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Texas Instruments ADS7818PB
- Part No.:
- ADS7818PB
- Manufacturer:
- Texas Instruments
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
ADS7818PB.pdf
- Description:
- IC ADC 12BIT SAR 8DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,691
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Product details
Overview
ADS7818PB from Burr-Brown (now Texas Instruments) is a 12-bit successive approximation register (SAR) analog-to-digital converter with integrated sample/hold, 2.5V internal reference, and synchronous serial interface. It delivers 500kHz throughput at 11mW, supports differential input (0–5V range), and operates from a single +5V supply across –40°C to +85°C. It is used in portable spectrum analyzers and battery-powered data loggers requiring low-power, high-speed digitization.
For engineers reviewing the ADS7818PB datasheet, ADS7818PB pinout, ADS7818PB application, or ADS7818PB equivalent, key selection considerations include guaranteed no-missing-codes performance, ±1 LSB integral linearity, MSOP-8 package compatibility, power-down mode (2.5mW), and support for external reference overdrive (2.0V–2.55V).
Technical Context
The ADS7818PB implements a capacitive redistribution SAR architecture fabricated in 0.6µm CMOS, enabling inherent sample/hold functionality without external components. Its conversion is clocked externally (200kHz–8MHz), with timing independent of CLK for CONV-triggered hold-mode transitions.
It features a buffered 2.5V bandgap reference with 20ppm/°C drift, decoupled via 0.1µF ceramic + 2.2µF tantalum at VREF. The differential analog inputs (+In/–In) accept unipolar signals up to 5V full-scale, with –In limited to ±0.2V for remote ground sensing-enabling common-mode rejection up to 70dB at DC.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 12-bit SAR with guaranteed no missing codes-ensures monotonicity and eliminates code gaps in control or measurement loops. |
| Throughput Rate | 500kHz maximum-supports real-time acquisition in wireless comms and DSP front-ends without pipeline latency. |
| Power Dissipation | 11mW at 500kHz; drops to 2.5mW in power-down-critical for extended battery life in portable instrumentation. |
| Integral Linearity | ±1 LSB max (ADS7818PB grade)-enables accurate voltage measurement within ±0.025% full-scale error at 5V span. |
| Reference Voltage | Internal 2.475–2.525V (±1%) with 20ppm/°C drift-provides stable 0–5V input range; overdrivable with 2.0–2.55V external reference. |
| Analog Input Range | 0 to 2×VREF (unipolar differential)-supports 0–5V with internal ref or 4.0–5.1V with external 2.048V/2.5V references. |
| Serial Interface | Synchronous CMOS, MSB-first by default-simplifies isolation and microcontroller/DSP interfacing with minimal GPIO overhead. |
Pinout & Package
ADS7818PB is packaged in an MSOP-8 surface-mount package (3.0mm × 4.9mm, 0.65mm pitch), optimized for space-constrained portable designs and compatible with standard reflow profiles.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VREF (Pin 1) | Reference output/buffer input | Provides 2.5V internal reference; accepts external 2.0–2.55V overdrive; requires 0.1µF ceramic + 2.2µF tantalum bypass. |
| +In (Pin 2) | Non-inverting analog input | Primary signal input; must stay within GND–0.2V to VCC+0.2V to maintain linearity; drives internal sampling capacitor. |
| –In (Pin 3) | Inverting analog input | Remote ground sense point; limited to ±0.2V range-used for noise rejection, not true differential signaling. |
| GND (Pin 4) | Analog/digital ground reference | Common return for analog inputs, reference, and digital I/O; must be low-impedance and separated from noisy digital planes. |
| CONV (Pin 5) | Convert control input | Asynchronous start-of-conversion trigger; controls sample/hold transition, serial data enable, and power-down entry/exit. |
| DATA (Pin 6) | Serial data output | CMOS-level 12-bit result (MSB first); tri-states when CONV is low; supports LSB-first mode via timed CONV assertion. |
| CLK (Pin 7) | Serial clock input | External timing source (200kHz–8MHz); rising edge clocks data; duty cycle flexible if tCKH/tCKL ≥50ns. |
