LTC2844CG#PBF Linear Technology, LTC2844CG#PBF Datasheet - Page 15

• Manufacturer Part Number: LTC2844CG#PBF
• Description: IC TXRX 3.3V MULTIPROTCOL 28SSOP
• Manufacturer: Linear Technology
• Type: Transceiverr

Specifications of LTC2844CG#PBF

• Number Of Drivers/receivers: 4/4
• Protocol: Multiprotocol
• Voltage - Supply: 3.3V
• Mounting Type: Surface Mount
• Package / Case: 28-SSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

APPLICATIONS
Receiver Fail-Safe
All LTC2846/LTC2844 receivers feature fail-safe opera-
tion in all modes. If the receiver inputs are left floating or
shorted together by a termination resistor, the receiver
output will always be forced to a logic high.
DTE vs DCE Operation
The DCE/DTE pin acts as an enable for Driver 3/Receiver 1
in the LTC2846, and Driver 3/Receiver 1 and Receiver 4/
Driver 4 in the LTC2844.
The LTC2846/LTC2844 can be configured for either DTE
or DCE operation in one of two ways: a dedicated DTE or
DCE port with a connector of appropriate gender or a port
with one connector that can be configured for DTE or DCE
operation by rerouting the signals to the LTC2846/LTC2844
using a dedicated DTE cable or dedicated DCE cable.
A dedicated DTE port using a DB-25 male connector is
shown in Figure 23. The interface mode is selected by logic
outputs from the controller or from jumpers to either V
or GND on the mode select pins.
A port with one DB-25 connector, but can be configured
for either DTE or DCE operation is shown in Figure 24. The
configuration requires separate cables for proper signal
routing in DTE or DCE operation. For example, in DTE
3.3V
V
IN
C1,C2: TAIYO YUDEN X5R JMK316BJ106ML
D1: ON SEMICONDUCTOR MBR0520
L1: SUMIDA CR43-5R6
SHDN
C6
10 F
Figure 22. Boost Switching Regulator
4
U
SHDN
V
IN
REGULATOR
SWITCHING
3
BOOST
5.6 H
GND
L1
INFORMATION
2, 34
U
SW
FB
36
35
D1
W
R2
4.3k
R1
13k
2844 F22
U
C5
10 F
V
5V
480mA
CC
IN
mode, the TXD signal is routed to Pins 2 and 14 via Driver 1
in the LTC2846. In DCE mode, Driver 1 now routes the RXD
signal to Pins 2 and 14.
Multiprotocol Interface with RL, LL, TM and a DB-25
Connector
If the RL, LL and TM signals are implemented, there are not
enough drivers and receivers available in the LTC2846/
LTC2844. In Figure 25, the required control signals are
handled by the LTC2845. The LTC2845 has an additional
single-ended driver/receiver pair that can handle two more
optional control signals such as TM and LL.
Cable-Selectable Multiprotocol Interface
A cable-selectable multiprotocol DTE/DCE interface is
shown in Figure 26. The select lines M0, M1 and DCE/DTE
are brought out to the connector. The mode is selected by
the cable by wiring M0 (connector Pin 18) and M1 (con-
nector Pin 21) and DCE/DTE (connector Pin 25) to ground
(connector Pin 7) or letting them float. If M0, M1 or DCE/
DTE is floating, internal pull-up current sources will pull
the signals to V
therefore, internally pulled high. When the cable is pulled
out, the interface will go into the no-cable mode.
Compliance Testing
The LTC2846/LTC2844 chipset has been tested by TUV
Rheinland of North America Inc. and passed the NET1,
NET2 and TBR2 requirements. Copies of the test report are
available from LTC or TUV Rheinland of North America Inc.
The title of the report is Test Report No. TBR2/051501/02
The address of TUV Rheinland of North America Inc. is:
TUV Rheinland of North America Inc.
1775, Old Highway 8 NW, Suite 107
St. Paul, MN 55112
Tel. [phone]
Fax [phone]
IN
. The select bit M2 is floating and
LTC2844
sn2844 2844fs
15