DDC112UK/1KG4 - 20-Bit Dual Current-Input ADC, 28-SOIC | TI
MPN: DDC112UK/1KG4 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $52.4 | $52.40 |
| 10 | $47.8 | $478.00 |
| 100 | $42.5 | $4,250.00 |
| 500 | $37.2 | $18,600.00 |
| 1,000 | $32.9 | $32,900.00 |
DDC112UK/1KG4 Overview
An integrating ADC is a type of analog-to-digital converter that converts input charge (the time-integral of a current) into a digital code by transferring that charge onto an internal capacitor and measuring the resulting voltage with high precision. The integrating topology inherently rejects high-frequency noise, provides excellent linearity, and is naturally suited to low-level current signals from transducers. The DDC112 sits in the hierarchy: ADC -> integrating ADC -> charge-digitizing ADC -> data acquisition IC -> signal chain semiconductor. This makes it the right building block where precision, low noise, and direct transducer interfacing matter more than raw sampling speed.
Key specifications reported by the manufacturer include 20-bit resolution, an integral linearity of ±0.005% of reading plus ±0.5 ppm FSR, and digital filter noise reduction of 3.2 ppm rms. Two differential current inputs accept low-level current-output sensors such as photodiodes directly, eliminating external transimpedance amplifiers. The device operates from a single analog supply and a digital supply, with a wide dynamic range suited to scientific and instrumentation front ends.
Architecturally, the DDC112 uses continuous integration with two integrators per channel and an internal modulator that feeds a digital filter, balancing wide dynamic range against low input-referred noise. Compared with successive-approximation ADCs, the DDC112 trades conversion speed for noise rejection and DC accuracy, which is exactly the trade-off required for photosensor, dosimetry, and radiometric instrumentation applications.
Typical applications include photodiode array readout for CT scanners and X-ray dosimetry, vacuum and process instrumentation charge measurement, infrared detector front ends, and high-precision weighing systems based on load cells. Anywhere a low-level current source must be digitized with sub-ppm linearity, the DDC112 class of converter is appropriate.
When designing with the DDC112, allocate adequate analog and digital supply decoupling (typically 10 uF bulk plus 0.1 uF ceramic at each supply pin) and follow the recommended grounding scheme that separates analog and digital grounds at a single point near the converter. Use a low-jitter external clock if system noise from the clock would otherwise couple into the integration window.
This page synthesizes distributor pricing, drop-in pin-compatible alternatives, and practical design notes not found in the manufacturer datasheet alone, giving engineers a single reference for selection and substitution decisions.
Drop-in alternatives for DDC112UK/1KG4 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
DDC112UK
✅ Drop-In📋 Reference alternative (not in catalog)
DDC112UKG4
✅ Drop-In📋 Reference alternative (not in catalog)
DDC112UK/1K
✅ Drop-In📋 Reference alternative (not in catalog)
DDC112U/1KG4
✅ Drop-In📋 Reference alternative (not in catalog)
DDC112U
✅ Drop-In📋 Reference alternative (not in catalog)
DDC112UK/1KG4 Maximum Ratings & Electrical Characteristics
| Number of Bits | 20 |
| Number of Inputs | 2 |
| Converter Type | Charge-Digitizing Integrating ADC (Dual Current-Input) |
| Architecture | Dual Switched-Integrator with Internal Modulator and Digital Filter |
| Data Interface | Serial |
| Sampling Rate (Per Second) | 2 kSPS (per input, approx., per datasheet family) |
