minikv bill of materials, rev 1
Components marked "crit" are critical and should be populated with exactly the recommended manufacturer part number in the table. Reasons for these critical parts are explained below so they may be substituted if absolutely necessary, but do this with care.
Components with no part number are common parts expected to be provided by the builder according to the description.
Parts with reference numbers greater than 10 are on the secondary winding board.
|Part||Description||Crit||Manufacturer||Manufacturer's part number|
|C1||Capacitor, MLCC, 47nF, 100V, C0G, 1206||KEMET||C1206C473J1GEC7210|
|C2-3||Capacitor, MLCC, 1µF, 25V, X5R, 0805|
|C4||Capacitor, MLCC, 330pF, 25V, C0G, 0603|
|C5||Do not populate|
|C11-14||Capacitor, MLCC, 6.8nF, 2kV, X7R, 1210||KEMET||C1210C682MGRAC7800|
|C15||Capacitor, MLCC, 27nF, 2kV, X7R, 2220||KYOCERA AVX||2220GC273KAZ1A|
|D11-14||Diode, 1kV, 1A, trr ≤ 75ns, SOD-128||Taiwan Semi||HS1MFS|
|J1||Header, shrouded, 1x8, 2.5mm||JST||B8B-XH-AM(LF)(SN)|
|L1||Inductor, 220µH, 600mA, 6x6mm||Yes||Bourns||SRN6045-221M|
|L11||Inductor, 1mH, 15mA, 1007||Taiyo Yuden||LB2518T102K|
|Q1, Q2||Transistor, NPN, 100V, 1A, low Vcesat, SOT-23||Yes||Nexperia||PBSS8110T,215|
|Q3||Transistor, NMOS, 40V, 20A, TO-252||Yes||Alpha & Omega||AOD454A|
|Q4*||Transistor, NPN, 40V, 200mA, SOT-23 (for mod)||any||MMBT3904|
|R1||Resistor, 10M, 1%, high voltage, 2010||Yes||Bourns||CHV2010-FX-1005ELF|
|R2||Resistor, 18k, 1%, 0603|
|R3||Resistor, 7.5k, 1%, 0603|
|R4||Resistor, 100k, 5%, 0603|
|R5||Resistor, 1.5M, 5%, 0603|
|R6||Resistor, 3.3k, 5%, 0603|
|R7, R11||Resistor, 430, 5%, 0.4W, 0805||Rohm Semi||ESR10EZPJ431|
|R8||Resistor, 1 ohm, 5%, 2/3 W, 1210||Rohm Semi||ESR25JZPF1R00|
|R8*||Resistor, 0.75 ohm, 1%, 1 W, 1210 (for mod)||Vishay Dale||RCWE1210R750FKEA|
|U1||1.24V shunt reference, 16V max, SOT-23-5||Yes||onsemi||TLV431BSNT1G|
|n/a||Planar E-core, 22x16mm||Yes||Ferroxcube||E22/6/16/R-3F36|
|n/a||Planar E-core plate, 22x16mm||Yes||Ferroxcube||PLT22/16/2.5/S-3F36|
|n/a||Planar E-core transformer clamp||Yes||Ferroxcube||CLM-E22/PLT22|
L1: "Critical" due to proprietary footprint. If you can find one that fits, go for it. Irms and Isat should both be 600mA or higher.
Q1, Q2: These are low-Vcesat transistors meant for use in SMPS circuits. Using "normal" transistors in place of these may cause overheating and failure. If needed, Zetex and Nexperia have many alternatives.
Q3: Because this MOSFET is used in a linear mode, it must have some specific properties. First, the datasheet must have a "forward-biased safe operating area" (FBSOA) plot. It will have several curves for different pulse durations. The transistor used here must have a "DC" curve in this plot, and that curve must include 3V, 1A. MOSFETs not meeting this may suffer from thermal runaway and fail. Second, the minimum VGS(th) (threshold voltage) must be no less than 1.5V at 250µA. This ensures that the TLV431 is capable of fully shutting it off. Third, RDS(on) must be less than 0.75 ohms. Most MOSFETs do meet this one, but it rules out some high-voltage parts that would otherwise be well suited.
R1: This resistor must permit continuous operation at up to 2000V and have a power rating of at least 250mW. Don't just filter for "high voltage" at Digi-Key, check for "maximum working voltage" in the datasheet.
U1: Not all TLV431s are equivalent. In this circuit, a maximum operating voltage ("cathode" voltage) of 16V or higher is required. Also, frequency response can slightly vary between manufacturers, so compensation components R5, C4, and C5 may need to be changed to support a different U1.
Transformer core components: These are completely critical, the board is designed around them. If you can find a piece of similar ferrite material that will fit in the same place, it might work, but don't count on it. If this piece is obsoleted we'll have to make a new minikv.