11/04/2004 shaomin 48V to 12V 1. without schottky rectifier D1 for 12V @ 5A --- Efficiency Report --- Efficiency: 95.1% Input: 63W @ 48V Output: 59.9W @ 12V Ref. Irms Ipeak Dissipation C1 0mA 0mA 0mW C2 0mA 0mA 0mW C3 0mA 0mA 0mW C4 1206mA 3622mA 146mW C5 1206mA 3622mA 146mW C6 491mA 6654mA 2mW Cboost 91mA 652mA 32mW Cbyp2 0mA 0mA 0mW Cdcp1 1016mA 1748mA 88mW Cdcp2 1mA 16mA 0mW Cdcp3 1909mA 4044mA 11mW Cdcp4 20mA 36mA 0mW Cdcp5 34mA 58mA 0mW Cdrvcc 74mA 1557mA 0mW Cmode 91mA 842mA 0mW Crunss 0mA 0mA 0mW Cvcc 0mA 0mA 0mW D1 33mA 71mA 8mW Dboost 6mA 159mA 1mW Dboost1 90mA 1634mA 9mW Dvccdv 4mA 4mA 44mW L1 1314mA 1393mA 69mW Ldcp 4997mA 5060mA 112mW Lout 5517mA 8957mA 548mW Mbg 4720mA 8699mA 407mW Mtg 2805mA 8835mA 1125mW Qvccdv 0mA 0mA 1mW R1 0mA 0mA 1mW R2 0mA 0mA 14uW R3 0mA 0mA 3uW Rb 0mA 0mA 79uW Rf 2mA 2mA 29uW Rimax 0mA 0mA 2uW Rset 0mA 0mA 60uW Rvccdv1 0mA 0mA 0uW Rvccdv2 4mA 4mA 128mW U1 222mA 2714mA 202mW 2. with schottky rectifier D2 for 12V @ 5A --- Efficiency Report --- Efficiency: 95.1% Input: 63W @ 48V Output: 59.9W @ 12V Ref. Irms Ipeak Dissipation C1 0mA 0mA 0mW C2 0mA 0mA 0mW C3 0mA 0mA 0mW C4 1203mA 3619mA 145mW C5 1203mA 3619mA 145mW C6 490mA 6620mA 2mW Cboost 91mA 651mA 32mW Cbyp2 0mA 0mA 0mW Cdcp1 1015mA 1763mA 88mW Cdcp2 1mA 16mA 0mW Cdcp3 1907mA 4042mA 11mW Cdcp4 20mA 35mA 0mW Cdcp5 34mA 58mA 0mW Cdrvcc 74mA 1556mA 0mW Cmode 90mA 842mA 0mW Crunss 0mA 0mA 0mW Cvcc 0mA 0mA 0mW D1 33mA 71mA 8mW Dboost 6mA 162mA 1mW Dboost1 89mA 1634mA 9mW Dsw 117mA 1272mA 9mW Dvccdv 4mA 4mA 44mW L1 1314mA 1393mA 69mW Ldcp 4997mA 5059mA 112mW Lout 5513mA 8951mA 547mW Mbg 4703mA 8710mA 396mW Mtg 2795mA 8829mA 1121mW Qvccdv 0mA 0mA 1mW R1 0mA 0mA 1mW R2 0mA 0mA 14uW R3 0mA 0mA 3uW Rb 0mA 0mA 79uW Rf 2mA 2mA 29uW Rimax 0mA 0mA 2uW Rset 0mA 0mA 60uW Rvccdv1 0mA 0mA 0uW Rvccdv2 4mA 4mA 128mW U1 221mA 2715mA 201mW 3. with D1 for 12V @ 10A --- Efficiency Report --- Efficiency: 93.9% Input: 127W @ 48V Output: 119W @ 12V Ref. Irms Ipeak Dissipation C1 0mA 0mA 0mW C2 0mA 0mA 0mW C3 0mA 0mA 0mW C4 2227mA 5418mA 496mW C5 2227mA 5418mA 496mW C6 850mA 10696mA 6mW Cboost 90mA 641mA 32mW Cbyp2 0mA 0mA 0mW Cdcp1 1024mA 1750mA 89mW Cdcp2 1mA 16mA 0mW Cdcp3 1922mA 4034mA 11mW Cdcp4 19mA 34mA 0mW Cdcp5 34mA 56mA 0mW Cdrvcc 74mA 1558mA 0mW Cmode 91mA 842mA 0mW Crunss 0mA 0mA 0mW Cvcc 0mA 0mA 0mW D1 34mA 71mA 8mW Dboost 7mA 170mA 1mW Dboost1 94mA 1690mA 9mW Dsw 210mA 2014mA 20mW Dvccdv 4mA 4mA 43mW L1 2647mA 2796mA 280mW Ldcp 9965mA 10028mA 447mW Lout 10265mA 13951mA 1897mW Mbg 8741mA 13668mA 964mW Mtg 5283mA 13827mA 2578mW Qvccdv 0mA 1mA 1mW R1 0mA 0mA 1mW R2 0mA 0mA 14uW R3 0mA 0mA 3uW Rb 0mA 0mA 79uW Rf 2mA 2mA 29uW Rimax 0mA 0mA 2uW Rset 0mA 0mA 60uW Rvccdv1 0mA 1mA 0uW Rvccdv2 4mA 4mA 