Part A
AD7687BRMZ
Analog Equipment GmbH.
- Lifecycle
- Active
- Stock
- 2542 PCS
- Package
- MSOP-10
- Series
- Acquisition de données - Convertisseur analogique - numérique (ADC)
Replacement verdict
Compatible functional replacement candidate
The AD7685BRMZRL7 and AD7687BRMZ are both 16-bit successive-approximation ADCs from the same Analog Devices PulSAR family, sharing the MSOP-10 package and identical pinout, which makes them strong functional replacement candidates. The AD7687BRMZ offers a higher throughput rate of 250 kSPS versus 250 kSPS-class operation and a differential input architecture, while the AD7685BRMZRL7 provides a pseudo-differential input with a slightly lower sample rate. Designers should validate the input configuration, reference requirements, and timing margins against the target application before substituting, but the shared footprint and core architecture support a straightforward evaluation path.
Resolution and Architecture
High match
Package and Pinout
High match
Input Configuration
Validation required
Throughput Rate
Validation required
Parts at a glance
Part B
AD7685BRMZRL7
Analog Equipment GmbH.
- Lifecycle
- Active
- Stock
- 4839 PCS
- Package
- MSOP-10
- Series
- Acquisition de données - Convertisseur analogique - numérique (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 | AD7685BRMZRL7 | AD7687BRMZ | 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 acquisition bandwidth requirements. |
| Input Type | Pseudo-differential (single-ended) | True differential | Input topology differs; a true differential input offers better common-mode rejection and noise immunity, so the parts are not drop-in substitutes for all signal chains. |
| Number of Input Channels | 1 | 1 | Both are single-channel devices, so channel count does not affect substitutability. |
| Interface | SPI / QSPI / MICROWIRE / DSP compatible | SPI / QSPI / MICROWIRE / DSP compatible | Identical serial interface simplifies board-level replacement and firmware reuse. |
| 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 redesign. |
| Package | 10-lead MSOP (RM) | 10-lead MSOP (RM) | Identical package and pinout enable direct PCB footprint compatibility. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Same temperature rating means both suit the same industrial environments. |
| INL (Integral Nonlinearity, max) | ±1.0 LSB typical | ±1.0 LSB typical | Comparable linearity performance supports similar accuracy budgets in precision measurement designs. |
| Power Consumption (typical) | ~4 mW at 5 V, 250 kSPS | ~4 mW at 5 V, 250 kSPS | Similar power draw means thermal and supply design considerations remain unchanged. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7687BRMZ | AD7685BRMZRL7 |
|---|---|---|
| Series | PulSAR® | PulSAR® |
| Part Status | Active | Active |
| Number of Bits | 16 | 16 |
| Sampling Rate(Per Second) | 250k | 250k |
| Number of Inputs | 1 | 1 |
| Input Type | Differential | Pseudo-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 AD7685BRMZRL7 and the AD7687BRMZ?
Both are 16-bit, successive-approximation register (SAR) analog-to-digital converters from Analog Devices in a 10-lead MSOP package, but they differ in throughput and input architecture. The AD7685BRMZRL7 is specified for 250 kSPS, while the AD7687BRMZ is specified for 250 kSPS as well but features a differential input with a different analog input range and reference configuration. Designers should confirm the exact input span, reference requirements, and timing from the respective datasheets before interchange.
Are the AD7685BRMZRL7 and AD7687BRMZ pin-compatible?
Both devices are offered in the same 10-lead MSOP (RM) package, and Analog Devices documents them with a common pinout family for the 10-lead MSOP SAR converters. However, pin function assignments such as the analog input configuration and reference connections must be verified against each datasheet, because the AD7685 uses a pseudo-differential input while the AD7687 uses a fully differential input. Do not assume direct drop-in substitution without confirming the pin functions.
What is the resolution and throughput of each converter?
Both the AD7685BRMZRL7 and the AD7687BRMZ are 16-bit SAR ADCs. The AD7685 is specified at 250 kSPS, and the AD7687 is also specified at 250 kSPS. Both use a serial SPI-compatible interface for output data.
How do the analog input configurations differ between the two parts?
The AD7685 features a pseudo-differential input, where the IN+ and IN- inputs are converted with respect to a common-mode level, while the AD7687 features a fully differential input that converts the difference between IN+ and IN-. This difference affects the input drive circuitry, common-mode requirements, and the achievable signal-to-noise performance in a given application, so the analog front end must be designed for the specific part.
Do both parts support the same reference voltage and supply requirements?
Both devices operate from a single 2.7 V to 5.5 V supply (VDD) and use an external reference (REF) to set the full-scale input range. The reference voltage range and the resulting input span should be confirmed from each datasheet, since the input architecture differs between the pseudo-differential AD7685 and the fully differential AD7687. Verify the reference and supply decoupling requirements for the selected part.
Can the AD7685BRMZRL7 be used as a replacement for the AD7687BRMZ in an existing design?
Direct replacement is not recommended without validation. Although both are 16-bit, 250 kSPS SAR ADCs in a 10-lead MSOP package, the AD7685 has a pseudo-differential input and the AD7687 has a fully differential input, which changes the analog front-end requirements, common-mode handling, and transfer function. The designer must verify pin functions, input drive, reference configuration, and timing against both datasheets before considering substitution.
What interface do these converters use for digital communication?
Both the AD7685BRMZRL7 and the AD7687BRMZ provide a serial, SPI-compatible interface for reading conversion results. The interface uses a serial clock (SCK), a chip-select (CS) or conversion-start signal, and a data output (SDO), allowing connection to common microcontrollers and DSPs. Confirm the exact timing and mode requirements from the respective datasheet.