ADC121S021CISDX - 12-Bit 50-200ksps SAR ADC | Texas Instruments
N.º de pieza: ADC121S021CISDX ✗ Fin de vida| Cant. | Precio unitario | Total |
|---|---|---|
| 1 | $2.94 | $2,94 |
| 10 | $2.65 | $26,50 |
| 100 | $2.36 | $236,00 |
| 500 | $2.1 | $1.050,00 |
| 1.000 | $1.85 | $1.850,00 |
ADC121S021CISDX Descripción general
A SAR ADC is a type of data converter that uses a binary-search successive-approximation algorithm to convert an analog input to a digital code in a fixed number of clock cycles, delivering deterministic latency and excellent dynamic performance without the pipeline delay of higher-speed flash or pipelined converters. SAR ADCs sit within the broader data-converter hierarchy as low-latency, low-power, medium-resolution samplers used in sensor, instrumentation, and control loops, and they form a key subclass of precision analog-to-digital converters in modern mixed-signal systems.
Key features of the ADC121S021 include ±1 LSB INL/DNL (max), a true no-missing-codes 12-bit output, an SINAD of 72 dB (typical at 200 ksps), a single-ended analog input span of 0 V to VREF (with VREF = V_A), an external reference or V_A supply, a 3-wire serial interface (CS, SCLK, DOUT), and a power-down mode that drops supply current to microampere levels between conversions. The wide supply range (2.7 V-5.25 V) makes the part compatible with both 3.3 V and 5 V microcontrollers.
The device uses a charge-redistribution DAC array and a high-speed comparator inside the SAR loop, clocked by the external SCLK input up to 20 MHz. Throughput scales linearly with SCLK frequency across the 50-200 ksps window, and the digital interface is independent of analog sampling rate, which simplifies host MCU firmware.
Typical applications include portable/battery-powered sensor digitizers, industrial process-control front ends, optical-module monitoring, low-cost instrumentation, and consumer audio/video signal monitoring. Designers pick this part for its tiny 6-pin WSON footprint, single-supply operation, and deterministic SPI behavior.
When designing with this device, place a 1 µF decoupling capacitor as close as possible to V_A and use the exposed thermal pad to lower θJA. A clean, low-impedance VREF (or simply tying REF to V_A) is essential to realizing full 12-bit performance. The original ADC121S021CISDX is now obsolete; the /NOPB lead-free and CISDX/NOPB reel-packaged variant is the recommended active replacement.
This page synthesizes distributor pricing, pin-compatible drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone, helping engineers select a 12-bit SAR ADC quickly and confidently.
Alternativas directas para ADC121S021CISDX — 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 ADC121S021CISDX (mismo factor de forma y huella) — difiere en Package, Resolution, RoHS Status, Architecture, Operating Temperature Range.
Herramienta de comparación rápida — seleccione piezas alternativas para compararlas lado a lado:
ADC121S021CISDX/NOPB
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
ADC121S021CIMFX/NOPB
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
ADC121S021CISD/NOPB
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
ADC121S021CISDX
✅ Sustitución directa✓ En stock
$1.85 / unidad
Ver hoja de datos →ADC121S021CISDX Valores máximos y características eléctricas
| Resolución | 12 bit |
| Number of Channels | 1 |
| Converter Type | SAR (Successive Approximation Register) |
| Sample Rate Range | 50 ksps to 200 ksps |
| Supply Voltage (V_A) | 2.7 V to 5.25 V |
| Supply Current (200 ksps, 3 V) | 1.4 mW typical |
| Analog Input Type | Single-ended (pseudo-differential) |
| Rango de tensión de entrada | 0 V to V_REF |
| Tensión de referencia | V_REF (external) or V_A |
| INL (max) | ±1 LSB |
| DNL (max) | +1.5 / -1 LSB |
| SINAD | 72 dB typical at 200 ksps |
| Serial Interface | SPI / QSPI / MICROWIRE-compatible (3-wire: CS, SCLK, DOUT) |
| SCLK Frequency (max) | 20 MHz |
| Encapsulado | 6-pin WSON (2.2 x 2.5 mm) with exposed thermal pad |
| Temperatura de funcionamiento | -40C to +85C (industrial) |
| Power-Down Current | Microampere-level (see datasheet) |
| Estado RoHS | Compliant (/NOPB variant) |
Configuración de pines de ADC121S021CISDX
| Pin 1 | VIN — Analog input (single-ended, 0 V to V_REF) |
| Pin 2 | GND — Ground return |
| Pin 3 | DOUT — Serial data output (SPI/QSPI/MICROWIRE) |
| Pin 4 | SCLK — Serial clock input (up to 20 MHz) |
| Pin 5 | CS — Active-low chip select |
| Pin 6 | V_A — Analog/digital supply (2.7 V to 5.25 V) |
| Pin EP | EPAD — Exposed thermal pad - tie to GND for thermal dissipation |
Aplicaciones típicas
ADC121S021CISDX es adecuado para 6 aplicacións: Portable Battery-Powered Sensor Digitizer, Industrial Process-Control Input Module, Optical Module Monitor (SFP/QSFP DOM), Low-Cost Handheld Instrumentation, Consumer Audio/Video Signal Monitoring, Automotive Sensor-Cluster Digitizer (non-safety).
Portable Battery-Powered Sensor Digitizer
The ADC121S021CISDX is well matched to portable sensor digitizers where 12-bit resolution at low sample rates is sufficient. With 1.4 mW typical power dissipation at 3 V and 200 ksps, plus a microampere power-down mode between conversions, it can run from a single Li-ion cell for months in duty-cycled temperature, pressure, or gas-sensor front ends. The 6-pin WSON (2.2 x 2.5 mm) footprint leaves room for surrounding analog signal conditioning on a tiny PCB.
