Application Note EVB90609L-xx Mixed mode small gyroscope PCB Scope This application note describes the schematic, the layout and the use of the series of small breakout boards for MLX90609 angular rate sensor. It is fully applicable to EVB90609L-N2, EVB90609L-E2 and EVB90609L-R2 boards and can be used as reference for populating the EVB90609L board. General Description Figure 1. Top view of EVB90609L board. EVB90609L-xx PCB is a small board, which uses the MLX90609 chip in a typical configuration. It can be directly connected to customer’s system to ease the development process. The EVB90609L-xx boards provide the possibility to work both in analogue and in digital mode. Both modes are available on different connector pins of the board. Next to the MLX90609 chip the board includes several passive components which are recommended according to the typical schematic. The board communicates with outside world through edge-type 14 pin connector. Pin names, numbers and functions are explained in table 1. Detailed Description Variants There are 4 variants of the EVB90609L-xx board, which differs only in MLX90609 chip type used (see Table 2). Table 2. Board variants Board Order option “xx” Chip type Note EVB90609L No Clear board EVB90609L N2 MLX90609N2 75 deg/s full range EVB90609L E2 MLX90609E2 150 deg/s full range EVB90609L R3 MLX90609R2 300 deg/s full range For more information about the MLX90609 chip and its operation, check the MLX90609 datasheets at www.melexis.com. ATTENTION: Breakout boards shipped before 2008 do not have the analog output available at the edge connector. You are NOT concerned if: • You intend to only use the digital SPI output. • The carry boxes do have an additional sticker on the top “For the latest documentation check out our website www.melexis.com” • The OUTAR edge connector pin is sensitive to angular rate applied for instance by hand. In all other cases, contact the Melexis representative, distributor or local sales engineer. A rework instruction can also be found at the end of this document. 3901190609A Rev 002 Page 1 of 4 Jan-08 Application Note EVB90609L-xx Mixed mode small gyroscope PCB Pinout Table 1. Pin out of the edge connector Pin Number Pin Name Pin Function 1 VCC Power pin +5V 2 VCC Power pin +5V 3 VREF Internal reference voltage 4 SCLK Cock for SPI 5 OUTAR Angular rate output voltage 6 -SS Slave select for SPI (negative logic) 7 OUTTMP Temperature output voltage 8 MISO Master-input-slave-output signal for SPI 9 SLFT1 Self test selection pin 1 10 MOSI Master-output-slave-input-signal for SPI 11 SLFT2 Self test selection pin 2 12 ERROR Gyro internal error signalization 13 GND Ground pin 14 GND Ground pin Dimensions A top view of EVB90609L-xx boards is represented in Figure 1. The dimensions of the boards are: 28 mm (length) x 18 mm (height) x 3.5 mm (thickness). Schematics Electrical schematic of the EVB90609L-xx board is presented at Figure 2 as it is based on the typical schematic from MLX90609 datasheet. The value of the capacitor C3 defines the output bandwidth of gyro. The –3dB bandwidth set by C3 is: fOUT =0.16 /(ROUT*C3), with ROUT = 200kΩ (typ.) For instance, with C3=82nF the bandwidth is 50Hz. VCC C1 100n R1 10k SLFT1 SLFT2 R2 10k 1 3 5 7 9 11 13 2 4 6 8 10 12 14 SCLK -SS MISO MOSI ERROR EDGIDC14 NC5 CASE SCLK VDDA SS VSSA MISO VREF U1 MOSI MLX90609BA OUTAR TEST FLT ERROR OUTTEMP SELFTEST HVIN 28 27 26 25 24 23 22 21 NC13 NC14 NC15 NC16 NC17 NC18 NC19 NC20 ERROR VREF OUTAR OUTTMP SLFT1 SLFT2 C2 100n VREF C3 82n C5 100n R3 0 OUTAR OUTTMP 13 14 15 16 17 18 19 20 5 6 7 8 9 10 11 12 VDD GND NC2 TOPCAP4 TOPCAP5 NC31 TESTOUT TESTIN 4 3 2 1 32 31 30 29 VCC SCLK -SS MISO MOSI VCC J1 Figure 2. Electrical schematic of the MLX90609 boards. 3901190609A Rev 002 Page 2 of 4 Jan-08 Application Note EVB90609L-xx Mixed mode small gyroscope PCB Component placement and PCB Layout Component placement at the board is presented at Figure 3. Figure 3. Component placement. The layouts of the top and bottom side of the board are presented at Figure 4. Figure 4. Board top (blue) and bottom (red) side layout. 3901190609A Rev 002 Page 3 of 4 Jan-08 Application Note EVB90609L-xx Mixed mode small gyroscope PCB Rework Instructions Do you need to rework? Rework instructions for breakout boards shipped before March 2008, which do not have the analog output available at the edge connector. You are NOT concerned if: • You intend to only use the digital SPI output. • The carry boxes do have a sticker on the top: • The OUTAR edge connector pin is sensitive to angular rate applied for instance by hand. In all other cases, contact the Melexis representative, distributor or local sales engineer or follow the following rework instruction. How to rework? An error had been detected on the first boards. The analog output was not routed correctly to the output pin of the breakout board It is however quite easy to modify those boards. The necessary modification is shown at Figure 5. The green square indicates and addition of a zero Ohm resistor (short circuiting, R3 in Figure 2 and 3). Figure 5. The modification of the PCB Revision history Rev.001 from July 2007. Initial release. Rev.002 from January 2008. Figure 2 was corrected. The output signal “OUTAR” which had been erroneously connected to pin 23 “FLT” of U1 was reconnected to pin 24 “OUTAR” of U1 trough jumper R3, which replaced capacitor C4. Figure 3 and Figure 4 were corrected too to reflect changes of the schematic. Text at page 2 was corrected. The paragraph “Rework Instructions” which contains explanations how customers themselves can modify boards was added. 3901190609A Rev 002 Page 4 of 4 Jan-08