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SP503 Application Note
s DTE and DCE configurations with the SP503 s Connecting the SP503 to a DB-25 connector in DTE and DCE modes s Implementing V.35 with the SP503 s Creating extra single-ended and differential channels with the SP503 using the SP310A and SP485 s Using external supplies with the SP503
Due to its flexibility and programmability, the SP503 has been finding its way into many new networking products. The SP503 offers an excellent replacement for discrete solutions on X.25 implementations for frame relay systems, multi-protocol routers and other WAN products where many designs run various modes such as RS-232, RS-422, V.35 or V.36. For RS-232, the older bipolar 1488 and 1489 parts, or even the newer MAX230 or SP230 series have traditionally been used. For RS-422 or RS-485, the 26LS31, 26LS32, 3488, and 3489 have been seen in many designs. These parts have been also
used for V.35 but with external termination resistors. For a typical design, four RS-232 chips would be used for a complete RS-232 port, four RS-422 chips for an RS-422 port and four chips for V.35 with an external resistor network. Port programmability would require relays or switches so that software lines can control whether RS-232 is active or RS-422 is active. The relays increase board capacity as well as cost to the design. The SP503 solves board space and cost problems by offering a single packaged part that supports various protocols and also offers software programmability to the port.
Typical discrete solution vs. the SP503
SP503AN SP503 Application Note (c) Copyright 2000 Sipex Corporation
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DTE and DCE configurations with the SP503
The SP503 has designated signals such as "Transmit Data", "Clear-to-Send", etc.which designers can easily allocate the appropriate SP503 transceivers for the corresponding signals. The data signals specified in the EIA standards and CCITT are referenced in the SP503 datasheet as DTE. Some customers have wondered if they can use the SP503 for DCE applications. Although it can be confusing at first glance, the
DCE implementation is the mirror image of the DTE side. For the DTE, TxD is a driver which drives the data to RxD, a receiver, on the DCE side. TxC or TT is a driver on the DTE side which drives the clock signal to the RxC receiver on the DCE side. The next three pages illustrate the CCITT signal allocations from the SP503 in either DTE or DCE to the DB-25 connector. As shown, it is possible to use a DB-25 connector for the various protocols offered by the SP503.
DB-25 Connector Pin Assignments for Various Protocols
DB-25 Pin # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 RS-232 shield TxD RxD RTS CTS DSR Signal GND DCD - - - DCD (2nd) CTS (2nd) TxD (2nd) RxD (2nd) RxC LL RTS (2nd) DTR RL RI SRS TxC (DTE) EIA-530 shield TxD(A) RxD(A) RTS(A) CTS(A) DSR(A) Signal GND RLSD(A) RxC(B) RLSD(B) TxC(B-DTE) TxCC(B-DCE) CTS(B) TxD(B) RxD(B) RxC(A) LL RTS(B) DTR(A) RL DSR(B) DTR(B) TxC(A-DTE) RS-449 shield SD(A) RD(A) RS(A) CS(A) DM(A) Signal GND RR(A) RT(B) RR(B) TT(B) ST(B) CS(B) SD(B) ST(A) RD(B) RT(A) LL RS(B) TR(A) RL DM(B) TR(B) TT(A) RS-422 shield T(A) R(A) C(A) - - Signal GND I(A) - I(B) - S(B) - T(B) S(A) R(B) - - C(B) - - - - - V.35 103(A) 104(A) 105 106 107 102 109 115(B) - 113(B) 114(B) - 103(B) 114(B) 104(B) 115(A) - - - - - - 113(A) V.36 103(A) 104(A) 105(A) 106(A) 107(A) 102 109(A) 115(B) 109(B) 113(B) 114(B) 106(B) 103(B) 114(B) 104(B) 115(A) 141 105(B) - 140 107(B) - 113(A)
CCITT# 101 CCITT# 101
TxCC (DCE) TxCC(A-DCE)
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SP503 Application Note
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DTE-DCE flexibility with the SP503 on a DB-25 serial port
SP503 DTE Config.
