Aeroflex Colorado Springs Product Advisory Datasheet Specification Clarification for the UT63M143 3.3V MIL-STD-1553A/B Bus Transceiver 1.0 Cross Reference of Affected Devices Table 1: Cross Reference of Affected Product Revisions Product Name PIC* Product Revision SMD Device Types RHA Levels UT63M143 MIL-STD-1553 Transceiver JB04 Rev A & B 5962-07242 01 & 02 R, F, G, &H UT63M143 MIL-STD-1553 Transceiver JB05 Rev B TBD n/a non-RHA * PIC = Aeroflex Internal Product Identification Code 2.0 Overview This product advisory is provided by Aeroflex Colorado Springs (Aeroflex) to clarify the test conditions associated with the tRXDD, tRCVPD, and VTH minimum voltage response parameters on the UT63M143 MIL-STD-1553A/B Bus Transceiver. This advisory is only applicable to the product revisions indicated in Table 1. 3.0 Explanation of Parameter tRXDD Parameter tRXDD is defined in the UT63M143 datasheet as the skew between RXOUT and RXOUT as shown in Figure 1. This skew is measured by applying the input waveform described in the Zero Crossing Distortion test of the MIL-STD-1553 RT Validation Test Plan (MIL-HDBK-1553A Section 100 paragraph 5.1.2.1.1). Specifically, the input waveform is driven to the receiver input pins RXIN and RXIN in a direct-coupled configuration, whose peakto-peak, line-to-line amplitude is 3.0V, and whose rise and fall times are 200ns +20ns with 500ns ideal zero crossings. Given this input waveform, the UT63M143 guarantees tRXDD of no more than +200ns. RXOUT tRXDD tRXDD RXOUT Figure 1. Relationships of tRXDD with RXOUT and RXOUT Original Release Date: 7/17/08 Page 1 of 5 Latest Modification Date: N/A Aeroflex Colorado Springs Product Advisory 4.0 Explanation of Parameter tRCVPD Parameter tRCVPD is defined in the UT63M143 datasheet as the propagation delay from zero-crossing on the MILSTD-1553 databus to a change in state of the RXOUT and RXOUT pins as shown in Figure 2. These propagation delays are measured by applying the input waveform described in the Zero Crossing Distortion test of the MIL-STD1553 RT Validation Test Plan (MIL-HDBK-1553A Section 100 paragraph 5.1.2.1.1). Specifically, the input waveform is driven to the receiver input pins RXIN and RXIN in a direct-coupled configuration, whose peak-to-peak, lineto-line amplitude is 3.0V, and whose rise and fall times are 200ns +20ns with 500ns ideal zero crossings. Given this input waveform, the UT63M143 guarantees tRCVPD of no more than 450ns. 0 ns 3.0V pp-ll 500 ns 1000 ns 1500 ns 2000 ns 2500 ns 3000 ns 0V tRCVPD = 450 ns max. tRCVPD = 0 ns min. RXOUT tRCVPD = 0 ns min. RXOUT# tRCVPD = 450 ns max. Figure 2. Test Waveform for tRCVPD In actuality, the typical propagation delay for this test condition ranges from about 200ns from zero crossing to the associated output falling edge and approximately 300ns from the same zero crossing to the corresponding output rising edge. This measurement is not tested by Aeroflex under a minimum receiver amplitude condition of 1.2V pp-ll for a direct-coupled bus (0.86V pp-ll for a transformer-coupled bus). Based on lab evaluation, the minimum amplitude test results in tRCVPD approaching 0ns for the receiver’s falling output edge while the rising edge of the complimentary output extends toward 450ns. Depending upon the time it takes for the incoming waveform to reach and stabilize at the minimum response amplitude of 1.2V pp-ll, the propagation delay from zero crossing to the receiver output rising edge will extend beyond 450ns. The following section of this advisory will discuss, in more detail, the effects that minimum input voltage testing has on the UT63M143 receiver. 