My friend wants the circuit DC to DC step down Converter. That can give current get tall about 3A one in the circuit that me advises. Be using integrated circuit number LM2576 because of build good easy. Follow this circuit be the character of DC switching supply 3A sizes interesting take voltage input 40V. Give Volt output many the level be LM2576-3.3 (3.3Vdc output), LM2576-5.0 (5Vdc output),LM2576-12 (12Vdc output),LM2576-15 (15Vdc output),LM2576-ADJ (1.23Vdc to 37Vdc output) ,
the next time is if , you want the circuit turns on the power 3A tall trends. Try out this circuit is the one choice be lucky sir.