EVAL-ADT7462EBZ ON Semiconductor, EVAL-ADT7462EBZ Datasheet - Page 49

• Manufacturer Part Number: EVAL-ADT7462EBZ
• Description: BOARD EVALUATION FOR ADT7462
• Manufacturer: ON Semiconductor
• Type: Temperature Sensorr

Specifications of EVAL-ADT7462EBZ

• Contents: Evaluation Board
• For Use With/related Products: ADT7462
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

freewheeling test:
Fans Present Register (0x1D)
Fan Freewheeling Test Enable Register (0x1E)
Fan Freewheeling Test Register (0x1C)
freewheeling test enable register (0x1E) should be
programmed before setting the relevant bits in the fan
freewheeling test register (0x1C). The host fan status
The freewheeling test procedure is as follows:
The following registers must be programmed for the fan
Both the Fans Present register (0x1D) and the
Set Bit 0 to 1 when a fan is connected to TACH1.
Set Bit 1 to 1 when a fan is connected to TACH2.
Set Bit 2 to 1 when a fan is connected to TACH3.
Set Bit 3 to 1 when a fan is connected to TACH4.
Set Bit 4 to 1 when a fan is connected to TACH5.
Set Bit 5 to 1 when a fan is connected to TACH6.
Set Bit 6 to 1 when a fan is connected to TACH7.
Set Bit 7 to 1 when a fan is connected to TACH8.
Set Bit 0 to 1 to enable the freewheeling test for Fan 1.
Set Bit 1 to 1 to enable the freewheeling test for Fan 2.
Set Bit 2 to 1 to enable the freewheeling test for Fan 3.
Set Bit 3 to 1 to enable the freewheeling test for Fan 4.
Set Bit 4 to 1 to enable the freewheeling test for Fan 5.
Set Bit 5 to 1 to enable the freewheeling test for Fan 6.
Set Bit 6 to 1 to enable the freewheeling test for Fan 7.
Set Bit 7 to 1 to enable the freewheeling test for Fan 8.
1. PWM1 and PWM2 go to full speed, and PWM3
2. After the spin−up time of PWM1 and PWM2 has
3. After the speed of Fan 1 and Fan 2 is measured,
4. After the speed of Fan 3 and Fan 4 is measured,
5. After the speed of all eight fans has been
•
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and PWM4 are switched off.
elapsed, the speed of Fan 1, Fan 2, Fan 3, and
Fan 4 is measured.
PWM1 is switched off and PWM3 is spun up.
After the spin−up time for PWM3 has elapsed, the
speed of Fan 5 and Fan 6 is measured.
PWM2 is switched off and PWM4 is switched on.
After the spin−up time of PWM4 has elapsed, the
speed of Fan 7 and Fan 8 is measured.
measured, the TACH and PWM configurations
return to their previous values.
Fans must be in continuous mode for the
freewheeling test; that is, the dc bits must be set
(Register 0x08).
To enable the freewheeling test, set the
freewheeling test enable register (0x1E) to a
nonzero value. Set Bit 0 = 1 to enable the
freewheeling test for Fan 1, and set Bit 1 for Fan 2,
all the way to Bit 7 for Fan 8. The freewheeling
test enable register should be programmed after the
fans present register is programmed. If the fans
present register is not programmed first, then the
values in the two registers do not match, and the
ADT7462 assumes that a fan is missing.
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register (0xBD) should be read directly after completion of
the test.
THERM I/O Operation
THERM2. Pin 28 and Pin 29 can both be configured as
THERM inputs or outputs.
THERM Output
but it can be enabled by setting the appropriate bits in
Register 0x0E (THERM1 configuration register) and
Register 0x0F (THERM2 configuration register). THERM1
and THERM2 can be configured to assert whenever a
specific channel exceeds the specified THERM limit (see
Table 30).
measured THERM temperature has exceeded pre−
programmed THERM temperature limits. The output is
automatically pulled high again when the temperature falls
below the (THERM − Hysteresis) limit. The value of
hysteresis for each channel is programmable in Register
0x54 and Register 0x55, where 1 LSB = 1°C, and the
maximum hysteresis for each channel is 15°C.
(default setting) in the THERM configuration register
(0x0D), sets the fans to full speed on an internal THERM
event.
THERM Input
THERM1_Timer_Enable (T1TE) bit (Bit 0) in the
THERM1
THERM2_Timer_Enable (T2TE) bit (Bit 0) in the
THERM2 configuration register (0x0F) must be set to
Logic 1. The ADT7462 can then be used to detect when the
THERM pins are asserted low. The THERM pins can be
connected to a trip point temperature sensor or to the
PROCHOT output of a CPU.
threshold for the AGTL + PROCHOT output is also reduced
as new processors become available.
the thresholds can be referenced to V
Configuration Register 3 (0x03) to 1, the THERM threshold
is 2/3 × V
The THERM assert bits in Host Thermal Status Register 2
Table 26. THERM Output Channel Select and Limits
Remote 2
Remote 3
Remote 1
Channel
This section describes the operation of THERM1 and
THERM
As an output, THERM is asserted low to signal that the
Setting the THERM boost bits, Bit 0 and Bit 1, to Logic 0
To
With processor core voltages reducing all the time, the
Because the THERM input is typically an AGTL + input,
Enable
Local
configure
CCP
is not enabled as an output by default on powerup,
configuration
, the correct threshold for an AGTL + signal.
THERM1,
Bit 1 = 1
Bit 2 = 1
Bit 3 = 1
Bit 4 = 1
Register
0x0E
Configuration
THERM
THERM2,
Bit 1 = 1
Bit 2 = 1
Bit 3 = 1
Bit 4 = 1
Register
0x0F
register
as
CCP
THERM1
0x4C
0x4D
0x4E
0x4F
(0x0E)
. By setting Bit 4 of
an
Limit Registers
input,
THERM2
and
0x50
0x51
0x52
0x53
the
the