3.3V VIO_REF VCC XR21B1411 USBD- LOWPOWER J GND J10

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1 REV..0.0 XRB_SP EVALUATION BOARD USER S MANUAL.0 INTRODUCTION This user s manual is for the XRB_SP evaluation board rev.. The XRB will be configured for the RS- mode when it is shipped from the factory. However, this manual describes how the evaluation board can be re-configured to operate in different modes..0 EVALUATION BOARD OVERVIEW A block diagram of the evaluation board is shown in Figure below.. FIGURE. EVALUATION BOARD BLOCK DIAGRAM SP0.V J VCC J USB Conn CON VBUS D+ D- Inrush Current Limiter Logic V VCC USBD+ USBD- XRB GPIO/RTS# GPIO/CTS# GPIO/DTR# GPIO/DSR# GPIO/CD# SP.V J0 U _EN _EN#.V J0 U RS#/RS The primary devices on the XRB evaluation board are all Exar devices. The XRB is an enhanced -ch USB UART that can be powered directly from the V from VBUS. The SP0 is an Exar LDO that regulates the V from VBUS to.v that is used as the supply voltage of the SP and for the of the XRB. The SP is Exar s programmable serial transceiver that can be programmed for RS- or RS-/ mode.

2 XRB_SP EVALUATION BOARD USER S MANUAL REV Evaluation Board Components Table shows where the Exar components are located and provides a brief description of some of the other components on the board. TABLE : COMPONENTS OF THE XRB EVALUATION BOARD UNIT PART FUNCTION U SP Exar s.v-v Programmable RS-/RS-/RS- Serial Transceiver. Refer to the table in the schematic to select the mode via J0. U XRBIL-F Exar s Enhanced -channel USB UART. U U SNLVCGDCT Analog switch. A logic on the "C" control inputs enables the switch connectivity between "A" and "B" pins. U and U control the mode select for Exar s SP transceiver. When the XRB enters the sleep mode, the output of the SNLVCG is tri-stated. The mode select pins have internal pull-up resistors that enables the shutdown mode for the SP. U SP0GEK-L Exar s 0mA RF Ultra Low Dropout Regulator used for converting V from VBUS to.v for the SP and of the XRB. CON DB9 male connector Communicate with remote UART or device via RS-. SW Switch Can be used to trigger remote wake-up event.. Description of Headers/Jumpers This section describes the headers/jumpers on this evaluation board that are installed as well as the headers/ jumpers that are not installed. Some headers/jumpers may not be installed because they are used for internal testing purposes only. The headers/jumpers that are installed are highlighted in Table below. TABLE : DESCRIPTION OF HEADERS/JUMPERS (INSTALLED) JUMPERS FUNCTIONS COMMENTS J Enables.V supply voltage for SP from SP0 By default, jumper is in. Caution: If using an external supply voltage for, J & should not be installed. J Testing RS-/ Header with all of the RS-/ I/Os J Header to easily connect to an external board/device NOTE: Pin of all jumpers is designate by a square pad. All of the UART I/O signals as well as the and pin are available on this header. J Selects input to VBUS_SENSE & selects voltage divider circuit from VBUS. This is only required for self-powered applications. & terminates VBUS_SENSE to (default) J Selects input to & selects input from J (same supply voltage as SP) & selects input from SP0 (default) J Selects input to RI# & selects RI# input from SP (trace is cut) & selects push button switch (default, jumper installed on &)

