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参数资料
| 型号： | TC670ECH |
| 元件分类： | 模拟信号调理 |
| 英文描述： | SPECIALTY ANALOG CIRCUIT, PDSO6 |
| 封装： | EIAJ, SC-74, SOT-23, 6 PIN |
| 文件页数： | 9/12页 |
| 文件大小： | 469K |
| 代理商： | TC670ECH |
TC670
DS21688B-page 6
2002 Microchip Technology Inc.
The design of the proper input SENSE circuitry is a
matter of scaling RSENSE to provide the necessary
amount of gain and proper selection of the sensing
capacitor. The following table (Table 4-1) lists some
recommended values for RSENSE according to the
nominal operating current of the fan. Please note that
the current draw specified by the fan manufacturer may
not be the fan’s nominal operating current, but a worst-
case rating. If the fan current falls between two of the
values listed, it is recommended that the higher value
resistor is used.
TABLE 4-1:
RECOMMENDED VALUES
FOR RSENSE PER FIGURE 4-2
A0.1
F ceramic capacitor is recommended for
CSENSE. Smaller capacitor values will require larger
sense resistors whereas larger capacitors are more
expensive and occupy more board space.
4.2
THRESHOLD Input
The voltage at the THRESHOLD input sets the
equivalent minimum allowable fan speed for the appli-
cation. As shown in Section 3.0 typical performance
curves, the relationship between the THRESHOLD
voltage and minimum fan speed is also power supply
and temperature dependant.
All the values for the THRESHOLD voltage that are
shown in these graphs represent typical numbers and
might not be optimized for all fans in all applications. To
ensure accurate fan speed monitoring of a specific fan
in a specific application, the user must perform a one-
time correlation check with the prototype.
There are two techniques that can be used to calibrate
the system. One approach is to find the fan’s full scale
capability and mathematically estimate the minimum
acceptable speed of the fan. A second technique is to
identify the fan’s minimum speed and calibrate the
THRESHOLD voltage accordingly.
4.2.1
THRESHOLD CALIBRATION USING
FAN’S FULL SCALE SPEED
The fan should first be run at full speed. At full speed
the THRESHOLD voltage level should be adjusted until
the ALERT output is asserted. With this full scale value
of the THRESHOLD voltage, the value can be scaled
down to the Fan Fault speed as a percentage of the full
speed. For example, if the fan full speed THRESHOLD
voltage is 1.5V, then the Fan Fault THRESHOLD
voltage at 30% of full speed would be 30% x 1.5V =
0.45V.
4.2.2
THRESHOLD CALIBRATION USING
FAN’S MINIMUM ALLOWABLE
SPEED ESTIMATE
For a more exact Fan Fault trip point, the user can run
the fan at its minimum allowed speed. At this speed, the
THRESHOLD voltage can be adjusted until the ALERT
output is asserted.
4.3
CLEAR Input
The CLEAR input allows the user to reset the ALERT
pin to a high status. This is an active HIGH input.
Consequently, as long as CLEAR is HIGH, ALERT will
always be HIGH as well. To allow ALERT to operate
correctly CLEAR must be held LOW. This feature can
be implemented so that false Fan Fault conditions do
not initiate system shutdown.
4.4
ALERT Output
The ALERT output is an open drain output capable of
sinking 2.5mA (typ). The ALERT output is asserted
whenever the detected fan speed equals or falls below
the equivalent voltage set at the THRESHOLD pin. The
ALERT output is only deactivated once the CLEAR pin
is brought to a HIGH state. Although the absolute
maximum output current of this pin is 25mA, it is
recommended that this current sinking into the ALERT
Output does not exceed 20mA.
4.5
Power Supply Input, VDD
To assure proper operation of the TC670 in a noisy
environment where the fans are running, the VDD pin
(Pin 4) must be decoupled with a 0.1
F capacitor as
shown in Figure 4-1. This capacitor should be located
as close to the TC670 VDD pin as possible as well being
promptly terminated to the ground plane. A Ceramic
capacitor is recommended.
4.6
Ground Terminal, GND
The GND pin (Pin 2) of the TC670 should be connected
directly to the analog ground plane of the circuit board.
Care should be taken in circuit layout to keep this pin
away from switching signals, such as the fan excitation
signals in order to avoid false signals on the SENSE
pin.
Nominal Fan Current
(mA)
RSENSE ()
100
4.7
200
2.4
300
1.8
400
1.3
500
1.0
600
0.8
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相关代理商/技术参数 |
参数描述 |
|---|---|
| TC670ECHTR | 功能描述:马达/运动/点火控制器和驱动器 Predictive Fan Failure Det RoHS:否 制造商:STMicroelectronics 产品:Stepper Motor Controllers / Drivers 类型:2 Phase Stepper Motor Driver 工作电源电压:8 V to 45 V 电源电流:0.5 mA 工作温度:- 25 C to + 125 C 安装风格:SMD/SMT 封装 / 箱体:HTSSOP-28 封装: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 |
| TC68 | 功能描述:铝质电解电容器 - 带引线 60uF 350V RoHS:否 制造商:Kemet 引线类型: 电容:220 uF 容差:20 % 电压额定值:25 V 工作温度范围: 端接类型:Radial 外壳直径:8 mm 外壳长度:11 mm 引线间隔:5 mm 产品:General Purpose Electrolytic Capacitors 封装:Bulk |
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