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SP504 Application Note
routers. These multi-protocol systems will usually contain multiple ports to accommodate the different interfaces. The SP504 can support all the ports through software and provide convenient DTE or DCE functionality to the port. DTE and DCE configuration is provided on the next page and also in the SP504 data sheet. The designer can evaluate the SP504 with our SP504 Evaluation Board. This evaluation board basically allows the user to access the pins directly through probe points on the board. The designer can also access the device by software through the three serial port connectors on the board. Details on the evaluation board can be found in the SP504 data sheet.
The introduction of our SP502 transceiver paved the way for a new generation of multi-mode transceivers that are being designed into next generation networking products. The SP504 multi-mode transceiver is the latest member of the family and offers: reduced external V.35 termination; V.36 & EIA-530A modes; and receiver tri-state and fail-safe ability. As with the SP502 and SP503, the SP504 can be programmed via software to the different available physical protocols and is also drop-in compatible with its predecessors. The versatility of the SP504 is ideal for multiprotocol applications such as Frame Relay systems, X.25 routers/switches and multi-protocol
PCs
Workstations
PCs
Workstations
Mainframe
Branch Office
Remote Office
MultiProtocol Router
2.1Mb/s
Frame Relay Switch Frame Relay
56/64kb/s 1.5Mb/s X.25 Switch
56kb/s
FRAD & X.25 Switch Engineering/Manufacturing
Corporate Office
Workstations
Mainframe
Workstation
Workstation
PC
PCs
Mainframe
PC
Typical Environment Using Frame Relay and X.25 Systems
SP504AN SP504 Application Note (c) Copyright 2000 Sipex Corporation
1
SP504 - Overvoltage and ESD Protection Using Transzorbs
+5V 22F 1N5819 22F
28
31
25
VCC
27
26 30 32 22F
C2+ C2-
VDD C1+ C1VSS
SP504CF
Drivers
TxD 14 DTR 13 RTS 16 TxC 15 ST 22 RL 17 LL 24
15
14 13
12
11 10
ProTek Devices SM16LC15C
2 3 4 5 6 7
Receivers
RxD 1 RxC 20 CTS 80 DSR 78 DCD 19 RI 21 SCT 79 2 3 4 5 6 7 15 14 13 12 11 10
ProTek Devices SM16LC15C
* - Please note that the ProTek transient voltage suppressors should also be connected to the other SP504 drivers and receivers in the same configuration as shown above.
Although the SP504 is internally protected for ESD and overvoltage, an external transient voltage suppression circuit can be added to increase the level of protection of the device. This may be desired for greater ESD protection or clamping the input or output voltages. The maximum driver output and receiver input voltages should not exceed 15V. The SP504 configuration above uses ProTek Devices'
SP504AN
SM16LC15C TVS devices to protect the receiver inputs and the driver outputs since these pins are directly exposed to the connector and the outside world. The Vwm of the TVS can be as low as 5V and high as 15V to cover the RS-232 voltage levels. However, the RS-232 3k to 7k input impedance will not comply if the voltage levels exceed the clamping voltage of the TVS.
