SNVAA29 October 2021 TPS542A50 , TPS543320 , TPS543B20 , TPS543C20A , TPS546A24A , TPS546B24A , TPS546D24A , TPS548A28 , TPS548B28 , TPS54J061
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Table 1-1 highlights the latest point-of-load DC/DC converters with integrated MOSFETs, linear regulators and power modules applicable to powering NICs; however, they are designed to accommodate the requirements for a wide range of markets. These devices are designed to achieve fast transient response, low output voltage ripple, high efficiency, good thermal performance, and high output voltage accuracy. Notice that different control architectures are suggested in the table below.
Fixed-frequency control architectures provide a predictable switching frequency and can be synchronized to an external clock. Current mode or voltage mode control is desirable in noise-sensitive applications that use data converters and high-speed analog circuits. On the other hand, devices implementing constant on-time control deliver a faster transient response than voltage or current mode control to quickly changing load profiles, since there is no internal clock to control the switching frequency. Several devices feature PMBus or I2C with adaptive voltage scaling and margining. Devices integrating PMBus or I2C with telemetry report voltage, current, and temperature information to a host.
IOUT Range | Constant On-Time Control | Fixed Frequency Control | PMBus / I2C without Telemetry | PMBus / I2C with Telemetry | Power Module with Integrated Inductor |
---|---|---|---|---|---|
Switch Mode Power Supplies | |||||
≤ 2 A | TPS62148 | TPS62912 | N/A | N/A | TPS82120 |
2 A – 3 A | TPS62135 | TPS62913 | N/A | N/A | TPS82130 |
3 A – 6 A | TPS54J061 | TPS543620 | TPS542A50 | TPS546A24A | TPSM84624 |
6 A – 10 A | TPS54JA20 | TPS54A24 | TPS542A50 | TPS546A24A | |
10 A – 15 A | TPS548A29 | TPS542A52 | TPS542A50 | TPS546B24A | TPSM41615 |
15 A - 20 A | TPS548B28 | TPS543B20 | TPS549B22 | TPS546B24A | TPSM41625 |
20 A – 25 A | TPS548B22 | TPS543B20 | TPS549B22 | TPS546D24A | TPSM41625 |
25 A – 40 A | TPS548D22 | TPS543C20A | TPS549D22 | TPS546D24A | TPSM846C24 |
Low Drop Out Regulators | |||||
IOUT | Device | Description | |||
1.5-A | TPS74801 | Linear Regulator with PG and Enable | |||
2-A | TPS7A52 | High-Accuracy (0.5%), Low-Noise (4.4 μVRMS), LDO Voltage Regulator with 65 mV Dropout | |||
3-A | TPS7A53 | High-Accuracy (0.5%), Low-Noise (4.4 μVRMS), LDO Voltage Regulator with 110 mV Dropout | |||
4-A | TPS7A54 | High-Accuracy (0.5%), Low-Noise (4.4 μVRMS), LDO Voltage Regulator with 175 mV Dropout |
Several Ethernet controllers on the market integrate SERDES, PLLs and I/O ports on-chip that require low voltage ripple noise levels. The traditional method for achieving low output voltage ripple noise is is to use a DC/DC converter followed by a low-dropout regulator (LDO) such as the TPS7A52, TPS7A53 or TPS7A54. This family of LDOs supports output currents up to 4-A with a low dropout voltage as low as 65 mV. As the output current increases, a linear regulator becomes less feasible due to added cost, board space, and power loss. Besides a linear regulator, another method to achieve low noise along with a switching DC/DC converter is to implement a second-stage L-C filter following the DC/DC converter. Every DC/DC converter generates an output voltage ripple at its switching frequency. Ethernet controllers with integrated noise-sensitive circuitry need low voltage ripple to minimize frequency spurs in the spectrum, which typically varies with switching frequency, inductor value, output capacitance, and equivalent series inductance and resistance. Low-ripple buck converters such as the 2-A TPS62912 and 3-A TPS62913 leverage an external ferrite-bead filter by integrating the compensation to accommodate the ferrite-bead. Using the inductance of the ferrite-bead along with an additional output capacitor removes the high frequency components of the output voltage ripple and achieves less than 10 uVrms ripple. Figure 2-1 shows the output voltage ripple with an input voltage of 12 V, an output voltage of 1.2 V, and output current of 1-A.