4 MHz synchronous buck regulator delivers 2.5 A of continuous output current at low output voltages

Linear Technology has developed a high efficiency, 4 MHz synchronous buck regulator that incorporates a constant frequency/controlled on-time, current mode architecture.

The LTC3604 can deliver up to 2.5 A of continuous output current at output voltages as low as 0.6 V from a 3 mm x 3 mm QFN or MSOP-16E package.

The device's current mode operation offers excellent line and load transient response even with high step-down ratios. The LTC3604 operates from an input voltage of 3.6 V to 15 V, making it ideal for applications powered from dual-cell Li-Ion battery stacks as well as 5 V and 12 V intermediate bus systems. Its switching frequency is user programmable from 800 kHz to 4 MHz, enabling the use of tiny, low cost capacitors and inductors.

The LTC3604 uses internal switches with RDS(ON) of only 100 mOhms and 130 mOhms to deliver efficiencies as high as 95 percent. The device's control architecture enables it to achieve duty cycles as low as five percent while maintaining switching frequencies as high as 2.25 MHz, making it ideal for high step-down ratio applications, such as 12 VIN to 1.2VOUT conversions. Burst Mode operation is used to maximize light load efficiency, requiring only 300 μA (at no load) and making the LTC3604 well suited for applications demanding maximum battery run time. For applications requiring the lowest possible noise, the LTC3604 can be configured to run in forced continuous mode, for minimum noise and potential RF interference. Additional features include a power good voltage monitor, output voltage tracking capability, and short circuit protection.

Summary of Features: LTC3604

  • 3.6 V to 15 V Operating Input Voltage Range
  • 2.5 A Output Current
  • Up to 95 percent Efficiency
  • Very Low Duty Cycle Operation: 5 percent at 2.25 MHz
  • Adjustable Switching Frequency: 800 kHz to 4 MHz
  • External Frequency Synchronization
  • Current Mode Operation for Excellent Line and Load Transient Response
  • User-Selectable Low Ripple (20 mVP-P ) Burst Mode (No Load IQ =300 μA) or Forced Continuous Operation
  • 0.6 V Reference Allows Low Output Voltages
  • Short-Circuit Protected
  • Output Voltage Tracking Capability
  • Power Good Status Output

  • Available in Small, Thermally Enhanced, 16-Pin QFN (3 mm x 3 mm) and MSOP Packages

Availability and Pricing

The LTC3604EUD is available in a 3 mm x 3 mm QFN-16 and the leaded version, the LTC3604EMSE, is available in a MSOP-16E package. Pricing starts at $3.25 each in 1,000-piece quantities. Industrial grade versions, the LTC3604IUD and LTC3604IMSE, are guaranteed to operate over the -40 to 125 degrees C operating junction temperature range, priced at $3.61 each in 1,000-piece quantities. All versions are available from stock.



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