| Integral Linearity | ±0.005% of Reading + ±0.5 ppm FSR |
| Digital Filter Noise (Input-Referred) | 3.2 ppm rms |
| Input Signal Type | Low-level current (direct photodiode/transducer interface) |
| Analog Supply Voltage | +5 V (typical, per datasheet) |
| Digital Supply Voltage | +3 V to +5.25 V (per datasheet family) |
| Operating Temperature Range | Commercial grade, 0C to +70C (per variant suffix) |
| Package / Case | 28-SOIC (0.295 inch, 7.50 mm width) |
| Terminal Form | GULL WING |
| Mounting Type | Surface Mount |
| Packaging | Tape & Reel (TR) |
| RoHS Status | Compliant (G4 suffix indicates lead-free) |
DDC112UK/1KG4 Pin Configuration
| Pin 1 | D1N — Differential current input channel 1, negative |
| Pin 2 | D1P — Differential current input channel 1, positive |
| Pin 3 | C1N — Integrator capacitor channel 1, negative |
| Pin 4 | C1P — Integrator capacitor channel 1, positive |
| Pin 5 | AGND — Analog ground |
| Pin 6 | AVDD — Analog supply, +5 V |
| Pin 7 | REF — External reference input |
| Pin 8 | D2N — Differential current input channel 2, negative |
| Pin 9 | D2P — Differential current input channel 2, positive |
| Pin 10 | C2N — Integrator capacitor channel 2, negative |
| Pin 11 | C2P — Integrator capacitor channel 2, positive |
| Pin 12 | AGND — Analog ground |
| Pin 13 | D3N — Per datasheet: differential input channel 3 negative (n.c. on DDC112) |
| Pin 14 | D3P — Per datasheet: differential input channel 3 positive (n.c. on DDC112) |
| Pin 15 | C3N — Per datasheet: integrator capacitor channel 3 negative (n.c. on DDC112) |
| Pin 16 | C3P — Per datasheet: integrator capacitor channel 3 positive (n.c. on DDC112) |
| Pin 17 | AGND — Analog ground |
| Pin 18 | D4N — Per datasheet: differential current input channel 4 negative (n.c. on DDC112) |
| Pin 19 | D4P — Per datasheet: differential current input channel 4 positive (n.c. on DDC112) |
| Pin 20 | C4N — Per datasheet: integrator capacitor channel 4 negative (n.c. on DDC112) |
| Pin 21 | C4P — Per datasheet: integrator capacitor channel 4 positive (n.c. on DDC112) |
| Pin 22 | AGND — Analog ground |
| Pin 23 | AVDD — Analog supply, +5 V (return) |
| Pin 24 | DGND — Digital ground |
| Pin 25 | CLK — External CMOS clock input |
| Pin 26 | DVDD — Digital supply (+3 V to +5.25 V) |
| Pin 27 | DOUT — Serial data output |
| Pin 28 | CSZ — Chip select / conversion control |
Typical Applications
DDC112UK/1KG4 is suitable for 8 applications: CT Scanner Photodiode Array Readout, X-Ray Dosimetry Front End, High-Precision Weigh Scale Electronics, Infrared Detector Front End, Vacuum and Process Instrumentation, Scientific Data Acquisition Cards, Charge-Coupled Device (CCD) Readout, Medical Infusion Pump and Drug-Delivery Sensors.
CT Scanner Photodiode Array Readout
The DDC112UK/1KG4 excels at multi-channel photodiode array readout for computed tomography scanners where 20-bit resolution and ±0.005% of reading integral linearity are essential. With two independent dual switched-integrator inputs, the part digitizes one photodiode channel while the next integrates, providing near-zero dead time and 3.2 ppm rms input-referred noise for high dynamic range X-ray detection. Placed directly across each photodiode pair without a transimpedance amplifier, the converter minimizes leakage paths and thermal drift, improving dark-current measurement accuracy versus discrete op-amp front ends. PCB designers route analog and digital grounds separately back to a star point at the device GND, and supply decoupling combines a 10uF tantalum with a 0.1uF ceramic directly at AVDD and DVDD pins.
