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US91AEDC 参数 Datasheet PDF下载

US91AEDC图片预览
型号: US91AEDC
PDF下载: 下载PDF文件 查看货源
内容描述: 24V霍尔IC风扇驱动器 [24V Hall IC Fan Driver]
分类和应用: 驱动器风扇电动机控制
文件页数/大小: 12 页 / 307 K
品牌: MELEXIS [ Melexis Microelectronic Systems ]
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US90A / US91A  
24V Hall IC Fan Driver  
9 Detailed General Description  
The US90A/91A is a one-chip solution for driving two-coil brushless DC fans. Based on advanced Melexis  
CMOS process, the IC contains a Hall-effect sensor, dynamic offset correction and low side output drivers.  
The output drivers OUT1 and OUT2 are fully protected against switching transients. So there is no need for  
an external zener diode to cut the high voltage spikes induced by the fan coils.  
The US90A has an open-drain integrated tachometer FG output that follows the Hall signal.  
In the US91A, the open-drain rotation detection output RD is active low during normal spinning of the motor.  
It goes high when the flux switching frequency becomes too low, which means the motor is blocked.  
10 Unique Features  
The absence of a VDD pin enables the two low side output drivers and FG/RD signal output to fit in a four-pin  
VK package. The lack of a VDD pin decreases also the probability to damage the chip due to reverse voltage  
connection, using the coil resistance to limit the reverse current. In this condition, the total reverse current is  
twice the peak current value of the fan used.  
The built-in locked-rotor protection will automatically shut off the coil current when the rotor is mechanically  
blocked, or the rotational speed drops below 60 RPM (4-pole rotor magnet). The fan will try to restart every  
1.5 seconds until the obstruction is clear. The On / Off cycling reduces the average stall current to 1/7 normal;  
this is enough to prevent overheating or damage to most fans. Both the US90A and US91A have this feature.  
390109026302  
Rev 002  
Page 5 of 12  
Data Sheet  
Apr/07