ECRI Microelectronics

Application Note

Appendix 1 Precautions of Application Note

1. Electrostatic protection: Electrostatic protection should be enhanced during the whole testing process. Precautions as below: testing staff must wear anti-electrostatic wristbands; bodies can not touch pin leads of products during the testing; please put products in electrostatic protection ware immediately after testing.

2. Testing requirements: The input power lines of oscilloscope must be connected with two phases power plugs without ground. Otherwise, the ground wire will be led in output of product that will cause product be burned out by short circuit. For all products powering on, must turn on Vcc(±15V)power firstly, then turn on Vs power; for shutting down , must turn off Vs power firstly, then turn off Vcc(±15V)power after the power indicating light is completely off. Please consider a better heat-dissipation for production testing, cooling equipments or heat sinks should be needed for dissipating heat.

3. Shell temperature requirements: The product is power circuit, please keep the shell temperature no more than 125℃ (H Grade thick film products) by connecting the heat sinks for a reliable working condition. The shell temperature of module products is no more than 85℃, otherwise, the products will be damaged by overheating.

4. Power supply bypassing installation requirements:There is a capacitor should be needed to connect in parallel between V+ pin and RTN pin of the power supply for a power circuit. The capacitor’s installation site will have an effect on the power supply noise filtering. At the same time; it can also suppress the peak ripple current of three-phase bridge. When MOS device switching circuit starts to work, there is a certain frequency series RLC tuned circuit exist in the circuit and the inductance of it is about 30mH per feet. So that, the capacitances are: the second capacitance is 5 or 10 times than the first capacitance, which can restrain the peak value of voltage, thus suppressing the interference which caused by the high frequency switching of electronic switch, this capacitor should connected to module as close as possible. There is a 10μF filter capacitor be also needed to connect in parallel between 15V pin and GND pin. Power supply’s connection method as follow:
Power supply connection diagram
Diagram 1 Power supply connection diagram

5. Keep all of large current loop as short as possible, and wiring by thick copper wire to reduce EMI.

6. Keep right correspondence for Hall IC ABC three-phase, motor three-phase, three-phase output of MSK4361 and Hall signal three-phase input during connection, otherwise, motor may not operate well, such as no turning, reversed turning and intense shaking. The decoupling capacitor can be added on three-phase Hall signal input port to restrain interference and increase the stability of system.

7. Keep the pin leads of the package straight to avoid insulator being broken, which may affect the sealing property of products.
8. Avoid short-circuit during the products connecting the load.

Appendix 2 Expanded Applications of Application Note

The input voltage of HSA03 and other products in catalogue is 3V to 7V unipolarity voltage signal . There is an external level conversion circuit can be added when the voltage range is ±10V, which can convert the voltage to 3V~7V. Conversion circuit diagram and parameters as below:
R21=39KΩ       R22=15KΩ      R23=100KΩ     R24=20KΩ
level conversion circuit diagram
Diagram 2 level conversion circuit diagram
For the different range of unipolarity voltage signal, according to the level conversion circuit diagram above, get the requied output voltage by chocing different resistance value.

Appendix 3 Radiator Design of Application Note

1. Calculation and selection of radiator
The most simple and practical cooling device is the radiator. A multi-bladed radiator or a large-area radiator will greatly increase the heat dissipation area, it brings great conveninence for the heat conduction, conveation and radiation. On the theory, an infinite-area radiator can make the thermal resistance zero, but in fact, it is impossible to achieve because the space is limited for the radiator. Thus, appropriate choices and area calculation are nesssary. According to conditions, the equation for temperature and heat flow as below:
PD(max)=(Tj(max)-TA(max)/θ
Where: PD(max)---Maximum dissipation power;
Tj(max)---Maximum tempeature allowed;
TA(max)---Maximum ambient temperature at work;
θ---The total heat resistance be produced by heat flow through the product
θ=θjc+θcs+θsa
Where: θjc---The heat resistance from semiconductor device PN junction to the package(℃/W);
θcs--- The heat resistance from the package to the radiator(℃/W);
θsa--- The heat resistance from the surface of radiator to the ambient enviroment(℃/W)。

