C-compatible interface – Rainbow Electronics MAX6651 User Manual
Page 18
up to four fans, ensuring any significant speed mis-
matches can be detected.
For parallel fan control while monitoring up to four fan
speeds, select the MAX6651.
For parallel fan control while monitoring only a single
fan, select the MAX6650.
Synchronized Fan Control (MAX6651 Only)
In systems with multiple fans, an audible beat frequency
can sometimes be detected due to fan speed mismatch.
This happens in systems where fans are connected in
parallel or in systems with a MAX6650 controlling each
fan. In parallel fan systems, speed mismatches occur
because no two fans are identical. Slight mechanical
variations or loading differences can result in enough of
a speed mismatch to cause an audible beat.
MAX6650/MAX6651
Fan-Speed Regulators and Monitors
with SMBus/I
2
C-Compatible Interface
18
______________________________________________________________________________________
MAX6650
V
CCIN
SCL
10k
SDA
GPIO0
OUT
ADD
GND
FB
TACH0
V
CC
3V TO 5.5V
V
FAN
5V OR 12V
C
COMP
10
µF
I
2
C/SMBus
INTERFACE
GPIO1
FULL ON
ALERT
FAN
MAX6501
TOVER
Figure 11. MAX6501 Hardware Fail-Safe
MAX6650
V
CCIN
SCL
10k
SDA
GPIO0
OUT
ADD
GND
FB
TACH0
V
CC
3V TO 5.5V
V
FAN
5V OR 12V
C
COMP
10
µF
I
2
C/SMBus
INTERFACE
GPIO1
FULL ON
ALERT
FAN
MAX6501
TOVER
MAX6501
TOVER
MAX6501
TOVER
Figure 12. MAX6501 Hardware Fail-Safe