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Texas Instruments ADS7844NB
- Part No.:
- ADS7844NB
- Manufacturer:
- Texas Instruments
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 20-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
ADS7844NB.pdf
- Description:
- IC ADC 12BIT SAR 20SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:140
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Product details
Overview
ADS7844NB from Texas Instruments is a 12-bit, 8-channel SAR analog-to-digital converter with synchronous serial interface, single-supply operation (2.7V–5V), ±1 LSB INL/DNL, and 200kHz max throughput at +5V. It integrates an on-chip 8-channel multiplexer, supports single-ended or differential input configurations, and targets precision data acquisition in battery-powered systems.
For engineers reviewing the ADS7844NB datasheet, ADS7844NB pinout, ADS7844NB application, or ADS7844NB equivalent, this page delivers verified technical context, real-world design meaning for key specs, validated pin functions, confirmed alternative options, and supply-chain support for industrial and portable measurement designs.
Technical Context
The ADS7844NB implements a capacitive redistribution successive approximation register (SAR) architecture with integrated sample/hold, requiring no external anti-aliasing filter for moderate bandwidths. Its analog front-end accepts eight single-ended inputs referenced to COM or four differential pairs, configurable via serial control bits (A2–A0, SGL/DIF).
Digital operation relies on a synchronous 3-wire serial interface (CS, DCLK, DIN/DOUT) with BUSY signaling and programmable power-down modes (PD1/PD0). Conversion timing is deterministic: 12 clock cycles for conversion + 3 for acquisition + overhead, supporting 15-, 16-, or 24-clock protocols depending on host controller capability.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 12-bit - delivers 4096 discrete output codes; LSB = VREF/4096 (e.g., 1.22mV at VREF = 5V) |
| Input Channels | 8 single-ended or 4 differential - enables multichannel sensing without external MUX, reducing BOM and layout complexity |
| Max Throughput | 200kHz at +5V - supports real-time sampling of signals up to ~80kHz (Nyquist-limited), suitable for dynamic sensor monitoring |
| INL / DNL | ±1 LSB max - ensures monotonicity and <0.025% full-scale linearity error, critical for closed-loop control accuracy |
| SINAD | 72dB at 10kHz - corresponds to ~11.9 effective bits, enabling high-fidelity digitization of low-noise analog signals |
| Supply Range | 2.7V to 5V - allows direct interfacing with Li-ion batteries (3.0–4.2V) or 3.3V/5V logic domains without level-shifting |
| Power-Down Current | <3µA - reduces system standby power by >99.9% vs active mode (900µA typ), extending battery life in intermittent-sampling applications |
Pinout & Package
ADS7844NB is packaged in a 20-lead SSOP (Shrink Small Outline Package), 0.65mm pitch, body size 7.2mm × 5.3mm, RoHS-compliant, moisture-sensitive level 3.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CH0–CH7 (Pins 1–8) | Analog input channels | Accept single-ended voltage relative to COM or differential pair; internally routed to SAR core via programmable MUX |
| COM (Pin 9) | Analog ground reference | Sets zero-code point in single-ended mode; must be connected to stable low-impedance ground or bias point |
| SHDN (Pin 10) | Hardware shutdown control | Active-low signal forcing sub-1µW quiescent power; overrides PD1/PD0 settings for immediate power gating |
| VREF (Pin 11) | External reference input | Defines full-scale range (0V to VREF); unbuffered, draws 13–40µA depending on VREF and sample rate |
| +VCC (Pins 12, 20) | Positive supply | Single 2.7–5V rail powering analog and digital sections; requires local 1µF + 0.1µF bypassing per supply pin |
| GND (Pins 13, 14) | Analog/digital ground | Common return for analog inputs, reference, and digital I/O; split-plane layout recommended for noise isolation |
| DOUT (Pin 15) | Serial data output | Tri-state CMOS output enabled only when CS is low; outputs MSB-first straight-binary conversion result |
| BUSY (Pin 16) | Conversion status indicator | Active-low open-drain signal asserting during DIN latching and conversion; used for hardware handshaking |
| DIN (Pin 17) | Serial data input | Accepts 8-bit control byte (S, A2–A0, SGL/DIF, PD1, PD0) on rising DCLK edges; overvoltage tolerant to 5.5V |
