1
dc1554af
DEMO MANUAL DC1554A
DESCRIPTION
LTM2882
Dual Isolated RS232 µModule
Transceiver with Integrated
DC/DC Converter
Demonstration circuit DC1554A is a dual isolated RS232
μModule
®
transceiver with integrated power featuring
the LTM
®
2882. The demo circuit provides 2-channel,
2500V
RMS
, galvanically isolated RS232 transceiver in-
terface. All components are integrated into the μModule
transceiver. The demo circuit operates from external
supplies on V
CC
and V
L
. The part generates the output
L, LT, LTC, LTM, μModule, Linear Technology and the Linear logo are registered trademarks of
Linear Technology Corporation. All other trademarks are the property of their respective owners.
voltage V
CC2
and communicates all necessary signaling
across the isolation barrier using LTC’s Isolation μModule
Technology.
Design fi les for this circuit board are available at
http://www.linear.com/demo.
OPERATING PRINCIPLES
The LTM2882 contains an isolated DC/DC converter
delivering power to V
CC2
at 5V from the input supply
V
CC
. Isolation is maintained by the separation of GND
and GND2 where signifi cant operating voltages and
transients can exist without affecting the operation of the
LTM2882. The logic side ON pin enables or shuts down the
LTM2882. RS232 signaling is controlled by the logic inputs
T1IN, T2IN, and DE. Connection to the transceiver pins,
R1IN – T1OUT or R2IN – T2OUT, permits RS232 com-
munication on the isolated side of the demo circuit. The
circuit features two channels, supporting multiple RS232
channels or the addition of fl ow control on a single RS232
interface. Jumpers and inclusion of a standard RS232
confi gured DB9 connector allow the RS232 Transceiver
interface to be looped back for easy performance verifi ca-
tion using a PC. Additional logic signaling from the logic
side to the isolated side is available with the DIN to DOUT
pins. This channel may be used to control the state of the
driver outputs from the logic side, T1OUT and T2OUT, by
connecting DOUT to DE.
Data is transmitted out the driver pins T1OUT and T2OUT
from the inputs T1IN and T2IN with the input DE set high.
Data is received through the receiver pins R1IN and R2IN
to the outputs R1OUT and R2OUT, receivers are always
active.
Table 1. Performance Summary (T
A
= 25°C)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
CC
Input Supply Range LTM2882-5
LTM2882-3
4.5
3.0
5
3
5.5
3.6
V
V
V
L
Logic Signal Supply Range 1.62 5.5 V
V
CC2
Output Voltage LTM2882-5 I
LOAD
= 150mA
LTM2882-3 I
LOAD
= 100mA
4.8
4.8
5
5
5.2
5.2
V
V
f
MAX
Maximum Data Rate R
L
= 3k, C
L
= 2.5nF
R
L
= 3k, C
L
= 1nF
R
L
= 3k, C
L
= 250pF
100
250
1000
kbps
kbps
kbps
V
IORM
Maximum Working Insulation Voltage GND to GND2 560 Vpk
Common Mode Transient Immunity 30 kV/μs
