XR21B1420 Enhanced 1-Ch Full-Speed USB UART FEATURES General Description 15kV ESD on USBD+/USBD- The XR21B1420 is an enhanced Universal Asynchronous Receiver and USB 2.0 Compliant, Full-Speed (12Mbps) Transmitter (UART) bridge to USB interface. The USB interface is fully Unique pre-programmed USB serial number compliant to the USB 2.0 (Full-Speed) specification with 12 Mbps USB Internally generated 48MHz core clock data transfer rate. The USB interface also supports USB suspend, Enhanced UART features resume and remote wakeup operations. The USB Vendor ID, Product ID, Baud rates up to 12 Mbps power mode, remote wakeup support, maximum power, and numerous other settings may be programmed in the on-chip OTP memory via the Fractional Baud Rate Generator USB interface. 512-byte TX and 512-byte RX FIFOs Auto Hardware / Software Flow Control The XR21B1420 includes an internal oscillator and does not require an Multidrop and Half-Duplex Modes external crystal/oscillator. Any UART baud rate up to 12 Mbps may be Auto RS-485 Half-Duplex Control generated with this internal clock and the fractional baud rate generator. Selectable GPIO or Modem I/O The UART pins may also be configured as GPIO direction, state, output Up to 10 GPIOs driver type and input pull-up or pull-down resistors are programmed either 5V tolerant GPIO inputs through on chip OTP, or on the fly via memory mapped registers. Suspend state GPIO configuration Large 512-byte TX and RX FIFOs prevent buffer overflow errors and opti- Configurable clock output mize data throughput. Automatic half-duplex direction control and optional 28-pin QFN package multi drop (9-bit) mode simplify both hardware and software in half-duplex Industrial -40C to +85C Temperature Range RS-485 applications. APPLICATIONS The XR21B1420 uses the native OS CDC-ACM driver or an Exar supplied custom driver. Exar provides WHQL/HCK-certified software drivers for Building Automation Windows 2000, XP, Vista, 7, 8, 8.1 as well as software drivers for Windows Security Systems CE, Linux and Mac OS X. Full source code is available. Factory and Process Control ATM Terminals The XR21B1420 operates from a single 5V or 3.3V power supply. When powered with 5V input, a regulated 3.3V output is supplied. USB to Serial Controllers Ordering Information page 60 Block Diagram Throughput Comparison Internal 1840k TX Fractional 512-byte Oscillator BRG TX FIFO (48MHz) 1610k Competitor RX 512-byte Exar 1380k RX FIFO USB 1150k USB Slave Interface Internal Status and 920k Control GPIOs/ Registers 690k Modem IO USB OTP Descriptors 460k 230k UART 0k 230k 460k 920k 1840k LDO 3V3 Data Rate (bps) 2014 Exar Corporation 1 / 60 exar.com/XR21B1420 Rev 1AXR21B1420 Absolute Maximum Ratings Operating Conditions Stresses beyond the limits listed below may cause perma- Operating Temperature Range................................-40C to +85C nent damage to the device. Exposure to any Absolute Max- imum Rating condition for extended periods may affect device reliability and lifetime. Supply Voltage (VCC REG)................................................+5.75V Supply Voltage (VCC)...............................................................+4V Input Voltage (VBUS SENSE)..................................-0.3 to +5.75V Input Voltage (All other pins).......................................-0.3 to +5.6V Junction Temperature............................................................125C Electrical Characteristics Unless otherwise noted: TA = -40C to +85C, VCC REG = +4.4V to +5.25V or +3.0V to +3.6V. Symbol Parameter Conditions Min Typ Max Units Power I Power Supply Current VCC REG = +4.4V to +5.25V 15 23 mA CC I Lowpower Mode Current 0.85 1.35 mA SUSP V Regulated Output Voltage (VCC pin) VCC REG = +4.4V to +5.25V. 33.3 3.6 V OUT Maximum output current = 200 mA including the supply current of the XR21B1420. UART, USB STAT and GPIO Pins V Input Low Voltage -0.3 0.25* V IL VCC V Input High Voltage 0.70* 5.5 V IH VCC V Output Low Voltage IOL = 1mA, VCC = +3.6V 0.5 V OL V Output High Voltage IOH = -1.5mA, VCC = +3.6V 2.8 VCC V OH I Input Low Leakage Current VCC = +3V to +3.6V, VCC REG = +4.4V to 10 A IL +5.25V, V = 0V INPUT I Input High Leakage Current VCC = +3V to +3.6V, VCC REG = +4.4V to 10 A IH +5.25V, V = +3.3V INPUT VCC = +3V to +3.6V, VCC REG = +4.4V to 120 A +5.25V, V = +5.5V INPUT C Input Pin Capacitance 5pF IN 2014 Exar Corporation 2 / 60 exar.com/XR21B1420 Rev 1A