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Technology is constantly improving – sometimes by leaps and bounds, sometimes by microscopic steps. What is overlooked most of the time, is how those small changes lead to the ground-breaking changes. Each improvement is an improvement on the previous platform – all the way back to the cave men. Today’s achievements stand on the shoulders of those who came before. The same goes for buck converters. The TPS6290x family is the next generation of 17V, low Iq, high efficiency, buck converters that improved upon the previous family TPS621x0. Table 1-1 shows the key features of each product and the improvements on the latest generation family. Each improved feature contributes to the leaps forward in the family. In turn, the improved device, a small part of a design, contributes to ground-breaking advancements in technology. But what does improved really mean? To understand how technology has improved, this application report provides a comparison of the previous version to the new version, as well as an explanation of how the changes benefit the user more than the previous version.
| Features | TPS621x0 | TPS6290x | Improvements |
|---|---|---|---|
| VOUT | 0.9 V to 6 V | 0.4 V to 5.5 V | Supports lower Vout down to 0.4 V |
| Typical quiescent current | 17uA | 4uA | 76% lower Iq |
| FB accuracy (-40°C< TJ <125°C) | 1.8% | <1% | 44% tighter Vref accuracy |
| Package size | 3.0mmx3.0mm QFN | 1.5mmx2.0mm QFN | 67% smaller package |
| Smart configuration | No | Yes | Fewer external components needed to configure device |
| Junction Temperature | -40C to 125C | -40C to 150C | Supports higher Tj up to 150C |
| Switching Performance | 2.5MHz | 2.5MHz and 1MHz | Provides Adj Fsw |
| RDS(ON) | 120mΩ/50mΩ | 62mΩ/22mΩ | Less power loss |
| Efficiency (12Vin, 1.2Vo, 2.2uH, 1MHz, 3 A) | 78.8% | 84% | Improved efficiency |
| Automatic Efficiency Enhancement | No | Yes | High efficiency for varying duty cycles |
| Capacitive discharge | Using PG | Using Smart Config | Achieved internally when selected |
| VSET | No | Yes | This allows for internal divider that has lower BOM count and better overs systems accuracy |
Power density is a term created to describe the power output of a device compared to its size. This is especially important in space constrained applications, or high functionality applications. These applications are mainly concerned with the space on the XY board area when talking about power density, but the Z (height) dimension can also be taken into consideration for total volume if desired. By shrinking the solution area, increasing the power output under similar conditions, or a combination of the two, the power density is positively impacted. As an example, comparing the 3-A rated parts in a case with 12 V on the input, 1.2 V on the output and in an ambient temperature of 65C, the TPS6290x is able to give the full 3-A load for a power density of 120mA/mm2. The TPS621x0 provides 2.7 A for a power density of 68mA/mm2 due to more power losses in the device. Section 3 provides additional detail of how the total solution size went from 40mm2 for TPS62130 to a solution size of 25mm2 in TPS62903. Section 4 describes how efficiency and thermals impact how much power is able to get out of a part.