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Texas Instruments ADC0838CIWM
- Part No.:
- ADC0838CIWM
- Manufacturer:
- Texas Instruments
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
ADC0838CIWM.pdf
- Description:
- ADC, SUCCESSIVE APPROXIMATION, 8
- Quantity:
- Payment:
- Shipping:
Inventory:2,144
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Product details
Overview
ADC0838CIWM from Texas Instruments (formerly National Semiconductor) is an 8-bit successive-approximation analog-to-digital converter with integrated 8-channel analog multiplexer, serial MICROWIRE™-compatible interface, and −40°C to +85°C industrial temperature rating. It supports single-ended, differential, and pseudo-differential input configurations, operates from a single 5 V supply, and delivers 32 µs conversion time with ±1 LSB total unadjusted error.
For engineers reviewing the ADC0838CIWM datasheet, ADC0838CIWM pinout, ADC0838CIWM application, or ADC0838CIWM equivalent, key selection considerations include its software-configurable 8-channel MUX, on-chip shunt regulator for remote sensing, TRI-STATE® serial output, and compatibility with microcontrollers lacking dedicated SPI peripherals via bit-banged MICROWIRE™ protocol.
Technical Context
The ADC0838CIWM implements a sample-data comparator architecture with successive approximation register (SAR) logic, enabling precise differential voltage measurement between programmable channel pairs. Its MUX addressing sequence-shifted in via DI prior to conversion-determines input mode (single-ended/differential/pseudo-differential), channel selection, and polarity assignment.
Digital interface timing follows NSC MICROWIRE™: CS must remain low throughout conversion; DO outputs MSB-first data on CLK falling edges after a ½-clock MUX settling delay; optional SE pin enables LSB-first output. The device includes internal zener regulation at V+, allowing direct connection to unregulated supplies up to 8.5 V while maintaining VCC within 4.5–6.3 V operational range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 8 bits - delivers 256 discrete digital codes over full-scale input range |
| Total Unadjusted Error | ±1 LSB - includes offset, full-scale, linearity, and MUX errors; no calibration required |
| Supply Voltage Range | 4.5 VDC to 6.3 VDC - supports ratiometric operation with system rail or external reference |
| Conversion Time | 32 µs - fixed duration at fCLK = 250 kHz; independent of input voltage |
| Analog Input Channels | 8 single-ended or 4 differential pairs - software-configurable via 4-bit MUX address |
| Reference Input Flexibility | VREF adjustable from 1.3 kΩ to 5.9 kΩ load - enables encoding sub-5V spans to full 8-bit resolution |
| Operating Temperature | −40°C to +85°C - qualified for industrial environments without derating |
Pinout & Package
ADC0838CIWM is supplied in a 20-pin Small Outline (SO) package (NS package code M20B), 7.5 mm body width, gull-wing leads, RoHS-compliant. Pin functions are validated per SNAS531A Figure 10 (ADC0838 Timing) and Functional Block Diagram (Figure 00558307).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (V+) | Unregulated Supply Input | Connects to internal 6.3–8.5 V zener shunt regulator; enables remote operation from high-voltage sources |
| 2 (VCC) | Regulated Core Supply | Output of internal series diode from V+; powers converter core at 4.5–6.3 V |
| 3 (GND) | Analog/Digital Ground | Common reference for analog inputs, digital I/O, and internal ladder network |
| 4–11 (IN0–IN7) | Analog Input Channels | Eight single-ended inputs; adjacent pairs support differential mode (e.g., IN0/IN1, IN2/IN3) |
| 12 (COM) | Common Reference Terminal | Used as pseudo-differential "−" input for all channels; accepts arbitrary bias voltage (not GND) |
| 13 (DI) | Serial Data Input | Accepts start bit and 4-bit MUX address during CS low; ignored during conversion |
| 14 (DO) | Serial Data Output | TRI-STATE® output; MSB-first on CLK falling edges; LSB-first when SE = low |
| 15 (CLK) | Serial Clock Input | Accepts 10–400 kHz clock; duty cycle 40–60%; stops allowed only when low |
| 16 (CS) | Chip Select | Active-low enable; must stay low for entire conversion (≥32 µs) |
| 17 (SE) | Shift Enable Control | High = MSB-first output; low = LSB-first output; not present on ADC0831/32/34 |
| 18 (VREF) | Reference Voltage Input | Sets full-scale span; internally connected to VCC on ADC0832; requires ≥1.3 kΩ drive capability |
