TLC549IDRG4 - 8-Bit 40kSPS Serial ADC | Texas Instruments
MPN: TLC549IDRG4 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.72 | $1.72 |
| 10 | $1.55 | $15.50 |
| 100 | $1.34 | $134.00 |
| 500 | $1.18 | $590.00 |
| 1,000 | $1.05 | $1,050.00 |
TLC549IDRG4 Overview
A SAR ADC is a converter architecture that uses a binary-search successive-approximation register to step an internal DAC toward the analog input, producing one conversion per N clock cycles where N equals the bit resolution. Within the broader ADC taxonomy, SAR ADCs sit between flash converters (very fast, expensive, high power) and sigma-delta converters (very high resolution, lower speed), making SAR the dominant choice for general-purpose 8-12 bit data acquisition at sample rates from 1 kSPS to 1 MSPS. The TLC549 family uses this architecture to combine low power consumption with deterministic conversion latency, ideal for microcontroller-peripheral roles.
Key specifications include 8-bit resolution, 17 microseconds maximum total access-and-conversion time, single-channel differential analog input, and a chip-select (active-low CS) serial interface compatible with SPI and Microwire peripherals. Per the TI datasheet, the converter draws approximately 1.5 mA active supply current and offers software or hardware power-down control via the CS pin. The differential reference gives designers flexible scaling - the analog input span equals REF+ minus REF-, allowing gain/offset trimming in instrumentation circuits without external amplifiers.
Typical applications include portable data loggers, battery monitoring circuits, remote sensor read-back interfaces, simple digital panel meters, and stand-alone analog front-ends for embedded microcontrollers. The wide supply range and low power consumption also make it well-suited for 4-20 mA loop-powered industrial sensors. The 8-bit resolution is adequate for temperature, position, and process-variable readouts where 1 LSB accuracy (»0.4% FS at 5V reference) is acceptable.
One design consideration is that the serial clock and chip-select timing must respect the 17-microsecond conversion budget; reading the previous conversion result overlaps with starting the next conversion in standard SPI mode 0, an efficient dual-purpose cycle that minimizes throughput overhead.
Drop-in alternatives for TLC549IDRG4 — 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 TLC549IDRG4 (same form factor and footprint) — differing in Conversion Time, Package, Resolution, RoHS Status, Data Interface.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
TLC549IDR
✅ Drop-In✓ In Stock
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View Datasheet →TLC549CD
✅ Drop-In✓ In Stock
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View Datasheet →TLC549CD
✅ Drop-In✓ In Stock
$1.02 / Unit
View Datasheet →TLC549IDRG4 Maximum Ratings & Electrical Characteristics
| Resolution | 8 bits |
| Sampling Rate | 40 kSPS |
| Number of Inputs | 1 single-ended |
| Architecture | SAR (Successive Approximation) |
| Data Interface | Serial (SPI / Microwire compatible) |
| Analog Supply Voltage | 3 V to 6 V |
| Digital Supply Voltage | 3 V to 6 V |
| Reference Inputs | Differential (REF+, REF-) |
| Conversion Time | 17 us max |
| Total Access and Conversion Time | 17 us max (per datasheet) |
| Supply Current (Active) | approximately 1.5 mA |
| Operating Temperature | -40C to +85C (industrial) |
| Package | 8-SOIC (D) 0.154 inch / 3.90 mm |
| Mounting Type | Surface Mount |
| Packaging | Tape & Reel (TR) |
| RoHS Status | Pb-free (G4 suffix) |
TLC549IDRG4 Pin Configuration
| Pin 1 | active-low CS — Chip select (active low); rising edge starts a new conversion |
| Pin 2 | AIN — Analog input |
| Pin 3 | REF- — Reference voltage negative input |
| Pin 4 | REF+ — Reference voltage positive input |
| Pin 5 | GND — Analog and digital ground |
| Pin 6 | DATA OUT — Serial data output (MSB first on first clock falling edge after CS low) |
| Pin 7 | I/O CLOCK — Serial clock input; data is clocked out on the falling edge |
| Pin 8 | VCC — Analog and digital supply (+3V to +6V) |
Typical Applications
TLC549IDRG4 is suitable for 6 applications: Battery Voltage Monitoring, Remote Sensor Read-back Interface, Digital Panel Meter, Industrial Process Control, Microcontroller Peripheral ADC, Portable Data Logger.
Battery Voltage Monitoring
Battery voltage monitoring for portable and battery-powered systems is a strong fit for the TLC549IDRG4 because of its low supply current and single-channel 8-bit resolution. The TLC549IDRG4 connects directly to a Li-ion or lead-acid battery through a resistive divider to VREF+ for full-scale scaling; the 17-microsecond conversion time means a host MCU can sample every few milliseconds while tracking cell voltage within roughly 20 mV accuracy at a 5V reference. Compared with dedicated battery-monitoring ICs, the TLC549IDRG4 keeps BOM cost low and adds flexibility: the host MCU can change the reference ratio in software to track charge curves across multiple chemistries.
Recommended
Remote Sensor Read-back Interface
Remote sensor read-back from 4-20 mA loops, thermistors, or strain gauges benefits from the TLC549IDRG4's differential reference and SPI interface. Place the TLC549IDRG4 at the sensor node with REF+ tied to a stable local reference (such as a TL431) and REF- at GND to scale the analog input to the sensor signal range; the three-wire serial interface allows a host microcontroller to daisy-chain multiple TLC549IDRG4 parts on independent CS lines for multi-point monitoring. The 8-bit resolution quantizing step is well-matched to industrial process variables where 1% accuracy is sufficient, and the 40 kSPS throughput supports oversampling to push effective resolution to 10-12 bits per TI datasheet recommendations.