128mW U1 223mA 2714mA 205mW 4. without D1 for 12V @ 10A --- Efficiency Report --- Efficiency: 94.0% Input: 127W @ 48V Output: 119W @ 12V Ref. Irms Ipeak Dissipation C1 0mA 0mA 0mW C2 0mA 0mA 0mW C3 0mA 0mA 0mW C4 2223mA 5412mA 494mW C5 2223mA 5412mA 494mW C6 843mA 10692mA 6mW Cboost 90mA 642mA 31mW Cbyp2 0mA 0mA 0mW Cdcp1 1023mA 1731mA 89mW Cdcp2 1mA 16mA 0mW Cdcp3 1919mA 4027mA 11mW Cdcp4 19mA 32mA 0mW Cdcp5 34mA 56mA 0mW Cdrvcc 74mA 1559mA 0mW Cmode 90mA 843mA 0mW Crunss 0mA 0mA 0mW Cvcc 0mA 0mA 0mW D1 34mA 71mA 8mW Dboost 7mA 167mA 1mW Dboost1 94mA 1691mA 9mW Dvccdv 4mA 4mA 43mW L1 2647mA 2796mA 280mW Ldcp 9966mA 10025mA 447mW Lout 10257mA 13940mA 1894mW Mbg 8773mA 13655mA 983mW Mtg 5266mA 13817mA 2553mW Qvccdv 0mA 1mA 1mW R1 0mA 0mA 1mW R2 0mA 0mA 14uW R3 0mA 0mA 3uW Rb 0mA 0mA 79uW Rf 2mA 2mA 29uW Rimax 0mA 0mA 2uW Rset 0mA 0mA 60uW Rvccdv1 0mA 1mA 0uW Rvccdv2 4mA 4mA 128mW U1 221mA 2713mA 203mW Conclusiton for 1,2,3,4: The objective for use of schottky diode D1 is to increase efficiency, however, because of its own dissipation. It helps little for efficiency. It's then removed to save space. In schematic is D5 (MBRS340: DIOSMC 8x6) 5. Qvccdv According to the simulation, Qvccdv or Q2 only needs very small current. So it's changed from FZT600 (6.5x7) to FMMT634 (2.55x1.3). In schematic is Q2. 12v to +/-6v @ 1.5A --- Efficiency Report --- Efficiency: 82.6% Input: 18.1W @ 11.8V Output: 14.9W @-6.07V Ref. Irms Ipeak Dissipation C1 540mA 1161mA 58mW C10 727mA 2007mA 21mW C12 540mA 1161mA 58mW C2 289mA 643mA 13mW C3 540mA 1161mA 58mW C4 0mA 0mA 0mW C5 194mA 533mA 6mW C6 14mA 26mA 0mW C8 1083mA 2424mA 47mW C9 14mA 27mA 0mW D1 1342mA 2238mA 453mW D2 0mA 8mA 0mW D3 0mA 8mA 0mW D4 2008mA 3181mA 733mW L1 2203mA 5016mA 291mW L2 2008mA 3181mA 242mW L3 1342mA 2238mA 108mW L4 1501mA 1589mA 106mW L5 990mA 1013mA 57mW L6 1480mA 1507mA 127mW R1 0mA 0mA 982uW R2 0mA 0mA 250uW R3 0mA 0mA 0uW U1 2207mA 5021mA 759mW 12V to +/-6v @ 1A --- Efficiency Report --- Efficiency: 83.1% Input: 14.5W @ 11.9V Output: 12W @-6.02V Ref. Irms Ipeak Dissipation C1 461mA 1071mA 42mW C10 774mA 2024mA 24mW C12 461mA 1071mA 42mW C2 206mA 535mA 6mW C3 461mA 1071mA 42mW C4 0mA 0mA 0mW C5 206mA 535mA 6mW C6 34mA 50mA 0mW C8 773mA 2024mA 24mW C9 34mA 50mA 0mW D1 1432mA 2406mA 489mW D2 0mA 9mA 0mW D3 0mA 9mA 0mW D4 1432mA 2405mA 489mW L1 1873mA 4537mA 210mW L2 1432mA 2405mA 123mW L3 1432mA 2406mA 123mW L4 1266mA 1374mA 75mW L5 1018mA 1050mA 60mW L6 1018mA 1050mA 60mW R1 0mA 0mA 967uW R2 0mA 0mA 246uW R3 0mA 0mA 0uW U1 1877mA 4542mA 632mW from above two, we could change schottky diode D1 & D4 with lower value: Replacement: Big value capacitor changed to ECJ-4YB P6KE15A changed to SMAJ20A DIOSMC changed to DIOSMA