TLC549IDR - 8-Bit 40kSPS Serial SAR ADC | Texas Instruments
MPN: TLC549IDR ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.45 | $2.45 |
| 10 | $2.18 | $21.80 |
| 100 | $1.92 | $192.00 |
| 500 | $1.71 | $855.00 |
| 1,000 | $1.52 | $1,520.00 |
| 2,500 | $1.38 | $3,450.00 |
TLC549IDR Overview
An SAR (Successive-Approximation Register) ADC is a type of data converter that performs bit-by-bit comparison of the analog input against an internal precision DAC, producing a digital code after N conversion cycles for N-bit resolution. SAR ADCs sit in the broader data-acquisition signal chain alongside delta-sigma and pipeline architectures, and the TLC549's low pin count and 3-wire serial interface make it one of the canonical microcontroller-peripheral ADCs of its generation.
Key features include 17 microsecond maximum total access and conversion time, a differential reference input that supports ratiometric measurements, and software-controlled sample-and-hold operation. The device is pin-compatible with the TLC540/545/1540 family, enabling easy migration to higher channel counts or 10-bit resolution. Its micropower consumption and tiny 8-SOIC footprint suit space- and battery-constrained designs.
The TLC549 uses a switched-capacitor charge-redistribution DAC core, controlled by an on-chip SAR. Conversion is triggered by the falling edge of CS, after which 8 I/O CLOCK cycles shift the conversion result out LSB-first on DATA OUT, supporting both standalone and microprocessor-peripheral operation.
Typical applications include portable instrumentation, sensor signal digitization (thermistors, potentiometers, strain gauges), battery monitoring, simple process control loops, and embedded data logging. Designers choose the TLC549 when 8-bit resolution and moderate speed are sufficient and PCB area is at a premium.
When designing with this device, place 0.1 microfarad decoupling capacitors close to both the analog and digital supply pins, keep the analog input traces short, and ensure that REF+ minus REF- stays within the 1V to 5V differential range. Driving CS low for longer than the conversion time initiates a new conversion cycle.
This page synthesizes distributor pricing, drop-in compatible alternatives, and practical design notes not found in the manufacturer datasheet, helping engineers evaluate the TLC549IDR for new designs and legacy system maintenance.
Drop-in alternatives for TLC549IDR — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with TLC549IDR (same form factor and footprint) — differing in Package, Sampling Rate, Conversion Time, Data Interface, Number of Channels.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
TLC549CDR
✅ Drop-In📋 Reference alternative (not in catalog)
TLC549ID
✅ Drop-In📋 Reference alternative (not in catalog)
TLC549IP
✅ Drop-In📋 Reference alternative (not in catalog)
TLC548IDR
✅ Drop-In📋 Reference alternative (not in catalog)
ADC0831CCN
✅ Drop-In✓ In Stock
$2.24 / Unit
View Datasheet →ADC0832CCN
✅ Drop-In✓ In Stock
$3.1 / Unit
View Datasheet →TLC549IDR Maximum Ratings & Electrical Characteristics
| Resolution | 8 bit |
| Number of Channels | 1 |
| Sampling Rate | 40 kSPS |
| Architecture | SAR (Successive Approximation) |
| Conversion Time | 17 microseconds max |
| Analog Input Range | 0 V to Vref+ (single-ended) |
| Reference Voltage (differential) | 1 V to 5 V (REF+ to REF-) |
| Supply Voltage (Analog) | 4.5 V to 5.5 V |
| Supply Voltage (Digital) | 4.5 V to 5.5 V |
| Operating Current | 1.8 mA typical |
| Interface | 3-wire Serial (CS, I/O CLOCK, DATA OUT) |
| Sample-and-Hold | On-chip, software-controllable |
| Operating Temperature | -40 C to +85 C (Industrial) |
| Package | 8-pin SOIC |
| Mounting Type | Surface Mount |
| MSL Level | 1 |
| RoHS Status | Compliant |
| Pin/Package Compatibility | TLC540, TLC545, TLC1540 families |
TLC549IDR Pin Configuration
| Pin 1 | REF+ — Positive reference voltage input |
| Pin 2 | AIN — Analog input channel |
| Pin 3 | REF- — Negative reference voltage input (typically ground) |
| Pin 4 | AGND — Analog ground |
| Pin 5 | DGND — Digital ground |
| Pin 6 | DATA OUT — Serial data output (3-state) |
| Pin 7 | I/O CLOCK — Serial clock input |
| Pin 8 | CS — Chip select (active low) |
Typical Applications
TLC549IDR is suitable for 7 applications: Portable Battery-Powered Instrumentation, Sensor Signal Digitization, Process Control Loop Monitoring, Embedded Data Logging, Automotive Cabin Electronics, Battery Monitoring and Fuel Gauge Systems, Hobby and Educational Microcontroller Projects.
