SLUP413A May   2024  – April 2026 TPS53689T

 

  1.   1
  2.   Abstract
  3. 1 Introduction
  4. 2 Converter Transient Response
  5. 3 Magnetics
  6. 4 TLVR Topology Operating Principles
    1. 4.1 Steady-State Operation
    2. 4.2 Load Transient Step-Up
    3. 4.3 Load Transient Step-Down
    4. 4.4 LC Inductor Selection
    5. 4.5 Steady-State Ripple
  7. 5 Power Loss and Efficiency
  8. 6 Phase Multiplication
  9. 7 PCB Layout
  10. 8 TLVR-Optimized Components
  11. 9 Example Side-by-Side Design
  12. 10Summary
  13. 11Additional Resources

9 Example Side-by-Side Design

The examples in earlier sections demonstrated the difference between a multiphase buck design and a TLVR design with the same external components. This comparison is not often practical, however, because the requirements of the load do not change – it is the design that must change to meet the load requirements. As we’ve discussed, TLVR inductors are footprint-compatible with standard single-winding inductors, enabling the testing of both designs with the same physical PCB layout.

Table 5 summarizes one such example. The TLVR design met the same specifications as the multiphase buck converter design with almost no impact on overall power losses, and an over 40% reduction in COUT required.

Table 5 Design parameters.
Parameter Multiphase buck TLVR
Controller/standby power supply TPS53689, CSD95440
Input voltage (VIN) 12 V
Output voltage (VOUT) 1.8 V
Minimum output voltage (VMIN) 1.59 V
Maximum output voltage (VMAX) 1.85 V
Number of phases 8
Switching frequency 900 kHz
Load step 60 A-430 A, 1,000 A/µs, 1 kHz-1 MHz
Load line 0.5 mΩ
LM/LBUCK 70 nH 120 nH
LC N/A 100 nH
CBULK (polymer) 5 × 470 µF 0 × 470 µF
Multilayer ceramic capacitors (MLCCs) 80 × 22 µF, 0402 80 × 22 µF, 0402
45 × 47 µF, 0805 56 × 47 µF, 0603
15 × 100 µF, 0805 0 × 100 µF, 0805
8 × 0.1 µF, 0402 8 × 0.1 µF, 0402
Peak power efficiency (ηPEAK) 94.0% 93.9%
Full load efficiency (ηFull) 88.1% 88.1%
VMIN measured (worst case) 1.600 V (+10-mV margin), dominated by RLL 1.600 V (+10-mV margin), dominated by RLL
VMAX measured (worst case) 1.846 V (+4-mV margin) 1.839 V (+11-mV margin)
Total output capacitance (COUT) 7.7 mF 4.4 mF

Figure 30 and Figure 31 illustrate the worst-case overshoot waveforms for this design.

Worst-case overshoot (multiphase buck converter).
VMAX = 1.846 V D = 20%
fSW = 330 kHz
Figure 30 Worst-case overshoot (multiphase buck converter).
Worst-case overshoot (TLVR).
VMAX = 1.839 V D = 10%
fSW = 190 kHz
Figure 31 Worst-case overshoot (TLVR).