DC497A - Demo Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 497
SOFTWARE-SELECTABLE MULTI-PROTOCOL TRANSCEIVER
LTC2846CG/LTC2844CG
DESCRIPTION
Demonstration circuit 497 is a complete DCE or DTE
serial port. The protocols supported are V.28
(RS232), V.35, V.36, RS449, EIA530, EIA530A and
X.21. Four jumpers select the proper protocol and
other port-configuration settings. One jumper
switches on/off the internal switching regulator of the
LTC®2846. The board provides a vehicle for observing the line drivers and receivers on the LTC2846 and
LTC2844. Logic-level signals enter and exit the board
on the left side and line-level signals enter and exit on
the right. The internally generated supplies are observable on the pins at the top of the board.
DC497 is intended for network equipment that interfaces to other equipment using standard serial connections. These applications include routers and wide
area networks. The interface design work is as simple
as placing this chipset on a board with a handful of
small, inexpensive components.
Design files for this circuit board are available. Call
the LTC factory.
LTC is a trademark of Linear Technology Corporation
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 497
SOFTWARE-SELECTABLE MULTI-PROTOCOL TRANSCEIVER
Table 1.
Performance Summary (TA = 25°C)
PARAMETER
CONDITION
VALUE
With Onboard Boost Regulator
3.3V
Without Boost Regulator
5.0V
Icc
No Cable Mode
300uA
Ishutdown
Boost Regulator Quiescent Current
10nA
Vquiescent
Boost Regulator Not Switching
4.2mA
D1,D2,D3,M0,M1,M2,DCE/DTE
2.0V
SHDN
2.4V
D1,D2,D3,M0,M1,M2,DCE/DTE
0.8V
SHDN
0.5V
V.11
103Ω
V.35
90-110Ω
V.28
3-7KΩ
Receiver Common Mode Input Impedance
V.35
135-165Ω
Transmitter Differential Mode Impedance
V.35
50-150Ω
Transmitter Common Mode Impedance
V.35
135-165Ω
V.11
15ns
V.35
5ns
V.28
4-30V/µs
V.11
15mV
V.35
15mV
V.28
50mV
Input Voltage
Logic Level Hi
Logic Level Low
Receiver Differential Input Impedance
Driver Tr , Tf
Driver Slew Rate
Receiver Input Hysteresis
QUICK START PROCEDURE
1. Connect the input voltage power supply, meters,
pulse generator and oscilloscope as shown in
Figure 1.
2. The pulse generator should be set to a 0V to 3.3V
swing.
3. The mode pins M0, M1 and M2, plus the configuration pin DCE/DTE should be configured for the
desired protocol and port setting. (M0 = 0, M1 =
1, M2 = 0 and DCE/DTE = 0 selects the RS530
DTE mode)
4. Observe the waveforms on the logic signal side
and the line signal side of the board. The line
driver (TXDA, TXDB) is connected to the line receiver (RXCA, RXCB) to demonstrate the line signals. RTS is also connected to DSR.
5. Observe the internally generated supplies (VCC , VEE
and VDD)
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 497
SOFTWARE-SELECTABLE MULTI-PROTOCOL TRANSCEIVER
Figure 1. Proper Measurement Equipment Setup
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 497
SOFTWARE-SELECTABLE MULTI-PROTOCOL TRANSCEIVER
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