3 REV..0.0 The headers/jumpers that are not installed are highlighted in Table below. XRB_SP EVALUATION BOARD USER S MANUAL TABLE : DESCRIPTION OF HEADERS/JUMPERS (NOT INSTALLED) JUMPERS FUNCTIONS COMMENTS J Power supply for XRB Trace between &. J9 Enabling V from VBUS to the rest of the board Trace between &..0 BOARD CONFIGURATION The RS- mode or RS- mode can be selected via the RS#/RS pin of the SP. This next section shows the default configuration (RS- mode) and how it can be re-configured for RS- mode.. RS- Mode (default) The RS- mode can be enabled by installing a jumper between pins & of J0 (RS#/RS pin will be 0 ). Jumpers should also be installed on J0 pins & (if not installed, the SP will be in shutdown mode). RS- mode is the default setting for the evaluation board (Figure ). In this mode, a null modem cable can be connected to the DB9 connector (CON) to communicate with another serial port that has a DB9 connector. Alternatively, a custom RS- connection can also be made using the signals at J. FIGURE. RS- MODE J GPIO/DTR# GPIO/RTS# T J CON Pin (RTS#) T CON Pin (DTR#) GPIO/DSR# T CON Pin () GPIO/CTS# 9 R GPIO/CD# 0 R CON Pin 9 (RI#) R CON Pin () 9 R CON Pin (DSR#) 0 R CON Pin (CTS#) SP CON Pin (CD#) J SW XRB

4 XRB_SP EVALUATION BOARD USER S MANUAL REV RS-/ Mode.. Full-Duplex RS-/ Mode The RS- mode can be enabled by removing the jumper between & of J0 (RS#/RS pin will be ). Jumpers should be installed on J0 pins & and J0 pins &. In this mode, the differential pairs can communicate with an external RS- network via J pins,, and (see Figure below). Note: When configured for this mode, the DB9 connector (CON) should not be used... Half-Duplex RS- Mode For half-duplex RS-, the full-duplex configuration below will need to be modified as follows: Remove jumpers on J0 pins & and J0 pins & Connect J pin to J pin Connect J pin to J pin Connect J0 pin and J0 pin with J pin Of course, the (RS-) Transceiver Enable feature needs to be enabled in the software driver/application. Note: When configured for this mode, the DB9 connector (CON) should not be used. FIGURE. FULL-DUPLEX RS- MODE J GPIO/DTR# GPIO/RTS# J0 & EN T J CON Pin (RTS#) CON Pin (DTR#) GPIO/DSR# T + - CON Pin () GPIO/CTS# 9 R CON Pin 9 (RI#) GPIO/CD# CON Pin () 9 0 J0 & EN R SP + - CON Pin (DSR#) CON Pin (CTS#) CON Pin (CD#) DO NOT USE DB9 CONNECTOR J SW XRB

5 REV SP in Shutdown Mode XRB_SP EVALUATION BOARD USER S MANUAL The shutdown mode for the SP is enabled when the EN pin is 0 and EN# pin is controlled via J0. (The SP also enters this mode when the XRB enters the suspend mode and the pin is asserted.) In this mode, the I/Os of the SP are at high impednace. Therefore, the UART I/Os can connect directly with an external UART or serial transceiver. In addition, the pin and pins are also available at J..0 DRIVERS AND SUPPORT For any questions about this evaluation board, software drivers or technical support, send an to uarttechsupport@exar.com. NOTICE EXAR Corporation reserves the right to make changes to the products contained in this publication in order to improve design, performance or reliability. EXAR Corporation assumes no responsibility for the use of any circuits described herein, conveys no license under any patent or other right, and makes no representation that the circuits are free of patent infringement. Charts and schedules contained here in are only for illustration purposes and may vary depending upon a user s specific application. While the information in this publication has been carefully checked; no responsibility, however, is assumed for inaccuracies. EXAR Corporation does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless EXAR Corporation receives, in writing, assurances to its satisfaction that: (a) the risk of injury or damage has been minimized; (b) the user assumes all such risks; (c) potential liability of EXAR Corporation is adequately protected under the circumstances. Copyright 00 EXAR Corporation Datasheet October 00. Send your UART technical inquiry with technical details to hotline: uarttechsupport@exar.com. Reproduction, in part or whole, without the prior written consent of EXAR Corporation is prohibited.