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參數(shù)資料
| 型號： | TC670ECH |
| 廠商： | Microchip Technology Inc. |
| 英文描述： | Tiny Predictive Fan Failure Detector |
| 中文描述： | 微型風(fēng)扇故障檢測預(yù)測 |
| 文件頁數(shù)： | 5/12頁 |
| 文件大小： | 469K |
| 代理商： | TC670ECH |
2002 Microchip Technology Inc.
DS21688B-page 5
TC670
4.0
DETAILED DESCRIPTION
The TC670 is an integrated fan speed sensor that
predicts/detects fan failure, consequently preventing
thermal damage to systems with cooling fans. When
the fan speed falls below a user programmed threshold
level, the TC670 asserts an ALERT signal. This
threshold is set with an external resistor divider
network.
FIGURE 4-1:
TC670 BLOCK DIAGRAM
As shown in Figure 4-1, the TC670 senses the fan
pulses and internally converts those pulses from a
frequency into an analog voltage. This voltage is then
compared with a DC voltage present on the THRESH-
OLD pin. If the converted frequency-to-voltage value
from the fan’s pulses falls below the THRESHOLD
voltage, a FAULT signal is asserted through the ALERT
pin (active LOW).
In a 3.0V system, the external fan alert level on the
THRESHOLD pin can be designed from 0.0V (stalled
fan) and up to 2.4V (for 13,000 RPM) to cover most of
the common fan speeds. This failure detection system
works with linear controlled 2-wire fans and eliminates
the need for 3-wire fans. The TC670 can work with 3-
wire fans as well either by using the SENSE circuit or
by directly sensing the RPM output from the 3rd wire.
A CLEAR pin is provided to allow the user to reset the
ALERT pin status back to a HIGH state. This CLEAR
option also allows the flexibility of connecting the
ALERT output of the TC670 with other Alert/FAULT
interrupts in the system without having a risk of a
system shutdown due to false Fan Fault condition.
FIGURE 4-2:
TYPICAL APPLICATION
CIRCUIT
4.1
SENSE Input
As shown in Figure 4-2, the SENSE input (Pin 6) is
connected through a sensing capacitor (C
SENSE
). A
low value current sensing resistor (R
SENSE
) is also
connected to the low side of the fan to the ground return
leg of the fan. During normal fan operation, commuta-
tion occurs as each pole of the fan is energized. This
causes brief interruptions in the fan current, seen as
pulses across the sense resistor.
These short rapid changes in fan current cause a
corresponding dV/dt voltage across the sense resistor
as well as a corresponding dI/dt current across the
sense capacitor. The current across C
SENSE
is termi-
nated with the internal 50k
input resistance at the
SENSE pin of the TC670. When positive going fan
pulses at the SENSE input are greater than 124mV
(typ) the TC670 latches in those voltage spikes. This
124mV (typ) SENSE input built-in threshold reduces
false triggering errors caused by extraneous noise
pulses associated with a running fan. The presence
and frequency of these pulses is a direct indication of
fan operation and fan speed.
THRESHOLD
124mV
50k
SENSE
ALERT
CLEAR
Logic
Frequency to
Voltage
GND
V
DD
Bandgap
Oscillator
From
Microcontroller
5
6C
SENSE
R
4
R
SENSE
+12V
ALERT
LED
FAN
DC
SENSE
ALERT
2
4
3
1
V
DD
= +5V
R
3
R
2
0.1
μ
F
V
DD
CLEAR
THRESHOLD
GND
V
threshold
VTHRESHOLD
VDD
R
2
R
3
R
=
Note:
This typical application circuit uses an LED to indicate that a
fan failure has occurred.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| TC670ECHTR | 功能描述:馬達(dá)/運動/點火控制器和驅(qū)動器 Predictive Fan Failure Det RoHS:否 制造商:STMicroelectronics 產(chǎn)品:Stepper Motor Controllers / Drivers 類型:2 Phase Stepper Motor Driver 工作電源電壓:8 V to 45 V 電源電流:0.5 mA 工作溫度:- 25 C to + 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:HTSSOP-28 封裝:Tube |
| TC670ECHTR | 制造商:Microchip Technology Inc 功能描述:IC CONTROLLER FAN MANAGEMENT 制造商:Microchip Technology Inc 功能描述:IC, CONTROLLER, FAN MANAGEMENT |
| TC670ECHTR | 制造商:Microchip Technology Inc 功能描述:Fan Management Controller IC Package/Cas |
| TC670ECHTR-CUT TAPE | 制造商:Microchip 功能描述:TC670 Series 3 to 5.5 V Tiny Predictive Fan Failure Detector - SOT-23-6 |
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