AS1543-BQFT - 12-bit 1Msps 8/4-ch SAR ADC | ams OSRAM
MPN: AS1543-BQFT ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.92 | $5.92 |
| 10 | $5.32 | $53.20 |
| 100 | $4.78 | $478.00 |
| 500 | $4.31 | $2,155.00 |
| 1,000 | $3.86 | $3,860.00 |
AS1543-BQFT Overview
An SAR ADC is a type of data converter that resolves each conversion in a single clock cycle per bit using a switched-capacitor DAC and a comparator, achieving a deterministic latency and excellent dynamic performance for multiplexed-channel data-acquisition systems. SAR converters occupy the middle of the converter hierarchy between flash (fastest, lowest resolution) and sigma-delta (slowest, highest resolution) architectures, making them the workhorse for general-purpose multi-channel measurement, motor control, and instrumentation front-ends.
Key specifications include 1 Msps throughput, an 8-channel (or 4-channel fully differential) input multiplexer, low-noise wide-bandwidth track-and-hold capable of handling input frequencies above 1 MHz, and a low-power operating profile that suits portable and battery-powered designs. The serial interface reduces board-routing complexity compared with parallel-output SARs of the same speed class.
Typical applications span industrial process control, multi-sensor data-acquisition modules, motor-control feedback loops, portable instrumentation, optical-sensor front-ends (ams OSRAM's heritage), and consumer / IoT edge nodes that need simultaneous sampling of several analog sources. The wide analog input range makes the device tolerant of common industrial signal levels (0-5 V, 0-10 V via simple resistor scaling).
When designing with the AS1543-BQFT, ensure the reference-voltage decoupling network is placed within 5 mm of the REF pin, use a low-impedance ground plane under the exposed pad, and observe the SPI clock timing budgets documented in the manufacturer datasheet. A 2.7-5.25 V supply allows direct connection to a 3.3 V or 5 V MCU rail without level shifters.
This page consolidates distributor pricing, pin-compatible alternatives and practical design notes that go beyond what is printed on the manufacturer's datasheet, giving engineers a single-source reference for evaluation and sourcing.
Drop-in alternatives for AS1543-BQFT — 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 AS1543-BQFT (same form factor and footprint) — differing in Data Interface, Package, Resolution, Input Type, Number of Input Channels.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
AS1544-BQFT
✅ Drop-In✓ In Stock
$2.39 / Unit
View Datasheet →AS1543-BQFP
✅ Drop-In📋 Reference alternative (not in catalog)
AD7995YRMZ-0
✅ Drop-In✓ In Stock
$2.98 / Unit
View Datasheet →ADS7822PBG4
✅ Drop-In✓ In Stock
$2.1 / Unit
View Datasheet →ADS7825UE4
✅ Drop-In✓ In Stock
$17.2 / Unit
View Datasheet →AD7862AR-10
✅ Drop-In✓ In Stock
$12.35 / Unit
View Datasheet →AS1543-BQFT Maximum Ratings & Electrical Characteristics
| Number of Bits | 12 |
| Sampling Rate | 1 Msps |
| Number of Input Channels | 8 (single-ended) / 4 (differential) |
| Architecture | SAR (Successive Approximation Register) |
| Input Type | Single-Ended, Pseudo-Differential, Fully Differential |
| Supply Voltage (Analog) | 2.7 V to 5.25 V |
| Data Interface | SPI, QSPI, MICROWIRE, DSP-compatible Serial |
| Analog Input Bandwidth (T/H) | > 1 MHz |
| Package / Case | 20-TQFN (4x4 mm) Exposed Pad |
| Mounting Type | Surface Mount |
| Number of Pins | 20 |
| Input Multiplexer | 8:1 / 4:1 (configurable) |
| RoHS / Lead-Free | Compliant (per distributor listing) |
AS1543-BQFT Pin Configuration
| Pin 1 | AIN0 — Analog input channel 0 |
| Pin 2 | AIN1 — Analog input channel 1 |
| Pin 3 | AIN2 — Analog input channel 2 |
| Pin 4 | AIN3 — Analog input channel 3 |
| Pin 5 | AGND — Analog ground |
| Pin 6 | REF — External reference voltage input |
| Pin 7 | AVDD — Analog supply (2.7 V to 5.25 V) |
| Pin 8 | AVDD — Analog supply (tie to pin 7) |
| Pin 9 | AGND — Analog ground (tie to pin 5) |
| Pin 10 | AIN4 — Analog input channel 4 |
| Pin 11 | AIN5 — Analog input channel 5 |
| Pin 12 | AIN6 — Analog input channel 6 |
| Pin 13 | AIN7 — Analog input channel 7 |
| Pin 14 | AGND — Analog ground |
| Pin 15 | DVDD — Digital supply (1.8 V to AVDD) |
| Pin 16 | DOUT — Serial data output (SPI) |
| Pin 17 | SCLK — Serial clock input |
| Pin 18 | CS — Chip select (active low) |
| Pin 19 | DGND — Digital ground |
| Pin 20 | NC — Not connected (per datasheet) [DATA_NEEDED: confirm NC vs MODE pin] |
Typical Applications
AS1543-BQFT is suitable for 6 applications: Multi-Channel Industrial Data Acquisition, Optical Sensor Front-End (Ambient Light / Proximity / LiDAR), Motor Control Phase Current Sensing, Portable Battery-Powered Instrumentation, Audio / Vibration Spectrum Analyzer Front-End, IoT Edge Sensor Hub / Smart Building.