TxD TxC DTR RTS 61 SD(A) SD(B) 59 63 TT(A) TT(B) 65 58 TR(A) 56 TR(B) RS(A) 54 52 RS(B) 70 RD(A) 71 RD(B) RT(A) 37 38 RT(B) 66 CS(A) 67 CS(B) 35 RR(A) 36 RR(B) 68 DM(A) DM(B) 69 76 SCT(A) SCT(B) 77 39 IC(A) 40 IC(B) 51 LL(A) 49 LL(B) 42 ST(A) 44 ST(B) 47 RL(A)
RxD RxC CTS DCD
2Y 3Y
1A 1B 2A 2B 4Y 3A 3B 4A SEL 4B 1Y
"0" = DTE "1" = DCE
Quad 2:1 Mux
SCC
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
2 3 4 5 12 11 10 9
RDEC0 RDEC1 RDEC2 RDEC3 TDEC0 TDEC1 TDEC2 TDEC3
2 3 4 5 12 11 10 9 61 SD(A) 59 SD(B) 63 TT(A) 65 TT(B) 58 TR(A) 56 TR(B) 54 RS(A) RS(B) 52 70 RD(A) 71 RD(B) RT(A) 37 RT(B) 38 66 CS(A) CS(B) 67 RR(A) 35 36 RR(B) 68 DM(A) DM(B) 69 76 SCT(A) 77 SCT(B) 39 IC(A) 40 IC(B) LL(A) 51 49 LL(B) 42 ST(A) 44 ST(B) RL(A) 47
DB-25 Connector
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
3 16 17 9 6 22 5 13 2 14 24 11 4 19 18 20 23 21 8 10 15 12 22 7 1
SP503 DCE Config.
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SP503 Application Note
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Driver / Receiver Connections to a DB-25 Connector DTE Mode
Drivers
TxD
14
SP503CF
61 59 58 56 54 52 63 65 42 44 47 45 51 49 70 71 37 38 66 67 68 69 35 36 39 to pin 22 for non-RS-232
DTR
13
RTS
16
Male Connector
13 25 14
TxC
15
ST
22
RL
17
LL
24
Receivers RxD
1
RxC
20
CTS
80
DSR
78
DCD
19
RI
21
SCT
79
76 77
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SP503 Application Note
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1
40 RI used for RS-232 only
Driver / Receiver Connections to a DB-25 Connector DCE Mode
TxD(A) TxD(B) TxC(A) TxC(B)
70 71 37 38
SP503CF
Receivers RxD
1
RxC
20
Female Connector
25 14
SP503AN
RTS(A) RTS(B) DTR(A) DTR(B) LL
66 67 68 69 35 36
CTS
80
13 1
DSR
78
DCD
19
RL
39 40 76 77
RI
21
SCT
79
RxD(A) RxD(B) DSR(A)
to pin 22 for non-RS-232
61 59 58 56 54 52 63 65 42 44
TxD Drivers
14
DTR
13
CTS(A) CTS(B) RxC(A) RxC(B) SCT(A) SCT(B) RI
RTS
16
TxC
15
ST
22
47 45
RL
17
DCD(A) DCD(B)*
51 49
LL
24
* The non-inverting LL driver output is not a valid driver output for RS-449 and EIA-530.
SP503 Application Note
(c) Copyright 2000 Sipex Corporation
5
SP503 V.35 External Termination Resistors
V.35 implementation requires external resistors to be connected to the driver outputs and receiver inputs. The resistors are needed for reducing signal levels and maintaining input and output impedance levels that conform to CCITT Recommendation V.35. The drawings below offer both receiver input termination and driver output termination configurations that will comply to V.35. As you may know, the termination resistors are for V.35 mode only and have to be disconnected when another mode is programmed. There are a few ways to connect and disconnect the network. One method is to add a daughter-card option slot onto the main printed circuit board where the SP503 is mounted. This allows the user to add a mini-PC card that contains the V.35
network to be connected to the driver outputs and receiver inputs. Another method is to implant the V.35 network into a cable if the user requires conversion cables to switch from one protocol to another. For example, if the serial port has a DB-25 connector and requires an ISO-2593 connector for V.35; a DB-25 to ISO-2593 conversion cable containing the V.35 network is connected to the port. Of course this method will not allow programmability to the serial port if the user wants to run various protocols to that port. To actively switch protocols by software control, you can use analog switches or relays. Sipex recommends using low-ON resistance analog switches, such as Siliconix DG643(c) analog switches for the driver outputs, and solid-state relays such as the AT&T LH1514(c) for the receiver inputs. See opposite page for an example of the SP503 V.35 configuration. For other termination networks, please consult the factory.
