AS1538-BTST - 12-Bit 8-Ch I2C ADC, 50ks/s, 16-TSSOP | ams OSRAM
N.º de pieza: AS1538-BTST ✓ Activo| Cant. | Precio unitario | Total |
|---|---|---|
| 1 | $6.5 | $6,50 |
| 10 | $5.85 | $58,50 |
| 100 | $5.1 | $510,00 |
| 500 | $4.55 | $2.275,00 |
| 1.000 | $4.05 | $4.050,00 |
AS1538-BTST Descripción general
An SAR ADC is a type of analog-to-digital converter that uses a binary-search successive-approximation algorithm against an internal precision DAC to determine the output code. SAR ADCs offer the best combination of low power, deterministic latency (one conversion = N clock cycles), and strong DC accuracy - they sit in the data-converter hierarchy alongside pipeline ADCs (high speed, high power) and sigma-delta ADCs (highest resolution, lowest bandwidth). The I2C interface enables connection to almost any microcontroller with only two wires, making the AS1538-BTST popular for adding analog sensing to low-pin-count MCUs.
Key features of the AS1538-BTST include 8 single-ended analog input channels selected by an internal analog multiplexer, 12-bit resolution with no missing codes, integrated track-and-hold, and selectable unipolar/bipolar input ranges via reference configuration. The 2.7-5.25 V single-supply operation covers both 3.3 V and 5 V system rails, and the TSSOP-16 footprint keeps board area under 35 mm². The companion part AS1540-BTST is the 4-channel version of the same die family for designs that only need fewer inputs.
Architecture-wise, the part uses a charge-redistribution SAR core with an internal reference input pin, allowing the user to supply a precision external reference for best DC accuracy or a low-cost reference for cost-sensitive designs. The I2C address is hardware-selectable via an address pin to allow multiple AS1538 devices on the same bus. This is a more efficient silicon use than discrete ADC + MUX designs because the multiplexer is integrated inside the same die, eliminating the need for a separate analog switch.
Typical applications include industrial process monitoring (multi-sensor data logging), portable medical instrumentation (battery-powered multi-channel measurements), consumer sensor hubs (multi-knob/multi-thermist-or reading via I2C), and HVAC / building-automation sensor interfaces. The wide supply range and small package also suit handheld multimeters and remote IoT sensor nodes powered by coin cells or 3.3 V system rails.
When designing with this part, ensure the analog and digital supplies are properly decoupled with 100 nF + 10 uF capacitors placed close to the AVDD and DVDD pins respectively, and that the reference pin is bypassed with a low-ESR 1-10 uF capacitor to preserve linearity at full-scale transitions. Power-on default state sets the input multiplexer to channel 0 and the I2C address to the value latched at the AD pin during the most recent reset.
This page synthesizes distributor pricing from DigiKey and Mouser, drop-in alternatives from the AS15xx and ADCAD/ADS series, and PCB-level design notes that are not consolidated in the manufacturer datasheet.
Alternativas directas para AS1538-BTST — mismo encapsulado, compatible pin a pin. Se excluyen las piezas de otro encapsulado que requieren retrabajo de la PCB.
Variantes de esta serie
Modelos de la misma serie compatibles directamente con AS1538-BTST (mismo factor de forma y huella) — difiere en Sampling Rate, Data Interface, Number of Input Channels, Package, Packaging.
Herramienta de comparación rápida — seleccione piezas alternativas para compararlas lado a lado:
AS1540-BTST
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
AS1538-BTSU
✅ Sustitución directa✓ En stock
$3.49 / unidad
Ver hoja de datos →AS1527-BSOT
✅ Sustitución directa✓ En stock
$2.55 / unidad
Ver hoja de datos →AS1538-BTST Valores máximos y características eléctricas
| Resolución | 12 bits |
| Number of Input Channels | 8 (single-ended) |
| Frecuencia de muestreo | 50 ks/s |
| Converter Architecture | SAR (Successive Approximation) |
| Data Interface | I2C (2-wire, address-selectable) |
| Analog Supply Voltage | 2.7 V to 5.25 V |
| Digital Supply Voltage | 2.7 V to 5.25 V |
| Input Type | Single-ended, pseudo-differential option |
| Encapsulado | 16-TSSOP (4.40 mm body width) |
| Tipo de montaje | Surface Mount |
| Packaging | Tape & Reel (TR suffix) |
| Rango de temperatura de funcionamiento | -40 C to +85 C |
| External Reference Pin | Yes (REFIN) |
| Track-and-Hold | Integrated |
| Estado RoHS | Compliant |
Configuración de pines de AS1538-BTST
| 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 | GND — Ground (analog/digital common) |
| Pin 6 | REFIN — External voltage reference input |
| Pin 7 | AVDD — Analog supply (2.7 V to 5.25 V) |
| Pin 8 | DVDD — Digital supply (2.7 V to 5.25 V) |
| Pin 9 | SCL — I2C clock |
| Pin 10 | SDA — I2C data (open-drain, requires pull-up) |
| Pin 11 | AD — I2C address-select (latched at reset) |
| Pin 12 | NC — Not connected (per datasheet) |
| Pin 13 | NC — Not connected (per datasheet) |
| Pin 14 | AIN4 — Analog input channel 4 |
| Pin 15 | AIN5 — Analog input channel 5 |
| Pin 16 | AIN6/AIN7 — Analog input channels 6 and 7 (multiplexed) |
Aplicaciones típicas
AS1538-BTST es adecuado para 6 aplicacións: Industrial Process Monitoring & Multi-Sensor Data Acquisition, Battery-Powered Portable Medical Instrumentation, HVAC and Building Automation Sensor Hubs, Handheld Digital Multimeters and Panel Meters, Industrial IoT Sensor Nodes with Coin-Cell Power, Audio and Power Amplifier Bias Monitoring.
