Analog Devices dBCool ADT7473 Manual page 32

ADT7473
If V goes high (the system processor power rail is powered
CC
up), a fail-safe timer begins to count down. If the ADT7473 is
not addressed by any valid SMBus transactions before the fail-
safe timeout (4.6 seconds) lapses, the ADT7473 drives the fans
to full speed. If the ADT7473 is addressed
transaction after this point, the fans stop, and the ADT7473
assumes its default settings and begins normal operation.
If V goes high (the system processor power rail is powered
CCP
up), then a fail-safe timer begins to count down. If the
ADT7473 is addressed by a valid SMBus transaction before the
fail-safe timeout (4.6 seconds) lapses, then the ADT7473
operates normally, assuming the functio
registers. See the flow chart in Figure 43.
by a valid SMBus
nality of all the default
Rev. A | Page 32 of 76
ADT7473 IS POWERED UP
HAS THE ADT7473 BEEN
ACCESSED BY A VALID
Y
SMBus TRANSACTION?
N
IS V ABOVE 0.75V?
CCP
Y
START FAIL-SAFE TIMER
HAS THE ADT7473 BEEN
ACCESSED BY A VALID
Y
SMBus TRANSACTION?
N
FAIL-SAFE TIMER ELAPSES
AFTER THE FAIL-SAFE TIMEOUT
HAS THE ADT7473 BEEN
ACCESSED BY A VALID
SMBus TRANSACTION?
Y
START UP THE
ADT7473 NORMALLY
Figure 43. Power-On Flow Chart
CHECK V
CCP
N
RUNS THE FANS
TO FULL SPEED
N
HAS THE ADT7473 BEEN
ACCESSED BY A VALID
SMBus TRANSACTION?
Y
SWITCH OFF FANS
N