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EMC2104-BP-TR 参数 Datasheet PDF下载

EMC2104-BP-TR图片预览
型号: EMC2104-BP-TR
PDF下载: 下载PDF文件 查看货源
内容描述: [Switching Controller]
分类和应用: 风扇控制器
文件页数/大小: 101 页 / 1474 K
品牌: SMSC [ SMSC CORPORATION ]
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Dual RPM-Based PWM Fan Controller with Hardware Thermal Shutdown  
Datasheet  
„
When using the RPM based Fan Speed Control Algorithm (either FSC Mode or LUT with FSC  
Mode), the stalled fan condition is checked whenever the Update Time is met and the fan drive  
setting is updated. It is not a continuous check.  
5.6.2  
32kHz Clock Source  
The EMC2104 allows the user to choose between supplying an external 32.768kHz clock or use of  
the internal 32kHz oscillator to measure the tachometer signal. This clock source is used by the RPM  
based Fan Speed Control Algorithm to calculate the current fan speed. This fan controller accuracy is  
directly proportional to the accuracy of the clock source.  
The external clock is provided on the CLK_IN. In order for the external clock to be used, the EXT_CLK  
bit must be set in the Configuration Register.  
5.6.3  
Aging Fan or Invalid Drive Detection  
This is useful to detect aging fan conditions (where the fan’s natural maximum speed degrades over  
time) or incorrect fan speed settings.The EMC2104 contains circuitry that detects that the programmed  
fan speed can be reached by the fan. If the target fan speed cannot be reached within a user defined  
band of tach counts at maximum drive then the DRIVE_FAIL status bits are set and the ALERT# pin  
is asserted.  
5.7  
Spin Up Routine  
The EMC2104 also contains programmable circuitry to control the spin up behavior of the fan driver  
to ensure proper fan operation.  
The Spin Up Routine is initiated in Direct Setting mode (with or without the Look Up Table - when  
enabled) when the setting value changes from 00h to anything else.  
When the Fan Speed Control Algorithm is enabled, the Spin Up Routine is initiated under the following  
conditions when the Tach Period Measurement method of tach measurement is used:  
1. The TACH Target Register value changes from a value of FFh to a value that is less than the Valid  
TACH Count (see Section 6.28).  
2. The RPM based Fan Speed Control Algorithm’s measured TACH Reading Register value is greater  
than the Valid TACH Count setting.  
When the Spin Up Routine is operating, the fan driver is set to full scale (optional) for one quarter of  
the total user defined spin up time. For the remaining spin up time, the fan driver output is set a a user  
defined level (30% through 65% drive).  
After the Spin Up Routine has finished, the EMC2104 measures the TACHx signal. If the measured  
TACH Reading Register value is higher than the Valid TACH Count Register setting, the FAN_SPIN  
status bit is set and the Spin Up Routine will automatically attempt to restart the fan.  
Figure 5.5 shows an example of the Spin Up Routine in response to a programmed fan speed change  
based on the first condition above.  
Revision 1.74 (05-08-08)  
SMSC EMC2104  
DATA3S2HEET