EG1162 Catium Power supply Buck adjustable

EG1162 Catium Power supply Buck adjustable box

EG1162 Catium Power high-power synchronous rectifying Buck adjustable power supply reduces the voltage of 8 series of lithium iron phosphate batteries to power the Yaesu FT-891 shortwave radio station, with a shell, small size (can be even smaller), the temperature of the shell is approximately fifty to sixty degrees when outputting ≈350W. The cover photo does not show the switch. The main control is EG1162, a high-power synchronous rectifying buck control chip, with overcurrent protection, short circuit protection, and external power MOS.

Design:
Because it is designed to power the radio station, the output voltage of 13.8V is required (when the radio is transmitting at full power), the output current is 23A, so the entire circuit is designed to a limit of 30A. The input voltage is provided by 8 series of lithium iron phosphate, not exceeding 29.2V, and the power MOSFET is preferably selected with a withstand voltage of 60V or higher, with as low internal resistance and junction capacitance as possible.

The author used the HD50N06D bought, not sure if the internal resistance is a bit high or for some other reason, the main heat generation is in the half-bridge part of the tube, the lower tube doesn’t generate much heat, and neither does the soft switch. I strongly suspect that parallel tubes will increase switch losses! If possible, use tubes with lower internal resistance and better performance directly!!
Speaking of soft switches, the negative terminal of the power supply is connected in series with a group of 2 MOSFETs in parallel as a soft switch, which basically does not generate heat, solving the switch problem.

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Schematic EG1162 Catium Power supply Buck adjustable

Schematic Eg1162 Catium Power Supply Buck Adjustable
Schematic

Ripple:
Because it is designed to power the radio station, the output ripple should be as small as possible, so according to the description in the EG1162 datasheet:

Eg1162 Catium Power Supply Buck Adjustable Calc

Among them, ⁣ Iripple and ΔIL Busy refers to the electrochemical current ripples. I don’t know why the two symbols are used in this manual. CO is an output capacitor. ESR is an equivalent series resistance of the output filter capacitor (you can see the data manual of the capacitor manufacturer), and FS is the operating frequency.

According to the above formula, select the inductance of the iron silicon aluminum magnetic ring with L = 47uH, buy in Taobao.

47Uh 30A Coil Inductor
47Uh 30A Coil Inductor

The operating frequency was originally scheduled to be 180kHz. The test found that the fever was severe. It was inferred that the switch loss may be too large, and the reduction frequency was improved after 90kHz.

The author choose the two 470UF solid capacitors and several MLCCs. ESR should be relatively low. Take ESR = 15mΩ, VIN = 25.6V, VOUT = 13.8V, FS = 90kHz fs = 90kHz calculates almost ΔIL = 1.5aΔIL = 1.5A, and then ΔVout = 25mV, I don’t know if this calculation is right.

For insurance, a π filter is added after the output. The inductance is 2.2UH, which will not be considered attenuation. It is okay to simulate the effect with Multisim 14. Buy in Taobao

There is no high level equipment such as an oscilloscope, the ripples can’t be tested, and the conditional guys can help me try it.

The output draws a bunch of NC MLCC positions, you can look at the addition of welding.

The circuit and PCB here are slightly different from what I use, mainly because the problems found in the debugging process have been modified.
The supporting shell is used, the shell link in Taobao

Voltage Output:
Can be adjusted by adjusting the feedback resistor, please refer to the EG1162 manual for details.

Testing:
When the author tested it, It used a 13.8V output, and connected two cooling fans 12715 and 12708, boiling water quickly (laughs), there is a video at the back. Also,  have already connected it to the radio station and tried it out, the FT-891 can be used continuously in FM mode (100w transmission), barely generating heat, the power supply even does not heat up the radio station itself.

Manufacturing:
Note that a small piece should be cut off from the board at the position of inductor L2, and plug it into the slot reserved on the mainboard.

