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This user’s guide describes EVM operation with respect to the ISOUSB211 single-channel isolated high-, full-, and low-speed USB 2.0 repeater. This guide also describes the EVM BOM, EVM schematic, EVM PCB layout, and typical laboratory setup.
The ISOUSB211 device is a galvanically-isolated USB 2.0 compliant repeater supporting low-speed (1.5 Mbps), full-speed (12 Mbps), and high-speed (480 Mbps) signaling rates. The device supports automatic connect and speed detection, reflection of pullups and pulldowns, and link power management allowing drop-in USB hub, host, peripheral and cable isolation. The device also supports automatic role reversal - if after disconnect, a new connection is detected on the upstream facing port, then the upstream and downstream port definitions are reversed. The ISOUSB211 has built-in programmable equalization to cancel signal loss caused by board traces, which helps in meeting USB 2.0 high-speed TX and RX eye-diagram templates. This device uses a silicon dioxide (SiO2) insulation barrier with a withstand voltage of 5700 VRMS and a working voltage of 1060 VRMS. Used in conjunction with isolated power supplies, the device protects against high voltage, and prevents noise currents from the bus from entering the local ground. The ISOUSB211 device is available for both basic and reinforced isolation. The ISOUSB211 device supports a wide ambient temperature range of –40°C to +115°C. The device is available in the small footprint 28-pin SSOP (DP-28) package.
The EVM enables users to evaluate the ISOUSB211 device thoroughly before incorporating the device into their designs. To facilitate the EVM to be powered from various power sources including regulated power supplies, standard USB2.0 connector, and standard DC adapter, the EVM includes a transformer driver (SN6501), a transformer (CMP-0030614-1), and five adjustable output LDOs (TPS76701 and TPS73701). This EVM can be configured to use the provided LDOs to power the 3.3-V and 1.8-V power supplies, or bypass these external LDOs and use the internal LDOs to power the 3.3-V and 1.8-V power supplies. The EVM can be configured to operate with and without external LDOs and test configurations details of which are provided in the following sections.
The EVM can be used to verify many of the ISOUSB211 data sheet parameters like data-rate, current consumption, and others. Some of the data sheet specifications require a different test setup configuration than the ISOUSB211DPEVM and hence, they cannot be verified from the EVM as is. The example parameters include maximum data rate, propagation delay, and other timing specifications.
Figure 3-1 shows the ISOUSB211 high-, full-, and low-speed isolated USB repeater pin configuration.
This section describes the typical setup and operation of the EVM for device evaluation. Figure 4-1 shows a typical test configuration for operating the ISOUSB211DPEVM using an USB 2.0 type-B receptacle.
Use a jumper to connect pin 2 to pin 1 of J15 to enable the U3 LDO. The U3 LDO provides a 5-V supply to the USB device, and it also powers the U6 and U7 LDOs to generate 3.3 V and 1.8 V for the ISOUSB211. If an external 5-V source is used to power the USB device through TP5, connect pin 2 to pin 3 of J15 to disable the U3 LDO and set its output to high impedance.
ISOUSB211DPEVM has many DNP resistors which can be populated or unpopulated to setup the EVM to the desired operating test conditions. Table 4-1 lists and describes all the possible test configurations that can be achieved by populating various resistors.
Resistor | Description |
---|---|
R11 | DNP by default. To disable the U4 LDO, populate a 0-Ω resistor on R11 and unpopulate R12. |
R12 | Connects U4 EN to ground to enable the LDO. When R12 is populated, unpopulate R11. |
R13 | Connects VBUS1 to the type-B receptacle VBUS. VBUS1 is powered at 5 V when R13 is populated. Unpopulate R14 and R15 to disconnect the U4 LDO from the VBUS1 and V3P3V1 pins. The internal LDO of ISOUSB211 generates 3.3 V for the V3P3V1 pin. |
R14, R15 | DNP by default. Populating R14 and R15 connects the U4 LDO to the VBUS1 and V3P3V1 pins. When these two resistors are populated, unpopulate R13. When R14 and R15 are populated, VBUS1 and V3P3V1 are set to 3.3 V. |
R16 | DNP by default. To disable the U5 LDO, populate a 0-Ω resistor on R16 and unpopulate R17. |
R17 | Connects U5 EN to ground to enable the LDO. When R17 is populated, unpopulate R16. |
R18 | Connects VCC1 to the VBUS of the type-B receptacle. VCC1 is powered at 5 V when R18 is populated. Unpopulate the R19 and R20 resistors to disconnect the U5 LDO from the VCC1 and V1P8V1 pins. The internal LDO of the ISOUSB211 generates 1.8 V for the V1P8V1 pin. |
R19, R20 | Populating R19 and R20 connects the U5 LDO to the VCC1 and V1P8V1 pins. When these two resistors are populated, unpopulate R18. When R19 and R20 are populated, VCC1 and V1P8V1 are set to 1.8 V. |
R21 | DNP by default. To disable the U6 LDO, populate a 0-Ω resistor on R21 and unpopulate R22. |
R22 | Connects U6 EN to ground to enable the LDO. When R22 is populated, unpopulate R21. |
R23 | DNP by default. The R23 resistor connects VBUS2 to the output of U3 LDO. VBUS2 is powered at 5 V when R23 is populated. Unpopulate the R24 and R25 resistors to disconnect the U3 LDO from the VBUS2 and V3P3V2 pins. The internal LDO of ISOUSB211 generates 3.3 V for the V3P3V2 pin. |
R24, R25 | Populating R24 and R25 connects the U6 LDO to the VBUS2 and V3P3V2 pins. When these two resistors are populated, unpopulate R23 . When R24 and R25 are populated, VBUS2 and V3P3V2 are set to 3.3 V by the U6 LDO. |
R26 | DNP by default. To disable the U7 LDO, populate a 0-Ω resistor on R26 and unpopulate R27. |
R27 | Connects U7 EN to ground to enable the LDO. When R27 is populated, unpopulate R26. |
R29 | DNP by default. The R29 resistor connects VBUS2 to the output of U7 LDO. VCC2 is powered at 5 V when R29 is populated. Unpopulate R28 and R30 to disconnect the U7 LDO from the VCC2 and V1P8V2 pins. The internal LDO of ISOUSB211 generates 1.8 V for the V1P8V2 pin. |
R28, R30 | Populating R28 and R30 connects the U7 LDO to the VCC2 and V1P8V2 pins. When these two resistors are populated, unpopulate R29. When R28 and R30 are populated, VCC2 and V1P8V2 are set to 1.8 V. |