Other Parts Discussed in Thread: TPS56C215
Tool/software: WEBENCH® Design Tools
Hi all
I have some confused points about efficiency between WEBENCH and real testing.
1. I changed all the components from WEBENCH(TPS56C215) the same as TPS56C215 except input cap and output cap. Just lack of one 0.1uF input cap and use the similar output cap.
2. I see the output current - efficiency chart. The information is below.
output current = 1.2A Vin=4.5V efficiency = 86.48 ; output current = 2.4A Vin=4.5V efficiency = 89.17 ; output current = 3.6A Vin=4.5V efficiency = 89.35
output current = 1.2A Vin=10.75V efficiency = 75.68 ; output current = 2.4A Vin=10.75V efficiency = 82.26 ; output current = 3.6A Vin=10.75V efficiency = 84.07
output current = 1.2A Vin=17V efficiency = 65.87 ; output current = 2.4A Vin=17V efficiency = 74.93 ; output current = 3.6A Vin=17V efficiency = 77.78
3.I tested the real board EVM-762.(I tested Vin from input cap and tested Vout from output cap) The information is below.
output current = 1.2A Vin=4.5V efficiency = 86.75 ; output current = 2.4A Vin=4.5V efficiency = 88.87 ; output current = 3.6A Vin=4.5V efficiency = 88
output current = 1.2A Vin=10.75V efficiency = 73.06 ; output current = 2.4A Vin=10.75V efficiency = 80.41 ; output current = 3.6A Vin=10.75V efficiency = 82.58
output current = 1.2A Vin=17V efficiency = 63.16 ; output current = 2.4A Vin=17V efficiency = 72.41 ; output current = 3.6A Vin=17V efficiency = 75.93
4. In high Vin voltage, it has 2.5% difference and I think the difference from input cap and output cap couldn't lead to big difference. And in low Vin voltage(4.5V) it almost the same.
5.I saw the EVM-762 user guide efficency, it only has Vin=5V and Vin=12V. The information is below
output current = 1.2A Vin=5V efficiency = 86 ; output current = 2.4A Vin=5V efficiency = 89 ; output current = 3.6A Vin=5V efficiency = 90
output current = 1.2A Vin=12V efficiency = 70 ; output current = 2.4A Vin=12V efficiency = 77 ; output current = 3.6A Vin=12V efficiency = 81
6.I also saw the frequency between simulation and did the test. There are all 1.2MHz and both inductors are the same.
I think the real test from EVM board is more accurate. And does any body know how can I do next step to examine where the simulation difference from real test to result in the 2.5% difference in high Vin voltage?