Recommended
Digital Panel Meter
Digital panel meters for analog gauges, bench instruments, and consumer appliance displays benefit from the TLC549IDRG4's small 8-SOIC footprint and deterministic SAR conversion. The differential reference allows direct connection to scaled analog signals - for example, a current shunt amplified to a 0-4V span can be digitized using VREF- = 0V and VREF+ = 4.096V from a precision reference, mapping 1 LSB to 16 mV. The serial interface simplifies PCB layout by requiring only three traces to the display MCU, and 40 kSPS supports continuous update rates beyond the visible persistence of the meter. Estimated reference accuracy contribution: a 16 mV LSB at 4.096V reference means 0.4% absolute read-out accuracy per bit.
Recommended
Industrial Process Control
Industrial process-control signal conditioning channels use the TLC549IDRG4 for digitizing 4-20 mA loops, thermocouple amplifiers, and 0-10V analog control signals. The chip-select-controlled conversion start makes the TLC549IDRG4 easy to synchronize with mains-line zero-crossing events in industrial PLCs, and its wide -40C to +85C industrial operating range handles factory-floor temperatures. Mounting the TLC549IDRG4 directly on the PLC front-end board saves space versus multi-channel ADCs; a single SPI bus can serve eight or more TLC549IDRG4 parts with one MCU peripheral. Per TI datasheet ratings, the converter survives harsh 24V transient exposure through external TVS and resistor networks that scale the input to the 0-5V span.
Recommended
Microcontroller Peripheral ADC
Microcontroller peripheral ADC roles are the TLC549IDRG4's primary use case. The 3-wire SPI interface uses only three of the host MCU's GPIO pins, leaving UART, I2C, and timer peripherals free for other tasks. Because the TLC549IDRG4 starts a new conversion whenever CS goes high, the host can chain a fast read of the prior conversion result followed by an immediate start of the next sample - an efficient dual-purpose cycle for high-rate streaming. The 17-microsecond conversion time budget gives a throughput of approximately 40 kSPS in polled mode; combined with the 8-bit resolution, this is sufficient for vibration monitoring, audio level metering, and motor speed feedback in 8-bit MCU designs.
Recommended
Portable Data Logger
Portable data loggers that must digitize slow analog signals (temperature, pressure, humidity) over weeks of battery operation are a strong fit for the TLC549IDRG4. Per the TI datasheet, the device draws around 1.5 mA active and supports a power-down mode via the CS pin held high indefinitely, allowing duty-cycled sampling at very low average current (microampere range for 1 Hz sample rates). The 8-bit quantizing step of approximately 20 mV at a 5V reference is more than adequate for thermistor or humidity-sensor readouts where 0.5C or 2% RH resolution is acceptable. The compact 8-SOIC footprint and tape-and-reel packaging suit high-volume SMT assembly of consumer data-logger products.
Recommended
Recommended Products Summary
Engineering reference data for TLC549IDRG4 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | TLC549IDR | TLC549CD | TLC549C |
|---|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Package | 8-SOIC (D) | 8-SOIC (D) - same | 8-SOIC (D) - same | 8-SOIC (D) - same |
| Resolution | 8 bits | 8 bits | 8 bits | 8 bits |
| Sampling Rate | 40 kSPS | 40 kSPS | 40 kSPS | 40 kSPS |
| Operating Temperature | -40C to +85C (industrial) | -40C to +85C (industrial) | 0C to +70C (commercial) | 0C to +70C (commercial) |
| Conversion Time | 17 us max | 17 us max | 17 us max | 17 us max |
| Reference Inputs | Differential (REF+, REF-) | Differential (REF+, REF-) | Differential (REF+, REF-) | Differential (REF+, REF-) |
| Pb-free / RoHS | Yes (G4 suffix) | Yes (MATTE-SN standard reel) | Yes | Yes |
Key Differentiators
- Industrial temperature range with guaranteed operation (vs TLC549CD)
- Pb-free terminal finish with identical electricals (vs TLC549IDR)
- Compact SAR with differential reference in 8-SOIC (vs TLC549C (commercial variant))
Design Notes
Place a 0.1 microfarat ceramic bypass capacitor as close as possible to the VCC pin (pin 8) and a bulk 1 microfarat to 10 microfarat electrolytic nearby, per TI datasheet decoupling guidelines. Add a separate low-impedance AGND/DGND connection (a single ground plane suffices below 40 kSPS). Apply a stable reference voltage at REF+ and REF- with low source impedance; reference noise above the ADC input bandwidth directly couples into conversion results.
A common pitfall is treating REF+ and REF- as bypassed analog pins. They are full reference inputs that establish the conversion full-scale; their absolute accuracy directly determines INL and gain error. Drive REF+ with a low-noise reference such as TL431, REF145, or REF50xx and add a 0.1 microfarat + 10 microfarat local RC network at each reference pin. Also note that driving the active-low CS pin low does not start a conversion - the rising edge of CS starts conversion, while the falling edge enables the serial port to clock out the prior result.
Use short, impedance-controlled traces for I/O CLOCK and DATA OUT to avoid ringing on the falling clock edge that clocks out the data MSB. Keep digital traces away from the analog input AIN (pin 2); route AIN as a guard-bounded trace with a ground shield on one side to minimize digital-to-analog crosstalk. For best AC performance, place a small RC anti-alias filter (typically 1 kohm + 1 nF) at the AIN pin if the input bandwidth exceeds the Nyquist frequency for 40 kSPS operation.
Compliance Information
G4 suffix indicates Pb-free terminal finish. RoHS-compliant per TI datasheet ordering information. Not AEC-Q100 qualified (industrial-grade, not automotive). Halogen-free status not explicitly stated in retrieved data.
