Texas Instruments ADS7844EBG4

Overview

ADS7844EBG4 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 features an integrated 8-channel multiplexer, programmable single-ended or differential input configuration, and shutdown mode drawing <1 µW. It is used in portable multichannel data loggers and battery-powered measurement equipment.

For engineers reviewing the ADS7844EBG4 datasheet, ADS7844EBG4 pinout, ADS7844EBG4 application, or ADS7844EBG4 equivalent, key selection considerations include its 20-lead QSOP package, 2.7–5 V single-supply operation, VREF range (100 mV to VCC), 12-bit no-missing-codes performance, and compatibility with isolated serial interfaces in remote DAQ systems.

Technical Context

The ADS7844EBG4 implements a capacitive redistribution successive approximation register (SAR) architecture with built-in sample/hold, fabricated in 0.6 µm CMOS. It requires an external clock (fCLK = 16 × fSAMPLE) and reference voltage, supporting both single-ended (8-channel) and differential (4-channel) acquisition via software-configurable A2–A0 and SGL/DIF bits.

Digital control uses a 24-clock-cycle protocol (or 16-clock overlapped mode) with start-bit-synchronized serial interface (DIN/DOUT), BUSY flag, and CS-active-low enable. Power management includes auto power-down (PD1=PD0=0) and hardware shutdown (SHDN low), enabling sub-µW quiescent operation between conversions without startup latency.

Key Specifications

Pinout & Package

The ADS7844EBG4 is housed in a 20-lead QSOP (DBQ) package with 0.65 mm lead pitch, surface-mount compatible, and rated for –40°C to +85°C operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS7844N and MAX147ACPP+, the ADS7844EBG4 offers the tightest INL/DNL (±1 LSB), integrated SHDN for ultra-low standby, and true single-supply operation-making it optimal for new portable and battery-constrained designs requiring guaranteed 12-bit monotonicity.

Availability

ADS7844EBG4 is available at Aetrix Electronics and suitable for portable multichannel data loggers, battery-powered sensor nodes, and industrial panel meters requiring stable component supply across extended production lifecycles.

Supply support for ADS7844EBG4 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 precision data converter innovation.

The ADS7844EBG4 belongs to TI's precision SAR ADC product line, designed specifically 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 ADS7844EBG4 and under what conditions?

The ADS7844EBG4 achieves a maximum throughput rate of 200 kHz when operated at +5 V supply, with VREF = +5 V and fCLK = 3.2 MHz (16 × fSAMPLE). At +2.7 V, the maximum rate drops to 125 kHz due to internal timing constraints. The device maintains 12-bit no-missing-codes performance across this full range. ADS7844EBG4 datasheet Section "SPECIFICATION: +5V" confirms these values under TA = –40°C to +85°C.

Does the ADS7844EBG4 support differential input mode, and how is it configured?

Yes, the ADS7844EBG4 supports 4-channel differential input mode using CH0–CH7 pairs (e.g., CH0/CH1, CH2/CH3). Configuration is done via the SGL/DIF bit (bit 2 of the control byte) set LOW, combined with A2–A0 address bits. Table II in the ADS7844EBG4 datasheet defines exact channel mapping. The COM pin is unused in differential mode, and input common-mode range is constrained to –0.2 V to +1.25 V on the negative input.

What is the purpose of the SHDN pin on the ADS7844EBG4, and how does it differ from auto power-down?

The SHDN pin on the ADS7844EBG4 provides hardware-controlled shutdown, reducing supply current to <1 µW regardless of serial interface state. Unlike auto power-down (PD1=PD0=0), which activates between conversions under software control, SHDN forces immediate deep sleep independent of PD bits or CS/DCLK activity. This makes ADS7844EBG4 ideal for systems requiring rapid, unconditional power gating-such as wake-on-interrupt sensor hubs.

Can the ADS7844EBG4 operate with a 2.5 V reference voltage, and what impact does that have on LSB size?

Yes, the ADS7844EBG4 supports VREF from 100 mV to VCC, including 2.5 V. With VREF = 2.5 V, the LSB size is 610 µV (2.5 V ÷ 4096). This is larger than the 24 µV LSB at 100 mV VREF, improving noise margin and stability. The ADS7844EBG4 specification tables explicitly list performance data for VREF = 2.5 V at +2.7 V supply, confirming full 12-bit functionality and ±1 LSB DNL at this setting.

Is the ADS7844EBG4 pin-compatible with the MAX147, and what are the key interface differences?

The ADS7844EBG4 is functionally and pin-compatible with the MAX147 in 20-lead SSOP (ADS7844N) and QSOP (ADS7844EBG4) packages per TI's datasheet statement. However, ADS7844EBG4 adds the SHDN pin (Pin 10) not present on MAX147, and uses a different control byte format (e.g., PD1/PD0 bits). While PCB layout may allow substitution, firmware must be updated to handle SHDN and revised serial protocol-so ADS7844EBG4 is not a drop-in replacement without software adaptation.