Overview
The DDC118IRTCR, produced by Texas Instruments, is a 20-bit, octal channel, current-input analog-to-digital (A/D) converter. This device is designed to combine both current-to-voltage and A/D conversion, allowing it to directly connect to and digitize low-level current output devices such as photodiodes. The DDC118IRTCR features a dual-switched integrator front-end for each of the eight inputs, enabling continuous current integration. This design ensures that while one integrator is being digitized by the onboard A/D converter, the other is integrating the input current, thus providing uninterrupted data acquisition.
Key Specifications
| Parameter | Min | Typ | Max | Units |
|---|---|---|---|---|
| Analog Input Range | 12 | - | 350 | pC |
| Integration Time (TINT) | 50µs | - | 1s | µs |
| Data Rate | 2.5 | - | 3.125 | kSPS |
| Resolution | 16/20 | - | - | Bits |
| Input Bias Current | 0.1 | - | 10 | pA |
| Analog Power-Supply Voltage (AVDD) | 4.75 | - | 5.25 | V |
| Digital Power-Supply Voltage (DVDD) | 2.7 | - | 5.25 | V |
| Total Power Dissipation per Channel | 13.5 | - | 18 | mW |
| Operating Temperature Range | -40°C | - | +85°C | °C |
Key Features
- Dual-Switched Integrator Front-End: Allows for continuous current integration, ensuring that while one integrator is being digitized, the other is integrating the input current.
- Adjustable Full-Scale Ranges: From 12pC to 350pC, enabling the measurement of currents from femtoamperes to microamperes with high precision.
- Low-Power and High-Speed Modes: Low-Power mode with 13.5mW per channel and High-Speed mode with 18mW per channel, supporting data rates up to 3.125kSPS.
- Serial Interface: Designed for daisy-chaining in multi-device systems, minimizing digital overhead.
- High Accuracy and Linearity: Integral linearity error of ±0.5ppm of the full-scale range and noise of 5.2ppm of the full-scale range.
- Test Mode: Allows for measuring zero input signals and applying packets of charge to the integrators for diagnostic tests.
Applications
- CT Scanners and Data Acquisition Systems (DAS): Suitable for medical imaging and data acquisition applications requiring high precision and low noise.
- Photodiode Sensors: Directly connects to photodiodes for precise current measurement.
- Infrared Pyrometers: Used in temperature measurement applications where high accuracy is crucial.
- Liquid/Gas Chromatography: Ideal for analytical instruments requiring precise measurement of low-level currents.
Q & A
- What is the resolution of the DDC118IRTCR?
The DDC118IRTCR has a resolution of 16 or 20 bits, depending on the FORMAT pin setting.
- What are the adjustable full-scale ranges of the DDC118IRTCR?
The full-scale ranges are adjustable from 12pC to 350pC.
- What are the power consumption modes of the DDC118IRTCR?
The device operates in Low-Power mode (13.5mW per channel) and High-Speed mode (18mW per channel).
- How does the serial interface of the DDC118IRTCR work?
The serial interface is designed for daisy-chaining in multi-device systems, using differential data clocks and serial data output/input pins.
- What is the operating temperature range of the DDC118IRTCR?
The operating temperature range is from -40°C to +85°C.
- Can the DDC118IRTCR be used in test mode?
Yes, the DDC118IRTCR has a test mode that allows for measuring zero input signals and applying packets of charge to the integrators.
- How many input channels does the DDC118IRTCR have?
The DDC118IRTCR has eight identical input channels.
- What is the typical noise performance of the DDC118IRTCR?
The noise is typically 5.2ppm of the full-scale range.
- What is the integral linearity error of the DDC118IRTCR?
The integral linearity error is ±0.5ppm of the full-scale range.
- Can the DDC118IRTCR be used with photodiode sensors?
Yes, the DDC118IRTCR is designed to directly connect to photodiode sensors for precise current measurement.
