原标题：Linear LT8616高效高速双路降压电源解决方案

　　Linear公司的LT8616是高效高速双路同步降压开关稳压电源,静态电源功耗仅为6.5uA.器件包括了开关和所有必需的电路,从而最少化外接元件.输入电压3.4V到42V,单独输入时的降压稳压器输出电流为2.5A和1.5A,输出波纹小于15mV,主要用在汽车和工业电源,以及通用电源.本文介绍了LT8616主要特性,框图,多种应用电路,以及演示板2169A主要特性,电路图,材料清单和PCB元件布局图.

　　The LTR8616 is a high efficiency, high speed, dual synchronousmonolithic step-down switching regulator that consumesonly 6.5μA of quiescent current with both channelsenabled. Both channels contain all switches and necessary circuitry to minimize the need for external components.

　　Low ripple Burst Mode operation enables high efficiencydown to very low output currents while minimizing outputripple. A SYNC pin allows synchronization to an externalclock. Internal compensation with peak current modetopology allows the use of small inductors and results infast transient response and good loop stability. The enablepins have accurate 1V thresholds and can be used toprogram undervoltage lockout. Capacitors on the TR/SSpins programs the output voltage ramp rate during startupwhile the PG pins signal when each output is within10% of the programmed output voltage. The LT8616 isavailable in a TSSOP package for high reliability.

　　LT8616主要特性:

　　Wide Input Voltage Range: 3.4V to 42V

　　2.5A and 1.5A Buck Regulators with Separate Inputs

　　Fast Minimum Switch On-Time: 35ns

　　Ultralow Quiescent Current Burst Mode® Operation:

　　6.5μA IQ Regulating 12VIN to 5VOUT and 3.3VOUT

　　Output Ripple < 15mV

　　180°Out of Phase Switching

　　Adjustable and Synchronizable: 200kHz to 3MHz

　　Accurate 1V Enable Pin Thresholds

　　Internal Compensation

　　Output Soft-Start and Tracking

　　TSSOP Package: Output Stays at or Below RegulationVoltage During Adjacent Pin Short or When a Pin IsLeft Floating

　　Thermally Enhanced 28-Lead TSSOP Package

　　LT8616应用:

　　Automotive and Industrial Supplies

　　General Purpose Step-Down

　　图1. LT8616框图

　　图2. LT8616应用电路图:5V, 3.3V, 700kHz降压转换器

　　图3. LT8616应用电路图:5V,2.5V,2.05MHz降压转换器

　　图4. LT8616应用电路图:3.3V,0.79V,1MHz 2级降压转换器,顺序起动

　　LT8816演示板2169A

　　Demonstration circuit 2169A is a dual monolithic step-downDC/DC switching regulator featuring the LT®8616. TheLT8616 is a high efficiency, high speed, dual synchronousmonolithic step-down switching regulator that consumesonly 6.5μA of quiescent current with both channels enabled.

　　The demo circuit is designed for 5V, 1.5A and 3.3V, 2.5Aoutputs. Both channels contain all switches and necessarycircuitry to minimize the external components andsolution size. Fast minimum ON time of 35ns enables high VIN to low VOUT conversion at high switching frequency.

　　Independent input voltage, feedback, soft-start and powergood pins for each channel simplify complex power supplytracking/sequencing requirements.The inputs of the two channels are connected on the demoboard by default. They can also be separated by removingthe 0Ω resistor (R13) from the board. Each output canbe independently disabled using its own EN/UV pin, while VIN1 must be connected to 3.4V or above even if onlychannel 2 is in use. The demo board has an EMI filterinstalled between VIN2 and VEMI. To use the EMI filter, theinputs should be tied to VEMI.

　　The switching frequency of both channels can be programmedeither via an oscillator resistor or a commonexternal clock up to 3MHz.The SYNC pin on the demoboard is grounded by default for Burst Mode® operation.

　　To synchronize to an external clock, move JP1 to SYNC/MODE and apply the external clock to the SYNC/MODEturret. The RT resistor (R5) should be chosen to set theLT8616 internal switching frequency at least 20% belowthe lowest synchronization input.

　　Low ripple Burst Mode operation increases the efficiencyat the light load while keeping the output ripple low.

　　The LT8616 data sheet gives a complete description of thepart, operation and application information. The data sheetmust be read in conjunction with this demo manual forDC2169A. The LT8616 is assembled in a 28-lead plastic TSSOP package. Proper board layout is essential for bothlow EMI operation and maximum thermal performance.See the data sheet sections for details.