θjc is given in the product characteristics table, θcs can be calculated by the contact form between radiator and package, θsa is the most impotant parametor in the three heat resistance for controling the junction temperature, it plays an important role in radiator selection. The smaller heat resistance  ,the smaller θ , the greater power can be consumed when the semiconductor device at no more than the highest junction temperature. θsa is the function about heat transfer coefficient(hc)and heat radiating area(A), the relation of them as below:
θsa=1/hc·a
Heat transfer coefficient hc is a complex function, it is hard to take a common coefficient. So, in order to use the radiator conveniently, the θsa  is often evaluated by the various practical curves.
From θsa equation, we can see that increasing the radiator area can reduce θsa and increasing the heat transfer coefficient hc can also reduceθsa as well. The natural convection is widely uesed in the nomal heat sink, so , increasing the radiator area is the only way to reduce θsa. If the radiator area can not be increased by the limited space, θsa is usually reduced by forced convection.
To avoid short-circuit, it is recommended to add insulation mats between radiator and package during the installation process. It must be noted that, the insulation mats’ material must be with the dual characteristics of high resistance and low thermal resistance, such as mica plate. For reducing θcs by the close contacted surface, the surface is usually painted by thermalconductive grease.
From the result of above cauculation to get θsa, select the thickness and area of radiator by the thermal plate characteristic curve from radiator manufacturer.Please set the radiator in the vertical direction to ensure a better cooling effect.

2. Process of circuit thermal design
2.1 In the thermal design of products, the main theraml parameter of products from the manufacturer list as follow:
1)η--- Power amplifier circuit efficiency;
2)Tj(max)--- Maximum tempeature allowed of power amplifier products;
3)θjc---Heat resistance of products
2.2 Amplifier users provide following parameters by design conditions:
1)Po--- Output Power of amplifier;
2)TA(max)--- Maximum ambient temperature of amplifier
3)The surrounding space and air flow situation of amplifier system
Based on the output power PO and efficiency η, the consumed power of supply can be calculated by the equation below:
PD=PO(1-η)/η
Temperature difference:
△T=Tj(max)-TA(max)
The total heat resistance θ can be calculated by equation(1)、(3) and(4). From equation (1), if PD  is fixed, to make the amplifier product temperature does not exceed its maximum rating, then the thermal resistance of the power amplifier product should be less than the required thermal resistance. If this case is true, the thermal design will be finished without an external radiator; otherwise, the external radiator will be needed to make sure the total heat resistance θ is less than required heat resistance. The radiator selection refers to appendix 1. In addition, If the radiator can not be set because the limited surrounding space of amplifier, using forced air to dissipate the heat is nessesary.

Appendix 4 Over-current protection technology of Application Note

The typical connection diagram of the external current limiting protection circuit is shown in Dagram 3:
The typical connection diagram of the external current limiting resistance
Dagram 3: The typical connection diagram of the external current limiting resistance

Over-current protection circuit makes sure the amplifier working in the SOA safty area. The cureent limitation should not over the max rated current of the amplifier, otherwise, the amplifier will be damaged.
Because the output current flow through the current limiting resistor, the rated power must be considered. From the reliability, the rated power of resistor should be as large as possible. The equation for current limiting resistance and its power dissipation as below:
Rlimit=0.1/Ilimit
PRLIMIT(watts)=0.1×Ilimit,Ilimit is the setting value of current limiting, R, C are set as 5K and 0.01μF. 0.1 is the threshold level of protection circuit, its unit is (V); Ilimit is the setting value of protection current depend on the working situation; PRlimit is the output power of resistor during the circuit protection, the actual power of the resistor can not be less than it.
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Application Note