ProTek Devices * Tempe, AZ. * 602-431-8101
SP504 Application Note
(c) Copyright 2000 Sipex Corporation
2
SP503/504 - One Chip Half-Duplex Configuration
1N5819 22F +5V 10F 22F 25
VCC
22F
27
VDD
26
30
28
31
32 61
22F
C1V C1+ C2+ C2- SS
Drivers
TxD 14 DTR 13 RTS 16 TxC 15 ST 22 RL 17 LL 24
59 58 56 54 52 63 65 42 44 47 45 51 49 70 71 37 38 66 67 68 69 35 36 39 40 76 77 9
TxD/RxD DTR/DSR RTS/CTS TxC/RxC ST/SCT RL/RI LL/DCD
Receivers
RxD 1 RxC 20 CTS 80 DSR 78 DCD 19 RI 21 SCT 79
TDEC3
Driver Decoder
9
RDEC3
Receiver Decoder
10
TDEC2
10
TDEC1
11
RDEC2
11
RDEC1
12
TDEC0
12
RDEC0
SP503CF or SP504CF
29, 34, 46, 50, 53, 57, 60, 64, 72, 75 GND
SP504AN
SP504 Application Note
(c) Copyright 2000 Sipex Corporation
3
SP504 - DTE/DCE Configuration
Many systems may require the serial port to be configured as either a DTE or DCE. The SP504 is an ideal candidate for a space saving DTE/ DCE solution. To perform this with the SP504, the driver outputs of the first SP504 are connected back into the receiver inputs of the second SP504, and vice versa. The common input/output lines can be routed to the connector and be used as either driver outputs or receiver inputs. Refer to the following page for configuration details. When the two SP504 devices are connected as such, one device must be disabled while the other is transmitting and receiving data. Disabling one of the SP504 devices allows the other to communicate over the serial bus. One is dedicated to a DTE configuration to the serial port and the other is a dedicated DCE device. Disabling the DTE device implies that the serial port will be configured as a DCE, and vice versa. Disabling the SP504 drivers are important because a bus contention problem can occur if two drivers are active at the same time. The drivers of the nonactive SP504 must be tristated by writing "0000" into the driver decoder (TDECX) lines when the I/O lines are used as inputs into the receivers. The receivers do not have to be tri-stated but should be configured so that the receiver input impedance is relatively high (12k) such as RS-422 or RS-485. The receiver inputs will not affect the signals on the driver outputs if the input impedance is at least 12k. If the RDECX is configured with "0000", the input impedance defaults to at least 12k.
Please note that most of the V.35 termination resistors are internal to the SP504. As such, the driver output impedance during tri-state is approximately 20k. This should not affect or degrade the incoming driver signal from the other end. Refer to the waveform graphs in the next few pages. The "DTE" waveforms capture the driver and receiver signals at the serial port containing the two SP504 devices. The "DCE" waveforms are measured in the SP504 at the other end. For example, the TxD driver output on the DCE side corresponds to the RxD receiver on the DTE side (side containing two SP504 devices). Similarly, the TxC driver output on the DTE side should be the same as the RxC receiver input on the DCE side. Even though the signal is not degraded, the lower impedance basically adds the driver output impedance (20k) and the receiver input impedance in parallel. When the active SP504 is configured to RS-232 mode, the typical receiver input impedance is 5k which will yield 4k. When in the other modes except V.35, the typical input impedance is 15k which yields 7.5k when the receivers are configured in differential mode (i.e. RS-422, RS-449, V.36, etc.) which is still greater than the 4k minimum requirement for RS-422 and RS-423. The input impedance for the V.35 receiver is typically 100. The driver tri-state impedance will decrease the input approximately 0.5 to 1 given that the external 150 termination resistor is switched off or disconnected from the noninverting driver output of the disabled SP504. This configuration will allow the proper data communications between DTE and DCE. However for NET1/NET2 certification testing, the driver outputs must be physically disconnected from the receiver inputs. The common I/O paths will interfere with various impedance and current testing for the driver or receiver in V.28, V.11 and V.35 modes.
SP504AN
SP504 Application Note
(c) Copyright 2000 Sipex Corporation
4
The tri-state enable and disable timing must be considered. Given two systems, each configured in DTE/DCE operation, containing two SP504's each, System 1 is the DTE, and System 2 is the DCE. Assume System 1 is now configured to a DCE and System 2 is configured to a DTE; the two SP504 devices within each system will have to switch states. If System 1 switches to DCE before System 2 tri-states its driver, the bus will share driver outputs until System 2 switches to DTE, thus causing bus contention problems. In both systems, the active SP504 should be tri-stated first before enabling the tri-stated SP504. Although the bus contention will not damage the SP504 devices, it should be avoided to prevent short circuit currents at the driver outputs. One last consideration for DTE/DCE hookup is the charge pump capacitors. Many have inquired about sharing the 22F caps. For a minimal requirement, the C1 and C2 capacitors must be separate for each SP504 device. Although this can be functionally done, Sipex does not recommend this practice. Please be aware that if one SP504 becomes nonfunctional, it can affect the other SP504 as well.
