AND8365/D 125 kbps with AMIS-4168x http://onsemi.com APPLICATION NOTE Introduction Question program the CAN−controller in such a way that the propagation segment of a bit time accounts for two maximum propagation delays to ensure correct function of the bus during arbitration and acknowledgment. In our example, the propagation segment shall be at least 3.11 ms long. If for instance the bit time is divided in 16 time quanta (tq), tq will be 0.5 ms and the Prop_Seg has to be set to 7 tq = 3.5 ms. By applying this CAN−controller setting, it’s ensured that the bus signal will be sampled correctly in all situations. “Is it possible to drive 125kB with the AMIS−41682?” Please consider all possible CAN bit timings (TSEG1, TSEG2, SJW), a capacitive load at each can pin about 300 pF and l = 20m line (5 ns/m) length. Please investigate different communication scenarios (e.g. arbitration). Conclusion The maximum propagation delay measured at 125 kB is 1.555 ms. This is for 270 pF capacitive load and a bus length of 20m. When using the AMIS−41682, the user has to Bit time (8 ms) tq Sync _Seg Prop _Seg Phase _Seg1 Phase _Seg2 Sample Point Figure 1. Example of CAN−Controller Setting Suitable for 125kB Operation with AMIS−4168x • Oscilloscope type: Agillent Infiniium 600 MHz, Overall, it is not a problem to drive 125 kB with the AMIS−41682. 4 GSa/s • Power supply: Thurlby Thandar Instruments Performed Measurements Propagation delay between Tx_1 and Rx_1 (transceiver 1) and Tx_1 and Rx_2 (receive transceiver 2) for different cable length, and CANL/CANH termination of 220 W. Used equipment: • Oscillator type: Hewlett−Packard 3310A Function Generator; frequency 62.5 kHz (tbit = 8 ms) © Semiconductor Components Industries, LLC, 2009 January, 2009 − Rev. 0 • PL310QMD Cable: Alcatel TIA/EIA 568−B.2 Category 5e; 100 W; propagation delay: 570 ns/100m at 1 MHz The circuit shown in was Figure 2 used for the measurement. 1 Publication Order Number: AND8365/D AND8365/D 1N4004 10mF 50V + +5V Tx_1 10 kohm 10 kohm 10 kohm L = 0m / 20m WAKE MP3 220 ohm CANL_1 CANH_1 220 ohm C1 MP4 C2 2 x 270 pF 220 ohm 220 ohm C1 +5V 10 nF C2 VBAT INH VCC 1 10 7 14 RTL 9 6 EN 4 ERR CANL 12 5 STB AMIS−41682 CANH 11 3 RxD RTH 8 2 x 270 pF 100 kohm MP5 Rx_2 2 TxD 13 GND 10 kohm Rx_1 10 kohm VCC INH VBAT WAKE 10 1 14 7 9 EN 6 RTL ERR 4 12 CANL STB 5 AMIS−41682 11 CANH RxD 3 TxD 2 8 RTH 13 GND 100 kohm 100 kohm +5V 10 kohm MP1 33 kohm 10 kohm 10 kohm 10 nF 10 nF 33 kohm 10 kohm +5V 10 nF 10 kohm +12V Tx_2 100 kohm MP2 Figure 2. Measurement Set−Up Measurements Results Propagation delay (see data sheet) L −> H and H −> L for different bus configurations. Tbit = 8 ms Tamb = 25°C Table 1. MEASURED PROPAGATION DELAYS Symbol Parameter Value Comment C1 = C2 = 270 pF L = 0m 1.041 ms See Figure 3 Propagation delay Tx_1 to Rx_1 low C1 = C2 = 270 pF L = 0m 1.107 ms See Figure 4 tPD(H) Propagation delay Tx_1 to Rx_2 high C1 = C2 = 270 pF L = 0m 1.051 ms See Figure 5 tPD(L) Propagation delay Tx_1 to Rx_2 low C1 = C2 = 270 pF L = 0m 1.110 ms See Figure 6 tPD(H) Propagation delay Tx_1 to Rx_1 high C1 = C2 = 270 pF L = 20m 1.536 ms See Figure 7 tPD(L) Propagation delay Tx_1 to Rx_1 low C1 = C2 = 270 pF L = 20m 1.176 ms See Figure 8 tPD(H) Propagation delay Tx_1 to Rx_2 high C1 = C2 = 270 pF L = 20m 1.555 ms See Figure 9 tPD(L) Propagation delay Tx_1 to Rx_2 low C1 = C2 = 270 pF L = 20m 1.244 ms See Figure 10 tPD(H) Propagation delay Tx_1 to Rx_1 high tPD(L) Condition http://onsemi.com 2 AND8365/D Measurements Cable Length 0m Figure 3. Propagation Delay tPD(H) Between Tx_1 and Rx_1 at 125kB and Cable Length 0m = 1.041 ms Figure 4. Propagation Delay tPD(L) Between Tx_1 and Rx_1 at 125kB and Cable Length 0m = 1.107 ms http://onsemi.com 3 AND8365/D Figure 5. Propagation Delay tPD(H) Between Tx_1 and Rx_2 at 125kB and Cable Length 0m = 1.051 ms Figure 6. Propagation Delay tPD(L) Between Tx_1 and Rx_2 at 125kB and Cable Length 0m = 1.110 ms http://onsemi.com 4 AND8365/D Measurements Cable Length 20m Figure 7. Propagation Delay tPD(H) Between Tx_1 and Rx_1 at 125kB and Cable Length 20m = 1.536 ms Figure 8. Propagation Delay tPD(L) Between Tx_1 and Rx_1 at 125kB and Cable Length 20m = 1.176 ms http://onsemi.com 5 AND8365/D Figure 9. Propagation Delay tPD(H) Between Tx_1 and Rx_2 at 125kB and Cable Length 20m = 1.555 ms Figure 10. Propagation Delay tPD(L) Between Tx_1 and Rx_2 at 125kB and Cable Length 20m = 1.244 ms Company or Product Inquires For more information about ON Semiconductor’s CAN/LIN transceivers, send an email to http://www.onsemi.com/sales. 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