Industrial Process Monitoring & Multi-Sensor Data Acquisition
The AS1538-BTST fits industrial process monitoring boards where multiple analog sensors (temperature via RTD/thermocouple amplifiers, pressure transducers, 4-20 mA loop shunts, flow meters) must be digitized and reported to a central PLC or SCADA host. Its 8 single-ended inputs cover typical 4-8 sensor count per node, and the 50 ks/s throughput suffices for control-loop feedback rates (typically 1-10 kHz per channel). The 2.7-5.25 V supply range tolerates the 24 V industrial bus after a downstream regulator, and the I2C bus lets a low-cost MCU consolidate all measurements with just two GPIO pins. Compared to a discrete ADC + 8:1 MUX solution, the integrated multiplexer inside the AS1538-BTST eliminates channel-to-channel crosstalk from external switches and reduces BOM and PCB area to a single 16-TSSOP footprint.
Recomendado
Battery-Powered Portable Medical Instrumentation
The AS1538-BTST is well matched to handheld medical instruments (pulse oximeter front-ends, multi-parameter patient monitors, glucose-meter reference designs) where multiple biosensor channels - SpO2 photodiode current, temperature, battery voltage, motion - must be digitized from a single 3 V lithium or 2x AA battery. Its 2.7 V minimum supply supports battery cut-off to 90% of nominal, and the I2C interface keeps the host MCU in low-power sleep between conversions. The 12-bit resolution (4096 codes) provides sufficient dynamic range for medically relevant sensor spans, and the integrated track-and-hold preserves accuracy on fast-changing SpO2 plethysmographic waveforms. The TSSOP-16 package is small enough to fit into a fingertip enclosure, and the -40 C to +85 C operating range tolerates refrigerated pharma storage environments.
Recomendado
HVAC and Building Automation Sensor Hubs
Commercial HVAC controllers, smart thermostats, and building automation sensor nodes can use the AS1538-BTST to digitize up to 8 analog signals from thermistors, humidity sensors, CO2 sensor analog outputs, occupancy PIR interface circuits, and supply voltage monitors. The wide 2.7-5.25 V supply permits operation from the same 24 VAC half-wave rectified rail as the rest of the HVAC controller (after regulation), eliminating a separate isolated supply. The I2C address-select pin allows multiple AS1538-BTST devices on a single MCU bus when more than 8 analog inputs are needed per controller. Compared to using multiple single-channel ADCs, the integrated 8:1 multiplexer saves PCB area in compact wall-mount thermostat enclosures and reduces MCU GPIO consumption to just two I2C wires.
Recomendado
Handheld Digital Multimeters and Panel Meters
Portable digital multimeters (DMMs), bench panel meters, and 4-20 mA loop displays can use the AS1538-BTST to digitize voltage, current (via shunt), and resistance (via ratiometric measurement) inputs in a single chip. The 12-bit SAR architecture provides a deterministic 1-conversion latency well suited to autoranging DMM front-ends that must digitize rapidly after a range-switch event. The external reference pin allows precision reference use for the highest accuracy ranges, while the integrated multiplexer routes any of the 8 measurement channels to the ADC core. The 16-TSSOP package fits into slim DMM enclosures, and the 50 ks/s conversion rate supports faster display update rates than the typical 3 conversions per second visible to the user.
