 3A/1A dual regulator or 2A/2A dual regulator configurations.

Supply operation is from 2.25V to 5.5V. The switching frequency can be set to 2.25MHz, adjustable from 0.75MHz to 4MHz, or synchronized to an external clock. Each output is adjustable from 0.6V to 5V and has output tracking on power-up. Internal synchronous low R_DS(ON) power switches provide high efficiency without external Schottky diodes.

User-selectable modes (Burst Mode® operation, pulse skipping and forced continuous) allow a trade-off between ripple noise and power efficiency. Burst Mode operation provides high efficiency at light loads. Pulse-skipping mode provides low ripple noise at light loads.

The device is capable of low dropout configurations and both channels can operate at 100% duty cycle. In shutdown, the device draws <1μA.