Texas Instruments AFE2256TDR

Overview

AFE2256TDR from Texas Instruments is a 256-channel analog front-end IC for flat-panel digital X-ray detectors, integrating 256 charge integrators, programmable gain amplifiers, correlated double samplers, four 16-bit SAR ADCs, and LVDS serial output. It delivers 750 e⁻ RMS noise at 1.2-pC input range, ±2 LSB INL, and scan times from <20 µs to 204.8 µs.

For engineers reviewing the AFE2256TDR datasheet, AFE2256TDR pinout, AFE2256TDR application, or AFE2256TDR equivalent, key selection criteria include photodiode short immunity, six selectable full-scale input ranges (0.6–9.6 pC), nap/total power-down modes, COF package compatibility, and LVDS serializer timing interface support.

Technical Context

The AFE2256TDR implements pipelined integrate-and-read architecture enabling concurrent integration and data readout, improving throughput in high-channel-count X-ray detector arrays. Its dual-bank correlated double sampling suppresses reset kTC noise and low-frequency drift while maintaining channel-to-channel matching across all 256 inputs.

Timing control is managed by an internal timing generator synchronized to external MCLK, FCLK, and SYNC signals; LVDS serialization uses DCLK_P/DCLK_M and DOUT_P/DOUT_M pairs with configurable SDATA/SDOUT/SCLK/SEN SPI interface for configuration and status monitoring.

Key Specifications

Pinout & Package

AFE2256TDR is supplied in a custom Chip-On-Film (COF) package designated TDR (325-pin), measuring 48.35 mm × 21.5 mm, with gold wire bonding and JEDEC tray packaging. The package supports high-density interconnect to TFT backplanes in flat-panel detectors.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar analog front-end applications.

Compared with AFE2256TBN and AFE2256TDU, the AFE2256TDR offers identical analog performance and feature set but differs in COF mechanical form factor, pin count (325), and pin assignment - requiring dedicated PCB layout and flex cable design for each variant.

Availability

AFE2256TDR is available at Aetrix Electronics and suitable for digital radiography detectors, portable X-ray systems, and high-precision charge integration arrays requiring stable component supply, RoHS-compliant sourcing, and long-term lifecycle support.

Supply support for AFE2256TDR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and medical applications.

The AFE2256 product line was developed specifically for high-channel-count, low-noise charge readout in flat-panel X-ray detectors - emphasizing photodiode short resilience, pipelined throughput, and COF-integrated packaging.

FAQ

What is the operating temperature range for AFE2256TDR?

The AFE2256TDR is rated for operation from 0°C to +85°C, as confirmed in TI's official packaging addendum. This extended industrial temperature range supports deployment in clinical environments and portable X-ray units where ambient conditions may fluctuate. The device maintains specified noise, INL, and timing performance across this full range, and its COF package is qualified for reflow per JEDEC Level-1-260°C-UNLIM standards. AFE2256TDR must be operated within these limits to guarantee compliance with published specifications.

Does AFE2256TDR support daisy-chained LVDS output?

No, AFE2256TDR does not support daisy-chained LVDS output. It provides a single LVDS data stream (DOUT_P/DOUT_M) and clock pair (DCLK_P/DCLK_M) for serialized 256-channel data. Multiple AFE2256TDR devices require individual LVDS receivers or multiplexing at the FPGA/ASIC level. The datasheet confirms no built-in daisy-chain logic or multi-drop LVDS driver capability - system-level synchronization must be handled externally via shared FCLK and SYNC signals. AFE2256TDR relies on point-to-point LVDS links for signal integrity.

How many ADCs does AFE2256TDR integrate, and how are they mapped to channels?

AFE2256TDR integrates four 16-bit successive-approximation register (SAR) ADCs, time-multiplexed across the 256 channels. Each ADC services 64 consecutive channels in sequence, enabling full-frame digitization within the specified scan time window (e.g., 204.8 µs). Channel-to-ADC mapping is fixed and defined by internal routing; no user reconfiguration is supported. This architecture balances speed, power, and silicon area - AFE2256TDR achieves 16-bit resolution without requiring 256 individual ADCs.

Is AFE2256TDR pin-compatible with AFE2256TBN or AFE2256TDU?

No, AFE2256TDR is not pin-compatible with AFE2256TBN or AFE2256TDU. Although all three share the same die and electrical specifications, they differ in COF package type (TDR vs. TBN vs. TDU), pin count (325 vs. 325 vs. 320), and physical pin assignment. TI's packaging addendum explicitly lists them as distinct orderable part numbers with separate mechanical drawings. AFE2256TDR requires its own dedicated flex cable and PCB footprint - no mechanical or electrical interchangeability exists without redesign.

What power supply voltages does AFE2256TDR require?

AFE2256TDR requires two analog supply rails: AVDD1 = 1.85 V and AVDD2 = 3.3 V, as specified in the TI datasheet. These must be low-noise, well-regulated supplies - particularly AVDD1, which powers the sensitive analog core including integrators and ADC references. The device does not include internal voltage regulation; external LDOs such as the TPS7A8300 are recommended. AFE2256TDR draws current from both rails simultaneously during active operation, and power sequencing (AVDD1 before AVDD2) is advised to prevent latch-up.