Datasheet
20 Datasheet
Intel
®
Celeron
®
Processor up to 1.10 GHz
2.5 Voltage Identification
The processor’s voltage identification (VID) pins can be used to automatically select the VCC
CORE
voltage from a compatible voltage regulator. There are five VID pins (VID[4:0]) on the S.E.P.
Package, while there are only four (VID[3:0]) on the PGA packages. This is because there are no
Celeron processors in the PGA package that require more than 2.05 V (see Table 2).
VID pins are not signals, but rather are an open or short circuit to V
SS on the processor. The
combination of opens and shorts defines the processor core’s required voltage. The VID pins also
allow for compatibility with current and future Intel Celeron processors.
Note that the ‘11111’ (all opens) ID can be used to detect the absence of a processor core in a given
slot (S.E.P. Package only), as long as the power supply used does not affect the VID signals.
Detection logic and pull-ups should not affect VID inputs at the power source (see Section 7.0).
External logic monitoring the VID signals or the voltage regulator may require the VID pins to be
pulled-up. If this is the case, the VID pins should be pulled up to a TTL-compatible level with
external resistors to the power source of the regulator.
The power source chosen must be guaranteed to be stable whenever the voltage regulator’s supply
is stable. This will prevent the possibility of the processor supply going above the specified
V
CC
CORE
in the event of a failure in the supply for the VID lines. In the case of a DC-to-DC
converter, this can be accomplished by using the input voltage to the converter for the VID line
pull-ups. In addition, the power supply must supply the requested voltage or disable itself.
NOTES:
1. 0 = Processor pin connected to V
SS.
2. 1 = Open on processor; may be pulled up to TTL V
IH
on motherboard.
3. The Celeron processor core uses a 2.0 V power source.
4. VID4 applies only to the S.E.P. Package. VID[3:0] applies to both S.E.P. and PGA packages.
Table 2. Voltage Identification Definition
VID4
(S.E.P.P. only)
VID3 VID2 VID1 VID0 V
CC
CORE
01111 1.30
01110 1.35
01101 1.40
01100 1.45
01011 1.50
01010 1.55
01001 1.60
01000 1.65
00111 1.70
00110 1.75
00101 1.80
00100 1.85
00011 1.90
00010 1.95
00001 2.00
00000 2.05
11111No Core
4
11110 2.1
4