TC665TEUN View Datasheet(PDF) - Microchip Technology
Part Name
Description
MFG CO.
'TC665TEUN' PDF : 36 Pages View PDF
TC664/TC665
6.0 REGISTER SET
The TC664/TC665 devices contain 7 registers that pro-
vide a variety of data and functionality control to the
outside system. These registers are listed in Table 6-1.
Of key importance is the command byte information,
which is needed in the read and write protocols to
select the individual registers.
TABLE 6-1: COMMAND BYTE ASSIGNMENTS
Register
Command Read Write POR Default State
Function
RPM
FAN_FAULT
CONFIG
STATUS
0000 0000
X
0000 0010
X
0000 0100
X
0000 0101
X
DUTY_CYCLE
0000 0110
X
MFR_ID
0000 0111
X
VER_ID
0000 1000
X
—
0 0000 0000 RPM Output
X
0000 1010
Fan Fault Threshold
X
0000 1010
Configuration
—
00X0 0X00
Status. See Section 6.4, Status Reg-
ister explanation of X
X
0000 0010
Fan Speed Duty Cycle
—
0101 0100
Manufacturer Identification
—
0000 00XX
Version Identification:
(XX = ‘10’ TC664, XX = ‘11’ TC665)
6.1 RPM-OUTPUT Register (RPM)
As discussed in Section 4.7, fan current pulses are
detected at the SENSE input of the TC664/TC665
device. The current pulse information is used to calcu-
late the fan RPM. The fan RPM data is then written to
the RPM register. RPM is a 9-bit register that provides
the RPM information in 50 RPM (8-bit) or 25 RPM (9-
bit) increments. This is selected via RES (bit 6<0>) in
the Configuration Register, with ‘0’ = 50 RPM and
‘1’ = 25 RPM. The default state is zero (50 RPM). The
maximum fan RPM value that can be read is
12775 RPM. If this value is exceeded, RCO (bit 3<0>)
in the Status Register will be set to a '1' to indicate that
a counter overflow of the RPM Register has occurred.
Register 6-1 shows the RPM output register 9-bit for-
mat.
REGISTER 6-1: RPM OUTPUT REGISTER (RPM)
D(8)
D(7)
D(6)
D(5)
D(4)
D(3)
D(2)
D(1)
D(0)
RPM
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
25
0
0
0
0
0
0
0
1
0
50
.
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1
1
1
1
1
1
1
1
0
12750
1
1
1
1
1
1
1
1
1
12775
2002-2013 Microchip Technology Inc.
DS21737B-page 17
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