Texas Instruments ADS8509IBDWG4

Overview

ADS8509IBDWG4 from Texas Instruments is a 16-bit, 250-kSPS successive approximation register (SAR) analog-to-digital converter with integrated sample-and-hold, internal 2.5-V reference, serial SPI-compatible interface, and single 5-V supply operation. It supports ±10 V, 0 V to 5 V, and other configurable input ranges via external resistor networks and delivers ±2 LSB max INL, ±1 LSB max DNL, and 85 dB SINAD at 20 kHz for precision industrial data acquisition.

For engineers reviewing the ADS8509IBDWG4 datasheet, ADS8509IBDWG4 pinout, ADS8509IBDWG4 application, or ADS8509IBDWG4 equivalent, key selection considerations include its SO-20 package compatibility, internal/external reference flexibility, BUSY-driven timing control, and daisy-chain-capable serial output with TAG synchronization for multi-channel systems.

Technical Context

The ADS8509IBDWG4 implements a capacitor-based SAR architecture with integrated CDAC, comparator, and clock generator. Its conversion cycle comprises 1.8 ms acquisition and 2.2 ms conversion, totaling 4 ms per sample at 250 kSPS - fully specified over –40°C to +85°C.

It supports dual clocking modes: internal DATACLK output (9 MHz, 16-pulse burst) when EXT/INT = low, or externally synchronized serial readout (0.1–26 MHz) when EXT/INT = high, with SYNC pulse generation for deterministic DSP interfacing and TAG-enabled daisy-chaining of multiple converters.

Key Specifications

Pinout & Package

ADS8509IBDWG4 is housed in a 20-pin SOIC (SO-20, DW package), surface-mount, RoHS-compliant package with 0.65 mm pitch and 12.8 mm × 7.5 mm footprint. Thermal resistance θ_JA = 46°C/W enables operation up to +85°C ambient without forced airflow.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 16-bit SAR ADC applications.

Compared with ADS8509IBDWG4, ADS8515IBDBR trades speed and interface flexibility for resolution, while AD7606BSTZ adds channel count and analog front-end integration at the cost of larger footprint and higher power - making ADS8509IBDWG4 optimal for space-constrained, single-channel, daisy-chainable 250 kSPS designs.

Availability

ADS8509IBDWG4 is available at Aetrix Electronics and suitable for industrial process control, medical equipment, and precision instrumentation requiring stable component supply, long-term lifecycle support, and guaranteed SO-20 packaging consistency.

Supply support for ADS8509IBDWG4 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 leader specializing in analog, embedded processing, and high-reliability ICs for industrial, automotive, and communications markets.

The ADS8509IBDWG4 belongs to TI's precision data acquisition portfolio, designed specifically for high-speed, high-accuracy industrial and medical SAR ADC applications where single-supply operation, reference integration, and serial interface simplicity are critical.

FAQ

What input voltage ranges does the ADS8509IBDWG4 support?

The ADS8509IBDWG4 supports ±10 V, ±5 V, ±3.33 V, 0 V to 4 V, 0 V to 5 V, and 0 V to 10 V input ranges using external precision resistors. Configuration is achieved via R1IN/R2IN/R3IN connections shown in Figure 29 of the SLAS324C datasheet. The ADS8509IBDWG4 achieves ±0.5% full-scale error across all ranges when using 0.1% fixed resistors and internal or external 2.5 V reference.

How does the BUSY signal function in ADS8509IBDWG4 timing control?

The BUSY signal in ADS8509IBDWG4 is an active-low open-drain status output that falls on the falling edge of the second asserted control signal (CS or R/C) and remains low until conversion completes and data is latched into the output shift register. It rises within 5 ns after completion, signaling valid data ready for serial readout - enabling precise interrupt-driven or polling-based timing in microcontroller or DSP interfaces.

Can ADS8509IBDWG4 operate with an external reference, and what are the requirements?

Yes, ADS8509IBDWG4 supports external reference voltages from 2.3 V to 2.7 V applied to the REF pin. When using external reference, full-scale error remains ±0.5% FSR with <±2 ppm/°C drift, and the device draws ≤100 μA from the reference source. External reference mode disables the internal 2.5 V regulator, requiring stable, low-noise source decoupling - typically a precision voltage reference IC with <10 μVpp noise.

What is the purpose of the TAG pin on ADS8509IBDWG4, and how is it used?

The TAG pin on ADS8509IBDWG4 enables daisy-chain configuration of multiple converters: DATA output of one ADS8509IBDWG4 connects to TAG input of the next. In external clock mode (EXT/INT = high), the TAG input value is shifted out on the DATA pin of the downstream device, allowing serial readout of all converters on a single data line. This eliminates additional GPIOs and simplifies firmware for multi-channel systems.

Does ADS8509IBDWG4 require external passive components, and which ones are mandatory?

Yes, ADS8509IBDWG4 requires mandatory external passives: a 2.2 μF tantalum capacitor from CAP to AGND2 for reference stability; 0.1 μF ceramic + 10 μF tantalum capacitors from VANA to AGND2 and VDIG to DGND for supply decoupling; and precision resistors (e.g., 10 kΩ/4.9 kΩ) on R1IN/R2IN/R3IN to configure input ranges. Omission of the CAP capacitor degrades full-scale accuracy beyond ±0.5% FSR.