36V, 1.5A Buck and 1.5A Boost 2MHz Step-Down DC/DC Converters & LDO Controller in 4mm × 4mm QFN
Linear Technology Corporation announces the LT3570, a 36V, 1.5A(ISW) buck and boost regulator combined with a linear controller packaged in a 4mm × 4mm QFN or TSSOP-20E. The LT3570 operates from a VIN range of 2.5V to 36V (40VMAX), making it ideal for the load dump and cold-crank conditions commonly found in automotive applications. Independent input pins can be tied together to run from a single input or can be run from independent input rails. The buck regulator can deliver up to 1A of continuous output current at voltages as low as 0.8V whereas the boost converter can deliver output voltages as high as 38V.
The LDO controller combined with an external NPN transistor can be run from the output of the buck regulator for maximum efficiency or via an independent input pin for design flexibility, either way providing low noise operation. Switching frequency is user programmable from 500kHz to 2MHz, enabling the designer to optimize efficiency while avoiding critical noise-sensitive frequency bands and is synchronizable from 650kHz to 2.5MHz. The combination of its 4mm × 4mm QFN package (or thermally enhanced TSSOP-20) and high switching frequency, which keeps external capacitors and the inductor small, provides a very compact, thermally efficient footprint.
Both the LT3570s buck and boost switchers utilize high efficiency 1.5A, 240mVCESAT switches, with the necessary oscillator, control, logic circuitry and LDO controller integrated into a single die. Special design techniques enable efficiencies of up to 88% over a wide input voltage range while current mode topology enables fast transient response and excellent loop stability. Other features include independent soft-start capability for each channel and thermal shutdown.
The LT3570EUF is packaged in a 4mm × 4mm QFN and pricing starts at $2.95 each, for 1,000-piece quantities. The LT3570EFE is packaged in a thermally enhanced TSSOP-20 and pricing starts at $3.05 each, for 1,000-piece quantities. The LT3570IUF and LT3570IFE are tested and guaranteed to operate from a –40°C to 125°C operating junction temperature and are priced at $3.39 each and $3.51each, respectively for 1,000-piece quantities. All versions are available from stock.
Summary of Features: LT3570
- 2.5V to 36V Input Voltage Range
- Programmable Switching Frequency from 500kHz to 2MHz
- Synchronizable Up to 2.5MHz
- Buck VOUT(MIN) = 0.8V
- Boost : VOUT(MAX) = 38V
- Independent Soft-Start for Each Converter
- Separate VIN Supplies for Each Converter
- Duty Cycle Range: 0% to 90% at 1MHz
- Available in Thermally Enhanced 24-Lead (4mm × 4mm) QFN & 20-Lead TSSOP Packages
36V, 1.5A (ISW), 2MHz Buck & Boost Switching Regulator with LDO Controller
Editor's Contact Information
- Doug Dickinson