MAX6621AUB+ MAXIM [Maxim Integrated Products], MAX6621AUB+ Datasheet - Page 9

• Manufacturer Part Number: MAX6621AUB+
• Description: PECI-to-I2C Translator
• Manufacturer: MAXIM [Maxim Integrated Products]

This optional feature can be enabled using bit 6 of
CONFIG0. When the alternate data format is enabled, the
temperature value is shifted right as shown in Table 9.
The most significant bits are set to all 0s or all 1s depend-
ing on the sign bit 15, also shown as S in Figure 3. Table
10 shows some example values. This translation is not
performed for error codes (16-bit values from 8000h
through 81FFh).
Excluding error codes, the software only has to exam-
ine the RESLO data byte, as it represents an integer
value in the range from -128°C to +127°C in 1°C steps.
The RESHI byte is all 0s or all 1s for valid return codes,
and either 80h or 81h for all error codes.
Table 9. Alternate Temperature
Representation
Table 10. Example Alternate Representation with No Offset (Activation Point = +95°C)
16-bit value
Alternate
representation
DESCRIPTION
TEMP (°C)
Alternate Temperature Value Representation
+94
+85
+70
+45
+20
15:15:15:15:15:15:15:15 15:12:11:10:9:8:7:6
15:14:13:12:11:10:9:8
_______________________________________________________________________________________
RELATIVE TEMP (°C)
RESHI
-10
-25
-50
-75
-1
7:6:5:4:3:2:1:0
RESLO
FFCEh
FFE7h
FFB5h
FFFFh
FFF6h
HEX
The MAX6621 can average several temperature read-
ings and return a value as calculated by:
where T
is the new value read from PECI, and T
stored temperature ready to be returned through I
This calculation can cause significant bits to be lost.
Enable temperature averaging by writing the desired
averaging amount to the CONFIG3 register. Writing 00h
to the CONFIG3 register disables temperature averaging.
Figure 3. Alternate Temperature Representation
PECI-to-I
(SIGN BITS)
RESHI
S
S
T
NEW
X
S
OLD
X
S
=
2
12 11 10
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
S
CONFIG
is the previously stored temperature, T
RESHI
1
S
3
S
x T
S
9
2
PECI
S
8
C Translator
BINARY
+
INTEGER VALUE (~ 1°C)
RESLO
S
⎛
⎜
⎝
7
Temperature Averaging
1
−
12 11 10
6
2
CONFIG
X
1
1111 0110
1110 0111
1100 1110
1011 0101
1111 1111
FRACTIONAL VALUE
NEW
RESLO
X
3
X
9
⎞
⎟
⎠
is the newly
x T
X
8
OLD
X
7
PECI
2
X
6
C.
9