| CS (Pin 18) | Chip select | Active-low enable for serial interface; disables DOUT/BUSY and places digital inputs in high-impedance when high |
| DCLK (Pin 19) | Serial clock input | Drives all timing; fCLK = 16 × fSAMPLE for standard mode; supports 15-/16-/24-clock protocols for flexible host integration |
Key Features
| Feature | Design Value |
|---|---|
| Single-supply 2.7V–5V operation | Eliminates dual-rail supplies and level shifters in portable/battery systems, simplifying power architecture |
| Onboard 8-channel analog multiplexer | Reduces external component count and PCB area versus discrete MUX + ADC solutions; supports channel scanning in firmware |
| Configurable single-ended/differential input | Enables flexible sensor interfacing-single-ended for grounded sensors, differential for noisy industrial transducers |
| Auto power-down mode (PD1=PD0=0) | Automatically powers down between conversions with zero wake-up latency-first result is valid, no timing penalty |
| CMOS-compatible serial interface | Direct connection to microcontrollers (e.g., MSP430, STM32) without glue logic; 5.5V-tolerant inputs ease mixed-voltage designs |
| –40°C to +85°C temperature rating | Qualified for industrial environments including factory automation, remote telemetry, and outdoor instrumentation |
Applications
| Portable Multichannel Data Logger | Industrial Process Monitoring |
|---|---|
|
Use Scenario: Battery-powered handheld device logging temperature, pressure, and humidity from 8 sensors across a manufacturing floor. IC Role / Device Role / Timing Role: Central 12-bit ADC acquiring synchronized samples from multiple analog sensors via internal MUX; serial interface streams data to low-power MCU. Use Value: 200kHz throughput enables oversampling for noise reduction; 3mW active power and µW shutdown extend 10+ hour runtime on 2000mAh Li-ion. |
Use Scenario: DIN-rail mounted PLC module measuring 4–20mA current loops and thermocouple outputs in chemical plant control cabinets. IC Role / Device Role / Timing Role: Precision front-end digitizer handling both single-ended (4–20mA shunt) and differential (thermocouple) inputs with channel isolation >100dB. Use Value: ±1 LSB INL ensures <0.025% measurement uncertainty across full scale; wide VREF range (100mV–5V) accommodates diverse sensor spans. |
| Personal Digital Assistant (PDA) Sensor Hub | Battery-Operated Test Equipment |
|
Use Scenario: Legacy PDA integrating ambient light, accelerometer, and battery voltage monitoring using minimal board space. IC Role / Device Role / Timing Role: Low-pin-count ADC consolidating multiple analog sensing paths into one serial interface, minimizing trace count and routing congestion. Use Value: SSOP-20 package (7.2×5.3mm) fits tight layouts; 2.7V minimum supply allows operation down to end-of-life battery voltage (~2.8V). |
Use Scenario: Handheld oscilloscope/multimeter performing real-time waveform capture and RMS calculation on analog inputs. IC Role / Device Role / Timing Role: High-speed sampling engine delivering 72dB SINAD for clean FFT-based spectral analysis of 10kHz signals. Use Value: 72dB SINAD translates to ~11.9 ENOB-sufficient for 4½-digit meter resolution; BUSY pin enables precise trigger synchronization. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar analog-to-digital converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ADS7844N | Same silicon, SSOP-20 package, but specified for ±2 LSB INL / ±4 LSB gain error (vs ±1/±3 for NB) | Lower accuracy grade; suitable for cost-sensitive industrial monitoring where 0.05% FS error is acceptable | Select ADS7844N if full 12-bit linearity is not required and budget constraints dominate |
| MAX147ACPP+ | Pin-compatible 12-bit 8-channel ADC; ±1 LSB INL, but 130kHz max throughput at +5V and higher 1.5mW active power | Lower speed and higher power limit use in high-throughput or ultra-low-power designs | Choose MAX147ACPP+ only if existing footprint compatibility is mandatory and 130kHz suffices |
Compared with ADS7844N and MAX147ACPP+, the ADS7844NB delivers tighter DC accuracy (±1 LSB INL/±3 LSB gain) and higher throughput (200kHz) at lower active power (3mW), making it optimal for precision, battery-constrained data loggers and portable test gear.
Availability
ADS7844NB is available at Aetrix Electronics and suitable for portable instrumentation, industrial process control, and battery-powered data acquisition requiring stable component supply, long-term lifecycle support, and guaranteed SSOP-20 packaging consistency.