SP504AN
SP504 Application Note
(c) Copyright 2000 Sipex Corporation
5
DTE/DCE Serial Port Configuration with the SP504
14 TxD 15 TxC 13 DTR 16 RTS 1 RxD 20 RxC 80 CTS 19 DCD 78 DSR 21 RI 79 SCT 24 LL 17 RL 22 ST
SP504 DTE Config.
SD(A) 61 SD(B) 59 TT(A) 63 TT(B) 65 TR(A) 58 TR(B) 56 54 RS(A) 52 RS(B) RD(A) 70 RD(B) 71 RT(A) 37 RT(B) 38 66 CS(A) CS(B) 67 RR(A) 35 RR(B) 36 DM(A) 68 DM(B) 69 SCT(A) 76 SCT(B) 77 IC(A) 39 IC(B) 40 51 LL(A) LL(B) 49 42 ST(A) ST(B) 44 RL(A) 47
2 3 4 5 12 11 10 9
0 1 1 0 0 0 0 0
14 15 13 16 1 20 80 19 78 21 79 24 17 22
2 3 4 5 12 11 10 9 61 SD(A) TxD SD(B) 59 TT(A) 63 TxC TT(B) 65 TR(A) 58 DTR TR(B) 56 RTS RS(A) 54 RS(B) 52 RxD 70 RD(A) RxC RD(B) 71 CTS RT(A) 37 38 RT(B) DCD CS(A) 66 67 DSR CS(B) RR(A) 35
DB-37 Connector
DB-37 Connector
2 3 4 5 12 11 10 9 61 59 63 65 58 56 54 52 70 71 37 38 66 67 35 SD(A) SD(B) TT(A) TT(B) TR(A) TR(B) RS(A) RS(B) RD(A) RD(B) RT(A) RT(B) CS(A)
0 1 1 0
TxD TxC DTR RTS RxD RxC CTS DCD DSR RI SCT LL RL ST 14 15 13 16 1 20 80 19 78 21 79 24 17 22
RI SCT LL RL ST
RR(B) 36 DM(A) 68 DM(B) 69 SCT(A) 76 SCT(B) 77 IC(A) 39 IC(B) 40 LL(A) 51 49 LL(B) 42 ST(A) ST(B) 44 RL(A) 47
SP504 DCE Config.
CS(B) RR(A) 36 RR(B) 68 DM(A) 69 DM(B) 76 SCT(A) 77 SCT(B) 39 IC(A) 40 IC(B) 51 LL(A) 49 LL(B) 42 ST(A) 44 ST(B) 47 RL(A)
SP504 DCE Config.
(V.35 150 termination resistors not shown)
SP504AN
SP504 Application Note
(c) Copyright 2000 Sipex Corporation
6
DRIVER INPUT
DRIVER OUTPUT
Waveform for TxD Input (c) Output; DCE, RS-422 mode @ 10Mbps
DRIVER INPUT
DRIVER OUTPUT
Waveform for TxD Input (c) Output; DTE, RS-422 mode @ 10Mbps
DRIVER INPUT
DRIVER INPUT
DRIVER OUTPUT
DRIVER OUTPUT
Waveform for RxD Input (c) Output; DCE, RS-422 mode @ 10Mbps
Waveform for RxD Input (c) Output; DTE, RS-422 mode @ 10Mbps
SP504AN
SP504 Application Note
(c) Copyright 2000 Sipex Corporation
7
DRIVER INPUT
DRIVER OUTPUT
Waveform for TxD Input (c) Output; DCE, V.35 mode @ 10Mbps
DRIVER INPUT
DRIVER OUTPUT
Waveform for TxD Input (c) Output; DTE, V.35 mode @ 10Mbps
DRIVER INPUT
DRIVER INPUT
DRIVER OUTPUT
DRIVER OUTPUT
Waveform for RxD Input (c) Output; DCE, V.35 mode @ 10Mbps
Waveform for RxD Input (c) Output; DTE, V.35 mode @ 10Mbps
SP504AN
SP504 Application Note
(c) Copyright 2000 Sipex Corporation
8
SP504 - Switching the 150 V.35 Termination Resistor
The SP504 requires one 150 resistor to ground on each non-inverting (b) driver output. The 150 resistor to ground is necessary to comply with the V.35 short circuit impedance of 15015. The resistors will need to be switched out when V.35 mode is not active. To perform this, the designer can use one of two methods: add a relay or switch in series with the resistor or implant the resistors inside the V.35 cable. Adding the resistors to the cable is relatively easy. In DTE mode, two drivers are usually active, therefore you will only need two resistors. The 150 resistors can be connected individually from pin S (data) to signal ground (pin B) and pin W (clock) to signal ground (pin B) of the V.35 ISO-2593 connector. For DCE applications, an additional driver may be used for a secondary clock signal. If a cable is used on the