LPC47S457-NC SMSC [SMSC Corporation], LPC47S457-NC Datasheet - Page 254

• Manufacturer Part Number: LPC47S457-NC
• Description: Advanced I/O with X-Bus Interface
• Manufacturer: SMSC [SMSC Corporation]

11.12 Fan Timing
Note 1: The period is 1/f
f
Note 2: When Bit 0 of the FAN register is 0, then the duty cycle is programmed through Bits[6:1] of these registers.
If Bits[6:1] = “000000” then the FAN pin is low. The duty cycle is programmable through Bits[6:1] to be between
1.56% and 98.44%. When Bit 0 is 1, the FAN pin is high.
Note 1: t
programmed in the Fan Control register.
SMSC LPC47S45x
out
is +/- 3%.
NAME
NAME
TACH
t1
t2
t1
t2
t3
is the clock used for the tachometer counter. It is 30.52 * DVSR, where the divisor (DVSR) is
FAN
FAN_TACH
PWM Period (Note 1)
PWM High Time (Note 2)
Pulse Time (1/2 Revolution Time=30/RPM)
Pulse High Time
Pulse Low Time
out
,where f
DESCRIPTION
DESCRIPTION
FIGURE 48 − FAN TACHOMTER INPUT TIMING
out
is programmed through the FAN and Fan Control registers. The tolerance on
FIGURE 47 − FAN OUTPUT TIMING
t2
DATASHEET
t2
t1
Page 254 of 259
t1
0.00033
t3
0.021
MIN
4t
3t
t
MIN
TACH
TACH
TACH
1
1
TYP
TYP
MAX
25.8
25.4
MAX
UNITS
UNITS
msec
msec
µsec
µsec
µsec
Rev. 06-01-06