LM64EVAL National Semiconductor, LM64EVAL Datasheet - Page 21

• Manufacturer Part Number: LM64EVAL
• Description: BOARD EVALUATION LM64
• Manufacturer: National Semiconductor

Specifications of LM64EVAL

• Sensor Type: Temperature, Fan Controller
• Sensing Range: 0°C ~ 85°C
• Interface: SMBus (2-Wire/I²C)
• Sensitivity: ±1°C
• Voltage - Supply: 3 V ~ 3.6 V
• Embedded: Yes, MCU, 8-Bit
• Utilized Ic / Part: LM64
• Lead Free Status / RoHS Status: Not applicable / Not applicable

ADDRESS
ADDRESS
47
MSB and ensure MSB and LSB are from the same reading)
49
03 (09)
2.0 LM64 Registers
03 (09)
Configuration Register
Tachometer Count And Limit Registers
HEX
HEX
Hex
Hex
47
46
49
48
TACHOMETER COUNT (MSB) and 46
TACHOMETER LIMIT (MSB) and 48
HEX
CONFIGURATION REGISTER
Read/
Write
Read/
Read
Read
Read
Write
Only
Only
Only
R/W
R/W
R/W
R/W
Bits
Bits
7:0
7:2
1:0
7:0
7:2
1:0
4:1
7
6
5
0
Value
POR
0xFF
0xFF
Value
N/A
N/A
0000
POR
00
0
0
0
0
(Continued)
Count (MSB)
Count (LSB)
Tachometer
Tachometer
Tachometer
Edge Count
Tachometer
Tachometer
PWM Disable
Limit (LSB)
in STANDBY
Limit MSB)
[Reserved]
RDTS Fault
STANDBY
Name
ALERT
Queue
Name
Mask
HEX
HEX
TACHOMETER LIMIT (LSB) REGISTERS
TACHOMETER COUNT (LSB) REGISTERS (16 bits: Read LSB first to lock
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.
Note: If PWM_Clock_Select = 360 kHz, then Tach_Count_Multiple = 1
regardless of the setting of these bits.
These registers contain the current 16-bit Tachometer Count, representing
the period of time between tach pulses. Fan RPM = (f
(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.
Not Used.
When this bit is a 0, ALERT interrupts are enabled.
When this bit is set to a 1, ALERT interrupts are masked, and the
ALERT pin is always in a high impedance (open) state.
When this bit is a 0, the LM64 is in operational mode, converting,
comparing, and updating the PWM output continuously.
When this bit is a 1, the LM64 enters a low power standby mode.
In STANDBY, continuous conversions are stopped, but a
conversion/comparison cycle may be initiated by writing any value to
register 0x0F. Operation of the PWM output in STANDBY depends on
the setting of bit 5 in this register.
When this bit is a 0, the LM64’s PWM output continues to output the
current fan control signal while in STANDBY.
When this bit is a 1, the PWM output is disabled (as defined by the
PWM polarity bit) while in STANDBY.
These bits are unused and always set to 0.
0: an ALERT will be generated if any Remote Diode conversion result is
above the Remote High Set Point or below the Remote Low
Setpoint.
1: an ALERT will be generated only if three consecutive Remote Diode
conversions are above the Remote High Set Point or below the
Remote Low Setpoint.
Bits
00:
01:
10:
11:
21
Edges Used
2
3
5
Description
Reserved - do not use
Description
Tach_Count_Multiple
4
2
1
*
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