24-W, 120-VAC to 24-VDC High-Voltage BuckReference Design
1 Description
This reference design uses a TL2842B as a high-side buck to convert a 120-VAC input to a 24-VDC output capable of 1-A loading. At full load it achieves a low peak-to-peak output ripple and over 88% efficiency at full load. This reference design was built using a 2-layer PCB and single-sided assembly.
Figure 1-1 PCB Top
Figure 1-2 Schematic2 Test Prerequisites
2.1 Voltage and Current Requirements
| Parameter | Specifications |
|---|---|
|
Input voltage range |
108–132 VAC, 60 Hz |
|
Output Voltage |
24 VDC, ±1% |
|
Max output current |
1 A |
2.2 Considerations
An electronic load was used for all tests.
Unless noted, all waveforms were captured at full load with a 120-VAC, 60-Hz input.
2.3 Dimensions
The PCB is a two-layer, 1 oz per layer design. The dimensions are 2.5 in × 2.75 in with a max component height is 0.84 in.
3 Testing and Results
3.1 Efficiency Graphs
Efficiency is shown in the following figure.
Figure 3-1 Efficiency and Power Loss With
120-VAC, 60-Hz Input3.2 Efficiency Data
Efficiency data for a 120-VAC, 60-Hz input is shown in the following table.
| PIN (W) | VOUT (V) | IOUT (A) | POUT (W) | PLOSS (W) | Efficiency (%) |
|---|---|---|---|---|---|
| 6.173 | 24.702 | 0.200 | 4.949 | 1.224 | 80.166 |
| 11.885 | 24.598 | 0.401 | 9.854 | 2.031 | 82.913 |
| 17.318 | 24.540 | 0.601 | 14.741 | 2.577 | 85.122 |
| 22.540 | 24.503 | 0.801 | 19.619 | 2.921 | 87.040 |
| 27.760 | 24.473 | 1.000 | 24.478 | 3.282 | 88.179 |
