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EMC2101-ACZL-TR 参数 Datasheet PDF下载

EMC2101-ACZL-TR图片预览
型号: EMC2101-ACZL-TR
PDF下载: 下载PDF文件 查看货源
内容描述: SMBus的风扇控制为1° C的精密温度监控 [SMBus Fan Control with 1∑C Accurate Temperature Monitoring]
分类和应用: 风扇传感器换能器温度传感器输出元件监控PC
文件页数/大小: 55 页 / 1171 K
品牌: SMSC [ SMSC CORPORATION ]
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SMBus Fan Control with 1°C Accurate Temperature Monitoring  
Datasheet  
Appendix A Advanced PWM Options  
The PWM Frequency Register determines the number of clocks (set by the CLK_SEL bit or the  
PWM_D register settings) represent 1/2 of the period of the final PWM output waveform. Therefore,  
as the PWM Frequency Register is updated, the PWM frequency is likewise updated. However, it also  
directly affects the PWM Resolution and PWM duty cycle.  
The PWM frequency is set according to Equation [8] or Equation [9] or, if the PWM Divide Register is  
used, Equation [5].  
The PWM Frequency Register does not affect the Fan Setting (either the Fan Setting Register or the  
Fan Setting entries in the Fan Control Look-up Table Registers).  
The Fan Setting Register determines the number of clocks that the PWM output is high for is always  
based on 64 time steps for a PWM cycle. As the PWM Frequency Register changes (or the Fan Setting  
changes) the effective duty cycle will vary according to Equation [6] and the PWM resolution will vary  
according to Equation [7]. This is a result of the “on” time determined by Fan Setting changing with  
respect to the overall PWM period determined by the PWM Frequency Register.  
APPLICATION NOTE: If the Fan Setting is set at a value that is higher than 2x the PWM Frequency Register  
settings, the PWM output will be at 100% duty cycle.  
Table 6.34 shows the effective resolution, duty cycle, and frequency as the PWM Frequency Register  
setting is changed.  
FAN_SETTING  
PWM_F × 2  
Where: PWM_F is the setting of the PWM  
Frequency Register (4Dh)  
--------------------------------------------  
EFFECTIVE_DUTY_CYCLE =  
× 100%  
[6]  
[7]  
100%  
PWM_F × 2  
Where: PWM_F is the setting of the PWM  
Frequency Register (4Dh)  
--------------------------------  
EFFECTIVE_RESOLUTION =  
Where: PWM_F is the setting of the  
PWM Frequency register (4Dh)  
PWM_D is the setting of the PWM  
Frequency Divide Register (4Eh)  
360k  
2xPWM_F  
-----------------------------  
PWM_FREQUENCY =  
PWM_FREQUENCY =  
[8]  
[9]  
CLK_SEL = ‘0’  
CLK_SEL = ‘1’  
1.4k  
-----------------------------  
2xPWM_F  
Revision 2.53 (03-13-07)  
SMSC EMC2101  
DATA4S8HEET