QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1492 16 BIT, DIFFERENTIAL, DELTA SIGMA ADC WITH SPI INTERFACE LTC2462 DESCRIPTION Demonstration circuit 1492 features the LTC2462, a 16 bit high performance analogto-digital converter (ADC) with an SPI interface. The input is bipolar with a range of REF/2. The modulator's proprietary sampling technique reduces the average input current to less than 50nA - orders of magnitude lower than typical delta sigma ADCs. the DC590 USB Serial Controller board and supplied software to measure performance. The exposed ground planes allow proper grounding to prototype circuitry. After evaluating with Linear Technology's software, the digital signals can be connected to the end application's processor / controller for development of the serial interface. DC1492 is a member of Linear Technology`s QuickEvalTM family of demonstration boards. It is designed to allow easy evaluation of the LTC2462 and may be connected directly to the target application's analog signals while using Design files for this circuit board are available. Call the LTC factory. LTC is a trademark of Linear Technology Corporation Figure 1. Proper Measurement Equipment Setup Ribbon cable To DC590 Controller Bipolar Input 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1492 16 BIT, DIFFERENTIAL, DELTA SIGMA ADC WITH SPI INTERFACE QUICK START PROCEDURE Connect DC1492 to a DC590 USB Serial Controller using the supplied 14 conductor ribbon cable. Connect DC590 to host PC with a standard USB A/B cable. Run the evaluation software supplied with DC590 or downloaded from http://www.linear.com/software. The correct program will be loaded automatically. Click the COLLECT button to start reading the input volt- age. Details on software features are documented in the control panel's help menu. Tools are available for logging data, changing reference voltage, changing the number of points in the strip chart and histogram, and changing the number of points averaged for the DVM display. Figure 2. Software Screenshot 2 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1492 16 BIT, DIFFERENTIAL, DELTA SIGMA ADC WITH SPI INTERFACE HARDWARE SET-UP CONNECTION CONTROLLER TO DC590 SERIAL J1 is the power and digital interface connector. Connect to DC590 serial controller with supplied 14 conductor ribbon cable. GND - This turret is connected directly to the internal ground planes. VCC - This is the supply and reference voltage for the ADC. Do not draw any power from this point. ANALOG CONNECTIONS IN+ - This is the positive input to the ADC Analog signal connections are made via the row of turret posts along the edge of the board. Also, when connecting the board to an existing circuit the exposed ground planes along the edges of the board may be used to form a solid connection between grounds. IN- - This is the negative input to the ADC. Refout - This turret is used as the reference voltage for the LTC2462. 3 GND VCC IN- IN+ E4 E3 E5 E1 VCC 1K R5 1K R1 0.1uF 0.1uF 0.1uF C8 C7 C2 0.1uF C3 10 9 0.1uF IN- IN+ VCC 12 E2 1 RE FO UT 2 CO MP G ND G ND G ND 13 11 7 VCC RE F8 REFOUT 3 U1 LTC2462CDD R3 4.99K 1% R2 4.99K 1% 10uF 0.1uF SCK 5 4 SDI 6 SDO CS C6 C4 1 2 3 7 6 A0 A1 A2 WP SCL CS SCK SDI SD0 8 V CC G ND 4 U2 24LC025-I/ST SDA 5 1% R4 4.99K 0.1uF C5 VCC 14 12 9 10 11 5 7 4 6 2 1 NC EEGND EESDA EEVCC EESCL MISO MOSI/SDA SCK/SCL CS 5V VUNREG J1 GND GND GND 3 8 13 C1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1492 16 BIT, DIFFERENTIAL, DELTA SIGMA ADC WITH SPI INTERFACE 4