SN65HVS885EVM

User's Guide SLAU275 – January 2009 SN65HVS885EVM The SN65HVS885EVM evaluation module (EVM) supports the rapid, parametric evaluation of the SN65HVS885 digital input serializer. It is intended to be used in conjunction with the SN65HVS885 data sheet, (SLASxxx). Note this EVM is not intended for electromagnetic compatibility (EMC) tests. 1 EVM Schematic and Layout Figure 1 shows the board circuit schematic and Figure 2 shows the board layout top view. The board includes a terminal block, TB1, and three connectors, JMP1 to 3. TB1 receives the board supply of 5 V nominal. VCC supplies the SN65HVS885 device and VIN provides the supply for sensor switches. Upon the application of VCC the red VCC LED indicates 5V availability to the device. JMP1 provides the field inputs IN0:IN7 for field voltages of 24 V nominal. They can be applied via: a. an external supply in series to a sensor switch connected to a field input, b. or a sensor switch connected between and input and VIN, c. or a direct connection between an input and VIN. In all three cases, a 24-V level represents the ON-status of a sensor switch, which is indicated by the corresponding LEDs D0:D7. JMP2 provides access to the control and data lines of the internal serializer. To operate the serializer CE must be connected either to ground or to CLK. Upon an active-low load pulse, (a high-to-low-to-high transition) at LD, the status information of the field inputs is latched into the serializer. Applying eight consecutive clock cycles at CLK, shifts out the serializer data at SOP with each rising edge of the clock. Cascading of multiple boards is also possible by connecting the SOP output of a leading device with the SIP input of a following device. JMP3 allows the selection of three different debounce times and 3 different current limits. Debounce default is 3-ms and does not require any connection between the DB inputs to ground. Otherwise for zero debounce time connect DB1 to ground, and for 1-ms debounce time connect DB0 to ground. Note, that open DB inputs are internally pulled high and will not float. Setting a specific current limit requires a connection between the RLIM output and one of the resistors, RLIM 1:3. For a current limit of 3.6 mA connect RLIM to R8, for 3 mA to R9, and for 2.5 mA to R10. For detailed information on device functionality and system design recommendations refer to the SN65HVS885 datasheet. SLAU275 – January 2009 Submit Documentation Feedback SN65HVS885EVM 1 EVM Schematic and Layout www.ti.com JMP1 R 0:7 1.2kΩ IN0 IN1 5 IN2 7 IN3 9 IN4 11 IN5 18 IN6 20 IN7 22 IP0 RE0 IP1 RE1 IP2 RE2 IP3 RE3 IP4 RE4 IP5 RE5 IP6 RE6 IP7 RE7 VIN 2.2uF 22nF GND 2.2uF 28 15 VCC 1 2 R8: 24.9kΩ R LIM 1:3 4 6 8 10 12 17 19 21 JMP2 27 SIP JMP4 TB1 D 0:7 (3mA) SN65HVS885 3 13 PAD LD GND CLK VCC CE DB0 SOP DB1 HOT RLIM VCC SIP 26 25 LD 24 CLK 23 CE 16 SOP 15 HOT R9: 30.0kΩ VCC 1.33k R10: 35.7kΩ 2.55k HOT VCC JMP3 Figure 1. SN65HVS885EVM Schematic JMP1 RIN 0:7 JMP3 LED 0:7 IN0 DB0 GND IN1 DB1 GND VIN IN3 SN65HVS885 IN4 R8 RLIM 1:3 IN2 R9 R10 IN5 IN6 SN65HVS885 EVM 6506253 IN7 VCC RLIM 1:3 GND HOT VIN JMP2 SIP LD CLK CE SOP HOT VCC VCC GND TB1 Figure 2. SN65HVS885EVM Layout 2 SN65HVS885EVM SLAU275 – January 2009 Submit Documentation Feedback IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment. TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where mandated by government requirements, testing of all parameters of each product is not necessarily performed. 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