5.0 Explanation of the Minimum Input Threshold Voltage that is Guaranteed to Generate a Response on RXOUT and RXOUT Aeroflex’s pass/fail criteria for a valid “response” at outputs RXOUT and RXOUT during minimum receiver amplitude testing is set to pass a minimum output pulse width of 100ns in response to a 1MHz, 50% duty cycle, trapezoidal, input waveform having 200ns rise/fall times with a direct-coupled amplitude of 1.2V pp-ll. Stated differently, a “response” during production testing means that the RXOUT and RXOUT pulse widths are > 100ns when receiving minimum MIL-STD-1553 amplitude, 500ns trapezoidal pulses with 200ns rise and fall times. Conversely, a “noresponse” during production testing will occur when the RXOUT and RXOUT pulse widths are less than 10ns while receiving an input waveform of 280mV pp-ll (direct-coupled). Depicted in figure 3 are the test waveforms used to measure the input voltage threshold response (VTH) conforming to the Amplitude Variations test of the MIL-STD-1553 RT Validation Test Plan (MIL-HDBK-1553A Section 100 paragraph 5.1.2.1.2). The applied signal is a trapezoidal waveform with rise and fall times of 200ns + 20ns applied to the receiver in the direct-coupled configuration. Under this test condition, the receiver is guaranteed to produce a response on the receiver output pins RXOUT and RXOUT, where the “response”, as defined above, is a positive pulse having a minimum width of 100ns. Original Release Date: 7/17/08 Page 2 of 5 Latest Modification Date: N/A Aeroflex Colorado Springs Product Advisory 0 ns 500 ns 1000 ns 1500 ns 2000 ns 2500 ns 3000 ns 300 ns 1.2V pp-ll 0V tRCVPD 450 ns RXOUT 100 ns min. tRCVPD 450 ns RXOUT# 100 ns min. Figure 3. Aeroflex Test Waveform for Minimum Receiver Input Voltage Response 6.0 Ensuring a Clear Status Remote Terminal Response During a Minimum Receiver Amplitude Test Condition A MIL-STD-1553 remote terminal using the UT63M143 can reliably operate under the minimum receiver amplitude levels described in MIL-HDBK-1553A Section 100 paragraph 5.1.2.1.2 when proper waveform conditions are satisfied, and the protocol decoding circuitry is designed to distinguish the minimum pulse widths associated with each of the three unique pulse streams defined in MIL-STD-1553. Table 2 describes the MIL-STD-1553 bit patterns that correlate to each of the three unique pulse streams. Table 2: MIL-STD-1553 Bit Pattern to Pulse Stream Comparison MIL-STD-1553 Bit Patterns Description of Bit Pattern Corresponding MIL-STD-1553 Pulse Stream Command and Status Sync-Pulse 1.5 bit times high followed by 1.5 bit times low 1.5μs Pulses: 1.5μs High - 1.5μs Low Data Sync-Pulse 1.5 bit times low followed by 1.5 bit times high 1.5μs Pulses: 1.5μs Low - 1.5μs High Alternating ...1-0-1-0... Bit Pattern No level transition occurs on bit time boundaries; an edge is only observed in the middle of a bit time. The bit stream will look like a 500kHz, 50% duty cycle clock. 1μs Pulses: 1μs High -1μs Low -1μs High ... Solid ...1-1-1-1... or ...0-0-0-0... Bit Pattern An edge transition will occur at each bit boundary and in the middle of each bit-time. The bit stream will look like a 1MHz, 50% duty cycle clock. 