SAS 3.3V LED driver characteristics - Feedback by 8/2/02 please!

George Penokie gop at us.ibm.com
Fri Jul 26 12:17:41 PDT 2002


* From the T10 Reflector (t10 at t10.org), posted by:
* George Penokie <gop at us.ibm.com>
*
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Alvin,
I have received the following feedback from the IBM designers:

The lower the current the better for us, but you also want to have
enough to light the LED. How about 15mA @ 0.2V spec, this would be a 13
Ohm pulldown that we can do using our standard library?

Bye for now,
George Penokie

Dept 2C6 114-2 N212
E-Mail: gop at us.ibm.com
Internal: 553-5208
External: 507-253-5208 FAX: 507-253-2880


 Alvin.Cox at seagate.com




=20
=09



	Alvin.Cox at seagate.com
Sent by: owner-t10 at t10.org=20

	07/19/02 03:23 PM




To: t10 at t10.org
cc:=20
Subject: SAS 3.3V LED driver characteristics - Feedback by 8/2/02
please!

=09

* From the T10 Reflector (t10 at t10.org), posted by:
* Alvin.Cox at seagate.com
*
The majority of the SAS PHY working group desires to change the LED
driver
characteristics to be 3.3V compliant rather than 5V compliant. As a new
interface, this seems to be the best opportunity to change. IC supply
voltages are lower and LED efficiencies are increasing. One =
complication
is
the old specification allowed a rather high output-low voltage. At 0.5V
maximum, it is a significant proportion of the nominal 3.3V supply. The
current was also rather high when considering the LED's available =
today.
The SAS PHY working group makes the following recommendation for
consideration in the SAS specification for the READY LED electrical
characteristics. We realize that this may be an aggressive =
specification
at
this time, but feel that it most likely can be achieved with today's
commonly used technologies. Check the SAS specification (Section 5) for
the
complete set of READY LED implementation requirements.

Output characteristics of the READY LED signal (tested through the
device
mated connector)

State Output current Output voltage

Drive LED off -100 =B5A < IOH < 100 =B5A 0 < VOH < 3.6 V
Drive LED on IOL > 10 mA 0 < VOL < 0.15V


Alvin Cox
Seagate Technology, LLC

*
* For T10 Reflector information, send a message with
* 'info t10' (no quotes) in the message body to majordomo at t10.org




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Alvin,
 I have received the following feedback from the IBM designers:
 
The lower the current the better for us, but you also want to have = enough to light the LED. How about 15mA @ 0.2V spec, this would be a = 13 Ohm pulldown that we can do using our standard library?
 
Bye for now,
 George Penokie
 
Dept 2C6 114-2 N212
 E-Mail: gop at us.ibm.com
 Internal: 553-5208
 External: 507-253-5208 FAX: 507-253-2880
 

Alvin.Cox at seagate.com
 



Alvin.Cox at seagate.com
 Sent by: owner-t10 at t10.org 07/19/02 03:23 PM 
	
 	To:	t10 at t10.org
 	cc:	
 	Subject:	SAS 3.3V LED driver = characteristics - Feedback by 8/2/02 please!
 

* From the T10 Reflector (t10 at t10.org), = posted by:
 * Alvin.Cox at seagate.com
 *
 The majority of the SAS PHY working group desires to change the LED = driver
 characteristics to be 3.3V compliant rather than 5V compliant. As a = new
 interface, this seems to be the best opportunity to change. IC = supply
 voltages are lower and LED efficiencies are increasing. One = complication is
 the old specification allowed a rather high output-low voltage. At = 0.5V
 maximum, it is a significant proportion of the nominal 3.3V supply. = The
 current was also rather high when considering the LED's available = today.
 The SAS PHY working group makes the following recommendation for
 consideration in the SAS specification for the READY LED electrical
 characteristics. We realize that this may be an aggressive = specification at
 this time, but feel that it most likely can be achieved with = today's
 commonly used technologies. Check the SAS specification (Section 5) for = the
 complete set of READY LED implementation requirements.
 
Output characteristics of the READY LED signal (tested through the = device
 mated connector)
 
State Output current Output voltage
 
Drive LED off -100 =B5A < IOH < 100 =B5A 0 < VOH = < 3.6 V
 Drive LED on IOL > 10 mA 0 < VOL < = 0.15V
 

Alvin Cox
 Seagate Technology, LLC
 
*
 * For T10 Reflector information, send a message with
 * 'info t10' (no quotes) in the message body to majordomo at t10.org
 



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