Supply support for ADS7844NB 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 and embedded processing technologies, with decades of expertise in precision data converters and industrial-grade ICs.
The ADS7844NB belongs to TI's precision SAR ADC product line, designed specifically for multichannel, low-power, high-accuracy measurement in portable and harsh-environment applications.
FAQ
What is the maximum sample rate of the ADS7844NB at 3.3V supply?
The ADS7844NB achieves up to 125kHz maximum throughput at +2.7V supply with VREF = +2.5V and fCLK = 2MHz. At 3.3V, performance aligns with the +2.7V specification since 3.3V falls within the 2.7V–3.6V operating range defined for that test condition. This rate supports accurate digitization of signals below 50kHz while maintaining ±1 LSB linearity and 72dB SINAD.
Does the ADS7844NB support true differential input mode across all eight channels?
No-the ADS7844NB supports differential input using only four channel pairs: CH0/CH4, CH1/CH5, CH2/CH6, and CH3/CH7-as defined by the SGL/DIF bit and A2–A0 address in Tables I and II of the datasheet. All eight channels remain accessible in single-ended mode, but differential operation is limited to those four dedicated pairs.
How does the SHDN pin interact with the PD1/PD0 power-down settings in the ADS7844NB?
The SHDN pin has priority over PD1/PD0: when SHDN is driven LOW, the ADS7844NB enters ultra-low-power shutdown (<1µW), regardless of PD1/PD0 state. When SHDN is HIGH, the device obeys the PD1/PD0 configuration-e.g., PD1=PD0=0 enables auto power-down between conversions. Both mechanisms reduce supply current, but SHDN provides hardware-level override.
Can the ADS7844NB interface directly with a 1.8V microcontroller SPI port?
No-while the ADS7844NB's digital inputs tolerate up to 5.5V, its outputs (DOUT, BUSY) swing between GND and +VCC (2.7–5V), so a 1.8V MCU cannot reliably read them without level translation. Additionally, VIH minimum is +VCC × 0.7 (e.g., 1.89V at 2.7V supply), exceeding 1.8V logic HIGH thresholds. Level shifters or GPIO-driven software SPI are required.
What is the purpose of the COM pin on the ADS7844NB, and how should it be connected?
The COM pin serves as the analog ground reference for single-ended inputs and the common-mode node for differential inputs. In single-ended mode, it sets the zero-volt code point-typically tied to system AGND. In differential mode, it defines the midpoint voltage for the selected channel pair. It must be connected to a low-impedance, noise-free reference; floating or poorly decoupled COM degrades INL and channel-to-channel isolation.
ADS7844NB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 20-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Number of Bits:
- 12
- Sampling Rate (Per Second):
- 200k
- Number of Inputs:
- 4, 8
- Input Type:
- Differential, Single Ended
- Data Interface:
- SPI
- Configuration:
- MUX-S/H-ADC
- Ratio - S/H:ADC:
- 1:1
- Number of A/D Converters:
- 1
- Architecture:
- SAR
- Reference Type:
- External
- Voltage - Supply, Analog:
- 2.7V ~ 3.6V, 5V
- Voltage - Supply, Digital:
- 2.7V ~ 3.6V, 5V
- Features:
- -
- Operating Temperature:
- -40°C ~ 85°C
- Supplier Device Package:
- 20-SSOP
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
ADS7844NB FAQ
1.How can I place an order for ADS7844NB through Aetrix?
Please submit a Request for Quotation (RFQ) for ADS7844NB on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for ADS7844NB reliable?
The price and inventory of ADS7844NB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ADS7844NB is usually 5 days.
3.What payment methods are accepted for ADS7844NB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ADS7844NB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ADS7844NB?
ADS7844NB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ADS7844NB order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for ADS7844NB?
For technical support, including ADS7844NB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ADS7844NB requirements.
6.How does Aetrix verify that ADS7844NB is sourced from the original manufacturer or authorized distributors?
All ADS7844NB products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that ADS7844NB meets industry standards.
7.What is the process for return or replacement of ADS7844NB?
All ADS7844NB units undergo pre-shipment inspection (PSI). If there is an issue with ADS7844NB, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The ADS7844NB part is unused and in its original packaging.
Return procedure for ADS7844NB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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