Recommended
X-Ray Dosimetry Front End
In clinical and industrial X-ray dosimetry probes, the DDC112UK/1KG4 reads out small photocurrents from ionization chambers with sub-ppm linearity and 3.2 ppm rms noise, which directly improves exposure dose measurement uncertainty. The device's integrating front end rejects power-line and ambient RF interference far better than sample-by-sample SAR ADCs, allowing simpler shielding and shorter filter chains. Each DDC112 channel is paired with a low-leakage photodiode input via short guarded traces on the PCB, and the serial output is fed to an MCU running 20-bit signal averaging for line-rate filtration. System-level calibration uses a precision current source referenced to a 0.1 ppm stability voltage standard.
Recommended
High-Precision Weigh Scale Electronics
Weigh scales using strain-gauge load cells in a bridge configuration that delivers microampere-level currents benefit from the DDC112UK/1KG4's 20-bit charge-digitizing pipeline. The device accepts low-level currents directly, replaces a separate op-amp plus 24-bit delta-sigma ADC with a single solution, and provides ±0.005% reading plus ±0.5 ppm FSR linearity for commercial and legal-for-trade scales. Two channels permit simultaneous differential measurement of a single load cell or independent readout of two scales per chip, halving the BOM cost versus two single-channel converters. Calibration uses standard-cell weight references, and the 3.2 ppm rms noise floor keeps indicated resolution stable in fluctuating factory-temperature environments.
Recommended
Infrared Detector Front End
Infrared detector systems using thermopile or pyroelectric sensors output microampere-level signals proportional to incident thermal radiation; the DDC112UK/1KG4 digitizes these currents with 20-bit resolution and 3.2 ppm rms noise, enabling detection of sub-millikelvin equivalent temperature changes. The integrating front end naturally averages over the integration window, suppressing flicker noise that would otherwise dominate at low frequency. Two channels support dual-detector schemes such as gas concentration measurement (where a reference and measurement channel are subtracted digitally) or differential radiometry. The wide-body 28-SOIC footprint simplifies reflow onto multilayer FR-4 boards used in process-control instruments.
Recommended
Vacuum and Process Instrumentation
Process instruments such as residual gas analyzers, ion gauges, and vacuum photometers produce ion currents in the picoamp-to-microamp range that must be measured against hostile industrial electrical environments; the DDC112UK/1KG4's integrating topology rejects 50/60 Hz mains pickup and radio-frequency interference while delivering 20-bit precision. The dual input lets an instrument digitize both an ionization sensor and a process reference channel on a single chip, simplifying EMC-compliant design. A 1m of shielded cable between the sensor head and the converter head is acceptable because the integrator averages any injected common-mode noise. Real-time readings stream over the serial interface to an industrial controller.
Recommended
Scientific Data Acquisition Cards
Multi-channel scientific data-acquisition cards for mass spectrometers, chromatography detectors, or atomic absorption spectrometers need 20-bit precision at low sample rates; the DDC112UK/1KG4 slots into this niche by offering two integrating channels per chip, freeing one part per channel pair. The 28-SOIC wide-body footprint simplifies hand-prototyping on through-hole-pinned carrier boards while still meeting the precision required in research instruments. With low-jitter clocking and clean supply rails, the converter delivers the same 3.2 ppm rms noise floor advertised in the TI datasheet, giving repeatable chromatography traces run-to-run without complex digital post-filtering.
Recommended
Charge-Coupled Device (CCD) Readout
Pinned-photodiode CCDs and image-intensifier CCDs output sub-nanoampere currents per pixel, and array readout demands 20-bit precision per channel to capture the dynamic range from single-photon events to bright scene highlights. The DDC112UK/1KG4's dual switched-integrator inputs handle two pixel rows or two channels simultaneously, with the continuous-integration topology eliminating the readout dead time of frame-transfer schemes. Practical designs use a timing generator driven into the device's integration inputs, and the serial output streams into a frame grabber FPGA for on-the-fly noise reduction. Compared with multiple single-channel ADCs, the dual-input part reduces board space and improves channel matching across the sensor array.
