1. EET 450 – Advanced Digital Chapter 24 Power

2. Power Supplies Power conversion Performs a voltage conversion from either 120vAC to desired or 12vDC to desired voltages Technologies Linear Not efficient – heat generated Switching

3. Power Supplies Power requirements Supplying adequate power (watts) Total ~ 150-350 watts Supply constant voltages + 5V -5 V + 12V - 12V +3.3V (ATX)

4. Power Supplies Device Power needs Table 24.1 Floppy – 1.4 W Video – 6.5 W HD – 2.2W – 6.5 W Memory 16.8 W/8M System Board – 25 W

5. Supply Voltage US Standard – 115 V – 60 Hz 100-240, 50/60 Hz is common Regulated supplies for AC Fairly uncommon – complex Regulation is typically done by converting to DC, regulating, then converting back to AC

6. Portable Power Batteries NiCad Lithium Ion NiMH – Smart Battery Notebook Power 2-6 hours

7. Power Connections Standard P/S D shaped device power connector +5/+12 3.5” power connector +5/+12 Main Board Power Connector See tables 24.3, 24.4

10. Power Management States of APM Full On APM Standby – memory powered APM Suspend - vegetable Hibernation – allows restoration to memory/ program state Off State

11. Energy Star PC Monitor able to switch to a low power mode. < 30 watts after 15 to 30 minutes Combo of PC/monitor < 60 watts Printer based on PPM

12. Power Protection Irregularities Overvoltage Surges Undervoltage brownout Noise RF

13. Surge Suppression Sinking energy spikes away from PC Sacrificial MOV Active Zener Diode

14. UPS Battery System Backup Power Supply Regulation and ‘clean’ output waveform True UPS Continuous power Switching power Computer Interface (network)

15. Other Considerations Phone Lines Static Electricity Network Interface

16. Cases The case dictates what can kind of power supply can be used.

17. Older case Styles PC/XT – Small Power Supply (63 watts) AT Style Desktop Tower Baby AT form factor LPX Style PS2 Style

18. Current case styles ATX form factor Power Supply used in ATX and NLX systems Power connector is substantially changed NLX style Low profile ATX SFX style Micro-ATX motherboards

19. Power Supply Connectors Standard M/B connector AT ATX Power expansion Y – cable ATX Auxiliary and Optional connector

20. Disk Drive Power Connectors Conventional drive D-shaped New ‘3.5”’ connector Keyed pin connector