500ns Pulses: 500ns High -500ns Low - 500ns High - 500ns Low -... In addition to providing consideration for the three unique pulse streams described in table 2, the MIL-STD-1553 decoder design must factor-in the actual pulse durations that the UT63M143 will present on the RXOUT/RXOUT pins in response to the various electrical conditions on the MIL-STD-1553 data bus. Table 3 provides a cross reference between incoming pulse width and the resulting RXOUT/RXOUT pulse widths. To ensure successful extraction of each bit from the incoming bit pattern, the decoder must be able to interpret the RXOUT/RXOUT pulses and separate them into the appropriate bit times. Original Release Date: 7/17/08 Page 3 of 5 Latest Modification Date: N/A Aeroflex Colorado Springs Product Advisory Table 3: Cross Reference of MIL-STD-1553 Bus Electrical Characteristics to Receiver Output Results MIL-STD-1553 Bus Electrical Characteristics Sync Pulses: Zero Crossing-to-Zero Crossing Duration: • 1.5μs High - 1.5μs Low • 200ns +/-20ns Rise & Fall Times Direct-Coupled Amplitude: 1.2 Vpp-ll Transformer-Coupled Amplitude: 0.86 Vpp-ll Alternating ...1-0-1-0... Pulses: Zero Crossing-to-Zero Crossing Duration: • 1.0μs High - 1.0μs Low • 200ns +/-20ns Rise & Fall Times Direct-Coupled Amplitude: 1.2 Vpp-ll Transformer-Coupled Amplitude: 0.86 Vpp-ll Solid ...1-1-1... or ...0-0-0... Pulses: Zero Crossing-to-Zero Crossing Duration: • 500ns High - 500ns Low • 200ns +/-20ns Rise & Fall Times Direct-Coupled Amplitude: 1.2 Vpp-ll Transformer-Coupled Amplitude: 0.86 Vpp-ll 0 ns 500 ns 1000 ns RXOUT/RXOUT High Pulse Widths Reference Figure 4 Min. High Pulse = 1.1μs Max. High Pulse = 1.5μs (Theoretical) Figure 5 Min. High Pulse = 600ns Max. High Pulse = 1.0μs (Theoretical) Figure 6 Min. High Pulse = 100ns Max. High Pulse = 500ns (Theoretical) 1500 ns 2000 ns 2500 ns 3000 ns 1300 ns 1.2V pp-ll 0V tRCVPD 450 ns RXOUT 1100 ns min. tRCVPD 450 ns RXOUT# 1100 ns min. Figure 4. RXOUT/RXOUT Worst Case Pulse Width When Receiving a MIL-STD-1553 Sync Pulse During Minimum Receiver Amplitude Testing Original Release Date: 7/17/08 Page 4 of 5 Latest Modification Date: N/A Aeroflex Colorado Springs Product Advisory 0 ns 500 ns 1000 ns 1500 ns 2000 ns 2500 ns 3000 ns 800 ns 300 ns 1.2V pp-ll tRCVPD 450 ns RXOUT 600 ns min. 100 ns min. tRCVPD 450 ns RXOUT# 600 ns min. 100 ns min. Figure 5. RXOUT/RXOUT Worst Case Pulse Widths When Receiving a MIL-STD-1553 Pattern of x-1-0-1-x During Minimum Receiver Amplitude Testing 0 ns 500 ns 1000 ns 1500 ns 2000 ns 2500 ns 3000 ns 300 ns 1.2V pp-ll 0V tRCVPD 450 ns RXOUT 100 ns min. tRCVPD 450 ns RXOUT# 100 ns min. Figure 6. RXOUT/RXOUT Worst Case Pulse Widths When Receiving a MIL-STD-1553 Pattern of x-1-1-1-x During Minimum Receiver Amplitude Testing Along with the critical nature of the decoder design, the electrical characteristics of the incoming waveform on the MIL-STD-1553 bus also play a significant role in the RXOUT/RXOUT pulse widths - particularly during minimum amplitude response testing. Specifically, if the incoming waveform takes longer than 220ns to reach a minimum response amplitude of 0.86V and 1.2V for the transformer- and direct-coupled configurations, respectively, then the RXOUT/RXOUT pulse widths may correspondingly shrink below durations presented in table 3. In general, the UT63M143 requires the incoming waveform to remain at the minimum response amplitude for at least 200ns before the RXOUT/RXOUT pins will transition to the appropriate states. After the incoming waveform has been stable for a minimum of 200ns, the RXOUT/RXOUT pins will resolve to their proper values on a ns-for-ns basis until the input waveform drops below the minimum response amplitude, at which time the UT63M143 will quickly respond by driving RXOUT and RXOUT low. If the MIL-STD-1553 protocol device is unable to detect and segregate pulse widths from the UT63M143 as described in table 3, then it would most likely result in a “no-response” failure during the Amplitude Variations portion of the RT Validation Test as the input signal approaches the minimum threshold for response condition. Original Release Date: 7/17/08 Page 5 of 5 Latest Modification Date: N/A