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08-09-2017

105V, 2.3A Synchronous Step-Down Regulator Delivers 96% Efficiency with Ultralow EMI/EMC Emissions

Analog Devices » LTC7103

Analog Devices, Inc., which recently acquired Linear Technology Corporation, announces the LTC7103, a 2.3 A, 105 V input capable synchronous step-down switching regulator. Its wide 4.4 V to 105 V input voltage range is designed for operation from a continuously high voltage input source or from an input that has high voltage surges, eliminating the need for external surge suppression devices. This makes the LTC7103 ideal for a variety of transportation, industrial and communications applications such as 48 V automotive, 36 V to 72 V telecom, avionics and dual battery vehicle systems.

Analog Devices - LTC7103

The LTC7103’s high efficiency internal power switches can deliver up to 2.3 A of continuous output current. The LTC7103 incorporates proprietary technology that reduces EMI/EMC emissions to an ultralow level, easily passing automotive CISPR#25, Class 5 limits without sacrificing efficiency. The LTC7103 delivers efficiencies over 96% while regulating a 12 V output and over 90% while regulating a 3.3 V output. To avoid noise-sensitive frequency bands, the switching frequency can be set between 200 kHz and 2 MHz, or synchronized anywhere in this range using the LTC7103’s internal phase-locked loop.

5 V to 105 V Input to 5 V/2.3 A Output Step-Down Regulator
5 V to 105 V Input to 5 V/2.3 A Output Step-Down Regulator.

The LTC7103 uses a unique constant frequency average current mode control architecture. This enables a fast transient response with excellent loop stability as well as fast and accurate output current programming and monitoring with no external sense resistor. This adjustable, brick-wall style current limit feature makes the LTC7103 well suited for current source applications such as battery or capacitor charging and LED lighting.

Efficiency vs Load Current
Efficiency vs Load Current.

The LTC7103 draws only 2 μA of input quiescent current while regulating the output voltage at no load, extending battery operating life in always-on applications. Low ripple Burst Mode® operation maintains high efficiency at light load currents while keeping output ripple small. To further minimize ripple, a pulse-skipping mode can also be selected. The LTC7103 features a low minimum on-time of 40 ns and a maximum duty cycle of 100%, enabling the output voltage to be set anywhere from 1 V up to the input voltage. The LTC7103 features eight pin-selectable fixed output voltage set points that include commonly used rails from 1.2 V to 15 V. These pre-programmed output voltages save board space and reduce the no-load quiescent current by eliminating an external resistor divider. Internal voltage loop compensation automatically adjusts based on the switching frequency to ensure both speed and stability.

DC2317A - 105 V, 2.3 A Low EMI Synchronous Step-Down Regulator Demo Board
DC2317A – 105 V, 2.3 A Low EMI Synchronous Step-Down
Regulator Demo Board.

Alternatively, the voltage loop can be optimized externally using OPTI-LOOP® compensation. The LTC7103 is packaged in a thermally enhanced 5 mm × 6 mm QFN-36(26) package with high voltage pin spacing. An industrial temperature version, the LTC7103IUHE, is tested and guaranteed to operate from a –40 °C to 125 °C operating junction temperature. Similarly a high temperature version, the LTC7103HUHE, operates from a –40 °C to 150 °C operating junction temperature. Finally, a high reliability version, the LTC7103MPUHE, operates from a –55 °C to 150 °C operating junction temperature. Pricing starts at $4.50 each in 1,000-piece quantities and all versions are available from stock.

Summary of Features: LTC7103

  • Wide VIN Range: 4.4 V to 105 V (110 V Abs Max)
  • Ultralow EMI/EMC Emissions: CISPR#25 Class 5 Compliant
  • 2 μA IQ When Regulating 48 VIN to 3.3 VOUT
  • Fast and Accurate Output Current Programming & Monitoring with No External RSENSE
  • Brick Wall Current Limit
  • Low Minimum On-Time: 40 ns
  • Wide VOUT Range: 1 V to VIN
  • 100% Maximum Duty Cycle Operation
  • Programmable Fixed Frequency: 200 kHz to 2 MHz
  • Eight, Pin-Selectable Fixed (1.2 V to 15 V) or Adjustable Output Voltages
  • Selectable Pulse-Skipping or Low Ripple Burst Mode® Operation at Light Loads
  • PLL Synchronization to External Clock
  • EXTVCC LDO Powers Chip from VOUT = 3.3 V to 40 V
  • OPTI-LOOP® or Fixed Internal Compensation
  • Input & Output Overvoltage Protection
  • Thermally Enhanced (5 mm × 6 mm) QFN Package
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