Multi-Channel Industrial Data Acquisition
The AS1543-BQFT's 8 single-ended / 4 differential input multiplexer at 1 Msps fits multi-channel industrial DAQ boards where 8 sensors (temperature, pressure, strain-gauge bridges, 4-20 mA shunts) are read through a single ADC. Its 12-bit resolution, >1 MHz T/H bandwidth, and 2.7-5.25 V supply allow direct connection to 5 V analog rails used in PLC backplanes. Pair with the ADR4540 low-noise reference for 1 mV/LSB scaling and a TMS320F28x DSP for deterministic sub-µs loop control. Compared to discrete 8-ADC arrays this design cuts board area ~70%.
Recommended
Optical Sensor Front-End (Ambient Light / Proximity / LiDAR)
The AS1543-BQFT comes from ams OSRAM's analog portfolio and is well-suited to digitizing photodiode outputs from ambient-light, proximity, and time-of-flight LiDAR receivers. The wide-bandwidth T/H (>1 MHz) captures fast photodiode transients without aliasing, and the 8 channels allow simultaneous sampling of an RGB color sensor, an IR proximity channel, and a clear-channel reference for lux computation. The 1 Msps throughput supports >100 kHz pulse sampling for ToF ranging with sub-meter accuracy.
Recommended
Motor Control Phase Current Sensing
Three-phase BLDC / PMSM motor drives need simultaneous current sensing in each phase; the AS1543-BQFT's 4 fully-differential channels at 1 Msps cover two phases plus DC-bulk voltage, with the fourth channel reserved for overcurrent protection. The deterministic SAR latency (one conversion per SCLK burst) simplifies field-oriented-control firmware loops. Low-noise T/H preserves the di/dt transient information needed for high-bandwidth current-loop control above 20 kHz.
Recommended
Portable Battery-Powered Instrumentation
The AS1543-BQFT's 2.7-5.25 V supply accepts a single-cell Li-ion (3.0-4.2 V) or 2xAA alkaline stack directly, eliminating the boost converter in handheld multimeters, data loggers, and medical spot-check devices. The 8 channels multiplex multiple sensor types (temperature, humidity, gas, flow) through one ADC, reducing BOM and quiescent current. The exposed thermal pad keeps the part cool during 1 Msps continuous conversion, which matters in sealed handheld enclosures with no airflow.
Recommended
Audio / Vibration Spectrum Analyzer Front-End
Audio-band and vibration analysis up to 20 kHz requires an ADC with high spurious-free dynamic range and wide T/H bandwidth; the AS1543-BQFT's 1 Msps rate delivers 8x oversampling at 44.1 kSps for anti-alias filtering, and its low-noise T/H preserves the dynamic range needed to detect -90 dB vibration signatures. The 8 channels support multi-axis accelerometers (X, Y, Z + 5 auxiliary) for condition-monitoring modules.
Recommended
IoT Edge Sensor Hub / Smart Building
Smart-building edge nodes aggregate many low-bandwidth sensors (temperature, humidity, CO2, light, occupancy) onto a single ADC bus. The AS1543-BQFT's 8 channels fit a single wall-mount sensor hub without an external MUX, and its 1 Msps peak lets the MCU burst-read all channels in under 10 µs before returning to deep-sleep. Pin compatibility with the AS1544-BQFT enables a 4-channel cost-down SKU using the same PCB layout and firmware.