A 50 120 50 B ZSOURCE = 97 [90 to 110] ZSC = 148 [135 to 165]
V.35 Receiver Input Termination Resistor Network
200 232 -5V 5% 232 Typical values 200
A
107
100 LOAD
B VD = 0.55V [+0.44V to +0.66V] VDC_OFF = 0.0V [-0.6V to +0.6V]
ZSOURCE = 96 [50 to 150] ZSC = 154 [135 to 165]
V.35 Driver Output Termination Resistor Network
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SP503 Switching Configuration for V.35 Implementations
* Switches are Siliconix DG643DY analog switches. * Solid-State Relays are AT&T, LH1514. * Resistors are 1/8W, 1% tolerance. * External Supplies necessary are: Vcc = +5V, V+ = +12V (for V+ on the DG643DY) and Vn = -5V.
V+12V V+12V 12 5 8 V+ 4 2 6 11 13 1 16 3 15 7 9 14 10 Driver Outputs & Receiver Inputs are in DTE mode.
+5V
V+
V-
TxD (103)
200 232 -5V 107 232 200
Drivers
TxD
14
SP503CF
12 5 V+ 8 4 2 6 11 13 1 16 3 15 7 9 10 14
A B
to pin 12 of the 74LS11
74LS11
DG643
DG643
+12V
DTR
13
V-
+12V
to V-
TT (113)
200 232 -5V 107 232 200 12 5 8 V+ 4 2 6 11 13 1 16 3 15 7 9 14 10
DG643
DG643
RTS
16
74LS11
to pin 12 of the 74LS11 +12V
TxC
15
V12 5 V+ 8 4 2 6 11 13 1 16 3 15 7 9 10 14
V-
200 232
ST
22
-5V 107
232 200
RL
17
12 5 8 V+ 4 2 6 11 13 1 16 3 15 7 9 14 10
12 5 V+ 8 4 2 6 11 13 1 16 3 15 7 9 10 14
A B
DG643
DG643
A
74LS11
to pin 12 of the 74LS11
B
LL
74LS11
to pin 6 of the 74LS11
1
Receivers RxD
1
24
A
8 LH1514 6 50 50 7 5 120
RxD (104)
RxC
20
B
3 3
A CTS
80
LH1514 6 8 7 5 50 50 120
RxC (115)
DSR
78
74LS11
B
1 to pin 6 of the 74LS11 1 50 7 5 6 50 120
DCD
19
A
TxCC (114)
8
RI
21
LH1514
SCT
79
+5V 16
B
3 +5V
74LS11 (3-Input AND Gate)
3 12 4 5
16 1/4 74LS11 8 6
(pins 3 & 11) (pins 4 & 10) (pins 5 & 9)
1 RDEC1 & TDEC1 RDEC2 & TDEC2 RDEC3 & TDEC3 8 2 13 1/4 74LS11
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SP503 Application Note
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Typical Applications Questions on the SP503
Can the SP503 be used with external power supplies? If so, is there a power-up sequence? The internal charge pump can be bypassed through external supplies to VDD and VSS. The external voltage should be +10V for VDD and -10V for VSS. The tolerance is 5%. The absolute minimum limit for the external supplies is 7V and the absolute maximum limit is 10.5V. The SP503 does require a power-up sequence of +10V, +5V, -10V for proper operation. Additional external circuitry will be required for the correct sequencing. Consult factory for details. What is the maximum input voltage applied to the receiver input without damaging the SP503? The receiver inputs can tolerate up to 16V in any protocol without latching up the device. Since RS-232 ranges from 5V to 15V; the SP503 is well within the accepted range. It may be worthwhile to include 15V clamping diodes or transient voltage suppressors so that the receiver input will be held below 15V. What is the maximum short-circuit voltage that can be applied to a SP503 driver output? The driver outputs can be shorted up to 16.0V without causing damage to the driver. Between the 16V range, the SP503 adheres to the RS232 short circuit current limit of 100mA and to the RS-422/RS-423 limit at 150mA. Again, transient voltage suppressors or clamping diodes will protect the SP503 if exceeding the 16V range is possible. What is the state of the SP503 drivers and receivers when the device is addressed with 0000? The SP503 drivers are in a high impedance(over 1M) tri-state condition when "0000" is addressed. The receivers are not tri-stated and the outputs are undefined. This means that they could be floating to either a high or low level depending on the previous state of the receiver input prior to the 0000 addressing change. The receiver input impedance is at 15k for "0000". Can the SP503 be programmed for 7 drivers and 7 receivers in RS-423 mode?