| +VCC (Pin 8) | Positive supply | +4.75V to +5.25V single supply; requires 0.1µF ceramic + 10µF tantalum decoupling close to pin. |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed no missing codes | Ensures monotonic transfer function-critical for closed-loop control and feedback systems where code repetition or omission causes instability. |
| Power-down mode (2.5mW) | Reduces quiescent current to 0.5mA between conversions-enables ultra-low average power in burst-mode acquisition (e.g., sensor wake-up). |
| Differential input with remote ground sensing | Allows +In signal routing from distant transducers while referencing local ground at –In-minimizing ground loop errors in multi-channel loggers. |
| External reference overdrive capability | Accepts 2.0–2.55V external references via 10kΩ series resistor-enables precise 0–4.095V (2.048V ref) or temperature-stable full-scale ranges. |
| Short-cycle conversion | Early termination of conversion via CONV assertion-reduces latency for threshold detection before full 12-bit resolution is needed. |
Applications
| Portable Spectrum Analyzer Front-End | Battery-Powered Multi-Channel Data Logger |
|---|---|
Use Scenario: Real-time RF signal capture and FFT analysis in handheld test equipment with limited thermal headroom and battery capacity. IC Role / Device Role / Timing Role: High-speed ADC digitizing IF or baseband signals; provides 500kHz sustained sampling with <350ns acquisition time. Use Value: 72dB SNR and 72dB SFDR at 100kHz enable clean spectral resolution; 2.5mW power-down extends field operation time between charges. |
Use Scenario: Simultaneous voltage monitoring across 8+ sensors in environmental monitoring nodes powered by coin-cell or solar-charged Li-ion. IC Role / Device Role / Timing Role: Low-power, precision digitizer for thermistor, RTD, and battery voltage inputs; interfaces directly to MSP430 or similar ultra-low-power MCU. Use Value: ±1 LSB INL ensures <0.025% measurement accuracy; single +5V supply simplifies power design; MSOP-8 footprint saves PCB area. |
| Digital Signal Processing Interface | Wireless Communication Baseband Acquisition |
Use Scenario: Analog front-end for FPGA- or DSP-based adaptive filtering, beamforming, or modulation analysis in compact embedded systems. IC Role / Device Role / Timing Role: Synchronous serial ADC feeding TI C6000 or Xilinx Zynq; leverages MSB-first output and CONV/CLK timing flexibility. Use Value: No pipeline delay enables deterministic sample-to-result timing; 16-cycle serial frame fits standard SPI peripherals with minor firmware adaptation. |
Use Scenario: Digitizing baseband I/Q signals in Bluetooth LE or Zigbee transceivers where size, EMI, and power are tightly constrained. IC Role / Device Role / Timing Role: Unipolar ADC capturing filtered analog outputs prior to digital demodulation; uses internal 2.5V reference for consistent scaling. Use Value: 500kHz throughput supports >200ksps complex sampling; differential input rejects PCB-level switching noise from RF section. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 12-bit SAR ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ADS7816EB | 10-bit resolution, same MSOP-8 package, 500kHz throughput, 2.5V ref, but ±2 LSB INL (vs ±1 for ADS7818PB) | Lower resolution acceptable in cost-sensitive industrial monitoring where 0.1% accuracy suffices | Select ADS7816EB only if 10-bit precision meets system requirements and BOM cost reduction is prioritized over measurement fidelity |
| ADS8320EB | 16-bit SAR, 100kSPS max, SPI-compatible, 2.5V ref, ±1 LSB INL, but higher power (15mW) and larger VSSOP-8 package | Required for high-precision sensor calibration or medical diagnostics needing >12-bit dynamic range | Choose ADS8320EB when resolution and SNR (>85dB) outweigh throughput and power constraints; not drop-in compatible due to timing and pinout differences |
Compared with ADS7816EB, ADS7818PB delivers 2-bit higher resolution and tighter linearity for the same footprint and interface; versus ADS8320EB, it trades resolution and SNR for 5× higher throughput and 30% lower active power-making it optimal for speed-critical, battery-limited applications.
Availability
ADS7818PB is available at Aetrix Electronics and suitable for portable instrumentation, battery-powered data acquisition, and wireless communication baseband design requiring stable component supply and long-term manufacturability.
