- Wide VIN Range: 4.4V to 105V (110V Abs Max)
- Ultralow EMI/EMC Emissions: CISPR 25 Compliant
- 2μA IQ When Regulating 48VIN to 3.3VOUT
- Fast and Accurate Output Current Programming and Monitoring with No External RSENSE
- Brick Wall Current Limit
- Low Minimum On-Time: 40ns
- Wide VOUT Range: 1V to VIN
- PassThru™/100% Duty Cycle Capable
- Programmable Fixed Frequency: 200kHz to 2MHz
- Eight, Pin-Selectable Fixed (1.2V to 15V) or Adjustable Output Voltages
- Selectable Continuous, Pulse-Skipping, or Low Ripple Burst Mode® Operation at Light Loads
- PLL Synchronization to External Clock
- EXTVCC LDO Powers Chip from VOUT = 3.3V to 40V
- OPTI-LOOP® or Fixed Internal Compensation
- Input and Output Overvoltage Protection
- Thermally Enhanced (5mm × 6mm) QFN Package
- AEC-Q100 Qualification in Process
The LTC7103-1 is a high efficiency, monolithic synchro-nous step-down DC/DC converter utilizing a constant frequency, average current mode control architecture. It operates from an input voltage range of 4.4V to 105V and provides an adjustable regulated output voltage from 1V to VIN while delivering up to 2.3A of output current.
The LTC7103-1 features high frequency operation and a low minimum on-time that reduce inductor size and enable constant-frequency operation even at very high step-down ratios. In addition, the LTC7103-1 achieves the lowest possible dropout voltage with 100% maximum duty cycle operation. During light load operation, converter efficiency and output ripple can be optimized by selecting Burst Mode, pulse-skipping or forced continuous operation.
The LTC7103-1 includes accurate, high speed average current programming and monitoring without the need for an external sense resistor. Additional features include a bypass LDO to maximize efficiency, fixed or adjustable output voltage and loop compensation, and a wide array of protection features to enhance reliability. Compared to the LTC7103, the LTC7103-1 is pin compatible, except that it also offers continuous inductor current mode.
- Battery Chargers and CC/CV Supplies
- Automotive and Military Systems
- Industrial, Avionics and Heavy Equipment
- Medical Instruments and Telecommunication
Demonstration circuit 2833A is a 100V monolithic DC/DC step-down regulator featuring the LTC7103-1. The demo board is designed for a 5V/2.3A output from a 5V to 100V input operation at a 400kHz switching frequency. The wide input range makes it suitable for automotive, industrial, medical instrument, and telecom applications. This buck regulator has a peak efficiency of 93.5% at 12VIN, 88.3% at 48VIN and 81.5% at 100VIN (see Figure 3 in the demo manual).
The LTC7103-1 is a compact, high efficiency synchronous monolithic step-down switching regulator with fast current programming. The power switches, compensation network and other necessary circuits are inside of the LTC7103-1 to minimize external components and simplify design. The LTC7103-1 has wide operating range from 4.4V to 105V. A 40ns minimum on-time, together with 100% maximum duty cycle allow practical use at any output voltage between 1V and VIN. The switching frequency can be programmed either via an oscillator resistor or an external clock over a 200kHz to 2MHz range. Additional features include a fast and accurate output current programming and monitoring, and ultralow EMI/EMC emissions.
The demo board has an EMI filter installed. The EMI performance of the board (with EMI filter) is shown in Figure 2 in the demo manual. The figure shows that the circuit passes the CISPR 25 radiated emission test with a wide margin. To achieve EMI/EMC performance as shown in Figure 2, the input EMI filter is required and the input voltage should be applied at +VIN_EMI turret pin.
The demo board provides current monitor and output clock signal to interface with an external application circuit. User selectable mode selection (JP1) is provided and Burst Mode® operation position is selected by default. Burst Mode operation increases light load efficiency while pulse-skipping mode allows constant-frequency operation to a lighter load. Forced continuous mode improves output voltage ripple at light load by allowing constant-frequency operation for entire range of output load. This demo board allows phase-locked loop (PLL) synchronization to an external clock by selecting SYNC mode on JP1 and by providing a clock signal on CLKIN turret.
The LTC7103-1 data sheet gives a complete description of the part, operation and application information. The data sheet must be read in conjunction with the demo manual for DC2833A. The LTC7103-1 is assembled in the 36 (26) lead QFN package. Proper board layout is essential for maximum thermal and electrical performance. See the data sheet sections for details.