SLVAFZ2A April 2025 – November 2025 TPS548B23 , TPS548B28
Introduction
Modern data center SoCs require more power and better thermals to maintain performance levels. Yet designers expect smaller BOM solution size as one of their key preferences. The 3 × 4mm package used by the previous generation TPS548B28 family is a widely-adopted industry standard, however the new generation TPS548B23 in 3 × 3mm offers an improvement in size and performance requiring less external components. This application brief describes the upgrades of the TPS548B23 in different aspects. Table 1 shows the key specification comparison. Table 2 shows the family devices of TPS548B28 and TPS548B23.
| TPS548B23 | TPS548B28 | |
|---|---|---|
| VIN | 4 – 16V | 4 – 16V |
| VOUT | 0.5 – 5.5V | 0.6 – 5.5V |
| IOUT | 20A | 20A |
| Control Mode | D-CAP4 | D-CAP3 |
| FB Accuracy (-40°C< TJ<125°C) | ±1.0% | ±1.0% |
| Package | 3mm × 3mm 19-pin QFN | 4mm × 3mm 21-pin QFN |
| Pin Pitch | 0.4mm | 0.4mm |
| Pin-Strap Configurability without External Components | Yes | No |
| Junction Temperature | –40°C to +125°C | –40°C to +125°C |
| Switching Frequency | 600KHz, 800KHz, 1MHz, 1.2MHz | 600KHz, 800KHz, 1MHz |
| RDS(ON) | 8.4mΩ/3.3mΩ | 7.7mΩ/2.4mΩ |
| Efficiency (12Vin, 3.3Vout, 800KHz, 10A, int VCC) | 95% | 93% |
| External VCC Bias Support | 3.1 – 5.3V | 3.13 – 3.6V |
| Devices | Package | IOUT | VREF |
| TPS548B28 | 3mm × 4mm | 20A | 600mV |
| TPS54JB20 | 20A | 900mV | |
| TPS548A28 | 15A | 600mV | |
| TPS54JA20 | 12A | 900mV | |
| TPS548B23 | 3mm × 3mm | 20A | 500mV |
| TPS548A23 | 12A | 500mV |
Efficiency and Thermal Performance
For a power-intensive server application, maintaining high efficiency in a buck converter is crucial because efficiency directly leads to reduced heat dissipation and, consequently, improved overall performance and reliability. Figure 1 shows the efficiency comparison between TPS548B23 and TPS548B28 at the condition of 12V input, 3.3V output, and 800KHz. Figure 1 shows that TPS548B23 has an overall efficiency upgrade compared with TPS548B28. Even though the on-resistance of the TPS548B28's power MOSFETs is slightly lower, the TPS548B23 efficiency is higher due to reduced package parasitics, gate drive, and dead-time improvements.
Figure 1 TPS548B23 and TPS548B28
Efficiency ComparisonThermal performance is a key specification in designing power systems. Poor thermal performance can degrade load performance, leading to damage, particularly in high-power applications. With more advanced process technology and larger ground pad area, TPS548B23 achieves better thermal performance compared with TPS548B28. Figure 2 and Figure 3 shows thermal images at the condition of 12Vin, 1Vout, 800KHz, 20A, where a 10.7℃ drop can be seen.
Figure 2 TPS548B23EVM Thermal Image at
12Vin, 1Vout, 800KHz, 20A
Figure 3 TPS548B28EVM Thermal Image at
12Vin, 1Vout, 800KHz, 20APackage
The previous generation TPS548B28 is designed in a 4mm × 3mm 21-pin QFN package as Figure 4 shows and previously was widely-adopted as the industry standard. However, as board area becomes increasingly limited, smaller size is required in power designs, especially for data center applications that are space-constrained. Figure 5 shows that TPS548B23 is designed in a smaller 3mm × 3mm 19-pin QFN package with a butterfly-style pin-out. The butterfly-style pin-out is a symmetric pin-out that simplifies PCB layout with the highest power density and best thermal at the lowest cost, as Figure 6 shows.
Figure 4 Bottom View of TPS548B28
Package - Asymmetric Pin-out
Figure 6 Butterfly-style Layout of TPS548B23D-CAP4 Control Mode
The D-CAP series of control modes is a TI proprietary method of constant-on-time control, designed to maximize device transient performance. TPS548B23 offers the latest generation D-CAP4 to achieve an ultra-fast transient response. Compared with the previous generation D-CAP3, D-CAP4 has faster transient response especially at high output voltage condition, as Figure 7 shows. D-CAP4 requires less output capacitance in high current power rail applications that demand premium load transient performance compared to D-CAP3.
Figure 7 D-CAP4 Versus D-CAP3 Transient Performance at the Condition of 12Vin, 5Vout, 800KHz, 5A to 15A to 5A, 1A/us Slew RatePinstrap Configurability
Unlike the TPS548B28, TPS548B23 configuration pins (CFG1-5) allow for less BOM components when adjusting:
- Overcurrent limit
- Faiult response
- Internal feedback
- External feedback
- Output voltage selection
- Switching frequency
- Soft-start time
Table 3 shows how to configure some of the key specifications for both TPS548B23 and TPS548B28. For more detailed configuration, see the TPS548B23 4V to 16V Input, 20A, Remote Sense, D-CAP4, Synchronous Buck Converter data sheet.
| TPS548B23 | TPS548B28 | |
|---|---|---|
| VOUT | By CFG3-5 when int Vfb, resistor divider when ext VFB | By resistor divider |
| Light Load Mode | By CFG3-5 | By connecting VCC, a resistor or AGND to MODE pin |
| Switching Frequency | By CFG1-2 both int and ext VFB | By connecting VCC, a resistor or AGND to MODE pin |
| Soft-Start | By CFG1-2 when ext VFB, fixed when int VFB | By connecting a capacitor between SS/REFIN pin and VSNS- pin |
| Fault Recovery Mode (Hiccup or Latch-off) | By CFG1-2 when ext VFB, hiccup when int VFB. | Fixed, hiccup for OC and UV faults, latch-off for OV Fault |
| Valley OCP | By CFG1-2 both int and ext VFB | By connecting a resistor to TRIP pin |
Conclusion
TPS548B23 is TI’s latest generation 16V, 20A DC/DC buck converter. Because of the efficiency and transient response upgrades, the TPS548B23 achieves better performance. Advanced pin-out leads to a more optimized layout, and configuration pins lead to less BOM components and easier design.