Eg1162 Catium Power Supply Buck Adjustable Pcb Eg1162 Circuits, Dc Dc, Power Supply, Rf Eg1162 Catium Power Supply Buck Adjustable

Eg1162 Catium Power Supply Buck Adjustable Coil Eg1162 Circuits, Dc Dc, Power Supply, Rf Eg1162 Catium Power Supply Buck Adjustable

The power MOSFET is on the back of the board, if running at high power, proper heat dissipation should be done, I used a copper plate + silicon thermal adhesive attached to the shell, which is made of aluminum. Some parts of the circuit are quite compact, such as between inductor L2 and the shell, output terminal blocks, pay attention to insulation.

After installing it into the shell, apply glue first

Eg1162 Catium Power Supply Buck Adjustable Detail Eg1162 Circuits, Dc Dc, Power Supply, Rf Eg1162 Catium Power Supply Buck Adjustable

remember to pile up solder or embed copper wire (also pile up solder on the small board of L2!)

Eg1162 Catium Power Supply Buck Adjustable Bottom
Eg1162 Catium Power Supply Buck Adjustable Bottom

After installing the outer shell, the groove of the outer shell baffle was opened with an electric drill and a hand file. The hole on the top can be used to install a cowl switch. I didn’t connect it here, so I just let the wire out.

Eg1162 Catium Power Supply Buck Adjustable Box
Eg1162 Catium Power Supply Buck Adjustable Box

Known issues:
However, it was found that short-circuiting the output inductor directly causes a howling sound, is it a problem with the sampling resistor? This diagram is slightly different from the part about current detection in the official data manual, not sure if that’s the reason. In other words, is the short-circuit protection not working?

BOM EG1162 Catium Power supply Buck adjustable

Parts Value Description Quantity
Resistors
R1,R3,R5 100kΩ R0603 – SMD resistor 3
R2,R4 10Ω R0805 – SMD resistor 2
R6,R7 4.7kΩ R0805 – SMD resistor 2
R8,R16,R20 1kΩ R0805 – SMD resistor 3
R9,R17 510Ω R0805 – SMD resistor 2
R10,R11,R12,R13,R14,R15 18mΩ R2512 – SMD resistor 6
R18,R19 10kΩ R0805 – SMD resistor 2
R21 2kΩ 3296P trimpot 1
Capacitors
C1,C6,C12,C14 100nF C0805 – SMD capacitor 4
C2,C3,C27 100pF C0603 – SMD capacitor 3
C4,C8,C20 10nF C0603 – SMD capacitor 3
C5,C11,C17 1uF C0805 – SMD capacitor 3
C7,C13 10uF C0805 – SMD capacitor 2
C9,C10 470uF  

25V 470uF D5.5xL15mm Solid Capacitor
2
C15,C16 470uF  

470uF 35V ,D10xL17 mm Aluminum Electrolytic Capacitor – Leaded
2
C18,C19,C21,C22,C23,C24,C25,C26 NC C0805 – SMD capacitor 8
Semiconductors
D1 SS14 40V 1A SMA(DO-214AC) Schottky Barrier Diode 1
D2,D3,D4 1N4148W 100V 8ns 150mA SOD-123 Switching Diode 3
Q1,Q2,Q3,Q4,Q5,Q6 HD50N06D  

60V 50A 15 mΩ N Channel TO-252-2 MOSFET
6
U1 EG1162 SOP-16 DC-DC Converter 1
Miscellaneous
CN1 XT60PW-M Power Connector 1
CN2,CN3 T44001 M4 PCB Welding Terminal 2
CN4 DC007B-2.0 Right-Angle DC Power Receptacle 2 mm 6 mm 7A 20V 1
CN5 2.54-1*3P 1×3P, P=2.54mm Pin Header 1
L1 47uH 47uH 30A 1
L2 2.2uH 2.2uH 30A 1
CN6,CN7 M3*12+3 PCB hole 2

Download files, links, and notes

Eg1162 Catium Power Supply Buck Adjustable Pcb 3D
Pcb 3D

Source: https://oshwhub.com/azez/lm2596

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Xtronic.org blog author. Electronics technician for the technical school of Brasilia - Brazil. Interested in electronics, circuits and technology in general.
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