ADT7476AARQZ-R ON Semiconductor, ADT7476AARQZ-R Datasheet - Page 14

• Manufacturer Part Number: ADT7476AARQZ-R
• Description: IC REMOTE THERMAL CTLR 24-QSOP
• Manufacturer: ON Semiconductor
• Series: dBCool®r

Specifications of ADT7476AARQZ-R

• Function: Fan Control, Temp Monitor
• Topology: ADC, Comparator, Fan Speed Counter, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: -40°C ~ 125°C, External Sensor
• Output Type: SMBus™
• Output Alarm: No
• Output Fan: Yes
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 24-QSOP
• Full Temp Accuracy: +/- 0.5 C
• Digital Output - Bus Interface: Serial (3-Wire, 4-Wire)
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

output codes of the 10-bit ADC.
voltage input in 0.7 ms and averages 16 conversions to
reduce noise; a measurement takes nominally 11 ms.
Extended Resolution Registers
using the extended resolution registers (0x76 and 0x77).
Whenever the extended resolution registers are read, the
corresponding data in the voltage measurement registers
(0x20 to 0x24) is locked until their data is read. That is, if
extended resolution is required, then the extended resolution
register must be read first, immediately followed by the
appropriate voltage measurement register.
Additional ADC Functions for Voltage Measurements
ADT7476A to offer the system designer increased
flexibility.
Turn-Off Averaging
value register, 16 readings have been made internally and the
results averaged before being placed into the value register.
When faster conversions are needed, setting Bit 4 of
Configuration Register 2 (0x73) turns averaging off. This
effectively gives a reading 16 times faster but the reading
can be noisier. The default round robin cycle time takes
146.5 ms.
default round robin cycle time increases to 240 ms.
Bypass All Voltage Input Attenuators
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.
Bypass Individual Voltage Input Attenuators
to bypass individual voltage channel attenuators.
Table 2. Conversion Time with Averaging Disabled
Voltage Channels
Remote Temperature 1
Remote Temperature 2
Local Temperature
Table 5 shows the input ranges of the analog inputs and
When the ADC is running, it samples and converts a
Voltage measurements can be made with higher accuracy
A number of other functions are available on the
For each voltage/temperature measurement read from a
When Bit 7 of Configuration Register 6 (0x10) is set, the
Setting Bit 5 of Configuration Register 2 (0x73) removes
Bits [7:4] of Configuration Register 4 (0x7D) can be used
Channel
Measurement Time (ms)
CCP
0.7
1.3
7
7
, V
CC
, 5.0 V, and
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Configuration Register 2 (0x73)
[4] = 1, averaging off.
[5] = 1, bypass input attenuators.
[6] = 1, single-channel convert mode.
TACH1 Minimum High Byte (0x55)
[7:5] Selects ADC channel for single-channel convert mode.
Single-Channel ADC Conversion
can be used to increase sampling times for a specific
channel, and therefore helps to analyze that channel’s
performance in greater detail, it can also have other
applications.
ADT7476A into single-channel ADC conversion mode. In
this mode, the ADT7476A can only read a single voltage
channel. The selected voltage input is read every 0.7 ms. The
appropriate ADC channel is selected by writing to Bits [7:5]
of the TACH1 minimum high byte register (0x55).
Table 3. Bypassing Individual Voltage Input
Attenuators
Table 4. Programming Single−Channel ADC Mode
1. In the process of configuring single-channel ADC conversion
Configuration Register 4 (0x7D)
While single-channel mode is intended as a test mode that
Setting Bit 6 of Configuration Register 2 (0x73) places the
Bits [7:4], Register 0x55
mode, the TACH1 minimum high byte is also changed, possibly
trading off TACH1 minimum high byte functionality with
single-channel mode functionality.
Bit No.
4
5
6
7
000
001
010
100
101
011
110
111
Bypass 2.5 V attenuator
Bypass V
Bypass 5.0 V attenuator
Bypass 12 V attenuator
CCP
Channel Attenuated
attenuator
2.5 V
V
V
5.0 V
12 V
Remote 1 temperature
Local temperature
Remote 2 temperature
CCP
CC
Channel Selected (Note 1)