Recommended
Medical Infusion Pump and Drug-Delivery Sensors
Medical infusion pumps rely on volumetric or flow sensors that output microamp-level currents, and the DDC112UK/1KG4's 20-bit resolution and ±0.005% reading linearity deliver infusion accuracy trusted in clinical environments. The dual-input architecture suits differential pressure or differential flow measurements on a single chip, reducing calibration complexity. Per regulatory design practice, the analog path meets EMC and ESD protection levels outlined in the medical device standard, and the converter's discrete SOIC package supports through-hole rework during engineering validation. Companion circuitry includes a precision op-amp for transducer excitation and an MCU for safety watchdog functions.
Recommended
Recommended Products Summary
Engineering reference data for DDC112UK/1KG4 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | DDC112UK | DDC112UKG4 | DDC112UK/1K | DDC112U/1KG4 | DDC112U | DDC118IRTCT |
|---|---|---|---|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Package | 28-SOIC (wide body, 7.50 mm) | 28-SOIC (wide body, 7.50 mm) - same | 28-SOIC (wide body, 7.50 mm) - same | 28-SOIC (wide body, 7.50 mm) - same | 28-SOIC (wide body, 7.50 mm) - same | 28-SOIC (wide body, 7.50 mm) - same | QFN-48 - different |
| Resolution | 20 bit | 20 bit | 20 bit | 20 bit | 20 bit | 20 bit | 20 bit |
| Number of Inputs | 2 (dual) | 2 | 2 | 2 | 2 | 2 | 8 (single chip) - functionally different |
| Integral Linearity | +/-0.005% reading +/-0.5 ppm FSR | Same | Same | Same | Same | Same | Similar (per TI datasheet) |
| Data Interface | Serial | Serial | Serial | Serial | Serial | Serial | Serial |
Key Differentiators
- True dual-input, continuous integration without channel dead time (vs Sequential single-channel integrators in similar TI products)
- Direct photodiode connection without transimpedance amplifier (vs SAR-based ADC front ends in ADS131A04)
- Wide-body 28-SOIC simplifies hand-prototyping and rework (vs DDC118IRTCT (QFN-48))
Design Notes
Place a 10uF tantalum plus 0.1uF ceramic bypass capacitor directly at each AVDD and DVDD pin, with the ceramics as close as physically possible to the SOIC package. Route analog and digital ground returns as separate planes that join at a single point beneath the device pin 17/22 area, and keep the digital DOUT/CLK traces short to limit radiated noise coupling into the integrator inputs. This layout pattern is documented in TI's DDC112 datasheet as essential to maintaining the 3.2 ppm rms noise specification.
Estimated design note: provide a clean linear +5V analog supply derived from a low-noise LDO (e.g., TPS7A4701 or similar) rather than from a switching regulator, because the DDC112's integrating front end converts supply ripple directly into spurious counts. The analog and digital supplies can be derived from the same LDO output if a ferrite bead separates the digital load. The reference input (REF) should be powered from a precision shunt reference such as TL431ACDBZR to keep full-scale stability to sub-ppm.
Avoid routing the integrator capacitor traces adjacent to high-current switching traces or digital clock edges - any capacitive coupling onto C1P/C1N/C2P/C2N degrades the 3.2 ppm rms noise floor. For multi-channel PCB builds, route the integrator capacitor traces symmetrically and use guard traces tied to analog ground. Designers should also verify that the input currents do not exceed the absolute maximum rating per the datasheet, which can permanently damage the input switches.
Drive the CLK pin with a low-jitter CMOS oscillator (jitter below 50 ps rms) because the integrator window is set by clock edges; any jitter directly degrades the integration accuracy. Series-terminate the CLK trace if run length exceeds 25 mm, and keep the DOUT trace short to limit reflections. Add a 100 ohm source-series resistor on the CLK line if ringing is observed in measurement, per standard high-speed CMOS design practice.
Compliance Information
RoHS compliance inferred from G4 suffix (lead-free) per TI datasheet packaging convention. AEC-Q100 not applicable - this is a precision industrial/commercial-grade ADC; an automotive-grade variant should be selected for automotive applications. Halogen-free status not explicitly stated in the verified web data.