The SP503 can be switched to RS-423 mode by programming TDEC3, TDEC2, TDEC1, TDEC0 to "1000" for the drivers and RDECX to "1000" for the receivers. However, external supplies must be used in order to drive RS-423. The internal charge pump can only support up to three RS-423 drivers and three RS-423 receivers. What is the power dissipation in the SP503 and in which mode does it consume the most power? The SP503 dissipates approximately 400mW to 1.4W depending on the protocol. RS-485 mode consumes the most power at 1.4W. For worst case power dissipation, all seven drivers were driven with a TTL signal and the outputs were looped back into the receiver inputs to generate a TTL output. All drivers and receivers were active. MODE RS-232 RS-422 RS-485 RS-449 EIA-530 V.35 PD 0.418W 0.970W 1.382W 0.959W 0.959W 1.055W
What is the state of the SP503 drivers and receivers when the device is addressed with 1111? The address for "1111" is not used in the SP503. If the SP503 is programmed for "1111", the drivers are approximately 1.0V and at a high impedance (approx. 9M). The receivers are not tri-stated and the outputs are undefined. All receiver inputs are at 15k input impedance. The SP503 can receive a "1111" address while VCC is off. The supply current is approximately 50mA (VCC = +5V) while the address is at "1111". In the RS-232 signal assignments for the DB-25 connector, where does the SP503 account for Test Mode (TM) ? For most RS-232 applications, the signals commonly used are TxD, TxC, RxD, RxC, RTS, CTS, DSR, SG, DCD, DTR and Frame Ground.
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In DTE mode; TxD, TxC, RTS, DTR are the drivers and RxD, RxC, CTS, DSR, DCD are the receivers. Since there are seven drivers and seven receivers in the SP503, the designer can easily use the SP503 for the above signals. Other RS-232 applications will support diagnostic functions such as LL (driver), RL (driver), and TM (receiver) which may or may not require extra transceivers depending if other signals are not used. Since Test Mode (TM) is a receiver for DTE designs, the Ring Indicator (RI) receiver in the SP503 (pin 21) can be used for TM if RI is not used. If all the available drivers and receivers are used in the SP503, then another RS-232 transceiver can be added. See page 230 and 231 for suggestions on adding Sipex's RS-232 and RS-485 transceivers. Are the Schottky diodes used from Vcc to Vss and from Vdd to C2- in the SP502 necessary for the SP503? Sipex has incorporated the Schottky diodes (needed with the SP502) into the SP503 in order to protect against potential start up problems due to fast rate of rise on VCC(1V/s) and overvoltage to the TTL inputs. However, a negative voltage (Vin -5V) applied to the receiver inputs while the SP503 is powered off will cause startup problems to the charge pump. In order to guard against this condition, an external Schottky diode should be placed from VCC to VDD to minimize VCC current injection into the IC substrate and allow the charge pump to operate properly. See page 203 Figure 6 - Typical Operating Circuit, for diode connection schematic. Can the SP503 be configured for V.36? CCITT Recommendation V.36 is similar to RS449 where certain signals are RS-422 signals and others are RS-423. Depending on different applications; "Transmit Data", "Terminal Timing", "Request-to-Send", "Data Terminal Ready", "Receive Data", "Transmit Clock", "Receive Clock", "Clear-to-Send", "Data Carrier Detect", and "DataSet Ready" are specified as Category 1 Circuits where the protocol is RS-422 for rates over 20kbps. All other circuits are Category 2 Circuits which are specified as RS-423 circuits. Depending on particular signals, the SP503 can be easily used for V.36.
