adt7476a Analog Devices, Inc., adt7476a Datasheet - Page 67

• Manufacturer Part Number: adt7476a
• Description: Dbcool Remote Thermal Controller And Voltage Monitor
• Manufacturer: Analog Devices, Inc.

Table 51. Register 0x78—Configuration Register 3 (Power-On Default = 0x00)
Bit
[0]
[1]
[2]
[3]
[4]
[5]
[6]
[7]
1
Table 52. Register 0x79— THERM Timer Status Register (Power-On Default = 0x00)
Bit
[7:1]
[0]
Table 53. Register 0x7A— THERM Timer Limit Register (Power-On Default = 0x00)
Bit
[7:0]
This register becomes read-only when the Configuration Register 1 lock bit is set to 1. Any further attempts to write to this register have no effect.
Name
LIMT
Name
TMR
ASRT/TMRO
Name
ALERT
THERM/
2.5 V
BOOST
FAST
DC1
DC2
DC3
DC4
R/W
Read/Write
R/W
Read/Write
Read/Write
Read/Write
Read/Write
Read/Write
Read/Write
Read/Write
Read/Write
R/W
Read-only
Read-only
1
Description
Sets maximum THERM assertion length allowed before an interrupt is generated. This is an 8-bit
limit with a resolution of 22.76 ms allowing THERM assertion limits of 45.52 ms to 5.82 sec to be
programmed. If the THERM assertion time exceeds this limit, Bit 5 (F4P) of Interrupt Status Register 2
(0x42) is set. If the limit value is 0x00, an interrupt is generated immediately on the assertion of the
THERM input.
Description
ALERT = 1, Pin 10 (PWM2/SMBALERT) is configured as an SMBALERT interrupt output to indicate
out-of-limit error conditions.
ALERT = 0, Pin 10 (PWM2/SMBALERT) is configured as the PWM2 output.
THERM = 1 enables THERM functionality on Pin 22 and Pin 14, if Pin 14 is configured as THERM,
determined by Bits 0 and 1 (PIN14FUNC) of Configuration Register 4. When THERM is asserted, if
the fans are running and the boost bit is set, then the fans run at full speed. Alternatively, THERM
can be programmed so that a timer is triggered to time how long THERM has been asserted.
THERM = 0 enables 2.5 V measurement on Pin 22 and disables THERM. If bits [5:7] of Configuration
Register 5 are set, THERM is bidirectional. If they are 0, THERM is a timer input only.
Pin14FUNC
00
01
10
11
00
01
10
11
When THERM is an input and BOOST = 1, assertion of THERM causes all fans to run at the maximum
programmed duty cycle for fail-safe cooling.
FAST = 1 enables fast TACH measurements on all channels. This increases the TACH measurement
rate from once per second to once every 250 ms (4 ×).
DC1 = 1 enables TACH measurements to be continuously made on TACH1. Fans must be driven by
dc. Setting this bit prevents pulse stretching because it is not required for dc-driven motors.
DC2 = 1 enables TACH measurements to be continuously made on TACH2. Fans must be driven by
dc. Setting this bit prevents pulse stretching because it is not required for dc-driven motors.
DC3 = 1 enables TACH measurements to be continuously made on TACH3. Setting this bit prevents
pulse stretching because it is not required for dc-driven motors.
DC4 = 1 enables TACH measurements to be continuously made on TACH4. Setting this bit prevents
pulse stretching because it is not required for dc-driven motors.
Description
Times how long THERM input is asserted. These seven bits read zero until the THERM assertion
time exceeds 45.52 ms.
This bit is set high on the assertion of the THERM input and is cleared on read. If the THERM
assertion time exceeds 45.52 ms, this bit is set and becomes the LSB of the 8-bit TMR reading. This
allows THERM assertion times from 45.52 ms to 5.82 sec to be reported back with a resolution of
22.76 ms.
Rev. 0 | Page 67 of 72
THERM/2.5 V
0
0
0
0
1
1
1
1
Pin 22
+2.5V
+2.5V
+2.5V
+2.5V
THERM
+2.5V
THERM
THERM
IN
IN
IN
IN
IN
Pin 14
TACH4
THERM
SMBALERT
GPIO6
TACH4
THERM
SMBALERT
GPIO6
ADT7476A