ADT7462ACPZ-5RL7 ON Semiconductor, ADT7462ACPZ-5RL7 Datasheet - Page 19

• Manufacturer Part Number: ADT7462ACPZ-5RL7
• Description: IC TEMP/VOLT MONITOR 32-LFCSP
• Manufacturer: ON Semiconductor

Specifications of ADT7462ACPZ-5RL7

• Function: Fan Control, Temp Monitor
• Topology: ADC, Comparator, 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 ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 32-LFCSP
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 3 V
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: ADT7462ACPZ-500RL7; ADT7462ACPZ-500RL7; ADT7462ACPZ-500RL7TR; ADT7462ACPZ-500RL7TR; ADT7462ACPZ-5RL7TR

constant current. Unfortunately, this technique requires
calibration to cancel the effect of the absolute value of V
which varies from device to device.
change in V
currents. Previous devices have used only two operating
currents; use of a third current allows automatic cancellation
of any resistances in series with the external temperature
sensor.
measure the output of an external temperature sensor. This
figure shows the external sensor as a substrate transistor, but
it could equally be a discrete transistor. If a discrete
transistor is used, the collector is not grounded and should
be linked to the base. To prevent ground noise from
interfering with the measurement, the more negative
terminal of the sensor is not referenced to ground but is
biased above ground by an internal diode at the D− input. C1
can optionally be added as a noise filter (recommended
maximum value 1000 pF). However, a better option in noisy
environments is to add a filter, as described in the Noise
Filtering section.
sensor is switched among three related currents. As shown
in Figure 33, N1 × I and N2 × I are different multiples of the
Current I. The currents through the temperature diode are
switched between I and N1 × I, giving DV
between I and N2 × I, giving DV
then be calculated using the two DV
method can also be shown to cancel the effect of any series
resistance on the temperature measurement.
has a resolution of 1°C. Only two bits in the temperature
LSB register are used, Bit 7 and Bit 6, giving a temperature
measurement resolution of 0.25°C. The temperature
measurement range for both local and remote measurements
is from −64°C to +191°C. However, the ADT7462 itself
should never be operated outside its operating temperature
range, which is from −40°C to +125°C. For the remote
diode, the user should refer to the data sheet of the diode.
The technique used in the ADT7462 is to measure the
Figure 33 shows the input signal conditioning used to
To measure DV
The temperature value is stored in two registers. The MSB
BE
when the device is operated at three different
BE
TRANSISTOR
, the operating current through the
SENSING
REMOTE
BE2
BE
. The temperature can
D+
C1*
D–
*CAPACITOR C1 IS OPTIONAL. IT SHOULD ONLY BE USED IN NOISY ENVIRONMENTS.
measurements. This
Figure 33. Input Signal Conditioning
I
BE1
N1
, and then
y
I
http://onsemi.com
DIODE
N2
BIAS
BE
y
,
I
19
I
BIAS
LOW−PASS FILTER
65 kHz low−pass filter to remove noise and then to a
chopper−stabilized amplifier. This amplifies and rectifies
the waveform to produce a dc voltage proportional to DV
The ADC digitizes this voltage, and a temperature
measurement is produced. To reduce the effects of noise,
digital filtering is performed by averaging the results of 16
measurement cycles for low conversion rates.
temperature sensor are performed in the same manner (see
Figure 33).
Temperature Measurement Results
measurements are stored in the local and remote temperature
value registers and are compared with limits programmed
into the local and remote high and low limit registers.
f
Table 8. Temperature Measurement Registers
Table 9. Temperature Data Format
V
C
Local Temperature, LSB
Local Temperature, MSB
Remote 1 Temperature, LSB
Remote 1 Temperature, MSB
Remote 2 Temperature, LSB
Remote 2 Temperature, MSB
Remote 3 Temperature, LSB
Remote 3 Temperature, MSB
The resulting DV
Signal conditioning and measurement of the internal
The results of the local and remote temperature
CC
Temperature Value
= 65kHz
Temperature Value
−50.25°C
+50.25°C
+100°C
−64°C
−25°C
+25°C
0°C
BE
waveforms are passed through a
0000 0000
0100 0000
0101 1001
1010 0100
0000 1110
0010 0111
0111 0010
MSB
TO ADC
Register 0x88, Bits [7:6]
Register 0x89
Register 0x8A, Bits [7:6]
Register 0x8B
Register 0x8C, Bits [7:6]
Register 0x8D
Register 0x8E, Bits [7:6]
Register 0x8F
V
V
OUT+
OUT–
Register Address
0000 0000
0100 0000
0000 0000
0000 0000
0000 0000
0100 0000
0000 0000
LSB
BE
.