Portable Battery-Powered Instrumentation
The TLC549IDR suits handheld meters and battery-powered data loggers because of its 1.8 mA typical operating current and on-chip sample-and-hold, which eliminate external analog front-end components. Designers use the 3-wire serial interface to connect directly to MSP430 or PIC microcontrollers without external glue logic, freeing GPIOs for buttons and displays. The 8-bit resolution is adequate for thermistor temperature sensing, single-cell battery voltage monitoring, and potentiometer position reading where 1 LSB of approximately 19.5 mV (assuming a 5 V reference) provides sufficient discrimination. The wide -40 C to +85 C industrial temperature range allows deployment in outdoor and automotive cabin environments without derating. Source: TI TLC549 datasheet.
Recommended
Sensor Signal Digitization
The TLC549IDR digitizes analog sensor outputs including strain gauges, photodiodes with transimpedance amplifiers, and NTC thermistor divider networks. Its differential reference inputs (REF+, REF-) support ratiometric measurements that cancel reference drift and supply-noise effects, a technique especially valuable when reading resistive sensor dividers powered from the same 5 V rail. The 17 microsecond conversion time easily tracks slowly varying signals such as temperature, pressure, or weight, while the 40 kSPS sample rate handles vibration and acoustic measurements on the order of 10 kHz. Designers add a simple RC low-pass filter on the analog input to limit broadband noise below the 200 kHz Nyquist region. Source: TI TLC549 datasheet application section.
Recommended
Process Control Loop Monitoring
Industrial process controllers use the TLC549IDR to digitize 4-20 mA current-loop signals after a sense resistor, or to read setpoint potentiometers on operator panels. The 8-pin SOIC footprint saves board space in DIN-rail-mounted controllers with high channel density, and the 3-wire interface allows multiple ADCs to share a single SPI bus with separate CS lines. The device's robustness to supply noise and its industrial temperature rating suit factory-floor installations where electromagnetic interference is common. Software-controllable sample-and-hold enables precise acquisition of multiplexed signals from external analog switches. Source: TI TLC549 datasheet.
Recommended
Embedded Data Logging
Embedded data loggers that record environmental parameters over hours or days benefit from the TLC549IDR's micropower operation and small 8-SOIC package. Designers connect the DATA OUT line to a microcontroller's MISO input and capture conversions triggered by CS transitions, then store the results in external EEPROM or SD card memory. The 8-bit resolution (256 codes) yields approximately 0.4% full-scale precision, more than adequate for trend logging of temperature, humidity, and battery voltage. The wide operating voltage range allows direct connection to 5 V microcontrollers without level shifters. Source: TI TLC549 datasheet timing section.
Recommended
Automotive Cabin Electronics
Inside automotive cabins (not under-hood), the TLC549IDR digitizes cabin temperature sensors, light-level sensors for automatic headlight control, and wiper position potentiometers. The -40 C to +85 C industrial temperature grade covers cabin extremes, and the SOIC package withstands standard PCB-level vibration and thermal-cycling stresses. Designers should note that AEC-Q100 qualification is not available for the TLC549 family, so it is not suitable for under-hood or safety-critical applications; for those, an AEC-Q100 ADC such as the ADS7042 should be substituted. Source: TI TLC549 datasheet reliability section.
Recommended
Battery Monitoring and Fuel Gauge Systems
Single-cell Li-ion battery monitors and multi-cell pack balancers use the TLC549IDR to digitize cell voltages through a resistive divider, providing data to a microcontroller for state-of-charge estimation. The differential reference inputs support ground-referenced measurements that reject common-mode noise from switching power converters in the same system. The 8-bit resolution yields 19.5 mV LSB at 5 V reference, sufficient for general-purpose battery monitoring where high-precision coulomb counting is not required. Designers can sample up to 40,000 cells per second when scanning multiple battery stacks through external multiplexers. Source: TI TLC549 datasheet reference input section.
