ALD500SWCL

Analog To Digital Converters (ADC) Overview

The ALD500SWCL is a precision integrating analog processor from Advanced Linear Devices, designed for high-resolution analog-to-digital conversion. It operates on ±5V power supplies and features a dual-slope architecture that provides inherent noise immunity and automatic offset compensation. The device accepts differential analog inputs with a wide bipolar range of ±3.5V and offers resolution up to 18 bits plus sign and over-range bits. Key electrical characteristics include a typical input current of 2pA, low linearity error of 0.002%, and power dissipation of 6mW. It is housed in a 16-pin Wide Body Plastic Small Outline Package (SOIC) and operates within a commercial temperature range of 0°C to +70°C.

Analog To Digital Converters (ADC) Feature Summary

• Dual-Slope Integration: Provides high noise immunity by averaging external noise spikes and rejecting line frequency interference through fixed integration periods.
• High Input Impedance: Features an input impedance of 10^12 Ω and low input current of 2pA typical, ensuring accuracy independent of source impedance.
• Automatic Calibration: Includes internal auto-zero and integrator zero phases to cancel offset voltages and minimize drift caused by component variations.
• Flexible Resolution: Supports resolutions up to 18 bits plus sign and over-range bits, with conversion speed trade-offs managed via digital controller clock rates.

Analog To Digital Converters (ADC) Applications

• 4 1/2 to 5 1/2 digits plus sign precision measurements
• Precision sensor interfaces requiring high accuracy DC measurement
• Portable battery-operated instruments due to low power consumption
• Computer peripherals and PCMCIA cards

Analog To Digital Converters (ADC) Procurement Notes

Verify the specific suffix 'SWCL' against manufacturer documentation to confirm package type and temperature grade. The standard datasheet lists the SWC variant as a 16-pin Wide Body SOIC with a 0°C to +70°C operating range. Confirm availability of industrial temperature options if required, as these may necessitate different ordering suffixes or direct factory contact.

Analog To Digital Converters (ADC) Selection Notes

Select the ALD500SWCL when designing systems requiring true differential inputs and high common-mode rejection (typically 95dB). Ensure the external integrating capacitor (CINT) has low dielectric absorption, such as polypropylene, to maintain linearity. Design the digital controller to manage the four-phase cycle (Auto Zero, Integrate, Deintegrate, Integrator Zero) using CMOS logic levels compatible with the A and B phase control inputs.

Analog To Digital Converters (ADC) Part Context

The ALD500 series comprises integrating analog processors available in AU, A, and base variants, corresponding to 18-bit, 17-bit, and 16-bit resolution capabilities respectively. The ALD500SWCL belongs to this family, utilizing the same core dual-slope architecture but packaged in a surface-mount Wide Body SOIC format suitable for commercial temperature applications.

Analog To Digital Converters (ADC) Replacement Considerations

Direct pin-compatible replacements are not explicitly listed in the provided documentation. When substituting, ensure the alternative device supports dual-slope integration, differential inputs, and similar supply voltage ranges (±5V). Verify that the replacement can interface with the required microcontroller logic for phase control and comparator output monitoring.

Analog To Digital Converters (ADC) FAQ

How does the ALD500 handle input signal polarity?

The device automatically detects input polarity during the Input Signal Integration Phase. The comparator output (COUT) goes HIGH for positive signals and LOW for negative signals, which the microcontroller reads to determine the sign bit of the conversion result.

What determines the resolution of the conversion?

Resolution is determined by the number of clock pulses counted during the fixed Input Signal Integration Phase. Higher resolution requires maximizing this count, typically by selecting appropriate clock frequencies and integration times.

Why is the Integrator Zero Phase necessary?

The Integrator Zero Phase ensures the integrator output returns to 0V before the next Auto Zero phase, preventing charge buildup from comparator delay overshoot. This minimizes errors in high-resolution applications where charge sharing could otherwise degrade performance.