At first sight, choose the first kind of solution, rated input voltage is 36V or the DC/DC converter with wider range of 60V, VIN is met more expensive, because the price of 1ku compares rated input voltage,lower converter wants tall.

 

But, the voltage clamp that protection of voltage of transient state of converter of low input voltage needs circuit can increase 10 to 12 exterior component, can add material detailed account (BOM) the dimension of number and cost and solution.

 

SIMPLE SWITCHER of article general contrast®Converter of solution of converter of step-down of LM43603 36 VIN, 3A and 17 VIN, 3A adds the clamp that absorbs surge voltage the dimension of circuit solution and cost.

 

 

If the graph is shown 1 times, circuit of position control of this input clamp and PFET added 13 exterior element for the solution.

 

If the graph is shown 2 times, the basis announces the price on the net of 1000 amounts, the cost that these 13 exterior component raise is 1.19 dollars. The price that adopts 1000 measures the cost of 0.96 dollars and inductance, capacitance and component of resistor substandard ministry, the cost of solution of 17VIN 3A converter is 1.62 dollars about.

 

Come so, converter of use 17VIN step-down adds clamp the totle drilling cost of circuit is 1.62+1.19=2.81 dollar about. Additional, control circuit and PFET increased the size of low VIN solution to make an appointment with 210 Mm2. 17VIN, 3A converter is 100 Mm2 about, the dimension of whole solution is 100+250=350 Mm2.

 

Graph 2: Control circuit cost detail

 

Another choice is to use resemble SIMPLE SWITCHER®Converter of synchronous step-down of LM43603 36 VIN, 3A inputs the DC/DC converter with voltage bigger range to cover peak value of the biggest VIN so.

 

Below the case that uses the wide VIN parts of an apparatus such as LM43603, design personnel need not use pincers circuit, OK and economic time, cost and advocate board space.

 

According to the price of the 1000 units that announce 1.85 dollars are mixed the cost of inductance, resistor and component of capacitance substandard ministry, the totle drilling cost of LM43603 solution is 2.51 dollars about. This is meant use wide VIN LM43063 to be able to save 0.3 dollars, or about 12% : Dollar of 2.51 dollars VS 2.81.

 

The dimension of the solution is another advantage. The total size of Lm43603 solution is 250 Mm2 about for the total size of 250 solutions about, before comparing one kind of solution is small 24% or 60mm2.

 

The another advantage of the wide VIN solution such as LM43603 is dependability tall. No less than mentions in my article before this, increase exterior component to be able to increase systematic risk.

 

The most credible solution is to employ the simplest solution with exterior least component, because of the risk that reduced component to malfunction so. It is especially in a few cars and industrial application, it is very important to increase dependability.

 

Additional, circuit of position control of design other clamp can be design cycle to increase very big workload. Use control circuit and PFET are meant must choose 12 exterior component again, undertake more tests and imitate, make sure element works normally.

 

The manostat that can adopt wide VIN range realizes lower systematic cost and higher reliability, why to expend Zhou Zhang greatly so even?

 

Of course, of the amount as a result of manufacturer and supplier and contract and design layout different, dimension of the price and solution may have bigger difference.

 

The measure that adopts wide VIN solution to save and cost per cent also can change subsequently. But, I hope the analysis of the article was revealed, although the imprest price of 1000 units is higher, when the wide VIN solution such as LM43603 is handling input voltage transient state to press an issue too, can save solution cost, advocate board space and design time.