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TC650(2004) Просмотр технического описания (PDF) - Microchip Technology

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TC650 Datasheet PDF : 16 Pages
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TC650/TC651
4.6 Temperature Selection Guide
(Minimum Fan Speed/Full Speed)
There are two temperature thresholds that determine
the characteristics of the device. The minimum fan
speed temperature (TL) and the full fan speed temper-
ature (TH). Depending on the TC65X device selected,
when the temperature is below the TL trip point, the
PWM output will perform a different operation. For the
TC650, the PWM will be driven at the minimum PWM
frequency, while the TC651 will shut down the PWM
(PWM = L).
TL and TH can be selected in 5°C increments. TL can
range from 25°C to 35°C. TH can range from 35°C to
55°C and must be 10°C (or more) than the specified TL.
The five temperature regions defined by the six
thresholds are defined in the TC650/TC651 by means of
factory trimming. Once a TL and TH are set, the T1 – T4
thresholds are automatically equally spaced between TL
and TH. Table 4-1 shows these 5 regions and what the
corresponding PWM duty cycle is.
TABLE 4-1: TEMPERATURE RANGE
DEFINITION
Temperature
(T = TJ)
(Note 1)
PWM Duty Cycle
TC650
(Minimum
Speed mode)
TC651
(Auto-shutdown
mode)
T < TL
40%
Off
TL< = T < T1
50%
50%
T1 < = T < T2
60%
60%
T2 < = T <T3
70%
70%
T3 < = T < T4
80%
80%
T4 < = T < TH
90%
90%
TH < = T < TOV
100%
100%
TOV < = T
100% with Overtemperature Alert
(TOVER = L)
Note 1: The temperature regions defined by the
six temperature thresholds are pre-
defined in the TC650/TC651 by means of
factory trimming. Once a TL and TH are
programmed, the T1 – T4 thresholds are
automatically equally spaced between TL
and TH.
Table 4-2 shows the device codes that specify the TH
and TL temperature thresholds. The following exam-
ples are given to assist in understanding the device-
ordering nomenclature.
Example 1: Suppose you wanted the fan to run at
40% speed at 25°C or less and go to full-
speed at 45°C. You would order the part
number TC650AEVUA.
Example 2: Suppose you wanted the fan to turn on at
30°C and go to full speed at 45°C. You
would order the part number
TC651BEVUA.
TABLE 4-2:
DEVICE CODES FOR
TEMPERATURE
THRESHOLDS
Temp.
Threshold
TL
Difference
TH
Threshold
Limits Code
10°C
25
30
35
15°C
25
30
35
20°C
25
30
35
30°C
25
35
AC (1)
40
BD (2)
45
CE (2)
40
AD (2)
45
BE (1)
50
CF (2)
45
AE (1)
50
BF (2)
55
CG (1)
55
AG (1)
Note 1: This temperature threshold option is
available for ordering.
2: This is a custom temperature threshold
option. Please contact the factory for
more information.
DS21450C-page 8
2004 Microchip Technology Inc.

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