USB MultiSwitchTM Hub
Datasheet
Table 4.1 Switching Hub Pin Descriptions (continued)
NAME | SYMBOL | TYPE | FUNCTION |
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Port [2:1] Green | LED_A[2:1]_N/ | I/O12 | Green indicator LED for ports 2 and 1. Will be active low |
LED | NON_REM[1:0] |
| when LED support is enabled via EEPROM or SMBus. |
& |
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| If the hub is configured by the internal default configuration, | |
Port Non- |
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Removable |
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| these pins will be sampled at RESET_N negation to |
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| determine if ports [3:1] contain permanently attached (non- | |
strapping option |
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| removable) devices. Also, the active state of the LED's will | |
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| |
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| be determined as follows: |
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| NON_REM[1:0] = '00', All ports are removable, |
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| LED_A2_N is active high, |
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| LED_A1_N is active high. |
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| NON_REM[1:0] = '01', Port 1 is |
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| LED_A2_N is active high, |
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| LED_A1_N is active low. |
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| NON_REM[1:0] = '10', Ports 1 & 2 are |
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| LED_A2_N is active low, |
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| LED_A1_N is active high. |
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| NON_REM[1:0] = '11', Ports 1, 2, & 3 are |
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| LED_A2_N is active low, |
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| LED_A1_N is active low. |
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Enhanced Port | LED_B[4:1]_N | I/O12 | These 4 pins in conjunction with the LED_A[4:1]_N pins |
LED Indicators |
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| provides a total of 8 LED pins which are used to indicate |
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| upstream host ownership of the downstream ports. |
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| 2 operational modes are available |
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| Single Color LED Mode: LED will light to show which host |
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| owns each of the downstream ports. If a port is |
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| “unassigned” then neither LED for that port will light up. |
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| Dual Color LED’s: (note; 4 possible states are displayed to |
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| the user, Green, Red, Orange and Off). |
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Port Power | PRTPWR_POL | I/O | Port Power Polarity strapping determination for the active |
Polarity strapping |
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| signal polarity of the PRTPWR[4:1] pins. |
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| While RESET_N is asserted, the logic state of this pin will |
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| (through the use of internal combinatorial logic) determine |
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| the active state of the PRTPWR[4:1] pins in order to ensure |
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| that downstream port power is not inadvertently enabled to |
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| inactive ports during a hardware reset. |
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| When RESET_N is negated, the logic value will be latched |
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| internally, and will retain the active signal polarity for the |
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| PRTPWR[4:1] pins. |
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| ‘1’ = PRTPWR[4:1] pins have active ‘high’ polarity |
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| ‘0’ = PRTPWR[4:1] pins have active ‘low’ polarity |
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| Warning: Active Low port power controllers may glitch |
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| the downstream port power when system power is first |
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| applied. Care should be taken when designing with |
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| active low components! |
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Over Current | OCS[4:1]_N | IPU | Input from external current monitor indicating an over- |
Sense |
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| current condition. {Note: Contains internal |
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| supply} |
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USB Transceiver | RBIAS | A 12.0kΩ (+/− 1%) resistor is attached from ground to this | |
Bias |
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| pin to set the transceiver’s internal bias settings. |
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SMSC USB2524 | 13 | Revision 1.91 |
| DATASHEET |
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