| 19 (AGND) | Analog Ground | Internally tied to Pin 3; separation from DGND not required |
| 20 (DGND) | Digital Ground | Internally tied to Pin 3; no separate ground plane needed |
Key Features
| Feature | Design Value |
|---|---|
| Software-Configurable Multiplexer | 8-channel analog switch with selectable single-ended/differential/pseudo-differential modes per conversion |
| MICROWIRE™-Compatible Serial Interface | Direct connection to COP420/COP8 family; bit-bangable on any GPIO without SPI hardware |
| On-Chip Shunt Regulator | Zener at V+ (6.3–8.5 V) enables operation from unregulated 7–12 V rails in remote sensor nodes |
| Pseudo-Differential Input Architecture | COM pin serves as common-mode reference for all channels, eliminating need for level-shifting circuitry |
| No Calibration Required | Zero and full-scale errors inherently bounded by ±1 LSB; eliminates production trim steps |
Applications
| Industrial Sensor Interface | Remote Environmental Monitoring |
|---|---|
|
Use Scenario: Reading thermistor, RTD, and pressure transducer outputs in PLC I/O modules with shared 5 V rail. IC Role / Device Role / Timing Role: ADC0838CIWM acts as front-end digitizer, sampling up to 8 sensors sequentially with software-defined gain and offset per channel. Use Value: Eliminates external MUX and op-amp signal conditioning; pseudo-differential mode rejects common-mode noise from long sensor cables. |
Use Scenario: Battery-powered weather station measuring temperature, humidity, barometric pressure, and solar irradiance. IC Role / Device Role / Timing Role: ADC0838CIWM provides low-power (15 mW), single-supply digitization with V+ zener regulation enabling direct connection to solar panel output. Use Value: Reduces BOM count by integrating voltage regulation and 8-channel acquisition in one SO-20 package. |
| Automotive Subsystem Diagnostics | Legacy Microcontroller Data Acquisition |
|
Use Scenario: Monitoring cabin air quality sensors (CO₂, VOC, PM2.5) in automotive HVAC control units. IC Role / Device Role / Timing Role: ADC0838CIWM interfaces to 8-bit MCU (e.g., PIC16F) via bit-banged MICROWIRE™, handling mixed analog inputs with varying common-mode voltages. Use Value: Differential mode suppresses 12 V battery ripple; COM pin accommodates sensor bias offsets without external level shifters. |
Use Scenario: Upgrading legacy industrial controllers using COP420 or INS8048 with minimal PCB changes. IC Role / Device Role / Timing Role: ADC0838CIWM replaces discrete ADC + MUX designs, leveraging native MICROWIRE™ support for seamless firmware integration. Use Value: Maintains existing software architecture while adding 8-channel capability and eliminating calibration routines. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 8-bit serial ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ADC0838CCWM | Same SO-20 package and pinout; rated for 0°C to +70°C only | Not suitable for extended-temperature industrial or automotive under-hood use | Select ADC0838CIWM when operation beyond 70°C is required; identical functionality otherwise |
| ADS7822U | 12-bit SAR ADC, SPI interface, 2.7–5.25 V supply, 2.5 µs conversion | Higher resolution and speed but lacks integrated MUX and zener regulator | Choose ADS7822U when >8-bit precision is needed and external MUX/regulation is acceptable |
Compared with ADC0838CCWM, ADC0838CIWM adds extended temperature support without design change; versus ADS7822U, it trades resolution and speed for integrated MUX, regulator, and industrial temp grade-reducing system-level component count and layout complexity.
Availability
ADC0838CIWM is available at Aetrix Electronics and suitable for industrial sensor interfaces, remote environmental monitoring, automotive subsystem diagnostics, and legacy microcontroller data acquisition requiring stable component supply across extended temperature ranges.
Supply support for ADC0838CIWM 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 acquired National Semiconductor in 2011 and maintains full technical support and manufacturing continuity for legacy precision analog products.
The ADC083x family was designed for cost-sensitive, space-constrained systems needing flexible analog input handling without external support components-targeting industrial automation, instrumentation, and embedded control.
FAQ
What is the maximum clock frequency supported by ADC0838CIWM?
