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TPS543C20ARVFR: A 40A Stackable Synchronous Buck SWIFT™ Converter
11/4/2026 11:07:34 PM
TPS543C20ARVFR: A 40A Stackable Synchronous Buck SWIFT™ Converter
1. Positioning
The TPS543C20ARVFR is a high-power-density synchronous step-down converter from Texas Instruments' SWIFT™ family. It delivers up to 40A of continuous output current from an input range of 4V to 16V, with an adjustable output from 0.6V to 5.5V, in a 40-pin, 5mm × 7mm LQFN package. Its role is not general-purpose power conversion, but point-of-load (POL) supply for ASIC, SoC, FPGA, and DSP core and I/O rails, with applications spanning enterprise servers, switches, routers, enterprise storage and SSDs, and wireless and wired communications infrastructure.
Unlike conventional current-mode converters that require an external compensation network, the TPS543C20ARVFR uses internally compensated advanced current-mode control, eliminating the need for external compensation components and the loop tuning they demand across a wide frequency range. It also integrates a 3.4mΩ / 0.9mΩ stacked NexFET™ power stage with lossless low-side current sensing, keeping power-stage losses contained at the 40A level. Both features point to the same engineering goal: a high-current, high-efficiency POL solution that fits within limited board area and a predictable design cycle.
2. Stackability and Transient Response
The TPS543C20ARVFR supports two-phase stacking. Two devices can be combined with current share, voltage share, and CLK sync to deliver up to 80A. The switching frequency in stacked mode ranges from 300kHz to 1MHz, while standalone operation is programmable up to 2MHz. This allows a single device type to cover current requirements from a single-phase 40A to a two-phase 80A, reducing bill-of-materials variation across power levels.
For transient performance, the device provides Asynchronous Pulse Injection (API) and Body Braking to reduce undershoot and overshoot during load steps, respectively. Combined with differential remote sensing, the output voltage can be regulated precisely at the load point, compensating for DC errors from PCB trace impedance. The reference voltage from 0.6V to 1.1V is pin-strap programmable with 0.5% accuracy, providing the setting precision required for low-voltage core rails.
3. Key Specifications
| Parameter | Specification |
|---|---|
| Input Voltage Range | 4 V to 16 V |
| Output Current (Single Phase) | 40 A |
| Output Current (Two-Phase Stack) | 80 A |
| Output Voltage Range | 0.6 V to 5.5 V |
| Control Architecture | Internally Compensated Advanced Current Mode |
| Power Stage | Integrated 3.4 mΩ / 0.9 mΩ stacked NexFET™, lossless low-side current sensing |
| Switching Frequency (Standalone) | 300 kHz to 2 MHz (pin-strap programmable) |
| Switching Frequency (Stacked) | 300 kHz to 1 MHz |
| Reference Voltage | 0.6 V to 1.1 V, 0.5% accuracy (pin-strap programmable) |
| Transient Enhancement | Asynchronous Pulse Injection (API), Body Braking |
| Remote Sense | Differential remote voltage sensing |
| Protection | High-accuracy hiccup current limit, safe start-up into prebiased output |
| Package | 40-pin LQFN, 5mm × 7mm, 0.5mm pitch, single thermal pad |
4. Questions and Answers
Q: What is the core difference between internal and external compensation, and why did the TPS543C20ARVFR choose internal compensation?
A: External compensation requires placing a resistor-capacitor network in the feedback loop and tuning it against power-stage parameters, output capacitance, and load conditions to balance bandwidth, phase margin, and stability. This process can iterate across wide input/output ranges and different output capacitor combinations. The TPS543C20ARVFR's internal compensation uses an integrator and ramp-tracking loop to shape the loop inside the device, removing the need for external compensation components. This makes system design simpler, denser, and flexible in switching frequency selection. The trade-off is that the loop characteristics are fixed by the device and cannot be further optimized externally, but for its target POL applications, this exchange buys a significantly shorter design cycle.
Q: How is thermal management handled for 40A in a single-phase LQFN package?
A: The core of thermal management is the low-loss power stage and the package's heat path. The integrated NexFET™ power stage has a 3.4mΩ high-side on-resistance and a 0.9mΩ low-side on-resistance, compressing conduction loss at 40A. The LQFN package uses a single large thermal pad to conduct heat directly into PCB copper. In practice, the via array beneath the thermal pad, copper area, and airflow together determine whether the junction temperature stays within safe limits. High current density means thermal design must proceed in parallel with electrical design, not rely on the package's heat-spreading capability alone.
Q: What should be considered when stacking two phases to 80A?
A: Stacking relies on three mechanisms: current share, voltage share, and CLK sync. The two devices require correct phase interleaving to reduce input and output ripple. Current-sharing accuracy depends on layout symmetry and device-to-device parameter matching. In stacked mode, the switching frequency ceiling is 1MHz (lower than the 2MHz standalone limit), a compromise between multi-phase coordination and switching loss. Additionally, the loop characteristics after stacking differ from a single phase; while internal compensation remains active, the current-sharing loop stability should be verified under actual load conditions.
5. Conclusion
The value of the TPS543C20ARVFR is not a single isolated parameter. It lies in integrating a 40A power stage, internal compensation, two-phase stackability, differential remote sensing, and transient enhancement mechanisms into a 5mm × 7mm LQFN package. For server and communications designs that need high-current POL supply for ASIC, SoC, or FPGA core rails while reducing the burden of external compensation design, it offers a solution balanced across power density, design simplicity, and expansion flexibility.
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