High Temperature Behavior of ISL3158AE ® Application Note Description July 7, 2009 AN1474.0 At a Data Rate of 10Mbps: The ISL3158AE is a 5V based RS-485 MIL temp rated transceiver aimed at addressing applications that require high operating temperatures. The receiver inputs A and B are presented in pins 6 and 7; when RE# is low this differential input signal is processed and available at the RO pin. The Driver input is presented at pin 4 and the driver differential outputs Z and Y are available at pins 6 and 7 respectively when DE is high. This Application Note aims at characterizing the device at temperatures of +125°C through +200°C. Device Pinout ISL3158AE (8 LD SOIC) TOP VIEW RO 1 8 VCC RE 2 7 B/Z DE 3 6 A/Y 5 GND DI 4 R D 2. First pulse missing Threshold at a die temperature range of min. = +175°C and a max of +191°C At a Data Rate of 400kbps: 1. Pulse width 90% threshold at a die temp of min. = +190°C and max = +196°C while operating at a data rate of 10Mbps As can be seen, operation at a data rate of 10Mbps limits the device operation to +160°C or less and a data rate of 400kbps allows the device to operate at a temperature of about +190°C. See “Typical Performance Curves” on page 3. This is based on a sample size of 15pcs. and a six sigma distribution. TX High Temperature Test Figure 1 shows the evaluation board schematic. The device evaluation board is common to both TX and RX. The mode of operation is determined by the logic presented to the DE and RE# pins. The TX was tested using a the EVALB TX portion of Figure 2. The 200ft cable was disconnected and terminations of 100Ω and 54Ω were connected based on test requirement. The parameters tested were: Driver differential output voltage, propagation delay, and skew. The results are per the “Typical Performance Curves” on page 3. Supply Current vs High Temperature RX High Temperature Test Figure 2 shows the High temperature test setup. The board wired up as the transmitter is called the EVALB TX and the one wired the receiver is called the EVALB RX. The differential lines were hooked up through 200ft of twisted pair cable terminated on either side by 120Ω. The VIN was set to a worst case of 4.5V. The driver input of the EVALB TX is connected to a function generator capable of providing fast rise and fall times. The function generator output was set to provide a burst mode of five pulses at a bit rate of 10Mbps.The RX device was wired up with two thermocouples one placed on the device case top and the the other placed on the PWB near the GND pin. The RX device was heated using a temperature forcing system from +25°C to +200°C. The Rx shows two threshold points as follows: 1 1. Pulse width 70% threshold at a die temperature of min. = +160°C and max. = +175°C while operating at a data rate of 10Mbps The supply current is found to have a knee at around +195°C, and increases rapidly thereafter.The supply current with (driver enabled) DE high is typically around 650µA. This value increases to about 1085µA at +240°C. With DE connected to GND (driver disabled) the supply current drops to about 450µA typical. This value of supply current increases from a temperature of +200°C and higher to about 704.5µA. Driver input vs High Temperature The Driver input is found to latch to a 5V state at around +215°C. This causes the drive signal to ride on a 5V DC. The driver output is non-existent. Some device failures were observed when left in this state for prolonged period of time. See Figures 1 and 2. CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc. Copyright Intersil Americas Inc. 2009. All Rights Reserved All other trademarks mentioned are the property of their respective owners. Application Note 1474 VCC/3.3V/PIN8 C6 10u TP3/RO/PIN1 0 U1 TP4/RE#/PIN2 1 2 3 4 TP5/DE/PIN3 TP6/DI/PIN4 RO RE DE DI C2B 0.1u VCC TX-Z / RX-B TX-Y / RX-A GND 8 7 6 5 0 TP8/TX-Z/RX-B/PIN7 R10 120 TP7/TX-Y/RX-A/PIN6 ISL3178 GND/PIN5 R5 49.9 0 R6 49.9 0 R7 49.9 0 FIGURE 1. EVALUATION BOARD SCHEMATIC SCOPE1/CH3 SCOPE1/CH1 SCOPE1/CH4 SCOPE1/CH2 CABLE 200ft V2 4.5V V3 TP4/RE#/PIN2 TP5/DE/PIN3 VCC/3.3V/PIN8 0 4.5V RX 0 TP4/RE#/PIN2 TP8/TX-Z/RX-B/PIN7 TP5/DE/PIN3 VCC/3.3V/PIN8 TX TP7/TX-Y/RX-A/PIN6 TP6/DI/PIN4 EVALB V1 = 0 V2 = 3 TD = 0 TR = 1ns TF = 1ns PW = 100ns PER = 200ns TP3/RO/PIN1 SCOPE1/CHx GND/PIN5 TP3/RO/PIN1 TP7/TX-Y/RX-A/PIN6 GND/PIN5 TP6/DI/PIN4 TP8/TX-Z/RX-B/PIN7 EVALB V1 0 0 0 SCOPE1/CHx FIGURE 2. HIGH TEMPERATURE TEST SETUP 2 AN1474.0 July 7, 2009 Application Note 1474 Typical Performance Curves 3.9 3.7 RDIFF = 100Ω 3.5 3.3 3.1 RDIFF = 54Ω 2.9 2.7 -55 0 55 110 TEMPERATURE (°C) 2.5 220 165 DIFFERENTIAL OUTPUT VOLTAGE (V) FIGURE 4. DRIVER INPUT LATCHED TO 5V at +215°C TYP FIGURE 3. DRIVER INPUT NORMAL AT +25°C FIGURE 6. DRIVER DIFFERENTIAL OUTPUT VOLTAGE vs TEMPERATURE FIGURE 5. RO OUTPUT PW IS 70% AT +170.5°C TYP 1200 12 1100 1000 900 8 800 6 ICC DE-VCC 700 4 ICC (µA) DATA RATE IN Mbps 10 600 500 2 400 ICC DE-GND 0 155 160 165 170 175 180 TEMPERATURE (°C) 185 190 FIGURE 7. DATA RATE vs TEMPERATURE 3 195 -100 -50 0 50 100 150 200 TEMPERATURE (°C) 250 300 300 FIGURE 8. SUPPLY CURRENT vs TEMPERATURE AN1474.0 July 7, 2009 Application Note 1474 Typical Performance Curves (Continued) 1.0 31 tPHL 25 tPLH 23 21 19 -100 -50 0 50 100 150 TEMPERATURE (°C) 200 17 250 FIGURE 9. DRIVER DIFFERENTIAL PROPAGATION DELAY vs TEMPERATURE FIGURE 11. PULSE MISSING AT +185°C TYP AND 10Mbps 0.8 0.7 0.6 0.5 0.4 SKEW (ns) 27 0.9 PROPOGATION DELAY (ns) 29 0.3 SKEW 0.2 0.1 -100 -50 0 50 100 150 TEMPERATURE (°C) 200 0 250 FIGURE 10. DRIVER DIFFERENTIAL SKEW vs TEMPERATURE FIGURE 12. TX/RX WAVEFORM AT +194°C TYP AND 400kbps Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that the Application Note or Technical Brief is current before proceeding. For information regarding Intersil Corporation and its products, see www.intersil.com 4 AN1474.0 July 7, 2009