Part A
AD7685BCPZRL7
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 4541 Stückzahl
- Package
- LFCSP-10
- Series
- Datenerfassung mit Analog to Digital Converters (ADC)
Replacement verdict
Compatible functional replacement candidate
The AD7685BCPZRL7 and AD7687BCPZRL are both 16-bit successive-approximation ADCs from the Analog Devices PulSAR family, sharing the same LFCSP-10 package and pinout, making them strong functional replacement candidates. The AD7687 offers a higher throughput rate of 250 kSPS versus 250 kSPS-class operation of the AD7685, while both deliver comparable INL and SINAD performance. Designers should validate the reference configuration and digital interface timing against their specific application requirements before final substitution.
Resolution
High match
Package Type
High match
Sampling Rate
Validation required
Interface Type
High match
Parts at a glance
Part B
AD7687BCPZRL
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 2962 Stückzahl
- Package
- VFDFN-10
- Series
- Datenerfassung mit Analog to Digital Converters (ADC)
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AD7685BCPZRL7 | AD7687BCPZRL | Why it matters |
|---|---|---|---|
| Resolution (bits) | 16 | 16 | Both are 16-bit ADCs, so resolution is identical and not a differentiator for substitutability. |
| Sampling Rate (max) | 250 kSPS | 250 kSPS | Identical throughput means either part can meet the same sampling bandwidth requirements. |
| Input Type | Pseudo-differential (single-ended) | True differential | Input topology differs; a true differential input rejects common-mode noise and requires different front-end driving circuitry than a pseudo-differential input. |
| Number of Input Channels | 1 | 1 | Both are single-channel devices, so channel count does not affect interchangeability. |
| Interface | SPI / DSP serial (QSPI, MICROWIRE, DSP compatible) | SPI / DSP serial (QSPI, MICROWIRE, DSP compatible) | Identical serial interface simplifies drop-in replacement at the digital interface level. |
| Supply Voltage (analog & digital) | 2.7 V to 5.5 V | 2.7 V to 5.5 V | Same supply range allows operation from the same rails without power redesign. |
| Package | 10-lead LFCSP (3 mm x 3 mm) | 10-lead LFCSP (3 mm x 3 mm) | Identical package and footprint enable direct PCB drop-in substitution. |
| INL (Integral Nonlinearity, max) | ±1.0 LSB typical | ±1.0 LSB typical | Matching linearity specs indicate comparable accuracy performance for precision measurement applications. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Same industrial temperature range means both parts suit the same environmental conditions. |
Need help validating a replacement?
Send your BOM and application constraints for technical and sourcing review.
Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7685BCPZRL7 | AD7687BCPZRL |
|---|---|---|
| Supplier | - | Analog Devices Inc. |
| Series | PulSAR® | PulSAR® |
| Part Status | Active | Obsolete |
| Number of Bits | 16 | 16 |
| Sampling Rate(Per Second) | 250k | 250k |
| Number of Inputs | 1 | 1 |
| Input Type | Pseudo-Differential | Differential |
| Data Interface | SPI, DSP | SPI, DSP |
| Configuration | S/H-ADC | S/H-ADC |
| Ratio - S / H: ADC | 1:1 | 1:1 |
| Number of A/D Converters | 1 | 1 |
| Architecture | SAR | SAR |
| Reference Type | External | External |
| Voltage - Supply, Analog | 2.3V ~ 5.5V | 2.3V ~ 5.5V |
| Voltage - Supply, Digital | 2.3V ~ 5.5V | 2.3V ~ 5.5V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
Frequently asked questions
What are the key differences between the AD7685BCPZRL7 and the AD7687BCPZRL?
The AD7685BCPZRL7 is a 16-bit, 250 kSPS PulSAR analog-to-digital converter, while the AD7687BCPZRL is a 16-bit, 250 kSPS PulSAR ADC with a different input structure: the AD7685 offers a pseudo-differential input with a single-ended input range of 0 V to VREF, whereas the AD7687 provides a true differential input. Both are pin-compatible in the 10-lead LFCSP package but differ in analog input configuration and therefore in signal-chain requirements.
Are the AD7685BCPZRL7 and AD7687BCPZRL pin-compatible and package-compatible?
Yes. Both devices are offered in the same 10-lead LFCSP (CP-10) package with identical pin assignments for the serial interface, reference, supply, and ground pins. The analog input pins (IN+ and IN−) are present on both, but their internal input structures differ, so board-level interchangeability requires verifying the analog front-end configuration.
Do the AD7685BCPZRL7 and AD7687BCPZRL have the same resolution and throughput?
Yes. Both are 16-bit successive-approximation register (SAR) ADCs with a maximum throughput of 250 kSPS. Both use the same PulSAR core architecture and provide a serial SPI-compatible interface, so resolution and sampling rate are identical between the two parts.
How do the analog input configurations of the AD7685BCPZRL7 and AD7687BCPZRL differ?
The AD7685BCPZRL7 has a pseudo-differential input: IN− is typically tied to a fixed potential (such as ground or a reference point), and the input range is 0 V to VREF on IN+. The AD7687BCPZRL has a true differential input, where IN+ and IN− are both actively driven and the converter digitizes the difference (IN+ − IN−) over the range −VREF to +VREF. This makes the AD7687 better suited to differential sensors and signals with common-mode content.
Can the AD7685BCPZRL7 and AD7687BCPZRL share the same external reference and supply voltages?
Yes. Both devices operate from a single 2.7 V to 5.5 V supply (VDD) and use an external reference applied to the REF pin, with the reference voltage setting the full-scale input range. The reference input structure and supply requirements are the same family-level design, so a common reference and supply rail can serve either part, provided the analog input configuration is matched to the chosen device.
Which part should be selected for a single-ended sensor interface versus a differential signal chain?
For a single-ended sensor whose output swings from 0 V to VREF, the AD7685BCPZRL7 is the appropriate choice because its pseudo-differential input directly accommodates a ground-referenced signal. For a differential source, such as a bridge sensor or a differential amplifier output, the AD7687BCPZRL is preferred because its true differential input rejects common-mode noise and uses the full ±VREF range.
Do both the AD7685BCPZRL7 and AD7687BCPZRL support the same digital interface and timing?
Yes. Both use a serial, SPI/QSPI/MICROWIRE/DSP-compatible interface with a similar pinout (SDI, SDO, SCK, CNV, and CS), and both are specified for the same 250 kSPS maximum conversion rate. The digital timing parameters are defined in the respective datasheets and are functionally equivalent for the serial readout, so a common digital host interface can be used with either device.
Are the AD7685BCPZRL7 and AD7687BCPZRL drop-in replacements for each other in an existing design?
They are not unconditional drop-in replacements. Although they share the same package, pinout, resolution, throughput, and supply/reference requirements, the analog input topology differs (pseudo-differential versus true differential). A design using the AD7685 with IN− tied to a fixed potential may not function correctly with the AD7687, and vice versa, unless the analog front-end and input drive are revalidated against the manufacturer datasheet.