SLUSBL5A February   2015  – June 2019

PRODUCTION DATA.

1. Features
2. Applications
3. Description
1.     Device Images
4. Revision History
5. Pin Configuration and Functions
6. Specifications
7. Detailed Description
1. 7.1 Overview
2. 7.2 Functional Block Diagram
3. 7.3 Feature Description
4. 7.4 Device Functional Modes
8. Application and Implementation
1. 8.1 Application Information
2. 8.2 Typical Application
3. 8.3 Do's and Don'ts
9. Power Supply Recommendations
10. 10Layout
11. 11Device and Documentation Support
1. 11.1 Device Support
1. 11.1.1 Development Support
2. 11.1.2 Device Nomenclature
2. 11.2 Documentation Support
4. 11.4 Community Resources
6. 11.6 Electrostatic Discharge Caution
7. 11.7 Glossary
12. 12Mechanical, Packaging, and Orderable Information

• D|7

8.2.2.2 Input Bulk Capacitance and Minimum Bulk Voltage

Bulk capacitance may consist of one or more capacitors connected in parallel, often with some inductance between them to suppress differential-mode conducted noise. EMI filter design is beyond the scope of this procedure.

Determine the minimum voltage on the input capacitance, CB1 and CB2 total, in order to determine the maximum NP to NS turns ratio of the transformer. The input power of the converter based on target full-load efficiency, minimum input RMS voltage, and minimum AC input frequency are used to determine the input capacitance value.

Maximum input power is used in the CBULK calculation and is determined by the VOCV, IOCC, and full-load efficiency targets.

Equation 8.

The below equation provides an accurate solution for input capacitance needed to achieve a minimum bulk valley voltage target VBULK(min), accounting for hold-up during any loss of AC power for a certain number of half-cycles, NHC, by an AC-line drop-out condition. Alternatively, if a given input capacitance value is prescribed, iterate the VBULK(min) value until that target capacitance is obtained, which determines the VBULK(min) expected for that capacitance.

Equation 9.