AD7940BCPZ-RL7 - 14-bit 100kSPS SAR ADC | Analog Devices
N.º de pieza: AD7940BCPZ-RL7 ✓ Activo| Cant. | Precio unitario | Total |
|---|---|---|
| 1 | $11.5 | $11,50 |
| 10 | $10.35 | $103,50 |
| 100 | $9.2 | $920,00 |
| 500 | $8.05 | $4.025,00 |
| 1.000 | $7.25 | $7.250,00 |
AD7940BCPZ-RL7 Descripción general
A SAR ADC is a type of data converter that performs a binary search through an internal capacitive DAC to digitize an input voltage, achieving high accuracy at moderate sample rates without the pipeline latency of higher-speed flash or pipelined architectures. SAR ADCs sit within the broader hierarchy of analog-to-digital converters -> data converters -> signal chain ICs -> mixed-signal semiconductors, and are favored in multiplexed data acquisition, industrial control, and portable instrumentation where deterministic single-cycle latency and excellent DC accuracy are required.
The AD7940 distinguishes itself with low power dissipation (typically well under 1 mW at 3 V and 100 kSPS), a high-speed SPI-/DSP-compatible serial interface, and a versatile REF pin that allows the analog input range to be scaled to either the supply rail or an external reference. The 8-lead LFCSP package offers a compact 3 mm x 3 mm footprint with an exposed pad for thermal dissipation and low-impedance ground return.
Architecturally, the part uses a charge-redistribution capacitive DAC core calibrated for 14-bit linearity (DNL typically within +/-1 LSB and INL typically within +/-1.5 LSB), followed by an auto-zeroing comparator and on-chip error correction. Internal digital filtering and a flexible CNV (convert) input enable both standard SAR timing and a burst-mode chain operation for multi-device synchronization.
Typical applications include industrial process control and instrumentation, portable battery-powered measurement equipment, data acquisition front ends, optical module monitoring, and precision sensor signal chains. Its wide supply range (2.5 V to 5.5 V) makes it compatible with both 3.3 V and 5 V microcontrollers without level shifters.
When designing with the AD7940BCPZ-RL7, place the reference decoupling capacitor and the supply bypass capacitor as close as possible to the REF and VDD pins respectively, and tie the exposed pad to a clean analog ground plane. The part is specified for operation from -40 C to +85 C, suitable for industrial but not full automotive AEC-Q100 environments.
This page synthesizes distributor pricing, drop-in 8-pin LFCSP alternatives from Analog Devices, and practical design notes that go beyond the manufacturer datasheet to help engineers choose and apply the AD7940 quickly.
Alternativas directas para AD7940BCPZ-RL7 — mismo encapsulado, compatible pin a pin. Se excluyen las piezas de otro encapsulado que requieren retrabajo de la PCB.
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AD7940BCPZ
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AD7940BCPZ-RL7 Valores máximos y características eléctricas
| Resolución | 14 bit |
| Architecture | SAR (Successive Approximation Register) |
| Number of Inputs | 1 |
| Sampling Rate (Throughput) | 100 kSPS |
| Input Type | Single-ended (pseudo-differential via REF pin) |
| Supply Voltage (Analog and Digital) | 2.5 V to 5.5 V |
| Interfaz | SPI / DSP-compatible serial |
| Reference | External or supply-referred (REF pin) |
| Encapsulado | 8-LFCSP (3 mm x 3 mm) with exposed pad |
| Tipo de montaje | Surface Mount |
| Temperatura de funcionamiento | -40 C to +85 C |
| Estado RoHS | Compliant |
Configuración de pines de AD7940BCPZ-RL7
| Pin 1 | GND — Analog ground |
| Pin 2 | VDD — Analog supply (2.5 V to 5.5 V) |
| Pin 3 | VIO — Digital I/O supply |
| Pin 4 | REF — Reference voltage input / analog input span |
| Pin 5 | AIN — Analog input |
| Pin 6 | CNV — Convert input / chip select |
| Pin 7 | SDO — Serial data output |
| Pin 8 | SCK — Serial clock input |
Aplicaciones típicas
AD7940BCPZ-RL7 es adecuado para 6 aplicacións: Industrial Process Control & Data Acquisition, Portable Battery-Powered Measurement, Optical Module Monitoring & Bias Control, Precision Sensor Signal Chain Front End, Medical Patient Monitoring, General-Purpose Data Acquisition Module.
Industrial Process Control & Data Acquisition
The AD7940BCPZ-RL7 fits industrial process control because its 14-bit resolution and 100 kSPS throughput digitize 4-20 mA loop signals and thermocouple/bridge outputs with sufficient accuracy for closed-loop control. The 8-LFCSP footprint is compact enough to mount in DIN-rail PLC analog input modules where board space is at a premium. SPI connectivity drops directly into ARM Cortex-M PLC host processors without glue logic, and the -40 C to +85 C industrial temperature rating covers factory-floor environments.
Recomendado
Portable Battery-Powered Measurement
The AD7940BCPZ-RL7 is well suited to portable battery-powered measurement because its 2.5 V to 5.5 V single-supply operation draws very low quiescent current (typically well under 1 mW at 3 V and 100 kSPS), extending runtime on Li-ion coin cells. The SAR architecture provides single-cycle deterministic conversion, simplifying firmware timing in handheld digital multimeters and field data loggers. Its small 8-LFCSP (3x3 mm) package also fits inside Bluetooth Low Energy sensor pods and wearable health monitors.
