SLVSEX0A March 2019 – July 2019
PRODUCTION DATA.
- 1 Features
- 2 Applications
- 3 Description
- 4 Revision History
- 5 Pin Configuration and Functions
- 6 Specifications
- 7 Detailed Description
- 8 Application and Implementation
- 9 Power Supply Recommendations
- 10Layout
- 11Device and Documentation Support
- 12Mechanical, Packaging, and Orderable Information
8.2.1.2.2 Inductor Selection
Because the selection of the inductor affects steady state operation, transient behavior, and loop stability, the inductor is the most important component in power regulator design. There are three important inductor specifications, inductor value, saturation current, and DC resistance (DCR). The TLV61048 is designed to work with inductor values between 2.2 µH and 10 µH. Use Equation 2 to Equation 4 to calculate the peak current of the application inductor. To calculate the current in the worst case, use the minimum input voltage, maximum output voltage, and maximum load current of the application. To have enough design margin, choose the inductor value with –30% tolerance, and a low power-conversion efficiency for the calculation. In a boost regulator, the inductor dc current can be calculated with Equation 2.
where
- VOUT = output voltage
- IOUT = output current
- VIN = input voltage
- η = power conversion efficiency, use 80% for most applications
The inductor ripple current is calculated with the Equation 3 for an asynchronous boost converter in continuous conduction mode (CCM).
where
- ΔIL(P-P) = inductor ripple current
- L = inductor value
- fSW = switching frequency
- VOUT = output voltage
- VIN = input voltage
Therefore, the inductor peak current is calculated with Equation 4.
Normally, it is advisable to work with an inductor peak-to-peak current of less than 40% of the average inductor current for maximum output current. A smaller ripple from a larger valued inductor reduces the magnetic hysteresis losses in the inductor and EMI. However, in the same way, load transient response time is increased. Table 2 lists the recommended inductor for the TLV61048 in the 600-kHz configuration.
Table 2. Recommended Inductors for the TLV61048 at 600-kHz Configuration
| PART NUMBER | L (µH) | DCR MAX (mΩ) | SATURATION CURRENT TYPICAL (A) | SIZE (L×W×H) (mm) | VENDOR(1) |
|---|---|---|---|---|---|
| SWPA5040S4R7NT | 4.7 | 39 | 3.9 | 5 × 5 × 4 | Sunlord |
| XAL4030-472ME | 4.7 | 44.1 | 4.5 | 4 × 4 × 3 | Coilcraft |
| SWPA5040S100MT | 10 | 83 | 2.9 | 5 × 5 × 4 | Sunlord |
| XAL4040-103ME | 10 | 92.4 | 3 | 4 × 4 × 4 | Coilcraft |