LPC47M142-NC Standard Microsystems (SMSC), LPC47M142-NC Datasheet - Page 121

• Manufacturer Part Number: LPC47M142-NC
• Manufacturer: Standard Microsystems (SMSC)

Specifications of LPC47M142-NC

• Lead Free Status / RoHS Status: Not Compliant

The following tables show examples of the desired functionality. Counts are based on 2 pulses per revolution
tachometer outputs with a default divisor of 2.
Pins 51 and 52 are the fan tachometer inputs, FAN_TACH2 and FAN_TACH1, respectively.
The configuration registers for the fan tachometer inputs are defined in the “Runtime Registers” section.
SMSC DS – LPC47M14X
Divide by 1
Divide by 2
Divide by 4
Divide by 8
SELECT
RPM
4400
3080
2640
2204
MODE
REVOLUTION
32 kHz
TIME PER
13.64 ms
19.48 ms
22.73 ms
27.22 ms
NOMINAL
RPM
8800
4400
2200
1100
REVOLUTION
Programmable
TIME PER
TERM 1 FOR “DIVIDE
BY 2” (DEFAULT) IN
13.64 ms
27.27 ms
54.54 ms
6.82 ms
1, 2, 4, 8
Divider
112 counts
160 counts
186 counts
223 counts
DECIMAL
PRELOAD
Latch on Read
32
32
32
32
Page 121
Counter
Preload
PRELOAD
COUNTS FOR
32
32
32
32
THE GIVEN
SPEED IN
DECIMAL
MSB
144
144
144
144
(maximum count)
Sync
(TERM 1) +
PRELOAD
COUNT =
144
192
218
255
70% RPM
6160
3080
1540
770
To nPME
Logic
FOR 70% RPM
REVOLUTION
COMMENTS
Typical RPM
TIME PER
70% RPM
60% RPM
50% RPM
19.48 ms
38.96 ms
77.92 ms
9.74 ms
Rev. 03/19/2001