MAX6621
PECI-to-I
2
C Translator
8 _______________________________________________________________________________________
CONFIG2
The CONFIG2 register holds the offset that is added to
all temperature return values that are not error codes.
The offset is enabled in CONFIG0, bit 6; +95°C is set
as 17C0h or 005Fh, depending on the data format. To
represent +95°C in 16-bit representation, convert
+95°C to binary using two’s complement and left-shift
six times. The MAX6621 automatically converts the off-
set value to the equivalent value when the data format
is changed. See Table 5 for the default offset and Table
6 for some example values.
When configured in CONFIG2, and the return code is not
an error code (see the
Error Codes
section), the device
adds the offset value stored in CONFIG2 to the return
value. For example, if the CPU’s thermal control circuit
activation point is at +95°C, CONFIG2 can be set to
+95°C (005Fh or 17C0h) and all return values are con-
verted to absolute temperatures. Note that the thermal
control circuit activation point is CPU specific. The offset
value is represented in the current data format.
CONFIG3
CONFIG3 register configures the temperature averaging
function. See the
Temperature Averaging
section for
more information. Table 7 shows the default settings.
Temperature Representation
Temperature data is formatted in 16-bit two’s comple-
ment representing a range from -512°C to +512°C in
steps of 1/64°C (Figure 1). Internally, the device always
uses the 16-bit data format. The temperature is given in
two’s complement and left-shifted so that the +1°C bit
is bit 6 (Figure 2). Temperatures can be represented
externally in alternate data format if fractional readings
are not needed. Table 8 shows some examples.
BIT(S) DESCRIPTION DEFAULT
15:0 Temperature offset 0000h
Table 5. CONFIG2 Register
BINARY
TEMP (°C) HEX
RESHI RESLO
0 0000h 0000 0000 0000 0000
+25 0640h 0000 0110 0100 0000
+50 0C80h 0000 1100 1000 0000
+75 12C0h 0001 0010 1100 0000
+95 17C0h 0001 0111 1100 0000
Table 6. Example Offset Values in 16-Bit
Temperature Representation
BIT(S) DESCRIPTION DEFAULT
15:8 Reserved, set to 0 00h
7:0 Averaging shift count, see formula 00h
Table 7. CONFIG3 Register
RESLO
1°C
1
4
1
2
°C °C °C
°C °C °C
1
8
1
32
1
16
1
64
01234567
Figure 1. Temperature Measured in 1/64°C Steps
-50°C
00110111
TWO'S
COMPLEMENT
RESLO
RESHI
01234567
89101112131415
Figure 2. Conversion of Temperature Done in Two’s
Complement
BINARY
TEMP
(°C)
RELATIVE
TEMP (°C)
HEX
RESHI RESLO
+94 -1 FFC0h 1111 1111 1100 0000
+85 -10 FD80h 1111 1101 1000 0000
+70 -25 FDC0h 1111 1101 1100 0000
+45 -50 F380h 1111 0011 1000 0000
+20 -75 ED30h 1110 1101 0100 0000
Table 8. Example 16-Bit Representation
with No Offset (Activation Point = +95°C)
