Texas Instruments ADS8345E/2K5

Overview

ADS8345E/2K5 from Texas Instruments is a 16-bit, 8-channel SAR analog-to-digital converter with synchronous serial interface, bipolar input range (±VREF), 100kHz throughput rate, and QSOP-20 package. It operates from a single 2.7V–5V supply, supports single-ended or differential input configurations, and delivers 85dB SINAD at 10kHz - ideal for portable multi-channel data loggers requiring precision and low power.

For engineers reviewing the ADS8345E/2K5 datasheet, ADS8345E/2K5 pinout, ADS8345E/2K5 application, or ADS8345E/2K5 equivalent, key selection considerations include its 16-bit resolution with ±8 LSB integral linearity error, 2.7V–5V supply flexibility, shutdown mode (<15µW), and compatibility with ADS7844/ADS8344 in QSOP-20 footprint.

Technical Context

The ADS8345E/2K5 implements a capacitive redistribution SAR architecture with integrated sample-and-hold, enabling true 16-bit conversion without external hold circuitry. Its 8-channel multiplexer supports configurable single-ended (8 channels) or differential (4 channels) acquisition, with COM pin referenced to VREF or system mid-supply.

Digital control uses a 24-cycle serial protocol with start bit (S), 3-bit channel address (A2–A0), SGL/DIF mode select, and PD1/PD0 power-down configuration. BUSY output signals conversion status, while DOUT provides binary two's complement output synchronized to DCLK falling edges.

Key Specifications

Pinout & Package

ADS8345E/2K5 is housed in a 20-pin QSOP (DBQ) package with 0.65 mm pitch, 7.2 mm × 4.4 mm body size, and exposed pad not connected internally. Pin functions are validated per TI SBAS177C datasheet (Rev. April 2003).

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS8345E/2K5, ADS8344N/1K offers improved linearity at higher cost, while ADS7844N trades resolution and noise performance for lower price and simpler control - making ADS8345E/2K5 optimal for applications demanding 16-bit fidelity with flexible power management.

Availability

ADS8345E/2K5 is available at Aetrix Electronics and suitable for portable data loggers, industrial process monitors, and battery-powered test equipment requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for ADS8345E/2K5 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 connectivity technologies, with decades of expertise in precision data converters and industrial-grade ICs.

The ADS8345 product line was designed for high-accuracy, low-power, multi-channel data acquisition in space-constrained, battery-operated systems - emphasizing serial interface simplicity, supply voltage flexibility, and robust thermal performance.

FAQ

What is the maximum clock frequency supported by ADS8345E/2K5 in external clock mode?

The ADS8345E/2K5 supports an external DCLK frequency up to 2.4 MHz in external clock mode, which corresponds to its maximum 100 kHz conversion rate (f_DCLK = 24 × f_SAMPLE). At this rate, the device consumes 7.5–10 mW from a +5 V supply. Operation above 2.4 MHz violates timing specifications and may cause invalid conversions or increased INL error in ADS8345E/2K5.

Does ADS8345E/2K5 support true differential input across all eight channels?

No - ADS8345E/2K5 supports differential input only across four channel pairs (CH0/CH4, CH1/CH5, CH2/CH6, CH3/CH7), selected via the SGL/DIF bit and A2–A0 address. In differential mode, each pair delivers a 2×VREF full-scale swing; single-ended mode uses all eight channels referenced to COM. This dual-mode capability is explicitly defined in Tables III and IV of the ADS8345E/2K5 datasheet.

What is the minimum VREF voltage allowed for ADS8345E/2K5, and how does it affect resolution?

The minimum VREF for ADS8345E/2K5 is 0.5 V, per Absolute Maximum Ratings and Electrical Characteristics tables. At 0.5 V, LSB size equals 7.63 µV (0.5 V / 65536), reducing effective resolution due to fixed internal noise (~20 µVrms). While the ADS8345E/2K5 still produces 16-bit codes, Gaussian code dispersion increases - requiring oversampling or digital filtering to recover usable ENOB. TI recommends VREF ≥ 1.25 V for stable 14+ bit performance.

Can ADS8345E/2K5 operate from a 3.3 V supply while maintaining full 16-bit performance?

Yes - ADS8345E/2K5 is fully specified at +2.7 V to +3.6 V (per +2.7 V Electrical Characteristics table), delivering 100 kHz throughput, ±8 LSB INL, and 81 dB SINAD at 1 kHz with VREF = 1.25 V. Quiescent current drops to 1.2–1.85 mA, and power dissipation is 3.2–5 mW. All timing parameters, including tACQ = 1.5 µs and aperture jitter = 100 ps, remain valid across this range for ADS8345E/2K5.

How does the SHDN pin interact with the power-down modes controlled by PD1/PD0 bits?

SHDN is a hardware override that forces ADS8345E/2K5 into ultra-low-power shutdown (<15 µW) regardless of PD1/PD0 state. When SHDN = LOW, the device ignores serial commands and disables all internal circuitry except wake-up logic. In contrast, PD1/PD0 = 00 enables auto power-down *between* conversions - retaining register state and enabling immediate valid conversion on next CS assertion. Both mechanisms coexist but serve distinct use cases in ADS8345E/2K5 system design.