User guide

MAX6678
OOTT
Status (05h)
Read the OT status register to determine which channel
recorded an overtemperature condition. Bit D7 is high if
the fault reading occurred from channel 1. Bit D6 is
high if the fault reading occurred in channel 2. The OT
status register is cleared only by reading its contents.
After reading the OT status register, a temperature reg-
ister read must be done. Reading the contents of the
register also makes the OT output high impedance. If
the fault is still present on the next temperature mea-
surement cycle, the corresponding bits and the OT out-
put are set again. The POR state of the OT status regis-
ter is 00h.
OOTT
Mask (06h)
Set bit D7 to 1 in the OT mask register to prevent the
OT output from asserting on faults in channel 1. Set bit
D6 to 1 to prevent the OT output from asserting on
faults in channel 2. The POR state of the OT mask reg-
ister is 00h.
2-Channel Temperature Monitor with Dual Automatic
PWM Fan-Speed Controller and Five GPIOs
12 ______________________________________________________________________________________
Table 2. Register Map (continued)
READ/
WRITE
REGISTER
NO.
/ADDRESS
POR
STATE
FUNCTION D7 D6 D5 D4 D3 D2 D1 D0
R 0Eh 0000 000x
PWMOUT2
instantaneous
duty cycle
MSB
(128/240)
—————
LSB
(2/240)
—
R/W 0Fh 0000 0000
Temperature
channel 1 fan-
start temperature
MSB — — ————LSB
R/W 10h 0000 0000
Temperature
channel 2 fan-
start temperature
MSB — — ————LSB
R/W 11h 0000 000x
Fan
configuration
Hys ter esi s:
0 = 5°C,
1 = 10°C
Temp
step: 0 =
1°C,
1 = 2°C
PWMOUT
1 control:
1 =
channel1
PWMOUT
1 control:
1 =
channel 2
PWMOUT
2 control:
1 =
channel 1
PWMOUT
2 control:
1 =
channel 2
——
R/W 12h 1011 01xx
Duty-cycle rate
of change
PWMOUT
1 MSB
—
PWMOUT
1 LSB
PWMOUT
2 MSB
—
PWMOUT
2 LSB
——
R/W 13h 0101 0101
Duty-cycle step
size
PWMOUT
1 MSB
——
PWMOUT
1 LSB
PWMOUT
2 MSB
——
PWMOUT
2 LSB
R/W 14h 010x xxxx
PWM frequency
select
Select A Select B Select C — — — — —
R/W 15h xxx0 0000 GPIO function — — —
GPIO4: 0
= output,
1 = input
GPIO3: 0
= output,
1 = input
GPIO2: 0
= output,
1 = input
GPIO1: 0
= output,
1 = input
GPIO0: 0
= output,
1 = input
R/W 16h xxx*** GPIO value — — — GPIO4 GPIO3 GPIO2 GPIO1 GPIO0
R FDh 0000 0001
Read device
revision
00000001
R FEh 1000 0110 Read device ID 1 0 0 0 0 1 1 0
R FFh 0100 1101
Read
manufacturer ID
01001101
***GPIO0 through GPIO4 POR values set by Preset0 through Preset4.