LTC4260CGN
1
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
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
2
QUICK START PROCEDURE
Demonstration circuit 827 is easy to set up for evaluat-
ing the LTC2803 and LTC2804. Refer to Figure 1 or
Figure 2 for proper setup and follow the procedure be-
low:
1.
Place jumpers in the following positions:
MODE H
PS 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. If a separate Logic Supply will be used, use
the “VL” setting and, with the power off, connect the
supply to VL and GND.
4.
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 don’t exceed 7V.) Omit Loopback jumpers
JP4 and JP5 for this mode.
5.
Alternatively, to operate the part in receiver loopback
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:
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.
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 = 6.5V to 7.5V, and VEE = -6.8V to -5.8V.
8.
Send data!
Notes:
1.
Inputs PS and MODE may be driven by signals in-
stead of set with jumpers. If done, ensure that the
voltage of PS doesn’t exceed VL.
2.
The terminal emulation program RealTerm can lock
up when RTS/CTS flow control is used in receiver
loopback mode.
JP1
JP2
JP4
JP5
LTC2803 AND LTC2804
3
Figure 1. Setup for Transmitter Loopback Mode
Figure 2. Setup for Receiver Loopback Mode
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