The ADC0838CIWM supports a clock frequency range of 10 kHz to 400 kHz, with optimal performance at 250 kHz where conversion time is guaranteed at 32 µs. At 400 kHz, conversion completes in 20 µs, but timing margins tighten; the datasheet specifies 40–60% duty cycle and minimum high/low times of 1 µs for reliable operation across the full temperature range of −40°C to +85°C. ADC0838CIWM does not require continuous clocking-the clock may be stopped when low, provided the analog input remains stable.
Does ADC0838CIWM require external zero or full-scale calibration?
No, ADC0838CIWM requires no zero or full-scale adjustment. Its total unadjusted error is specified at ±1 LSB over temperature, covering offset, full-scale, linearity, and multiplexer errors. This specification holds for VCC = 5 V, fCLK = 250 kHz, and TA = −40°C to +85°C. The internal resistor ladder and comparator design ensure inherent accuracy without trimming components, simplifying production test and reducing bill-of-materials cost for ADC0838CIWM-based systems.
How does the COM pin function in pseudo-differential mode on ADC0838CIWM?
In pseudo-differential mode, the COM pin on ADC0838CIWM serves as the common "−" input for all eight analog channels (IN0–IN7). Unlike true differential mode-which restricts pairing to adjacent channels like IN0/IN1-the COM pin allows any channel to be measured relative to a shared reference voltage that need not be ground. This is especially valuable in single-supply systems where sensor outputs are biased above ground; ADC0838CIWM uses COM to reject common-mode offset, eliminating external level-shifting circuitry.
Can ADC0838CIWM operate from an unregulated power source?
Yes, ADC0838CIWM can operate directly from an unregulated supply via its V+ pin, thanks to an integrated 6.3–8.5 V zener shunt regulator. When V+ exceeds ~6.3 V, the zener conducts, dropping excess voltage across an external current-limiting resistor to maintain VCC within the 4.5–6.3 V operating range. This feature enables remote sensor placement powered from 9–12 V batteries or solar panels without additional regulators-making ADC0838CIWM ideal for distributed data acquisition where board space and component count are constrained.
Is ADC0838CIWM pin-compatible with other members of the ADC083x family?
No, ADC0838CIWM is not pin-compatible with ADC0831, ADC0832, or ADC0834 due to differing pin counts and functions: ADC0831/32 use 8-pin DIP/SO, ADC0834 uses 14-pin SO, while ADC0838CIWM uses 20-pin SO with dedicated SE, COM, and V+ pins. However, the serial interface protocol (MICROWIRE™), command structure, and register mapping are consistent across the family-enabling firmware reuse when migrating from smaller-channel variants to ADC0838CIWM in upgraded designs.
ADC0838CIWM Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Bulk
- Product Status:
- Active
- Number of Bits:
- 8
- Sampling Rate (Per Second):
- 31.25k
- Number of Inputs:
- 8
- Input Type:
- Differential, Single Ended
- Data Interface:
- Microwire
- Configuration:
- MUX-ADC
- Ratio - S/H:ADC:
- -
- Number of A/D Converters:
- 1
- Architecture:
- SAR
- Reference Type:
- External
- Voltage - Supply, Analog:
- 4.5V ~ 6.3V
- Voltage - Supply, Digital:
- 4.5V ~ 6.3V
- Features:
- -
- Operating Temperature:
- -40°C ~ 85°C
- Supplier Device Package:
- 20-SOIC
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
ADC0838CIWM FAQ
1.How can I place an order for ADC0838CIWM through Aetrix?
Please submit a Request for Quotation (RFQ) for ADC0838CIWM 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 ADC0838CIWM reliable?
The price and inventory of ADC0838CIWM are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ADC0838CIWM is usually 5 days.
3.What payment methods are accepted for ADC0838CIWM?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ADC0838CIWM transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ADC0838CIWM?
ADC0838CIWM orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ADC0838CIWM 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 ADC0838CIWM?
For technical support, including ADC0838CIWM datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ADC0838CIWM requirements.
6.How does Aetrix verify that ADC0838CIWM is sourced from the original manufacturer or authorized distributors?
All ADC0838CIWM 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 ADC0838CIWM meets industry standards.
7.What is the process for return or replacement of ADC0838CIWM?
All ADC0838CIWM units undergo pre-shipment inspection (PSI). If there is an issue with ADC0838CIWM, 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 ADC0838CIWM part is unused and in its original packaging.
Return procedure for ADC0838CIWM:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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