EVAL-ADT7463EB Analog Devices Inc, EVAL-ADT7463EB Datasheet - Page 15

• Manufacturer Part Number: EVAL-ADT7463EB
• Description: BOARD EVAL FOR ADT7463
• Manufacturer: Analog Devices Inc

Specifications of EVAL-ADT7463EB

• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

VID CODE MONITORING
The ADT7463 has five dedicated voltage ID (VID code) inputs.
These are digital inputs that can be read back through the
VID register (Reg. 0x43) to determine the processor voltage
required/being used in the system. Five VID code inputs support
VRM9.x solutions. In addition, Pin 21 (12 V input) can be recon-
figured as a sixth VID input to satisfy future VRM requirements.
VID CODE REGISTER – Register 0x43
<0> = VID0 (reflects logic state of Pin 5)
<1> = VID1 (reflects logic state of Pin 6)
<2> = VID2 (reflects logic state of Pin 7)
<3> = VID3 (reflects logic state of Pin 8)
<4> = VID4 (reflects logic state of Pin 19)
<5> = VID5 (reconfigurable 12 V input). This bit reads 0 when
Pin 21 is configured as the 12 V input. This bit reflects the logic
state of Pin 21 when the pin is configured as VID5.
VID CODE INPUT THRESHOLD VOLTAGE
The switching threshold for the VID code inputs is approximately
1 V. To enable future compatibility, it is possible to reduce the
VID code input threshold to 0.6 V. Bit 6 (THLD) of VID register
(Reg. 0x43) controls the VID input threshold voltage.
VID CODE REGISTER – Register 0x43
<6> THLD = 0; VID Switching Threshold = 1 V,
RECONFIGURING PIN 21 (+12V/VID5) AS VID5 INPUT
Pin 21 can be reconfigured as a sixth VID code input (VID5)
for VRM10 compatible systems. Since the pin is configured as
VID5, it will no longer be possible to monitor a 12 V supply.
Bit 7 of the VID register (Reg. 0x43) determines the function of
Pin 21. System or BIOS software can read the state of Bit 7 to
determine whether the system is designed to monitor 12 V or is
monitoring a sixth VID input.
VID CODE REGISTER – Register 0x43
<7> VIDSEL = 0; Pin 21 functions as a 12 V measurement
input. Software can read this bit to determine that there are five
VID inputs being monitored. Bit 5 of Register 0x43 (VID5)
always reads back 0. Bit 0 of Status Register 2 (Reg. 0x42)
reflects 12 V out-of-limit measurements.
VIDSEL = 1; Pin 21 functions as the sixth VID code input
(VID5). Software can read this bit to determine that there are
six VID inputs being monitored. Bit 5 of Register 0x43 reflects
the logic state of Pin 21. Bit 0 of Status Register 2 (Reg. 0x42)
reflects VID code changes.
VID CODE CHANGE DETECT FUNCTION
The ADT7463 has a VID code change detect function. When
Pin 21 is configured as the VID5 input, VID code changes can
be detected and reported back by the ADT7463. Bit 0 of Status
Register 2 (Reg. 0x42) is the 12V/VC bit and denotes a VID
change when set. The VID code change bit gets set when the
REV. B
V
THLD = 1; VID Switching Threshold = 0.6 V,
V
OL
OL
< 0.8 V, V
< 0.4 V, V
IH
IH
> 1.7 V, V
> 0.8 V, V
MAX
MAX
= 3.3 V
= 3.3 V
–15–
logic states on the VID inputs are different than they were 11 ms
previously. The change of VID code can be used to generate
an SMBALERT interrupt. If an SMBALERT interrupt is not
required, Bit 0 of Interrupt Mask Register 2 (Reg. 0x75),
when set, will prevent SMBALERTs from occurring on VID
code changes.
STATUS REGISTER 2 – Register 0x42
<0> 12V/VC = 0; If Pin 21 is configured as VID5, then a
Logic 0 denotes no change in VID code within last 11 ms.
<0> 12V/VC = 1; If Pin 21 is configured as VID5, then a Logic 1
means that a change has occurred on the VID code inputs within
the last 11 ms. An SMBALERT will be generated if this function
is enabled.
ADDITIONAL ADC FUNCTIONS
A number of other functions are available on the ADT7463 to
offer the systems designer increased flexibility, including:
Turn-Off Averaging
For each voltage measurement read from a value register, 16
readings have actually been made internally and the results
averaged before being placed into the value register. There may
be an instance where you would like to speed up conversions.
Setting Bit 4 of Configuration Register 2 (Reg. 0x73) turns
averaging off. This effectively gives a reading 16 times faster
(711ms), but the reading may be noisier.
Bypass Voltage Input Attenuators
Setting Bit 5 of Configuration Register 2 (Reg 0x73) removes
the attenuation circuitry from the 2.5 V, V
12 V inputs. This allows the user to directly connect external
sensors or rescale the analog voltage measurement inputs for
other applications. The input range of the ADC without the
attenuators is 0 V to 2.25 V.
Single-Channel ADC Conversion
Setting Bit 6 of Configuration Register 2 (Reg. 0x73) places the
ADT7463 into single-channel ADC conversion mode. In this mode,
the ADT7463 can be made to read a single voltage channel
only. If the internal ADT7463 clock is used, the selected input
will be read every 711 ms. The appropriate ADC channel is
selected by writing to Bits <7:5> of the TACH1 Minimum
High Byte Register (0x55).
Bits <7:5>
Reg 0x55
000
001
010
011
100
Configuration Register 2 (Reg. 0x73)
<4> = 1 Averaging Off
<5> = 1 Bypass Input Attenuators
<6> = 1 Single-Channel Convert Mode
TACH1 Minimum High Byte (Reg. 0x55)
<7:5> Selects ADC Channel for Single-Channel Convert Mode
Channel
Selected
2.5 V
V
V
5 V
12 V
CCP
CC
CCP
ADT7463
, V
CC
, 5 V, and