DC827A - Demo Manual

DEMO CIRCUIT 827
QUICK LTC4260CGN
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 Transceiverfeaturing the LTC2803 and LTC2804.
VERSION
DC827A-A
DC827A-B
P/N
LTC2803CDHC
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
VCC
VL
SR(D)
--
PARAMETER
Input Supply Voltage
Logic Supply Voltage
Driver Slew Rate
Maximum Data Rate
CONDITIONS
MIN
1.8
1.8
RL=3kΩ, 50pF<CL<2.5nF
LTC2803:
LTC2804:
RL = 3kΩ, CL = 2.5nF
RL = 3kΩ, CL = 1.0nF
RL = 3kΩ, CL = 250pF (LTC2804)
4
4
100
250
1000
TYP
MAX
5.5
5.5
UNITS
V
V
30
150
V/µs
V/µs
kbps
kbps
kbps
JUMPERS
SCH NAME
JP1, MODE,
JP2 PS
JP3
LOGIC
SUPPLY
JP4, TD/RD,
JP5 RTS/CTS
PURPOSE
Mode control, as follows:
PS MODE MODE NAME
OFF L
Shutdown
OFF H
Receivers Active
ON L
Drivers Disabled
ON H
Normal
Selects supply for VL pin. Use setting “VL” for a
separate logic supply, or “VCC” to share a single
supply.
Selects Receiver loopback mode, for use with the
DB9 connector. In this configuration, R1OUT is connected to T1IN and R2OUT is connected to T2IN.
SCH NAME
PURPOSE
For the UART connected to the DB9, this wraps TD
back to RD and RTS back to CTS.
1
QUICK START PROCEDURE
Demonstration circuit827is easyto setupforevaluating the LTC2803 and LTC2804. Refer to Figure 1 or
Figure 2 for proper setup andfollow the procedure below:
1.
Check for the proper generated supply voltages:
VDD = 6.5V to 7.5V, and VEE = -6.8V to -5.8V.
8.
Send data!
Placejumpersinthe following positions:
JP1
JP2
MODE
PS
H
ON
2.
With power off, connect the primary power supply
to VCC and GND.
3.
Set JP3 “Logic Supply”to the correct position.If a
separate logic supply isn’t needed, use the “VCC”
setting.Ifa separate Logic Supply willbe used, use
the“VL” setting and, with the power off,connectthe
supplyto VL and GND.
4.
For transmitterloopback mode (Figure 1), connect
each driver outputto a receiverinput. Connectinput
sources to the driverinputs.(Make sure thatinput
voltages don’t exceed 7V.) Omit Loopback jumpers
JP4 and JP5 forthis mode.
5.
Alternatively,to operatethe partinreceiverloopback
mode (Figure 2),connecta 9-wire RS-232 cable between DB9 connector J1 and the serial port of a
computer. Placejumpersin thetwo LOOPBACK positions:
JP4
JP5
TD/RD
CTS/RTS
Data may be transmitted and monitored using a
terminal emulation program such as Terminal,
HyperTerminal,Tera Term Pro, or RealTerm.
6.
7.
Turn on the input supply/supplies in any order.
(Note: Make sure that the voltage doesn’t exceed
7V.)
2
Notes:
1.
Inputs PS and MODE may be driven by signalsinstead of set with jumpers.If done, ensure thatthe
voltage of PS doesn’texceed VL.
2.
The terminal emulation program RealTerm can lock
up when RTS/CTS flow controlis used in receiver
loopback mode.
LTC2803 AND LTC2804
Figure 1. Setup for Transmitter Loopback Mode
Figure 2. Setup for Receiver Loopback Mode
3
4
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