Recomendado
Industrial Process-Control Input Module
In 4-20 mA or 0-10 V industrial input modules, the ADC121S021CISDX provides 12-bit (±1 LSB INL) digitizing of a single-ended analog signal with deterministic latency from its SAR architecture. The 2.7-5.25 V supply range accepts 3.3 V and 5 V backplanes, while the 50-200 ksps throughput handles multiplexed thermocouple, RTD, or strain-gauge bridges. The exposed thermal pad and 6-pin WSON simplify thermal management in sealed IP65 enclosures.
Recomendado
Optical Module Monitor (SFP/QSFP DOM)
Digital Diagnostic Monitoring (DOM) inside SFP and QSFP optical transceivers requires a low-power, small-footprint ADC for bias current, TX power, and received-power measurements. The ADC121S021CISDX's 6-pin WSON (2.2 x 2.5 mm) package, 12-bit resolution, and SPI interface up to 20 MHz match typical microcontroller companion chips in these modules. Power-down mode enables sub-mA standby between host polls.
Recomendado
Low-Cost Handheld Instrumentation
Handheld multimeters, data loggers, and bench instruments use the ADC121S021CISDX to digitize a single high-impedance analog channel with 12-bit accuracy at sample rates up to 200 ksps. The 3-wire SPI interface attaches directly to a low-cost MCU such as an MSP430 or Cortex-M0 without glue logic. The 1.4 mW power budget at 3 V permits battery-only designs running from two AA cells in series.
Recomendado
Consumer Audio/Video Signal Monitoring
In set-top boxes, A/V receivers, and TV-side monitoring ports, the ADC121S021CISDX samples audio-level, video-sync, or backlight-current sense nodes for housekeeping and protection. The 50-200 ksps window comfortably digitizes audio-band signals, while 12-bit resolution provides sufficient dynamic range for level meters. The WSON package and 1.4 mW power keep thermal and PCB real estate negligible inside space-constrained consumer enclosures.
Recomendado
Automotive Sensor-Cluster Digitizer (non-safety)
For non-safety body and chassis functions (e.g., seat-position, HVAC flap position, ambient light), the ADC121S021CISDX delivers 12-bit digitizing on a 6-pin WSON footprint that drops into cluster PCBs alongside a 3.3 V MCU. The -40 °C to +85 °C industrial temperature range covers cabin environments. Note: for ASIL-rated applications use the AEC-Q100-qualified ADC121S021-Q1 family variant instead.
Recomendado
Resumen de productos recomendados
Datos de referencia de ingeniería para ADC121S021CISDX — comparación, orientación de diseño e información de cumplimiento.
Guía de selección
Comparación con alternativas
| Parámetro | Este producto | ADC121S021CISDX/NOPB | ADC121S021CISD/NOPB | ADC121S021CIMFX/NOPB |
|---|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Package | 6-WSON (2.2x2.5) | 6-WSON (2.2x2.5) - same | 6-WSON (2.2x2.5) - same | 6-SOT-23 - different footprint |
| Resolution | 12 bit | 12 bit | 12 bit | 12 bit |
| Sample Rate | 50-200 ksps | 50-200 ksps | 50-200 ksps | 50-200 ksps |
| Supply Voltage | 2.7 V to 5.25 V | 2.7 V to 5.25 V | 2.7 V to 5.25 V | 2.7 V to 5.25 V |
| Interface | SPI up to 20 MHz | SPI up to 20 MHz | SPI up to 20 MHz | SPI up to 20 MHz |
| RoHS / Lead-Free | Non-RoHS (tin-lead, obsolete) | RoHS / lead-free (active) | RoHS / lead-free (active) | RoHS / lead-free (active) |
| Lifecycle | Obsolete | Active | Active | Active |
Diferenciadores clave
- WSON (2.2 x 2.5 mm) is the smallest 12-bit 200 ksps SAR footprint in TI's S021 family (frente a ADC121S021CIMFX/NOPB (SOT-23))
- Lead-free /NOPB finish enables modern RoHS-compliant builds (frente a ADC121S021CISDX (obsolete tin-lead base part))
- Single-channel SAR with deterministic latency vs sigma-delta settling delays (frente a Higher-channel-count pipelined ADCs)
Notas de diseño
Place a 1 µF X7R/X5R ceramic decoupling capacitor as close as possible to the V_A pin (Pin 6) with a short, wide trace to ground. The exposed thermal pad (EP) must be soldered to a grounded copper pour of at least 10 mm² to keep θJA within the datasheet spec. Avoid routing digital SCLK/DOUT traces parallel to the analog VIN trace to minimize digital-to-analog coupling.
Do not leave CS floating - it must be driven low to enable the serial interface and high to put the part in power-down. A floating CS can cause continuous conversion and elevated supply current. Use a 10 kΩ pull-up to V_A if the host MCU does not drive CS between conversions. Also ensure the SCLK line idles low, since the ADC samples on the SCLK rising edge.
For full 12-bit no-missing-codes performance, drive V_REF from a low-noise source. Tie V_REF to V_A when a 5 V supply is used, or use a dedicated shunt reference (e.g., TL431) when V_A is 3.3 V and the analog input swing must reach 3.3 V. Adding a 0.1 µF ceramic bypass right at the V_A pin suppresses high-frequency V_A ripple that would otherwise appear as conversion noise.
Información de cumplimiento
Base part ADC121S021CISDX is non-RoHS (tin-lead finish) and obsolete. The /NOPB variants are RoHS compliant and lead-free. Not AEC-Q100 qualified; use ADC121S021-Q1 family for automotive.
