DEMO CIRCUIT 827 LTC4260CGN QUICK START GUIDE LTC2803 and LTC2804 1.8V to 5.5V RS-232 Dual Transceiver DESCRIPTION Demonstration circuit 827 is a 1.8V to 5.5V RS-232 Dual Transceiver featuring the LTC2803 and LTC2804. VERSION P/N DC827A-A LTC2803CDHC DC827A-B LTC2804CDHC Design files for this circuit board are available. Call the LTC factory. , LTC and LT are registered trademarks of Linear Technology Corporation. ThinSOT and PowerPath are trademarks of Linear Technology Corporation. PERFORMANCE SUMMARY SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V Input Supply Voltage 1.8 5.5 V CC V Logic Supply Voltage 1.8 5.5 V L SR(D) Driver Slew Rate R =3kW, 50pF<C <2.5nF L L LTC2803: 4 30 V/s LTC2804: 4 150 V/s Maximum Data Rate R = 3kW, C = 2.5nF 100 kbps -- L L R = 3kW, C = 1.0nF 250 kbps L L R = 3kW, C = 250pF (LTC2804) 1000 kbps L L JUMPERS SCH NAME PURPOSE SCH NAME PURPOSE JP1, MODE, Mode control, as follows: For the UART connected to the DB9, this wraps TD JP2 back to RD and RTS back to CTS. PS PS MODE MODE NAME OFF L Shutdown OFF H Receivers Active ON L Drivers Disabled ON H Normal JP3 LOGIC Selects supply for VL pin. Use setting VL for a separate logic supply, or VCC to share a single SUPPLY supply. JP4, Selects Receiver loopback mode, for use with the TD/RD, JP5 DB9 connector. In this configuration, R1OUT is con- RTS/CTS nected to T1IN and R2OUT is connected to T2IN. QUICK START PROCEDURE Demonstration circuit 827 is easy to set up for evaluat- Check for the proper generated supply voltages: ing the LTC2803 and LTC2804. Refer to Figure 1 or VDD = 6.5V to 7.5V, and VEE = -6.8V to -5.8V. Figure 2 for proper setup and follow the procedure be- Send data low: Place jumpers in the following positions: JP1 MODE H Notes: JP2 PS ON Inputs PS and MODE may be driven by signals in- With power off, connect the primary power supply stead of set with jumpers. If done, ensure that the to VCC and GND. voltage of PS doesnt exceed VL. Set JP3 Logic Supply to the correct position. If a The terminal emulation program RealTerm can lock separate logic supply isnt needed, use the VCC up when RTS/CTS flow control is used in receiver setting. If a separate Logic Supply will be used, use loopback mode. the VL setting and, with the power off, connect the supply to VL and GND. For transmitter loopback mode (Figure 1), connect each driver output to a receiver input. Connect input sources to the driver inputs. (Make sure that input voltages dont exceed 7V.) Omit Loopback jumpers JP4 and JP5 for this mode. Alternatively, to operate the part in receiverl oopback mode (Figure 2), connect a 9-wire RS-232 cable be- tween DB9 connector J1 and the serial port of a computer. Place jumpers in the two LOOPBACK po- sitions: JP4 TD/RD JP5 CTS/RTS Data may be transmitted and monitored using a terminal emulation program such as Terminal, HyperTerminal, Tera Term Pro, or RealTerm. Turn on the input supply/supplies in any order. (Note: Make sure that the voltage doesnt exceed 7V.)