17V, 1A Synchronous Step-Down Regulator with 3.5μA Quiescent Current IC

Features
* Wide VIN Range: 2.7V to 17V
* Wide VOUT Range: 0.6V to VIN
* 95% Max Efficiency
* Low IQ < 3.5µA, Zero-Current Shutdown
* Constant Frequency (1MHz/2.25MHz)
* Full Dropout Operation with Low IQ
* 1A Rated Output Current
* ±1% Output Voltage Accuracy
* Current Mode Operation for Excellent Line and Load Transient Response
* Pulse-Skipping, Forced Continuous, Burst Mode® Operation
* Internal Compensation and Soft-Start
* Overtemperature Protection
* Compact 6-Lead DFN (2mm × 3mm) Package or 8-Lead MSOPE
   Package with Power Good Output and Independent SGND Pin
Applications

* Portable-Handheld Scanners
* Automotive Applications
* Emergency Radio

Description

The LTC®3621/LTC3621-2 is a high efficiency 17V, 1A synchronous monolithic step-down regulator. The switching frequency is fixed to 1MHz or 2.25MHz. The regulator features ultralow quiescent current and high efficiencies over a wide VOUT range. The step-down regulator operates from an input voltage range of 2.7V to 17V and provides an adjustable output range from 0.6V to VIN while delivering up to 1A of output current. A user-selectable mode input is provided to allow the user to trade off ripple noise for light load efficiency; Burst Mode operation provides the highest efficiency at light loads, while pulse-skipping mode provides the lowest voltage ripple.

Typical Application

Absolute Maximum Ratings
VIN Voltage (Note 2)................................... 17V to –0.3V
SW Voltage DC................................. VIN + 0.3V to –0.3V
Transient (Note 2)...................................19V to –2.0V
RUN Voltage................................................ VIN to –0.3V
INTVCC, PGOOD Voltages ............................ 6V to –0.3V
Operating Junction Temperature Range (Note 3)
    .................................................. –40°C to 125°C
Storage Temperature Range .................. –65°C to 125°
CMODE, FB Voltages ...................................... 6V to –0.3V

Typical Performance CharacteristicsTJ = 25°C, unless otherwise noted.