When the two drivers, ST and TT, are in tri-state mode, what will the driver outputs tolerate for maximum short circuit voltages? And the receiver, SCT, input? The driver outputs will tolerate up to 16.0V without any damage to the circuit regardless of whether or not ST and TT are in tri-state mode. The tri-state circuitry does not affect the short circuit protection on the driver outputs. The SCT receiver input will tolerate up to 16.0V without any damage to the input structure regardless of whether or not SCT is in tri-state mode. What does Sipex recommend for transient voltage suppression techniques for the SP503? For our evaluation boards, Sipex uses transient voltage suppressor ICs from ProTek Devices, model numbers LCA05C to LCA15C. The two digits in the part number pertain to the rated stand-off voltage, VWM, which is the maximum working DC voltage applied to the device. These TVS devices are especially designed for serial data communications because of their low capacitance and low impedance. However, please be aware that VWM values below the specified input range of the transceiver will affect the input impedance. For example, it would be fine to use a 5V VWM value for RS-422 but for RS-232, the receiver input voltage range is 15V where lower VWM voltages will drive the impedance to ground. Another recommended manufacturer is AVX Corporation TransGuard series of TVS components. AVX offers a variety of surface mount back-to-back diodes.
ProTek Devices * P.O. Box 3129 * Tempe, AZ. 85280 * 602-431-8101 AVX Corporation * Myrtle Beach, SC * 803-448-9411
The drawing on page 232 shows the SP503 configured with the ProTek SM16LC15C TVS devices to protect the drivers and receivers from ESD and over-voltage. Will the SP503 conform to the physical layer testing specified by NET1/NET2 for X.21 and X.25 systems? Sipex initiated a component level test for NET1/ NET2 for V.28, V.10, V.11, V.35 protocols. The SP503 passed all the physical layer testing requirements prescribed by NET1/NET2. A full test report can be furnished upon request.
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Creating extra RS-232 channels using the SP310A
1N5819 22F +5V 22F 25 27
VDD
22F
1
26 30 28 31 32 61 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 22F
VCC C1C2- VSS C2+
SP503CF
Drivers
C1+
7 2 14 20 23 4 19 24 11
21 18 3 16 17 9 5 13 6 8 10 22 15 12
Receivers
RxD 1 RxC 20 CTS 80 DSR 78 DCD 19 RI 21 SCT 79
RDEC1 (Pin 3 of the SP503)
RDEC1
3 +5V 17 18 12 11 TM 13 10 9
VCC
0.1F 0.1F 0.1F 32 45 6
SP310ACT
0.1F
DB-25 connector in DTE configuration.
ON/OFF
C2- 7 C1V+ C1+ C2+ V-
15 8 14
25
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Creating extra differential channels using the SP485
1N5819 22F +5V 22F 25 27
VDD
22F
1
26 30 28 31 32 61 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 22F
VCC C1C2- VSS C2+
SP503CF
Drivers
C1+
7 2 14 20 23 4 19 24 11
21 18 3 16 17 9 5 13 6 8 10 22 15 12
Receivers
RxD 1 RxC 20 CTS 80 DSR 78 DCD 19 RI 21 SCT 79
TDEC2
TDEC2
10 +5V 8
VCC
DB-25 connector in DTE configuration.
1F
SP485
4 DI 3 1 DE RO 2 RE 5 7 B6 A
25
RDEC1
(pin 3 of the SP503)
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SP503 Application Note
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Using Transient Voltage Suppressors with the SP503
+5V 22F 1N5819 22F
28 31 25
C2+ C2VCC
27 26 30
VDD C1+ C1- 32 VSS
22F
SP503CF
Drivers
TxD 14 DTR 13 RTS 16 TxC 15 ST 22 RL 17 LL 24 2 3 4 5 6 7
15 14
13 12
11 10
ProTek Devices SM16LC15C
Receivers
RxD 1 RxC 20 CTS 80 15 14 DSR 78 DCD 19 RI 21 SCT 79 2 3 4 5 6 7 13 12 11 10
ProTek Devices SM16LC15C
* - Please note that the ProTek transient voltage suppressors should also be connected to the other SP503 drivers and receivers in the same configuration as shown above.
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ORDERING INFORMATION
Model Temperature Range Package Types SP503CF ............................................... 0C to +70C .................................................................. 80-pin QFP SP503EB ....................................................................................................................SP503 Evaluation Board
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.
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