Recomendado
Optical Module Monitoring & Bias Control
The AD7940BCPZ-RL7 fits optical module monitoring because its 100 kSPS throughput is more than adequate to digitize photodiode current-sense amplifiers and laser-bias monitor signals in SFP/QSFP modules. The single-ended analog input with a flexible REF pin accepts either the module's 3.3 V rail or an external reference for high-accuracy laser threshold tracking. Its small LFCSP-8 footprint fits in the constrained PCB area inside pluggable optics where every square millimeter matters.
Recomendado
Precision Sensor Signal Chain Front End
The AD7940BCPZ-RL7 fits precision sensor signal chain front ends (load cells, strain gauges, RTDs) because its 14-bit resolution provides adequate dynamic range after the front-end instrumentation amplifier for weighing scales and pressure transducers. The integrated track-and-hold amplifier removes the need for an external sample-and-hold, reducing BOM cost. Its low-noise reference path supports ratiometric measurement with bridge-type sensors, improving rejection of supply and temperature drift.
Recomendado
Medical Patient Monitoring
The AD7940BCPZ-RL7 fits medical patient monitoring equipment such as infusion pumps, blood-pressure monitors, and pulse-oximetry front ends because its low power dissipation keeps thermal rise inside small plastic enclosures. The deterministic SAR latency avoids the pipeline-delay artifacts of higher-speed ADCs, simplifying ECG front-end signal processing. Combined with the industrial -40 C to +85 C rating, it is qualified for the operating environments of bedside and ambulatory medical devices.
Recomendado
General-Purpose Data Acquisition Module
The AD7940BCPZ-RL7 fits general-purpose data acquisition modules because its 100 kSPS single-channel SAR performance hits the sweet spot for USB- and Ethernet-connected DAQ boards targeted at laboratory and educational markets. The SPI interface allows up to 8-16 channels to be multiplexed using an external analog switch with synchronized conversion, and the compact LFCSP-8 package keeps the analog-input stage small. Combined with a low-cost reference like the ADR01, a complete 14-bit DAQ channel can be built with minimal external parts.
Recomendado
Resumen de productos recomendados
Datos de referencia de ingeniería para AD7940BCPZ-RL7 — comparación, orientación de diseño e información de cumplimiento.
Guía de selección
Comparación con alternativas
| Parámetro | Este producto | AD7940BCPZ | AD7693BCPZRL | AD7680BRMZ-REEL |
|---|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | 8-LFCSP (3x3 mm) | 8-LFCSP (3x3 mm) - same | 10-LFCSP (3x3 mm) - different | MSOP-10 - different |
| Resolution | 14 bit | 14 bit | 18 bit (upgrade) | 16 bit (upgrade) |
| Throughput | 100 kSPS | 100 kSPS | 500 kSPS (5x faster) | 100 kSPS (same) |
| Supply Voltage | 2.5 V to 5.5 V | 2.5 V to 5.5 V | 2.5 V to 5.5 V | 2.5 V to 5.5 V |
| Interface | SPI / DSP serial | SPI / DSP serial | SPI / DSP serial | SPI / DSP serial |
| Pin Compatibility | Reference | Yes (drop-in) | No - different pin count | No - different package |
| Operating Temperature | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C |
Diferenciadores clave
- Smallest-package 14-bit/100 kSPS SAR ADC in Analog Devices' portfolio (frente a AD7680BRMZ-REEL)
- Lower cost than the 18-bit AD7693 family for true 14-bit applications (frente a AD7693BCPZRL)
- Versatile REF pin enabling both supply-referred and external-reference modes (frente a AD7940BCPZ)
Notas de diseño
Power the AD7940BCPZ-RL7 from a clean analog rail. Place a 10 uF ceramic bypass capacitor as close as possible to the VDD pin and a 0.1 uF decoupling capacitor in parallel for high-frequency noise suppression. The reference voltage (REF) should also be heavily bypassed - typically with a 10 uF ceramic - because reference noise couples directly into the conversion result and degrades SNR at 14-bit resolution. Avoid routing digital lines directly under the analog power section to prevent switching noise injection.
Solder the exposed thermal pad (EP) of the LFCSP-8 to a continuous analog ground plane to provide a low-impedance thermal and electrical return path. Use a 4-layer stack-up with the analog ground plane on layer 2 directly beneath the top-side analog traces. Keep analog input traces short, guarded by GND on either side, and never run digital signals (SCK, SDO, CNV) parallel to AIN for more than a few millimeters to minimize crosstalk and preserve the ADC's SNR.
Estimated: the part's analog input range is 0 V to REF (not 0 V to VDD) when REF is driven by an external reference - misreading the datasheet and connecting AIN above REF will saturate or damage the converter. Also, the -RL7 suffix means tape-and-reel; do not order -RL7 for prototype builds that require cut-tape or tube, and instead order AD7940BCPZ (tray). Finally, the part is industrial-grade (-40 C to +85 C), not AEC-Q100 automotive; for under-hood automotive applications, select an ADI automotive-qualified SAR ADC.
For the SCK digital input, route it as a controlled-impedance trace and keep it short to avoid ringing; SCK frequencies above 30 MHz in noisy environments may require a series-termination resistor. The SDO output impedance is typically tens of ohms, so a small series resistor (33 ohm) near the ADC can help if the trace to the host MCU is long. Ensure the host MCU's SPI mode is configured correctly - the AD7940BCPZ-RL7 typically expects SPI mode 1 (CPOL=0, CPHA=1) or mode 2; check the datasheet's timing diagram for the exact configuration required by your firmware.
Información de cumplimiento
RoHS compliant and lead-free per Analog Devices product page. AEC-Q100 NOT qualified (industrial grade only); choose an ADI automotive-qualified SAR ADC for automotive applications. Halogen-free per the LFCSP package family.
