Maxim Integrated MAX31782 - Manual (Page 90)

  MaximIntegrated 10-2
MAX31782 User’s Guide
Revision 0; 8/11
SECTION 10: FAN TACHOMETER
The MAX31782 provides six independent fan tachometers that can be used to monitor the speed of six fans indepen-
dently . When the fan tachometer functionality of a pin is disabled, that pin can be used as a general-purpose input/
output (GPIO) .
Figure 10-1 shows a diagram for one individual fan tachometer block .
Figure 10-1. Tachometer Input Block Diagram
CLOCK
PRESCALER
TEXF
0000h
TACHVn REGISTER
TACHRn REGISTER
15 0
15 0
TF
TACHIE
TACHOMETER
INTERRUPT
SYSTEM
CLOCK
ƒ
TACHE
CAPTURE
TACH.n
PIN
REVOLUTION
PRESCALER
TEXEN
TPS[2:0]
000
001
010
011 SYSTEM CLOCK /1
100
101
11x
SYSTEM CLOCK /4
SYSTEM CLOCK /16
SYSTEM CLOCK /64
SYSTEM CLOCK /256
SYSTEM CLOCK /1024
SYSTEM CLOCK /1
TRPS[1:0]
00
01
10
11 DIVIDE BY 1
DIVIDE BY 2
DIVIDE BY 4
DIVIDE BY 8
THIS DIAGRAM SHOWS ONE OF THE SIX INDEPENDENT TACHOMETERS.
THE “n” SUFFIX IS USED TO DENOTE THE NAME OF THE TACHOMETER’S
PIN AND REGISTERS, WHERE n = 0 TO 5. THE BITS AND FLAGS SHOWN
ARE LOCATED IN EACH TACHOMETER’S CONTROL REGISTER, TACHCn.