DCE end, a conversion or "mini" cable is necessary to insert the resistors and route the proper signals to the DTE cable. The resistors can be connected from pin S (data), pin W (clock) and an unassigned pin (2nd clock) to signal ground, pin B. Of course the pins on the "mini" cable will have to be routed to the appropriate end on the DTE V.35 cable. (ie. pin S, pin W and the unassigned pin will be routed to pin T, pin X and pin AA, respectively, on the DTE end.) Another method is to include the 150 resistors on the printed circuit board with the SP504 adding switches or relays. This method may be preferred if a common connector/cable (ie. DB-25) is used for V.35 and some other mode. The switches must have low on-resistance, preferably less than 1. NMOS FETs can be used as configured on the opposite page. The gate of the NMOS device is connected to pin 18 of the SP504. This pin is HIGH when the SP504 is in V.35 mode and goes LOW in all other modes. Pin 18 is not described in the data sheet for the SP504 but can be used to control the switching of the FETs or relays. Sipex recommends Siliconix's LITTLE FOOTTM MOSFET devices such as the Si9959DYTM Dual N-Channel Enhancement-Mode MOSFET. The rDS(on) is typically less than 0.3 and the devices are in 8-pin SOIC packages.
SW
XT AA
W - Terminal Timing (b)
B
EE
150
150
150
B
S - Transmit Data (b)
AA - Transmit Timing (b)
B - Signal Ground B - Signal Ground T - Receive Data (b) X -Receive Timing (b)
ISO-2593 male connector
ISO-2593 female connector
Termination Resistor Implementation in the Cable
TM - LITTLE FOOT is a trademark of Siliconix, member of TEMIC Group.
SP504AN
SP504 Application Note
(c) Copyright 2000 Sipex Corporation
9
1N5819 22F +5V 10F 22F 25
VCC
22F
27 26
VDD C1+
30
28
31
32
22F
C1V C2+ C2- SS
SP504CF
Drivers
TxD 14 DTR 13 RTS 16 TxC 15 ST 22 RL 17 LL 24 51 70 54 63 65 42 44 47 61 59 58
TxD
DTR 150 RTS Pin 18 TxC ST
RL 150 LL Pin 18 Pin 18 RxD RxC CTS 150
Receivers
RxD 1 RxC 20 CTS 80 DSR 78 DCD 19 RI 21 SCT 79
RD RD
71 37 38 66
68
DSR
35
DCD RI SCT
39 76
RD
Driver Decoder
77 9
1 1 1 0
TDEC3
9
RDEC3
Receiver Decoder
TDEC2
10
10
TDEC1
11
RDEC2
11
TDEC0
12
RDEC1
12
RDEC0
29, 34, 46, 50, 53, 57, 60, 64, 72, 75 GND
Termination Resistor Implementation on PC Board.
SP504AN
SP504 Application Note
(c) Copyright 2000 Sipex Corporation
10
ORDERING INFORMATION
Model Temperature Range Package Types SP504CF ............................................... 0C to +70C ............................. 80-pin JEDEC (BE-2 Outline) QFP
Corporation
SIGNAL PROCESSING EXCELLENCE
Sipex Corporation Headquarters and Sales Office 22 Linnell Circle Billerica, MA 01821 TEL: (978) 667-8700 FAX: (978) 670-9001 e-mail: sales@sipex.com Sales Office 233 South Hillview Drive Milpitas, CA 95035 TEL: (408) 934-7500 FAX: (408) 935-7600
Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the application or use of any product or circuit described hereing; neither does it convey any license under its patent rights nor the rights of others.
SP504AN
SP504 Application Note
(c) Copyright 2000 Sipex Corporation
11

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