Supply support for ADS7818PB 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
Burr-Brown Corporation, acquired by Texas Instruments in 2000, specialized in high-precision analog ICs including data converters, amplifiers, and references-known for metrology-grade performance and rugged industrial qualification.
The ADS7818PB belongs to Burr-Brown's legacy high-speed, low-power SAR ADC family designed specifically for portable test equipment and remote sensing applications demanding accuracy, small size, and single-supply operation.
FAQ
What is the guaranteed integral linearity error for ADS7818PB?
The ADS7818PB guarantees ±1 LSB integral linearity error over the full –40°C to +85°C temperature range, as specified in the "PACKAGE/ORDERING INFORMATION" table for the "PB" grade. This is tighter than the ±2 LSB spec for the "P" and "E" variants, making ADS7818PB suitable for applications requiring sub-0.025% full-scale accuracy without post-calibration.
Does ADS7818PB support external reference voltage, and what is the valid range?
Yes, ADS7818PB supports external reference voltage applied to the VREF pin. The valid range is 2.0V to 2.55V, corresponding to an analog input full-scale span of 4.0V to 5.1V. This is enabled by an internal 10kΩ series resistor connecting the external source to the internal 2.5V bandgap reference, as confirmed in the "REFERENCE INPUT" section of the datasheet.
What package type is ADS7818PB shipped in, and is it RoHS-compliant?
ADS7818PB is supplied in an MSOP-8 package (drawing number 337), as documented in the "PACKAGE/ORDERING INFORMATION" table. While the original 2000-era datasheet does not state RoHS compliance, Texas Instruments' current product change notices confirm legacy Burr-Brown parts-including ADS7818PB-are available in lead-free, RoHS-compliant versions under updated ordering codes (e.g., ADS7818PBR).
Can ADS7818PB operate with a non-continuous clock, and how is timing controlled?
Yes, ADS7818PB supports asynchronous operation where CONV initiates conversion independently of CLK. As shown in Figure 3 and described in "DIGITAL INTERFACE", the falling edge of CONV triggers hold-mode entry regardless of CLK state. CLK may be gated or started after CONV assertion-enabling SPI-like microcontroller interfacing without requiring continuous clock generation.
What is the minimum acquisition time required for ADS7818PB to achieve 12-bit settling?
The minimum acquisition time for ADS7818PB is 350ns, as specified in the "SAMPLING DYNAMICS" table under "Acquisition Time". This is the time required for the internal sampling capacitor to settle to 12-bit accuracy after the CONV falling edge, assuming proper analog source drive capability and layout-critical for maintaining full-resolution performance at 500kHz throughput.
ADS7818PB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Number of Bits:
- 12
- Sampling Rate (Per Second):
- 500k
- Number of Inputs:
- 1
- Input Type:
- Differential
- Data Interface:
- SPI
- Configuration:
- S/H-ADC
- Ratio - S/H:ADC:
- 1:1
- Number of A/D Converters:
- 1
- Architecture:
- SAR
- Reference Type:
- Internal
- Voltage - Supply, Analog:
- 5V
- Voltage - Supply, Digital:
- 5V
- Features:
- -
- Operating Temperature:
- -40°C ~ 85°C
- Supplier Device Package:
- 8-PDIP
- Mounting Type:
- Through Hole
- Grade:
- -
- Qualification:
- -
ADS7818PB FAQ
1.How can I place an order for ADS7818PB through Aetrix?
Please submit a Request for Quotation (RFQ) for ADS7818PB 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 ADS7818PB reliable?
The price and inventory of ADS7818PB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ADS7818PB is usually 5 days.
3.What payment methods are accepted for ADS7818PB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ADS7818PB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ADS7818PB?
ADS7818PB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ADS7818PB 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 ADS7818PB?
For technical support, including ADS7818PB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ADS7818PB requirements.
6.How does Aetrix verify that ADS7818PB is sourced from the original manufacturer or authorized distributors?
All ADS7818PB 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 ADS7818PB meets industry standards.
7.What is the process for return or replacement of ADS7818PB?
All ADS7818PB units undergo pre-shipment inspection (PSI). If there is an issue with ADS7818PB, 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 ADS7818PB part is unused and in its original packaging.
Return procedure for ADS7818PB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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