Linear LTC2803 User manual

LTC4260CGN
1
DESCRIPTION
Demonstration circuit827 is a 1.8V to 5.5V RS-232
DualTransceiverfeaturing theLTC2803 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
CC
Input Supply Voltage 1.8 5.5 V
V
L
Logic Supply Voltage 1.8 5.5 V
SR(D) Driver Slew Rate R
L
=3kΩ, 50pF<C
L
<2.5nF
LTC2803:
LTC2804:
4
4
30
150
V/µs
V/µs
--
Maximum Data Rate R
L
= 3kΩ, C
L
= 2.5nF
R
L
= 3kΩ, C
L
= 1.0nF
R
L
= 3kΩ, C
L
= 250pF (LTC2804)
100
250
1000
kbps
kbps
kbps
JUMPERS
SCH NAME PURPOSE
JP1,
JP2
MODE,
PS
Mode control, as follows:
PS MODE MODE NAME
OFF L Shutdown
OFF H Receivers Active
ON L Drivers Disabled
ON H Normal
JP3 LOGIC
SUPPLY
Selects supply for VL pin. Use setting “VL” for a
separate logic supply, or “VCC” to share a single
supply.
JP4,
JP5
TD/RD,
RTS/CTS
Selects Receiver loopback mode, for use with the
DB9 connector. In this configuration, R1OUT is con-
nected 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.
DEMO CIRCUIT
827
QUICK START GUIDE
LTC2803 and LTC2804
1.8V to 5.5V RS-232 Dual Transceiver
Downloaded from Arrow.com.

2
QUICK START PROCEDURE
Demonstrationcircuit827iseasytosetupforevaluat-
ing the LTC2803 and LTC2804. Referto Figure 1 or
Figure 2forpropersetup andfollowthe procedurebe-
low:
1. Placejumpersinthefollowing positions:
MODE H
PS ON
2. With power off,connect the primary power supply
to VCC and GND.
3. Set JP3 “Logic Supply”tothe correctposition.Ifa
separatelogic supplyisn’t needed, use the “VCC”
setting.IfaseparateLogic Supply willbe used,use
the“VL”settingand, withthepoweroff,connectthe
supplyto VL and GND.
4. Fortransmitterloopback mode (Figure 1),connect
each driveroutputtoareceiverinput.Connectinput
sourcestothe driverinputs.(Make surethatinput
voltages don’texceed 7V.) Omit Loopbackjumpers
JP4 and JP5 forthis mode.
5. Alternatively,tooperatethepartinreceiverloopback
mode(Figure2),connecta9-wire RS-232 cablebe-
tween DB9 connector J1 and the serial port of a
computer.Placejumpersinthetwo LOOPBACK po-
sitions:
TD/RD
CTS/RTS
Data may be transmitted and monitored using a
terminal emulation program such as Terminal,
HyperTerminal,TeraTerm Pro,or RealTerm.
6. Turn on the input supply/supplies in any order.
(Note: Make sure that the voltage doesn’t exceed
7V.)
7. Check for the proper generated supply voltages:
VDD = 6.5Vto 7.5V,and VEE =-6.8Vto-5.8V.
8. Send data!
Notes:
1. Inputs PS and MODE may be driven by signalsin-
stead of set withjumpers.If done, ensurethatthe
voltage of PS doesn’texceed VL.
2. Theterminalemulation program RealTerm canlock
up when RTS/CTS flow controlis used in receiver
loopback mode.
JP1
JP2
JP4
JP5
Downloaded from Arrow.com.Downloaded from Arrow.com.

LTC2803 AND LTC2804
3
Figure 1. Setup for Transmitter Loopback Mode
Figure 2. Setup for Receiver Loopback Mode
Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.

4
Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.