Adjustable embedded universal serial bus 2 low-impedance driving duration

Abstract

Aspects of the present disclosure provide for a system. In at least some examples, the system includes an embedded Universal Serial Bus 2 (eUSB2) device having a first receiver and a first transmitter, a processor, a second transmitter coupled to the processor, a second receiver coupled to the processor, a drive low circuit coupled to the processor second transmitter, and differential signal lines having a length greater than ten inches. The differential signal lines are coupled at a first end to the first receiver and the first transmitter and at a second end to the second transmitter and the second receiver. The processor is configured to control the drive low circuit to drive the differential signal lines low with a logic ‘0’ to cause the first receiver to receive the logic ‘0’ and a value of a signal present on the differential signal lines to reach about 0 volts.

What is claimed is: 
     
         1 . A circuit, comprising:
 an amplifier having a first output coupled to a first node and a second output coupled to a second node;   a first resistor coupled between the second node and a ground terminal;   a second resistor coupled between the first node and the ground terminal;   a third resistor;   a fourth resistor;   a first switch coupled to the first resistor; and   a second switch coupled to the second resistor.   
     
     
         2 . The circuit of  claim 2 , wherein the third resistor is coupled between a third node and the ground terminal, wherein the fourth resistor is coupled between a fourth node and the ground terminal, wherein the first node is coupled to the fourth node through the second switch, and wherein the second node is coupled to the third node through the first switch. 
     
     
         3 . The circuit of  claim 2 , wherein the third node is a negative differential terminal of a Universal Serial Bus (USB) differential signal line, wherein the fourth node is a positive differential terminal of USB differential signal line, and wherein the amplifier is implemented as an embedded USB 2 transmitter. 
     
     
         4 . The circuit of  claim 1 , wherein the third resistor is coupled between the second node and the ground terminal, wherein the fourth resistor is coupled between the first node and the ground terminal, wherein the first resistor is coupled to the ground terminal through the first switch, and wherein the second resistor is coupled to the ground terminal through the second switch. 
     
     
         5 . The circuit of  claim 4 , wherein the first node is a positive differential terminal of a Universal Serial Bus (USB) differential signal line, wherein the second node is a negative differential terminal of USB differential signal line, and wherein the amplifier is implemented as an embedded USB 2 transmitter.