DEMO MANUAL DC2520A LTC2344 16-/18-Bit, Octal 400ksps, SAR ADC DESCRIPTION Demonstration circuit 2520A shows the proper way to drive demonstrate DC performance such as peak-to-peak noise the LTC 2344 ADC. The LTC2344 is a low noise, high speed, and DC linearity. Use the DC890 if precise sampling rates simultaneous sampling 16-/18-bit successive approximation are required or to demonstrate AC performance such as register (SAR) ADC. The LTC2344 has a flexible SoftSpan SNR, THD, SINAD and SFDR. The DC2520A is intended to interface that allows conversion-by-conversion control of demonstrate recommended grounding, component place- the input voltage span on a per-channel basis. An internal ment and selection, routing and bypassing for this ADC. A 2.048V reference and 2 buffer simplify basic operation suggested driver circuit for the analog inputs is also presented. while an external reference can be used to increase the input Design files for this circuit board including the schematic, range and the SNR of the ADC. layout and BOM are available at The DC2520A demonstrates the DC and AC performance of DEMO MANUAL DC2520A ASSEMBLY OPTIONS Assembly Max Conversion Number of Number of Max CLK IN CLK IN/fs Version U1 Part Number Rate Channels Bits Frequency Ratio DC2520A-A LTC2344-18 400ksps 4 18 68.8MHz 172 DC2520A-B LTC2344-16 400ksps 4 16 68.8MHz 172 DC890 QUICK START PROCEDURE Check to make sure that all jumpers are set to their default Run the PScope software (Pscope.exe version K86 or settings as described in the DC2520A Jumpers section of later) which can be downloaded from www.linear.com/ this manual. The default connections configure the ADC to designtools/software. use the onboard reference and regulators to generate all Complete software documentation is available from the the required bias voltages. The analog inputs by default are Help menu. Updates can be downloaded from the Tools DC coupled. Connect the DC2520A to a DC890 USB High menu. Check for updates periodically as new features Speed Data Collection Board using connector P1. Then, may be added. connect the DC890 to a host PC with a standard USB A/B The PScope software should recognize the DC2520A and cable. Apply 9V to the indicated terminals. Then apply configure itself automatically. a low jitter signal source to J5 and J6. Use J7 to route the signal sources of J5 and J6 to the desired AIN0-AIN3 Click the Collect button (See Figure 3) to begin acquiring inputs. Observe the recommended input voltage range data. The Collect button then changes to Pause, which for each analog input. Connect a low jitter 2.5V sine P-P can be clicked to stop data acquisition. wave or square wave to connector J1. See the Assembly Options table for the appropriate clock frequency. Note that J1 has a 50 termination resistor to ground. DC590/DC2026 QUICK START PROCEDURE IMPORTANT To avoid damage to the DC2520A, make and J6. Use J7 to route the signal sources of J5 and J6 sure that VCCIO (JP6 of the DC590, JP3 of the DC2026) to the desired AIN0-AIN3 inputs. No Clock is required on of the DC590/DC2026 is set to 3.3V before connecting J1 when using the DC590/DC2026. The clock signal is the DC590/DC2026 to the DC2520A. provided by the DC590/DC2026. To use the DC590/DC2026 with the DC2520A, it is necessary Run the QuikEval software (quikeval.exe version K110 or to apply 9V and ground to the 9V and GND terminals of later) which is available from www.linear.com/designtools/ the DC2520A. Connect the DC590/DC2026 to a host PC software. The correct control panel will be loaded auto- with a standard USB A/B cable. Connect the DC2520A to matically. Click the COLLECT button (Figure 6) to begin a DC590/DC2026 USB serial controller using the supplied reading the ADC. 14-conductor ribbon cable. Apply a signal source to J5 dc2520af 2