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USB2512B-AEZG 参数 Datasheet PDF下载

USB2512B-AEZG图片预览
型号: USB2512B-AEZG
PDF下载: 下载PDF文件 查看货源
内容描述: USB 2.0高速集线器控制器 [USB 2.0 Hi-Speed Hub Controller]
分类和应用: 外围集成电路控制器PC时钟
文件页数/大小: 72 页 / 1689 K
品牌: SMSC [ SMSC CORPORATION ]
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USB 2.0 Hi-Speed Hub Controller  
Datasheet  
8.3.9  
SMBus Alert Response Address  
The SMBALERT# signal is not supported by the hub.  
8.3.9.1  
Undefined Registers  
The registers shown in Table 8.2 are the defined registers in the hub. Reads to undefined registers  
return 00h. Writes to undefined registers have no effect and do not return an error.  
8.3.9.2  
Reserved Registers  
Reserved registers should be written to ‘0’ unless otherwise specified. Contents read should be  
ignored.  
8.4  
Default Configuration Option:  
To configure the SMSC hub in its default configuration, strap CFG_SEL[2:0] to 00h. This procedure  
configures the hub to the internal defaults and enables the strapping options. Please see Section 8.2.1,  
"Internal Register Set (Common to EEPROM and SMBus)" for the list of the default values. For specific  
pin strapping options, please see Chapter 5, Pin Descriptions for instructions on how to modify the  
default values. Options include port disable and non-removable pin strapping.  
8.5  
Default Strapping Options:  
The USB251x can be configured via a combination of internal default values and pin strap options.  
Please see Table 8.2 for specific details on how to enable the default/pin-strap configuration option.  
The strapping option pins only cover a limited sub-set of the configuration options. The internal default  
values will be used for the bits & registers that are not controlled by a strapping option pin. Please  
refer to Table 8.2 for the internal default values that are loaded when this option is selected.  
8.6  
Reset  
There are two different resets that the hub experiences. One is a hardware reset via the RESET_N  
pin and the second is a USB Bus Reset.  
8.6.1  
External Hardware RESET_N  
A valid hardware reset is defined as assertion of RESET_N for a minimum of 1 μs after all power  
supplies are within operating range. While reset is asserted, the hub (and its associated external  
circuitry) consumes less than 500 μA of current from the upstream USB power source.  
Assertion of RESET_N (external pin) causes the following:  
1. All downstream ports are disabled, and PRTPWR power to downstream devices is removed (unless  
BC_EN is enabled).  
2. The PHYs are disabled, and the differential pairs will be in a high-impedance state.  
3. All transactions immediately terminate; no states are saved.  
4. All internal registers return to the default state (in most cases, 00(h)).  
5. The external crystal oscillator is halted.  
6. The PLL is halted.  
The hub is “operational” 500 μs after RESET_N is negated. Once operational, the hub immediately  
reads OEM-specific data from the external EEPROM (if the SMBus option is not disabled).  
SMSC USB251x  
55  
Revision 1.0 (3-11-09)  
DATASHEET  
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