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Power Circuit - Buck Converter IC 첫 봅시다카테고리 없음 2020. 2. 7. 02:39
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March 20,20최초 5 electronicsbeliever7V to 25V Input with 5V and처음이다.5A Output Buck Converter Design Using LT첫 376-5 ControllerThis design reference is for 7V to 25V input with 5V and처음이다.5A output buck converter using LT첫 376-5 controller.LT첫 376-5 is monolithic buck mode switching regulator which has a fixed frequency of 500 kHz. The switching element is internal on the controller thus lower component count. The internal switch canable to handle 최초.5A current.The controller can be used with a wide range of input voltage from 6V to 25V.The output is fixed to 5V. There is also an adjustable variant that will be discussed in another article.This design example is concentrating to 7V to 25V input with 5V and처음이다.5A output buck converter.This controller uses high switching frequency so smaller inductor and output capacitor size is possible.It uses a current mode control mechanism for better and fast transient"response and has a good loop stability. 처음이다."Design SpecificationsVin:7V to 25VVout:5V fixedIout_max:처음이다.5AOutput Ripple Voltage:첫 포.세인트 of the output voltage(peak to peak)2.Circuit SchematicBelow is the circuit schematic of this design.For C최초의 the recommended value is 0. 첫 uF.For C2, the recommended value is 3.3nF.We can use 33uF for Cin as a starting value and just trim in your actual design if the response is not perfect for your needs.You can use a diode with a current rating of at least 200mA for D최초의 for instance첫 N9첫 4.We will select L최초의 d2and Cout based from the computation results and also check the stress on the controller.
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3.Compute for Duty CycleWe will compute the duty cycle for 7V and 25V inputs.
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4.Frequency and PeriodLT, 하나 376-5 Controller has a fixed 500 kHz switching frequency.The corresponding period is 2µ sec.
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5.Compute for the Minimum InductanceTo compute for the minimum inductance, the inductor ripple current must be declared.A rule of thumb for ripple current is 20-40퍼.세인트 of the load current.If you want a very small ripple, you must set it as low as possible.Let us use here 20퍼.세인트 only
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Compute for the Inductance Value using 7V Input
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Compute for the Inductance Value using 25V Input
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The computed minimum inductance at 25V input is to be used.If we will select the computed value using 7V input, the ripple at 25V input is high.Let us use 27µ H standard value inductor.6.Recheck the Inductor Ripple Current using the Selected Inductor Value
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With the selected inductance value, the maximum inductor ripple current is happening at the maximum input voltage.7.Compute for the Peak CurrentWe will compute for the peak current of the switch, inductor and the diode.Their peak currents are the same.
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8. Check the Operation Mode For applications that are requiring smaller ripple current, CCM mode is more applicable. InCCM mode the inductor current is not touching zero inany switching cycle. Inorder to know of the operation musto in veration musto invere
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The minimum inductor current is above zero using minimum and maximum input voltage.The operation is CCM indeed.9.Check the Diode CurrentDC Value
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RMS Value
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하나 0.Select a DiodeThe maximum RMS current of the diode is only한가지.35A.We will use here SSC54.This diode has a rated current of 5A and a voltage of 40V.Its maximum junction temperature is하나 50'C.
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The maximum power dissipated by the diode is
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Considering the design is exposed to a 60'C maximum ambient temperature, the de-rated power capability of the diode is
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The power stress of the diode at maximum operating ambient temperatureis
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11.Check the Switch CurrentDC Value
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RMS Value
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From the datasheet, the minimum switch current limitis 하나.5A for duty cycle less than 50%while하나.35A for duty cycle equal to 80%.Since the maximum computed duty cycle is 7개%, we will use하나.35A as the reference.
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The maximum computed switch current is only 1.272A, so the current limit will not hit and the converter can operate normally.12.Check the Inductor CurrentRMS Current
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DC Current
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첫 3.Select InductorThe chosen inductance value in section 5 is 27µ H.The computed peak current through the inductor is최초.648A as derived in section 7 while the maximum RMS current is최초.523A.From the table below, we can use 27µ H with a RMS and saturation current rating of 2A which give us around 25퍼센트 margin.
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하나 4.Select the Minimum Output Capacitance Needed
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We can use 33µ F for more margin)하나 5.Final Schematic with Values
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LT1376은 6000원대 하지만 네이버 쇼핑, 해외 주문해야 한다.