_____________________ | | ........ | . sense . -------- | Uin + --------. LM2596. -----^^^^^^^ ------ Uout | . GND . | 33 uH | | ........ | | === | k diode === --- 220 u | a 1N5822 --- 220 u | | | | Uin - -------------------------------| | Chip LM2596 3.3 (fixed) /// L 33 uH Cin = Cout = 220 uF Diode 1N5822
Uout 3.3 V( fixed) Iout .82 A (fixed) Pout = 3.3 x .82 = 2.7 W
Uin(V) Iin(A) Pin(W) efficiency(%)
4.7 .79 3.71 73
9 .39 3.51 77
12 .3 3.6 75
22 .15 3.3 82
4.7 V seems the lowest input voltage before the 3.3 V output starts dropping. In all cases the output ripple looked like a nice triangle / sawtooth, so the inductor current must be too.
I got the chips from ebay, the diodes and inductors (open core type) too, Ordered May 17, arrived today May 24, makes 7 days from Hongkong (airmail free shipping).
So much for the local shops. Ebay is faster, cheaper, and it seems better in the sense I can get everything. Also got loads of other chips...