Industrial Temperature Rated USB 2.0
Datasheet
4.6.2External Hardware RESET_N
A valid hardware reset is defined as assertion of RESET_N for a minimum of 1us after all power supplies are within operating range. While reset is asserted, the Hub (and its associated external circuitry) consumes less than 500μA 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.
2.The PHYs are disabled, and the differential pairs will be in a
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” 500μs after RESET_N is negated.
Once operational, the Hub immediately reads
4.6.2.1RESET_N for Strapping Option Configuration
Hardware |
| Drive Strap | Attach |
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Read Strap | Outputs to | USB Reset |
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reset | USB | Idle | |||||
Options | inactive | recovery | request | ||||
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RESET_N |
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VSS |
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Strap Pins |
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| Figure 4.3 Reset_N Timing for Default/Strap Option Mode |
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| Table 4.3 Reset_N Timing for Default/Strap Option Mode |
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NAME |
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| DESCRIPTION |
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| TYP |
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| MAX |
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t1 | RESET_N Asserted. |
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| 1 |
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t2 | Strap Setup Time |
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| 16.7 |
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t3 | Strap Hold Time. |
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| 16.7 |
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| 1400 |
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t4 | hub outputs driven to inactive logic states |
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t5 | USB Attach (See Note). |
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t6 | Host acknowledges attach and signals USB | 100 |
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| Reset. |
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Revision 1.97 | 28 | SMSC USB2512Ai |
| DATASHEET |
|