Recomendado
Industrial IoT Sensor Nodes with Coin-Cell Power
Wireless IoT sensor nodes (Zigbee, LoRa, Bluetooth LE-based environmental sensors) can use the AS1538-BTST to digitize 4-8 analog sensor inputs while the host radio sleeps between transmissions. The 2.7 V minimum supply enables direct operation from a CR2032 or 2x AA battery pack, and the I2C interface allows the host MCU to wake the AS1538, take a burst of conversions, then return it to standby. The wide -40 C to +85 C operating range suits outdoor sensor enclosures (cold-chain monitoring, agriculture, weather stations) without additional thermal protection. The TSSOP-16 footprint keeps node PCB area minimal so the battery occupies the majority of the enclosure volume, extending operating life on a single coin cell to multi-year battery life targets.
Recomendado
Audio and Power Amplifier Bias Monitoring
Professional audio power amplifiers, Class-D amplifier output stages, and rack-mount amplifier banks can use the AS1538-BTST to digitize supply rail voltages, output current shunt signals, and temperature feedback from thermal sensors. The 8 channels allow a single ADC to monitor all rails in a multi-channel amplifier (e.g., 4 channels plus supplies and temperature = up to 8 channels per chip). The 50 ks/s sampling rate is sufficient for amplifier protection loops that react in milliseconds, and the I2C interface can be shared with the amplifier's main DSP/controller. Compared to dedicated amplifier monitor ASICs, a generic ADC like the AS1538-BTST provides flexibility - the protection thresholds are software-defined, allowing the same hardware to be reused across different amplifier product variants.
Recomendado
Resumen de productos recomendados
Datos de referencia de ingeniería para AS1538-BTST — comparación, orientación de diseño e información de cumplimiento.
Guía de selección
Comparación con alternativas
| Parámetro | Este producto | AS1540-BTST | AS1538-BTSU | AS1527-BSOT |
|---|---|---|---|---|
| Package | 16-TSSOP (Tape & Reel) | 16-TSSOP (Tape & Reel) - same | 16-TSSOP (Tube) - same | 8-SOIC - DIFFERENT (smaller) |
| Brand | ams OSRAM (formerly ams AG) | ams OSRAM - same brand | ams OSRAM - same brand | ams OSRAM - same brand |
| Resolution | 12 bits | 12 bits - same | 12 bits - same | 10 bits - lower |
| Number of Input Channels | 8 | 4 - fewer | 8 - same | 8 - same |
| Interface | I2C | I2C - same | I2C - same | I2C - same |
Diferenciadores clave
- Integrated 8-channel analog multiplexer eliminates external 8:1 switch (frente a ADS7822 family)
- Hardware address-select pin allows multiple AS1538-BTST devices on a single I2C bus (frente a ADS7822PBG4)
- Wide 2.7-5.25 V supply range covers both 3.3 V and 5 V rails (frente a 5 V-only competitor ADCs)
Notas de diseño
The AS1538-BTST has separate AVDD and DVDD pins; per the manufacturer datasheet both operate from the same 2.7-5.25 V range and should be powered from the same rail but with separate local decoupling. Place a 100 nF X7R 0402/0603 ceramic as close as possible to each of the AVDD (pin 7) and DVDD (pin 8) pins, and add a shared 10 uF X5R bulk capacitor at the regulator output. This dual-supply decoupling strategy is critical because any high-frequency noise on AVDD is digitized by the SAR comparator and appears as ADC output codes.
The I2C address of the AS1538-BTST is latched at the AD pin during reset (rising edge of DVDD per the datasheet). If the AD pin is left floating, the address is not deterministic. Always tie the AD pin to either GND or DVDD through a 100 kohm resistor (or directly, depending on datasheet section). For designs that need to change addresses dynamically, drive AD through an MCU GPIO before bringing DVDD up; otherwise the address latches at the wrong value and the bus returns NACK on every transaction.
For best linearity across all 8 input channels, place the AS1538-BTST away from switching converters, digital clocks, and high-current traces. Keep analog input traces short and surrounded by a ground pour on the same layer. Use a guard trace (driven from a low-impedance ground) between adjacent AIN pins when sensor input impedances exceed 1 kohm. The TSSOP-16 thermal pad is not internally connected - no thermal via stitching is required, but routing GND on the layer immediately beneath the IC keeps the analog ground reference low-impedance.
Estimated: At a 50 ks/s throughput and 12-bit resolution, the SAR core settles in roughly 1.6 us per conversion. The reference pin (REFIN, pin 6) is sensitive to dynamic loading during the bit-trial phase, so a 1-10 uF ceramic + 100 nF ceramic bypass on REFIN is recommended to preserve DNL within +/-1 LSB. The reference source impedance should be below 1 ohm at frequencies up to 1 MHz to prevent reference-voltage droop during the heaviest bit trials.
Información de cumplimiento
RoHS compliant per DigiKey / Mouser listings. Not AEC-Q100 qualified - not suitable for automotive under-hood applications. For automotive sensor hubs choose AEC-Q100 qualified parts from TI (ADS7822 family variants).
