SNVSB29C October   2018  – June 2021

PRODUCTION DATA

1. Features
2. Applications
3. Description
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
9. Application and Implementation
1. 9.1 Application Information
1. 9.1.1 Power Train Components
2. 9.1.2 Error Amplifier and Compensation
2. 9.2 Typical Applications
1. 9.2.1 Design 1 – High Efficiency, Dual-Output Buck Regulator for Automotive Applications
2. 9.2.2 Design 2 – Two-Phase, Single-Output Buck Regulator for Automotive ADAS Applications
10. 10Power Supply Recommendations
11. 11Layout
1. 11.1 Layout Guidelines
2. 11.2 Layout Example
12. 12Device and Documentation Support
1. 12.1 Device Support
2. 12.2 Documentation Support
1. 12.2.1 Related Documentation
4. 12.4 Support Resources
6. 12.6 Electrostatic Discharge Caution
7. 12.7 Glossary
13. 13Mechanical, Packaging, and Orderable Information

• RWG|40

9.1.2 Error Amplifier and Compensation

Figure 9-3 shows a Type-II compensator using a transconductance error amplifier (EA). The dominant pole of the EA open-loop gain is set by the EA output resistance, RO-EA, and effective bandwidth-limiting capacitance, CBW, as shown in Equation 28.

Equation 28.

The EA high-frequency pole is neglected in the Equation 28. The compensator transfer function from output voltage to COMP node, including the gain contribution from the (internal or external) feedback resistor network, is calculated in Equation 29.

Equation 29.

where

• VREF is the feedback voltage reference of 0.6 V
• gm is the EA gain transconductance of 1200 µS
• RO-EA is the error amplifier output impedance of 64 MΩ
Equation 30.
Equation 31.
Equation 32.

The EA compensation components create a pole close to the origin, a zero, and a high-frequency pole. Typically, RCOMP << RO-EA and CCOMP >> CBW and CHF, so the approximations are valid.

Figure 9-3 Error Amplifier and Compensation Network