Rainbow Electronics LM63 - Manual (Page 20)

2.0 LM63 Registers
(Continued)
Tachometer Count And Limit Registers
ADDRESS
Hex
Read/
Write
Bits
POR
Value
Name Description
47
HEX
TACHOMETER COUNT (MSB) and 46
HEX
TACHOMETER COUNT (LSB) REGISTERS (16 bits: Read LSB first to lock
MSB and ensure MSB and LSB are from the same reading)
47
Read
Only
7:0 N/A
Tachometer
Count (MSB)
These registers contain the current 16-bit Tachometer Count, representing
the period of time between tach pulses.
Note that the 16-bit tachometer MSB and LSB are reversed from the
16-bit temperature readings.
46
Read
Only
7:2 N/A
Tachometer
Count (LSB)
Read
Only
1:0 00
Tachometer
Edge Count
Bits Edges Used Tach_Count_Multiple
00: Reserved - do not use
01: 2 4
10: 3 2
11: 5 1
Note: If PWM_Clock_Select = 360 kHz, then Tach_Count_Multiple = 1
regardless of the setting of these bits.
49
HEX
TACHOMETER LIMIT (MSB) and 48
HEX
TACHOMETER LIMIT (LSB) REGISTERS
49 R/W 7:0 0xFF
Tachometer
Limit MSB)
These registers contain the current 16-bit Tachometer Count, representing
the period of time between tach pulses. Fan RPM = (f * 5,400,000) /
(Tachometer Count), where f = 1 for 2 pulses/rev fan; f = 2 for 1 pulse/rev
fan; and f = 2/3 for 3 pulses/rev fan. See the Applications Notes section
for more tachometer information. Note that the 16-bit tachometer MSB and
LSB are reversed from the 16 bit temperature readings.
48
R/W 7:2 0xFF
Tachometer
Limit (LSB)
R/W 1:0 [Reserved] Not Used.
Local Temperature And Local High Setpoint Registers
ADDRESS
Hex
Read/
Write
Bits
POR
Value
Name Description
00
HEX
LOCAL TEMPERATURE REGISTER (8-bits)
00
Read
Only
7:0 N/A
Local
Temperature
Reading (8-bit)
8-bit integer representing the temperature of the LM63 die.
05 (0B)
HEX
LOCAL HIGH SETPOINT REGISTER (8-bits)
05 R/W 7:0
0x46
(70˚)
Local HIGH
Setpoint
High Setpoint for the internal diode.
LM63
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