MEMO TO: Henning Schulzrinne		DATE:May 17, 2000

FROM: Hal Weinreb
	
Cc: Joe Flicek, Mike Keating, Art Brody

					
SUBJECT: Engineering Review of the Schematics for ephone 2.0/2.1

Mike Keating and his staff have essentially completed their engineering review of the schematics and PCB artwork for ephone 2.0 prior to their revision to version 2.1. His status report and engineering review are being separately emailed to you. 

We are getting ready to use the revised schematics for fabrication of the new PCB and the altered Sprint case and we would appreciate your comments before proceeding. In particular, your comments on the following components (Mike Keating has also pointed out pin connection and tracing omissions which are covered in his report but not listed here):

-Schematic Sheet 4 (EPLD, LCD and KEY Circuit)
1. PS2701 (Optocoupler OPT0) and the alarm connector J13 are shown on the schematic but not installed on the board. I assume we will install on the 2.1 board.
2. Also on this sheet, the 2 pin jack connector SW-1 and HK are shown on the schematic but not on board. I assume we will install.

-Schematic Sheet 5 (ETHERNET Circuit)
3. R30, C49 and L5 (ferrite) are shown together on the schematic but not installed. 

-Schematic Sheet 6 ( A/D and D/A Circuit )
4. Speaker jack J6 is shown on the schematic but not installed. I assume we will install for convenience.

-Schematic Sheet 7 (POWER circuit)
5. This sheet is being redone by Mike Keating (PPT) because of the overheating of the power regulator. The LM7805CXT (MAX787) is being replaced with a National Semiconductor LM2575-5.0 and a Renco 330uH inductor and a low ESR capacitors.
6. The schematic shows C45 and C47 to be 220uF and 470uF respectively whereas the installed units are 1000uF each.
7. LT 1054CP and UA79M05AUC (also known as LM79M05) are shown in the schematic but not installed on board. Keating believes these are intended to provide -5V power to the LCD. Keating is following up contacting the LCD provider (Optrex and their distributor Appolo Display) to pin down the LCD specs.   

 
Hgw;G1(SIP) Engineering Review of the Schematics ephone 2.0/2.1