Recommended
Hobby and Educational Microcontroller Projects
Arduino, Raspberry Pi Pico, and PICAXE hobby projects use the TLC549IDR as an external ADC because it provides 8-bit analog input capability to platforms that have no built-in ADC or where all ADC channels are consumed. The simple 3-wire interface (any three GPIO pins) requires only a few lines of code to initiate conversion and read the result, and the breadboard-friendly 8-SOIC or 8-PDIP packages solder easily to perfboard. The low cost (around $2 per unit) makes it accessible for student projects and maker prototypes where higher performance is unnecessary. Source: TI TLC549 datasheet timing section.
Recommended
Recommended Products Summary
Engineering reference data for TLC549IDR — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | TLC549CDR | TLC549ID | TLC549IP | TLC548IDR | |
|---|---|---|---|---|---|---|
| Package | SOIC-8 | SOIC-8 - same | SOIC-8 - same | PDIP-8 (through-hole) | SOIC-8 - same | |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Resolution | 8 bit | 8 bit | 8 bit | 8 bit | 8 bit | 8 bit |
| Sampling Rate | 40 kSPS | 40 kSPS | 40 kSPS | 40 kSPS | 4 kSPS | 31 kSPS |
| Number of Channels | 1 | 1 | 1 | 1 | 1 | 1 (single-ended) |
| Interface | 3-wire Serial | 3-wire Serial | 3-wire Serial | 3-wire Serial | 3-wire Serial | 2-wire Serial |
| Operating Temperature | -40 C to +85 C | 0 C to +70 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | 0 C to +70 C |
| Supply Voltage | 5 V (4.5 V to 5.5 V) | 5 V (4.5 V to 5.5 V) | 5 V (4.5 V to 5.5 V) | 5 V (4.5 V to 5.5 V) | 5 V (4.5 V to 5.5 V) | 5 V (4.5 V to 6.3 V) |
Key Differentiators
- Higher sample rate than the TLC548 family member (vs TLC548IDR)
- 3-wire serial interface versus the ADC0831's 2-wire interface (vs ADC0831CCN)
- On-chip software-controllable sample-and-hold (vs ADC0832CCN)
Design Notes
Place 0.1 microfarad ceramic decoupling capacitors as close as possible to both the analog supply pin (AVDD) and the digital supply pin (DVDD). According to the TI TLC549 datasheet, the device draws 1.8 mA typical with brief current spikes during conversion; adding a 10 microfarant bulk capacitor on the analog supply rail helps suppress supply droop during high-frequency digital activity on the serial interface. Separating analog and digital ground planes with a single-point star connection reduces digital switching noise coupling into the analog input.
Route the analog input trace away from digital clock lines and the serial DATA OUT trace to minimize capacitive coupling of digital edges into the analog signal. According to the TI TLC549 datasheet, the analog input bandwidth exceeds the 200 kHz Nyquist limit, so any digital noise within that band can alias into the conversion result. A grounded guard trace between the analog input and digital signals on the PCB further reduces cross-talk in densely routed designs.
Do not leave CS floating; an un-driven CS pin can randomly trigger conversions and produce noisy readings. According to the TI TLC549 datasheet, CS must be tied high when the device is not in use and driven low for at least 17 microseconds to complete a full conversion cycle. Also, ensure that REF+ minus REF- stays within the 1 V to 5 V differential range; using a reference below 1 V degrades ADC linearity. For ratiometric measurements, tie REF+ to the sensor excitation and REF- to the sensor ground to cancel supply and reference drift.
The DATA OUT pin is a 3-state output; ensure the master microcontroller releases the MISO line when CS is high, otherwise bus contention can damage either device. According to the TI TLC549 datasheet, the TLC549 only drives DATA OUT while CS is held low, so an external pull-up resistor is not required if the master MCU provides a default high level on its MISO input. The I/O CLOCK signal should not exceed 2.048 MHz to allow the internal SAR to settle properly.
Compliance Information
RoHS and REACH compliant per TI product page. Not AEC-Q100 qualified; for automotive under-hood applications, use AEC-Q100 qualified ADC such as ADS7042. Halogen-free per TI's green-compliance policy.
