Texas Instruments ADS7844NB/1KG4

Overview

ADS7844NB/1KG4 from Texas Instruments is a 12-bit, 8-channel SAR analog-to-digital converter with synchronous serial interface, ±1 LSB INL/DNL, 72 dB SINAD, and 200 kHz max throughput at +5 V. It supports single-ended (8-channel) or differential (4-channel) inputs, operates from 2.7 V to 5 V, and features shutdown mode (<1 µW). It is used in portable multichannel data loggers and battery-powered measurement equipment.

For engineers reviewing the ADS7844NB/1KG4 datasheet, ADS7844NB/1KG4 pinout, ADS7844NB/1KG4 application, or ADS7844NB/1KG4 equivalent, key selection considerations include its 20-lead SSOP package, CMOS-compatible serial interface (DIN/DOUT/BUSY/DCLK), reference voltage flexibility (0.1 V to VCC), and guaranteed operation across –40°C to +85°C.

Technical Context

The ADS7844NB/1KG4 implements a capacitive redistribution successive approximation register (SAR) architecture with integrated sample-and-hold. Its eight-channel analog multiplexer supports configurable single-ended or differential input modes via SGL/DIF and A2–A0 control bits transmitted serially over DIN.

Digital timing is synchronous: each conversion requires 16 clock cycles (DCLK) for full throughput, with BUSY indicating acquisition/conversion status and DOUT outputting straight-binary 12-bit data on falling DCLK edges. Power management includes auto power-down (PD1=PD0=0) and hardware shutdown (SHDN low).

Key Specifications

Pinout & Package

The ADS7844NB/1KG4 is housed in a 20-lead SSOP (Shrink Small Outline Package) with 0.65 mm lead pitch, moisture sensitivity level (MSL) 3, and RoHS-compliant finish.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 12-bit SAR ADC applications.

Compared with ADS7844EB/2K5, the ADS7844NB/1KG4 offers identical electrical performance but in a smaller SSOP package-ideal for space-constrained portable designs. Against MAX147ACPP+, it adds SHDN control and lower power-down current, enabling longer battery life in new designs.

Availability

ADS7844NB/1KG4 is available at Aetrix Electronics and suitable for portable multichannel data loggers, battery-powered measurement equipment, and industrial process control sensors requiring stable component supply and long-term production continuity.

Supply support for ADS7844NB/1KG4 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 over 50 years of precision data converter innovation.

The ADS7844NB/1KG4 belongs to TI's precision SAR ADC product line, engineered for low-power, multi-channel data acquisition in portable and industrial instrumentation where size, accuracy, and supply flexibility are critical.

FAQ

What is the maximum sample rate of the ADS7844NB/1KG4 at 2.7 V supply?

The ADS7844NB/1KG4 achieves a maximum throughput rate of 125 kHz when operated at +VCC = +2.7 V, VREF = +2.5 V, and fCLK = 2 MHz. This is specified in the +2.7 V section of the SBAS100A datasheet and reflects reduced clock speed and settling constraints at lower supply voltage. At +5 V, the device supports up to 200 kHz.

Does the ADS7844NB/1KG4 require an external reference, and what voltage range is supported?

Yes, the ADS7844NB/1KG4 requires an external reference applied to the VREF pin. It supports a reference voltage range from 0.1 V to +VCC (i.e., 0.1 V to 5 V), enabling flexible full-scale input spans. With VREF = 2.5 V, the LSB size is 610 µV; with VREF = 5 V, it is 1.22 mV. The reference input is unbuffered and draws current dependent on sample rate and VREF magnitude.

How does the SHDN pin function on the ADS7844NB/1KG4, and how does it differ from PD1/PD0 auto power-down?

The SHDN pin on the ADS7844NB/1KG4 provides hardware-controlled shutdown: pulling SHDN low reduces supply current to <1 µW immediately, independent of CS state or clock activity. In contrast, PD1/PD0 bits (set via DIN) enable auto power-down between conversions only when CS remains low and DCLK is active. SHDN overrides all digital control and is intended for system-level power gating.

What are the absolute maximum ratings for analog input voltage on the ADS7844NB/1KG4?

The absolute maximum analog input voltage on the ADS7844NB/1KG4 is –0.3 V to (+VCC + 0.3 V) on the positive input (CHx), and –0.2 V to +1.25 V on the negative input (–IN) in differential mode. Exceeding these ranges risks latch-up or permanent damage. Input leakage is ±1 µA, and capacitance is 25 pF - design must ensure source impedance is low enough to meet acquisition time requirements.

Is the ADS7844NB/1KG4 pin-compatible with the MAX147, and what are the key functional overlaps?

Yes, the ADS7844NB/1KG4 is a direct pin-compatible and functionally equivalent replacement for the MAX147 in 20-lead SSOP packaging. Both offer 12-bit resolution, 8-channel single-ended/4-channel differential input, serial interface, and similar timing. Key differences include ADS7844NB/1KG4's SHDN pin, lower power-down current (<1 µW vs ~1 µA), and guaranteed 2.7 V operation - making it suitable for modern low-voltage designs.