DC2135A Analog Devices

DEMO MANUAL DC2135A LTC2378-20 2ppm Linearity, DC Accurate Driver Description Demonstration circuit 2135A shows a simple DC accurate used with either the DC890 or DC590 USB controllers. ADC driver circuit that converts a 10V single-ended input Use the DC890 if precise sampling rates are required or to signal into a fully differential signal capable of driving the demonstrate AC performance such as SNR, THD, SINAD LTC2378-20 with a combined linearity error of only 2ppm. and SFDR. Use the DC590 to look at DC performance or The LTC2378-20 is a low power, low noise 20-bit SAR to generate histograms showing peak-to-peak noise. The ADC with a serial output that operates from a single 2.5V demonstration circuit 2135A also is intended to show supply. The following text refers to the LTC2378-20 but recommended grounding, component placement and applies to all parts in the family, the only difference being selection, routing and bypassing for this ADC. the maximum sample rate. The LTC2378-20 supports a 5V Design files for this circuit board are available at fully differential input range with a 104dB SNR, consumes DEMO MANUAL DC2135A Dc 890 Quick s p D Check to make sure that all switches and jumpers are set Run the PScope software (PScope.exe version K75 or as shown in the connection diagram of Figure 1. In par- later) which can be downloaded from www.linear.com/ ticular make sure that VCCIO (JP3) is set to the 2.5V po- software. sition. Operating the DC2135A with the DC890 while JP3 Complete software documentation is available from the is in the 3.3V position will cause noticeable performance Help menu. Updates can be downloaded from the Tools degradation in SNR and THD. The default connections menu. Check for updates periodically as new features configure the ADC to use the onboard reference and reg- may be added. ulators to generate the required common mode voltages. The PScope software should recognize the DC2135A and The analog input is DC-coupled. Connect the DC2135A configure itself automatically. to a DC890 USB High Speed Data Collection Board using connector P1. Then, connect the DC890 to a host PC with Click the Collect button (See Figure 4) to begin acquiring a standard USB A/B cable. Apply 16V to the indicated data. The Collect button then changes to Pause, which terminals. Then apply a low jitter sine source to J4. For can be clicked to stop data acquisition. the maximum recommended sampling rate of 800ksps connect a low jitter 64MHz 2.5V sine wave or square P-P wave to connector J1. Note that J1 has a 50 termination resistor to ground. Dc 590 Quick s p D IMPORTANT To avoid damage to the DC2135A, make serial controller using the supplied 14-conductor ribbon sure that VCCIO (JP6) of the DC590 is set to 3.3V before cable. Apply the signal source to J4. connecting the DC590 to the DC2135A. Run the QuikEval software (version K101 or later) which VCCIO (JP3) of the DC2135A should be in the 3.3V position can be downloaded from www.linear.com/software. The for DC590 operation. To use the DC590 with the DC2135A, correct control panel will be loaded automatically. Click the it is necessary to apply 16V and ground to the appropriate COLLECT button (See Figure 5) to begin reading the ADC. terminals. Connect the DC590 to a host PC with a standard USB A/B cable. Connect the DC2135A to a DC590 USB a o Table 1. DC2135A Assembly Options Assembly Version U1 Part Number Max Conversion Rate Number of Bits Max CLK IN frequency DC2135A LTC2378CMS-20 800ksps 20 64MHz dc2135af 2 ptions ssembly ure roce tart ure roce tart