Features

• Wide V_IN Range: 3.4V to 60V
• Wide V_OUT Range: 0V to –28V
• Single Resistor V_OUT Programming
• Integrated 110mΩ Top N-Channel/50mΩ Bottom N-Channel MOSFETs
• Regulated I_Q: 440μA, Shutdown I_Q: 15μA
• Board GND Referenced I/O Pins (RUN, PGOOD, MODE/SYNC)
• Accurate Resistor Programmable Frequency (300kHz to 3MHz) with ±50% Frequency Sync Range
• 92% Efficiency with 12 V_IN and –5V_OUT
• ±0.8% Output Voltage Accuracy
• Peak Current Mode Operation
• Burst Mode® Operation, Forced Continuous Mode
• Programmable Soft-Start
• Overtemperature Protection
• Available in 28-Lead (4mm x 5mm) QFN and TSSOP Packages

Typical Application

Description

The LTC®7149 is a high efficiency 60V, 4A synchronous monolithic step-down regulator for inverting output applications. The regulator features a single resistorprogrammable output voltage and high efficiency over a wide V_OUT range.

The inverting regulator operates from an input voltage range of 3.4V to 60V and provides an adjustable output from (–28V) to zero volts while delivering up to 4A of inductor current. The switching frequency is also set with an external resistor. A user-selectable mode input is provided to allow the user to trade off ripple noise for efficiency at light loads; Burst Mode operation provides the highest efficiency at light loads, while forced continuous mode provides low output ripple. The MODE/SYNC pin can also be used to synchronize the switching frequency to an external clock. Internal level-shift circuits allow the I/O pins (RUN, MODE/SYNC, PGOOD) to be referenced to board GND.

The LTC7149 operates with a peak current mode architecture that allows for fast transient response with inherent cycle-to-cycle current limit protection.