QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 513 SOFTWARE-SELECTABLE MULTI-PROTOCOL TRANSCEIVER LTC2846CG/LTC2845CG DESCRIPTION Demonstration circuit 513 is a complete DCE or DTE DC513 is intended for network equipment that inter- serial port. The protocols supported are V.28 faces to other equipment using standard serial con- (RS232), V.35, V.36, RS449, EIA530, EIA530A and nections. These applications include routers and wide X.21. Six jumpers select the proper protocol and area networks. The interface design work is as simple other port-configuration settings. One jumper turns as placing this chipset on a board with a handful of on/off the internal switching regulator of the small, inexpensive components. LTC 2846. The board provides a vehicle for observ- ing the line drivers and receivers on the LTC2846 and LTC2845. Logic-level signals enter and exit the board Design files for this circuit board are available. Call on the left side and line-level signals enter and exit on the LTC factory. the right. The internally generated supplies are ob- servable on the pins at the top of the board. LTC is a trademark of Linear Technology Corporation 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 513 SOFTWARE-SELECTABLE MULTI-PROTOCOL TRANSCEIVER Table 1. Performance Summary (T = 25C) A PARAMETER CONDITION VALUE With Onboard Boost Regulator 3.3V Input Voltage Without Boost Regulator 5.0V I No Cable Mode 300uA cc I Boost Regulator Quiescent Current 10nA shutdown V Boost Regulator Not Switching 4.2mA quiescent D1,D2,D3,M0,M1,M2,DCE/DTE 2.0V Logic Level Hi SHDN 2.4V D1,D2,D3,M0,M1,M2,DCE/DTE 0.8V Logic Level Low SHDN 0.5V V.11 103 Receiver Differential Input Impedance V.35 90-110 V.28 3-7K Receiver Common Mode Input Impedance V.35 135-165 Transmitter Differential Mode Impedance V.35 50-150 Transmitter Common Mode Impedance V.35 135-165 V.11 15ns Driver T T r , f V.35 5ns Driver Slew Rate V.28 4-30V/ s V.11 15mV Receiver Input Hysteresis V.35 15mV V.28 50mV QUICK START PROCEDURE 1. Connect the input voltage power supply, meters, desired protocol and port setting. (M0 = 0, M1 = pulse generator and oscilloscope as shown in 1, M2 = 0 and DCE/DTE = 0 selects the RS530 Figure 1. DTE mode) 2. The pulse generator should be set to a 0V to 3.3V 5. Observe the waveforms on the logic signal side swing. and the line signal side of the board. The line driver (TXDA, TXDB) is connected to the line re- 3. SHDN should be set to 1 to turn on the internal ceiver (RXCA, RXCB) to demonstrate the line sig- switching regulator of the LTC2846 nals. RTS is also connected to DSR. 4. The mode pins M0, M1 and M2, plus the configu- 6. Observe the internally generated supplies (V , V CC EE ration pin DCE/DTE should be configured for the and V ) DD 2