SNVSBJ0A December   2019  – June 2020

PRODUCTION DATA.

1. Features
2. Applications
3. Description
1.     Device Images
4. Revision History
5. Description (continued)
6. Pin Configuration and Functions
7. Specifications
8. Detailed Description
1. 8.1 Overview
2. 8.2 Functional Block Diagram
3. 8.3 Feature Description
4. 8.4 Device Functional Modes
5. 8.5 Programming
9. Application and Implementation
1. 9.1 Application Information
2. 9.2 Typical Application
1. 9.2.1 60-A, Dual-Phase, 48-V to 12-V Bidirectional Converter
1. 9.2.1.1 Design Requirements
2. 9.2.1.2 Detailed Design Procedure
3. 9.2.1.3 Application Curves
10. 10Power Supply Recommendations
11. 11Layout
12. 12Device and Documentation Support
13. 13Mechanical, Packaging, and Orderable Information

• PHP|48
• PHP|48

#### 9.1.2.2 Inner Current Loop Compensation

Equation 24 indicates that the power plant is basically a first-order system. A Type-II compensator as shown in Figure 50 is adequate to stabilize the loop for both buck and boost mode operations.

Assuming the output impedance of the gm amplifier is RGM, the gain from the inductor to the output of gm amplifier is determined by Equation 25:

Equation 25. where

• the coefficient 50 is the current sense amplifier gain;
• Gm is the transconductance of the gm error amplifier, which is 1 mA/V;
• ZCOMP(s) is the equivalent impedance of the compensation network seen at the COMP pin (see Equation 26)
Equation 26. Usually CHF is << CCOMP. Thus Equation 26 can be simplified to Equation 27:

Equation 27. Because RGM is > 5 MegΩ, and the frequency range for loop compensation is usually above a few kHz, the effects of RGM on the loop gain in the interested frequency range becomes negligible. Therefore, substituting Equation 28 into Equation 25, and neglecting RGM, one can get the following:

Equation 28. The total open-loop gain of the inner current loop is the product of H(s) and G(s):

Equation 29. Or:

Equation 30. The poles and zeros of the total loop transfer function are determined by:

Equation 31. Equation 32. Equation 33. Equation 34. To tailor the total inner current loop gain to cross over at fCO, select the components of the compensation network according to the following guidelines, then fine tune the network for optimal loop performance.

1. The zero fz is placed at the power stage pole fp2,
2. The pole fp3 is placed at approximately two decade higher then fCO,
3. The total open-loop gain is set to unity at fCO, namely,

Equation 35. Therefore, the compensation components can be derived from the above equations, as shown in Equation 36.

Equation 36. 