Voltage Regulator-Down (VRD) 10.1 Design Guide

Electrical Simulation

Design Guide

11 Electrical Simulation

The following electrical models are enclosed to assist with VRD design analysis and component

evaluation for load line compliance. The block diagram shown in Figure 11-1 is a simplified

representation of the Vcc power delivery network of the Intel four-layer reference board

interfaced with the LGA775 socket. The board model, detailed in Figure 11-4, characterizes the

power plane layout of Figure 10-2 to Figure 10-5. The socket, detailed in Figure 11-6, models the

LGA775 electrical parasitics; it also provides a current load step model for exploring the system

droop response. The multiphase buck regulator and capacitor models should be obtained from

each selected vendor. When fully integrated into electrical simulation software, this model can be

used to evaluate PWM controller, capacitor, and inductor performance against the load line and

tolerance band requirements detailed in Section 2.2. To obtain accurate results, it is strongly

recommended to create and use a custom model that represents the specific board design, PWM

controller, and passive components that are under evaluation.

Figure 11-1. Simplified Block Diagram Representing Electrical Connectivity for the VRD on

the Four-Layer Intel Reference Motherboard

East Phase Inductors

North Phase Inductors

Error Amplifier Input

Output: North Phases

Output: East Phases

North

Bulk

Caps

East

Bulk

Caps

High

Frequency

Filtering

Capacitance

Multi-Phase Buck

Regulator

Socket

Motherboard

NOTE: Consult Figure 10-2 to Figure 10-5 for reference layout.