Texas Instruments ADS5421Y/R

Overview

ADS5421Y/R from Texas Instruments is a 14-bit, 40 MSPS pipelined analog-to-digital converter (ADC) with on-board differential track-and-hold, 4 VPP full-scale input range, 85 dBFS spurious-free dynamic range at 10 MHz input, and LQFP-64 package. It targets high-fidelity digitization in IF sampling receivers and test instrumentation requiring low aperture jitter (1 ps rms) and high SNR (75 dBFS).

For engineers reviewing the ADS5421Y/R datasheet, ADS5421Y/R pinout, ADS5421Y/R application, or ADS5421Y/R equivalent, key selection considerations include differential input biasing at +2.5 V CM, 10-clock-cycle data latency, 3-state CMOS-compatible parallel outputs, internal/external reference flexibility, and thermal resistance of 48 °C/W in LQFP-64.

Technical Context

The ADS5421Y/R implements a fully differential pipeline architecture with digital error correction logic per stage to ensure ±0.5 LSB differential linearity at 10 MHz input. Its track-and-hold amplifier supports >500 MHz analog input bandwidth and enables undersampling applications up to Nyquist.

It accepts differential or single-ended clock inputs down to 0.5 VPP sine/square wave, with programmable threshold level and 3 ns aperture delay. Output coding supports straight offset binary or binary two's complement via BTC pin, with 3-state enable (OE) and data valid (DV) signaling.

Key Specifications

Pinout & Package

LQFP-64 package with exposed thermal pad (not electrically connected); 1.6 mm nominal height; RoHS-compliant lead finish.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-speed ADC applications.

Compared with ADS5421Y/R, ADS5422Y offers extended temperature capability and marginally better SFDR without layout changes, while ADS5463IPFP delivers higher resolution and rate at the cost of power, size, and design complexity - making ADS5421Y/R optimal for cost-sensitive, thermally constrained 40 MSPS applications.

Availability

ADS5421Y/R is available at Aetrix Electronics and suitable for communications receivers, test instrumentation, professional CCD imaging, and IF sampling spectrum analyzers requiring stable component supply and long-term production continuity.

Supply support for ADS5421Y/R 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-performance data converters for industrial, automotive, and communications markets.

The ADS5421Y/R belongs to TI's high-speed precision ADC product line, designed specifically for IF sampling, test equipment, and imaging systems demanding high SFDR, low jitter, and flexible reference architecture.

FAQ

What is the maximum sampling rate supported by the ADS5421Y/R?

The ADS5421Y/R supports a maximum sampling rate of 40 MSPS. This rate is specified under standard operating conditions: +VSA/+VSD = 4.75–5.25 V, differential input range = 4 VPP, internal reference, and VDRV = +3 V. At this rate, the device achieves 85 dBFS SFDR at 10 MHz input frequency and maintains 10-clock-cycle deterministic data latency. Exceeding 40 MSPS is not characterized and may degrade dynamic performance.

Does the ADS5421Y/R require external analog input biasing?

Yes, the ADS5421Y/R requires external biasing of its differential analog inputs (IN and IN) to a common-mode voltage of +2.5 V. The CM pin connects directly to the internal reference ladder and must be loaded with <100 µA to prevent nonlinearity. External bias networks-such as resistor dividers or dedicated driver amplifiers like the THS4502-are necessary; the device does not provide internal input buffering or active bias generation.

Can the ADS5421Y/R operate with an external reference voltage?

Yes, the ADS5421Y/R supports external reference operation. To enable it, tie VREF to +VSA and configure SEL1/SEL2 appropriately (per Table I in the datasheet). The full-scale range becomes twice the external reference value-for example, a 2.0 V external reference yields a 4 VPP differential input range. External reference mode allows tighter tolerance control than the internal ±50 mV reference and supports custom scaling for specialized signal chains.

What is the purpose of the VDRV pin on the ADS5421Y/R?

The VDRV pin supplies power to the ADS5421Y/R's digital output drivers and must be set to either +3 V or +5 V to match the target logic family. It electrically isolates output switching noise from the analog (+VSA) and digital (+VSD) supplies, preserving SNR and SFDR. Driving outputs at 3 V reduces power dissipation to 850 mW (vs 925 mW at 5 V), while maintaining compatible voltage levels for modern FPGA and ASIC I/O banks.

How does the ADS5421Y/R handle clock input signal types?

The ADS5421Y/R accepts both differential (CLK/CLK) and single-ended clock inputs, supporting sine or square waveforms down to 0.5 VPP amplitude. Its clock input circuitry includes a variable threshold level that can be adjusted via external biasing, allowing robust operation across clock sources with varying slew rates and noise margins. Conversion is triggered on the rising edge of the clock signal, with 3 ns aperture delay and 1 ps rms jitter.