HP dc7800 manual Usdt Power Distribution

7

Power and Signal Distribution

7.1Introduction

This chapter describes the power supplies and discusses the methods of general power and signal distribution. Topics covered in this chapter include:

■Power distribution (7.2)

■Power Control (7.3)

■Signal distribution (7.4)

7.2Power Distribution

Each form factor uses a unique power supply assembly and implements different methods of power generation and distribution. The USDT form factor uses an external (“brick”) supply while the SFF and CMT form factors use a power supply unit contained within the system chassis. The subassemblies are not interchangeable between the three form factors.

7.2.1 USDT Power Distribution

The USDT form factor uses an external (“brick”) supply that connects to the chassis through a three-conductor cable (Figure 7-1). All voltages required by the processing circuits, peripherals, and storage devices are produced on the system board from the 19.0 VDC produced by the extrernal power supply assembly. The external power supply always produces 19.0 VDC as long as it is connected to an active AC outlet.

Front Bezel

Power Button

Power On

90 - 264 VAC

USDT Chassis

System Board

Power Logic,

Voltage Regulators

+19.0	Rtn	Pwr rating
VDC		& ID

External

Power Supply

Unit

Figure 7-1. USDT Power Generation, Block Diagram

Technical Reference Guide www.hp.com 7-1