ADT7462ACPZ-REEL ON Semiconductor, ADT7462ACPZ-REEL Datasheet - Page 43

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

Specifications of ADT7462ACPZ-REEL

• 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
• Number Of Voltages Monitored: 1
• Monitored Voltage: 0.9 V to 12 V
• Manual Reset: Not Resettable
• Watchdog: No Watchdog
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 3 V
• Supply Current (typ): 4000 uA
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

time means that T
very fast temperature transients, the dynamic T
loop is always lagging. If a cycle time that is too short is
chosen, the full benefit of changing T
T
overshooting. It is necessary to carry out some calibration to
identify the most suitable response time.
Table 25. Cycle Bit Assignments
MIN
Code
The cycle time must be chosen carefully. A long cycle
Figure 68 shows the steps taken during the short cycle.
Figure 69 shows the steps taken during the long cycle.
000
001
010
011
100
101
110
111
MEASUREMENT
MEASUREMENT
TEMPERATURE
TEMPERATURE
TEMPERATURE
OPERATING
MEASUREMENT
TEMPERATURE
TEMPERATURE
PREVIOUS
CURRENT
T1 (n – 1)
OPERATING
POINT
needs to change again on the next cycle. In effect, it is
T1(n)
CURRENT
OP1
POINT
T1(n)
OP1
1024 cycles
128 cycles
256 cycles
512 cycles
16 cycles
32 cycles
64 cycles
8 cycles
Short
Cycle
Figure 68. Short Cycle Steps
Figure 69. Long Cycle Steps
IS T1(n) − T1(n − 1) = 0.5 − 0.755C
IS T1(n) − T1(n − 1) = 1.0 − 1.755C
IS T1(n) − T1(n − 1) > 2.05C
IS T1(n) < LOW TEMP LIMIT
T
MIN
MIN
IS T1(n) – T1(n – 1)
< HIGH TEMP LIMIT
IS T1(n) > OP1
MONITORING
MONITORING
T1(n) > T
T
(OP1 – HYS)
MIN
CYCLES
WAIT 2n
CYCLES
is updated less often. If a system has
IS T1(n) >
≤ 0.25°C
WAIT n
Duration
AND
AND
AND
128 sec
16 sec
32 sec
64 sec
< OP1
1 sec
2 sec
4 sec
8 sec
YES
NO
NO
NO
MIN
NO
YES
YES
YES
Long Cycle
1024 cycles
2048 cycles
128 cycles
256 cycles
512 cycles
16 cycles
32 cycles
64 cycles
MIN
DECREASE T
DECREASE T
DECREASE T
DECREASE T
is not realized and
COOLING IS OFF
OR CONSTANT)
T
INCREASE
DO NOTHING
DO NOTHING
MIN
CHANGE
DO NOT
(SYSTEM
BY 15C
BY 15C
MIN
MIN
MIN
MIN
BY 15C
BY 25C
BY 45C
MIN
Duration
128 sec
256 sec
16 sec
32 sec
64 sec
2 sec
4 sec
8 sec
control
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43
circumstances that may cause T
stay the same.
Example 1: Normal Operation, No T
temperature nor the low temperature limit has been
exceeded, the T
a speed determined by the fixed T
defined in the automatic fan speed control mode.
Example 2: Operating Point Exceeded, T
point temperature minus the hysteresis, T
same. Once the temperature exceeds the operating
temperature minus the hysteresis (OP − Hyst), T
to decrease as illustrated in Figure 71. This occurs during the
short cycle (see Figure 68). The rate at which T
decreases depends on the programmed value of n. It also
depends on how much the temperature has increased
between this monitoring cycle and the last monitoring cycle;
that is, if the temperature has increased by 1°C, then T
is reduced by 2°C. Decreasing T
increasing the fan speed, thus providing more cooling to the
system.
(OP − Hyst), that is, ≤0.25°C per short monitoring cycle,
then T
temperature in the desired operating zone without changing
T
temperature range (OP − Hyst), because the temperature has
not exceeded the operating temperature.
the long cycle causes T
cycle while the temperature remains above the operating
temperature. This takes place in addition to the decrease in
T
because the temperature is increasing at a rate ≤0.25°C per
short cycle, no reduction in T
short cycle.
Figure 70. Temperature Between the Operating Point
MIN
MIN
The following examples illustrate some of the
Because neither the operating point minus the hysteresis
When the measured temperature is below the operating
If the temperature is slowly increasing only in the range
When the temperature exceeds the operating temperature,
1. If the measured temperature never exceeds the
2. If the measured temperature never drops below the
THERM LIMIT
. The long cycle makes no change to T
OPERATING
that would occur due to the short cycle. In Figure 70,
HIGH TEMP
MIN
LOW TEMP
programmed operating point minus the hysteresis
temperature, T
remains at its current setting.
low temperature limit, T
POINT
LIMIT
LIMIT
T
does not decrease. This allows small changes in
MIN
and the Low Temperature Limit
MIN
ACTUAL
TEMP
HYSTERESIS
value is not adjusted, and the fan runs at
MIN
MIN
is not adjusted; that is, it
to be reduced by 1°C every long
MIN
MIN
MIN
MIN
to increase, decrease, or
MIN
takes place during the
is not adjusted.
MIN
and T
has the effect of
MIN
Adjustment
MIN
RANGE
Reduced
remains the
MIN
MIN
values
in the
starts
MIN
MIN