USB Type-C is a kind relative to standard of newer peripheral of high power USB, use at the computer and portable electron equipment.

 

USB Type-C standard urged the change of standard of USB power supply, unlike standard of long-standing 5 V USB, the total line voltage of Type-C standard is highest can amount to 20 V, electric current conveys ability highest can amount to 5 A.

 

Connective USB-C equipment can identify each other and negotiate —— of bus line voltage to output a few from acquiescent 5 V USB taller set voltage social estate beforehand, so that be when need,the batteries with quicker implementation charges and higher power is carried (highest can amount to 100 W) .

 

What use in batteries charger is simple and compact model step-down adjuster and linear manostat, need 5 V, 500 MA only the USB power supply to 2 A, cover range of power source of all Type-C USB not adequately. The voltage scope that Type-C USB power source increases (5 V comes 20 V) , of need is 9 V not just to 36 V (or 60 V) car batteries or other charge the step-down changeover of power source, still need adjustable step-down – step up converter, so that can be opposite at the same time,the input undertakes step up and step-down to output voltage.

 

In addition, to charger of USB of high power car, step-down – step up converter should support 10 A or rating of electric current of switch of higher peak value, provide low EMI performance. switch frequency the setting is besides AM radio frequency band the ability that makes the solution holds small size is to suffer quite chase after the character that hold in both hands. High pressure is odd a converter (belt piece on switch) cannot bear electric current of so tall peak value switch and not burn down.

 

LT8390A is a distinctive 2 MHz synchronous quarto closes step-down – step up controller. When frequency of 2 MHz switch, it can offer 5 V the output voltage to 15 V (when 3 A highest 45 W) , it is USB-C equipment power supply in order to carry car battery. So tall controller switch frequency makes solution size very small, bandwidth is very tall, and the EMI besides AM radio frequency band is very low. Enlarge frequency frequency modulation and low EMI electric current detect the strict test that the framework all conduces to LT8390A application adopting standard of EMI of class of CISPR 25 Class 5.

 

 

High power density changes: Dimension (with power) , efficiency, quantity of heat

 

The design of the voltage regulator system that works in car or environment of portable electron equipment, be restricted by the caloric of the generation when the dimensional demand of circuit and job. When giving a design to restrain the job below the condition, two elements decided above to be able to achieve the upper limit of power level.

 

The switch frequency that improves a design allows to use lesser inductance, and this often quarto of wide input voltage closes step-down – the element with the largest size in design of step up manostat. Design photograph comparing with 150 KHz or 400 KHz, the support of competence of frequency of 2 MHz switch of LT8390A uses measure small much inductance. Graph 1 showed a sound design. Besides lesser inductance, this solution uses electric capacity of pottery and porcelain output only, need not use volume bigger electroanalysis capacitance. What what this design needs is all yuan of parts of an apparatus (include IC) include in a 1 square inch small-sized circuit board on, if pursue,1 is shown.

 

 

 

 

Graph 1. 1 square inch the solution of power source of efficient, low EMI USB Type-C of size.

 

Pursue 2 showed one employs the solution of 45 W LT8390A that accords with yuan of parts of an apparatus of AEC standard.

 

 

 

 

Graph 2. Solution of this LT8390A manostat uses the MOSFET that accords with AEC standard, magnetic component and electric capacity, offer output of low EMI of electric current of highest 3 A and optional 5 V, 9 V or 15 V.

 

This design photograph is 65°C than the highest temperature rise of environmental temperature, if pursue,3 are shown.

 

 

 

 

Graph 3. While generation 45 W outputs power, this the biggest temperature rise of small-sized circuit compares environmental temperature tall 65°C only.

 

Although solution size is very small, but the peak value efficiency when LT8390A system is offerring 45 W to output can be amounted to 94% ; Inside complete input limits, to the every output tension that produces, efficiency deviation is less than 10% , if pursue,4 medium chart are shown.

 

 

 

 

Graph 4. When using power supply of car SLA batteries, to outputting voltage completely, LT8390A manostat system maintains 94% to the efficiency of 84% .

 

 

LT8390A has a variety of unique character that reduce EMI, can achieve high power changeover and low noise performance, simplify thereby its are carried out mediumly in car system. LT8390A and other quarto close the notable difference between controller to depend on inductance electric current detecting the position of resistor. Most quarto closes step-down – step up controller often uses ground connection radical to allow electric current to detect plan will obtain information of switch electric current, and LT8390A detects its electric current resistor and inductance series connection. Through will detecting resistor and inductance establish ties, can heat up resistor effectively annulus from step-down and step up move in the road except, narrow annulus road measure improves EMI performance thereby.

 

Detect besides inductance outside the framework advantage of resistor position, LT8390A is returned inside the EMI that function of frequency modulation of buy enlarge frequency produces with reducing controller further. In addition, the edge rate of step-down and switch of step up power uses a few discrete element to control only, with slow down MOSFET guide, ensure to proper balance is reached between the high frequency EMI that reducing power switch and temperature rise. Reduce the character of EMI by right of these, the small-sized ferrite filter that goes up by input and output offers the exclusive filter that place of standard of contented CISPR 25 needs, is not large ferrite crust and blundering LC filter. The solution that the graph shows 1 times uses those who accord with AEC-Q100 standard design of yuan of parts of an apparatus.

 

 

The output voltage of LT8390A can fall in the case that does not close converter undertake adjustment, the method is to use logistic n signal to come drive MOSFET, adjust thereby the resistor voltage divider that outputs end in order to change set voltage. The USB PD source control that takes GPIO to cite a base implement can cooperate to use with LT8390A system, join for lead plane and USB between equipment negotiate a process to offer advantage, install needs total line voltage.

 

Graph 5 showed LT8390A system output outputs voltage to be changed smoothly to another to output voltage from. Should input power source power supply from 12 V when, the ascendant follow that commands signal from the number begins to measure, change higher output voltage to need 150μs to be able to be stabilized at most every time. During output voltage is changed, step-down – step up and step-down of experience of step up controller, step-down – the mode changeover between step up operation, specific depend on input and the relation that output voltage. These mode changeover are carried out with controlled means, prevent to output voltage to be spent too rush or drop.

 

 

 

 

Graph 5. LT8390A system outputs smooth between 5 V, 9 V and 15 V output transition, carry power continuously to output end at the same time.

 

 

Want to will output power level to raise 45 W above, need works with inferior switch frequency, so that reduce switch loss, otherwise level of this kind of power may bring thermal stress to MOSFET. Serve as LT8390A replace a product, the working frequency interpose of LT8390 is mixed at 150 KHz between 600 KHz, have as same as LT8390A characteristic combination, can realize step-down of low EMI, high power – step up design. Use bigger inductance and the system of 400 KHz LT8390 that export capacitance, can use car batteries easily to input the output power that achieves 100 W, temperature rise is inside acceptable range. Graph the 6 power ability that showed all sorts of batteries power supply input next LT8390A and LT8390 product line.

 

 

 

 

Graph 6. LT8390A and LT8390 covered all sorts of output power social estate of USB power supply.

 

Be aimed at the new USB standard of the manostat that is join equipment power supply, the output voltage range that support can offer through increasing manostat and electric current are carried will realize higher power to transmit. Portable need step-down of a kind of wide VIN/VOUT with the USB-C charger equipment of car batteries power supply – step up manostat, so that carry prep above or the total line voltage under input voltage. Frequency of 2 MHz switch makes LT8390A can provide the output power of highest 45 W, solution size is very small. To exceeding the power level of 45 W, can use LT8390, nevertheless meeting appreciably increases solution size, switch frequency can be reduced.