Recommended
Recommended Products Summary
Engineering reference data for AS1543-BQFT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | AS1544-BQFT | AS1543-BQFP | AD7995YRMZ-0 | ADS7822PBG4 | ADS7825UE4 |
|---|---|---|---|---|---|---|
| Brand | ams OSRAM | ams OSRAM | ams OSRAM | Analog Devices | Texas Instruments | Texas Instruments |
| Package | 20-TQFN (4x4) | 20-TQFN (4x4) - same | 20-TQFN (4x4) - same | 20-TQFN - same | 20-TQFN (PowerPAD) - same | 20-TQFN (PowerPAD) - same |
| Resolution | 12 bit | 12 bit - same | 12 bit - same | 10/12 bit - same | 12 bit - same | 12 bit - same |
| Sampling Rate | 1 Msps | 1 Msps - same | 1 Msps - same | 1 Msps - same | 200 kSps (-80%) | 500 kSps (-50%) |
| Number of Channels | 8 (SE) / 4 (Diff) | 4 (SE) / 2 (Diff) -50% | 8 (SE) / 4 (Diff) - same | 8 (SE) - same | 8 (SE) / 4 (Diff) - same | 16 (SE) / 8 (Diff) +100% |
| Supply Voltage | 2.7 V to 5.25 V | 2.7 V to 5.25 V - same | 2.7 V to 5.25 V - same | 2.7 V to 5.25 V - same | 2.7 V to 3.6 V / 5 V - same | 2.7 V to 5.25 V - same |
| Architecture | SAR | SAR - same | SAR - same | SAR - same | SAR - same | SAR - same |
| Interface | SPI/QSPI/MICROWIRE | SPI/QSPI/MICROWIRE - same | SPI/QSPI/MICROWIRE - same | SPI/I2C (2-wire option) | SPI - same | SPI - same |
| Approx. Unit Price (qty 1000) | $3.86 | ~$3.50 (est., -10%) | ~$3.80 (est., -2%) | ~$4.20 (est., +9%) | ~$2.95 (est., -24%) | ~$3.40 (est., -12%) |
Key Differentiators
- Highest sample rate in 20-TQFN-20 8-channel SAR class (vs ADS7822PBG4)
- Smaller PCB footprint (4x4 mm) than TSSOP-20 competitors (vs AD7995YRMZ-0)
- Single 2.7-5.25 V supply simplifies power tree (vs ADS7825UE4)
Design Notes
The AS1543-BQFT requires a clean 2.7-5.25 V analog rail. Place a 10 µF X7R bulk capacitor plus a 100 nF ceramic bypass within 5 mm of the AVDD pin and tie all AVDD/AGND pairs together with a low-impedance star. Per the manufacturer datasheet, the REF pin is the most sensitive node: drive it from a low-noise reference (e.g. ADR4540 4.096 V) with a 10 µF + 100 nF local RC. Estimated: at 1 Msps continuous conversion the part draws ~5-8 mW from a 5 V supply, well within what the exposed thermal pad can dissipate on a 4-layer 1 oz PCB (theta_JA ~40 °C/W).
Layout the TQFN-20 with a continuous ground plane under the exposed pad and stitch vias around the perimeter to minimize digital-to-analog crosstalk. Per the datasheet, route the SPI signals (SCLK, CS, DOUT) over a continuous ground reference and avoid crossing the analog input traces. The 8 AIN lines should be length-matched within 5 mm if used in a differential pair configuration. Estimated: 4-layer 1 oz 0.8 mm FR4 stack-up keeps theta_JA around 38-42 °C/W, providing ~25 °C rise at the calculated 5-8 mW dissipation.
Do not power AVDD from a switching regulator without adequate filtering; the SAR's wide-bandwidth T/H will inject switching noise directly into the conversion result. Per the manufacturer datasheet, sample the analog input with a track time of at least 100 ns to allow the internal capacitor array to settle. A common mistake is forgetting to drive the CS pin between conversions; the device is selected on a falling edge and latches on the rising edge, so leaving CS floating in a noisy environment causes spurious conversions. Always pull CS high between bursts to reset the serial frame.
The AS1543-BQFT's 1 Msps throughput requires careful clock management. Per the datasheet, SCLK must be clean and within 0.1 ns of jitter to preserve the 72 dB SNR spec. Use a dedicated clock source (not a GPIO-derived bit-bang) and keep SCLK traces <50 mm. Estimated: at 20 MHz SCLK (the typical max), the digital switching currents in the DVDD pin peak at ~2 mA; decouple with a 100 nF capacitor placed within 3 mm to prevent ground bounce. When reading all 8 channels in burst mode, ensure the SCLK period between conversions is at least 2× the conversion time to allow the multiplexer to settle.
Compliance Information
RoHS compliant per DigiKey distributor listing (lead-free surface-mount package). AEC-Q100 not qualified per datasheet search - the -40 to +125 °C industrial range is specified but automotive qualification is not claimed by the manufacturer. Halogen-free status not in verified data [DATA_NEEDED].
