Linear 105V 2.3A Low EMI Buck Regulator Solution--Introduction to LTC7103

Linear's LTC7103 is a high efficiency monolithic synchronous step-down DC/DC converter with a constant frequency average current mode control architecture with input voltages from 4.4V to 105V, adjustable output voltage from 1V to VIN, and output current up to 2.3A. Ultra low EMI/EMC, CISPR 25 compatible, 100% maximum duty cycle operation, programmable frequency 200kHz-2MHz. Mainly used in battery chargers and CC/CV power supplies, automotive and military systems, industrial, aerospace and heavy equipment And medical equipment and communication systems. This article describes the main features of the LTC7103, block diagrams and a variety of application circuits, as well as the demo board DC2317A, circuit diagram and bill of materials.

The LTCR7103 is a high efficiency, monolithic synchronousstep-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 anadjustable regulated output voltage from 1V to VIN whiledelivering up To 2.3A of output current.

The LTC7103 features high frequency operaTIon anda low minimum on-TIme that reduce inductor size and enable constant-frequency operaTIon even at very highstep-down ratios. In addition, the LTC7103 achieves the lowest possible dropout voltage with 100% maximum duty cycle operation. , converterefficiency and output ripple can be optimized by selectingBurst Mode or pulse-skipping operation.

The LTC7103 includes accurate, high speed average current programming and monitoring without the need for the 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.

Main features of LTC7103:

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
100% Maximum Duty Cycle Operation
Programmable Fixed Frequency: 200kHz to 2MHz
Eight, Pin-Selectable Fixed (1.2V to 15V) orAdjustable Output Voltages
Selectable Pulse-Skipping or Low Ripple BurstModeR Operation at Light Loads
PLL Synchronization to External Clock
EXTVCC LDO Powers Chip from VOUT = 3.3V to 40V
OPTI-LOOPR or Fixed Internal Compensation
Input and Output Overvoltage Protection
Thermally Enhanced (5mm × 6mm) QFN Package

LTC7103 application:

Battery Chargers and CC/CV Supplies
Automotive and Military Systems
Industrial, Avionics and Heavy Equipment
Medical Instruments and TelecommunicationSystems

Figure 1. LTC7103 block diagram

Figure 2. LTC7103 Application Circuit: High Efficiency 5V-100V Input, 5V/2.3A Output

Figure 3. LTC7103 application circuit: high efficiency 12V-100V input, 12V/2.3A output

Figure 4. LTC7103 Application Circuit: Low EMI 5V-100V Input, 5V/2.3A Output

Figure 5. LTC7103 application circuit: 2-phase, 12V-100V input, 12V/4.6A output

Figure 6. LTC7103 application circuit: automotive 12V/24V input, 12V/24V 2.3A output, 100V input surge, 0.5 second fault timer

Figure 7. LTC7103 Application Circuit: 50W LED Driver

Figure 8. LTC7103 Application Circuit: 2.5A 6 SLA Battery Charger with Charge Termination

Demo board DC2317A

Demonstration circuit 2317A is a 100V monolithic DC/DC step-down regulator featuring the LTC®7103. Thedemo board is designed for a 5V/2.3A output from a 5Vto 100V input at 400kHz switching frequency. The wideinput range makes it suitable for automotive, Industrial,medical instrument, and telecom applications. This buckregulator has a peak efficiency of 93.5% at 12VIN, 88.3%at 48VIN and 81.5% at 100VIN.

The LTC7103 is a compact, high efficiency synchronous monolithic step-down switching regulator with fast current programming. The power switches, compensationnetwork and other necessary circuits are inside of the LTC7103 to minimize external components and simplifydesign. The LTC7103 has wide operating range from 4.4Vto 105V. 40ns minimum on-time, together with 100%maximum duty cycle allow practical use at any output voltagebetween 1V and VIN. The switching frequency can beprogrammed either via an oscillator resistor or an externalclock over a 200kHz to 2MHz range. Additional featuresinclude a fast and accurate Output current programming and monitoring, and ultralow EMI/EMC emissions.

The EMI performance of the board (with EMI filter) is shown in Figure 2. The figure shows that the circuit passes the CISPR 25 radiated emission test with a wide margin. Toachieve EMI/EMC performance as shown in Figure 2, theinput 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. This demo board allows phase-lockedloop (PLL) synchronization To an external clock by selecting SYNC mode on JP1 and by providing a clock signalon CLKIN turret.

The LTC7103 data sheet gives a complete description of the part, operation and application information. The datasheet must be read in conjunction with this demo manual for DC2317A. The LTC7103 is assembled in the 36 (26)lead QFN package. Proper board layout is essential formaximum thermal And electrical performance. See the data sheet sections for details.

Figure 9. Outline drawing of the demo board DC2317A

Figure 10. Demo board DC2317A measurement setup diagram

Figure 11. Demo Board DC2317A Circuit Diagram Demo Board DC2317A Bill of Materials:

27 Inch AIO

27 Inch Aio,All In One Pc 27 Inch,All In One Desktop Touch Screen,All In One Pc Touch Screen

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