Part A
AD7685BRMZ
Компания Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 1331 ПКС
- Package
- TFSOP-10
- Series
- Сбор данных - аналогово-цифровые преобразователи (ADC)
Replacement verdict
Compatible functional replacement candidate
The AD7685BRMZ and AD7686CRM share the same 16-bit SAR architecture, MSOP-10 footprint, and 5 V single-supply operation, making them functionally interchangeable in many designs. However, the AD7686CRM offers a faster 500 kSPS throughput versus 250 kSPS on the AD7685BRMZ, while the AD7685BRMZ provides a wider digital supply range and superior INL performance. Designers should validate timing margins and digital interface levels before substituting, but the two parts are strong functional replacement candidates for most precision data-acquisition applications.
Package Type
High match
Resolution
High match
Sampling Rate
Validation required
Digital Supply Voltage
Validation required
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AD7685BRMZ | AD7686CRM | Why it matters |
|---|---|---|---|
| Resolution | 16 bits | 16 bits | Both are 16-bit ADCs, so resolution is identical and not a differentiator for substitutability. |
| Sampling Rate | 250 kSPS | 500 kSPS | The AD7686 offers twice the throughput, which matters for higher-bandwidth signal acquisition. |
| Input Type | Pseudo-differential (single-ended) | Differential | Input topology affects signal conditioning, common-mode rejection, and board-level wiring. |
| Package | 10-lead MSOP | 10-lead MSOP | Same package footprint allows drop-in PCB compatibility. |
| Supply Voltage | 2.7 V to 5.5 V | 2.7 V to 5.5 V | Identical supply range means the same power rail can be reused. |
| Interface | SPI / QSPI / MICROWIRE / DSP compatible | SPI / QSPI / MICROWIRE / DSP compatible | Same serial interface simplifies firmware and host-controller reuse. |
| INL (Integral Nonlinearity) | ±1.0 LSB typical | ±1.0 LSB typical | Matching linearity ensures comparable accuracy in precision measurement applications. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Same temperature range supports use in identical industrial environments. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7685BRMZ | AD7686CRM |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC |
| Series | PulSAR® | PulSAR® |
| Part Status | Active | Obsolete |
| Number of Bits | 16 | 16 |
| Sampling Rate(Per Second) | 250k | 500k |
| Data Interface | SPI, DSP | SPI, DSP |
| Number of A/D Converters | 1 | 1 |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
| Number of Inputs | 1 | - |
| Input Type | Pseudo-Differential | - |
| Configuration | S/H-ADC | - |
| Ratio - S / H: ADC | 1:1 | - |
| Architecture | SAR | - |
| Reference Type | External | - |
| Voltage - Supply, Analog | 2.3V ~ 5.5V | - |
| Voltage - Supply, Digital | 2.3V ~ 5.5V | - |
Frequently asked questions
What are the key differences between the AD7685BRMZ and AD7686CRM?
The AD7685BRMZ is a 16-bit, 250 kSPS PulSAR ADC, while the AD7686CRM is a 16-bit, 500 kSPS PulSAR ADC. Both are offered in a 10-lead MSOP package and share a similar pinout, but the AD7686CRM provides twice the throughput of the AD7685BRMZ. The AD7685BRMZ is specified for operation from a 2.7 V to 5.5 V supply, whereas the AD7686CRM is specified for a 5 V supply.
Are the AD7685BRMZ and AD7686CRM pin-compatible?
Yes. Both devices are available in a 10-lead MSOP (RM) package and share the same pin configuration, including VDD, REF, IN+, IN-, GND, CNV, SDO, SCK, and SDI. This pin compatibility allows the AD7686CRM to be used as a higher-throughput drop-in replacement for the AD7685BRMZ, provided the system supply and timing requirements are met.
What is the maximum sampling rate of each device?
The AD7685BRMZ has a maximum throughput of 250 kSPS. The AD7686CRM has a maximum throughput of 500 kSPS. Both are successive-approximation register (SAR) ADCs with a PulSAR architecture and provide a 16-bit resolution with no missing codes.
What supply voltage does each ADC require?
The AD7685BRMZ operates from a single 2.7 V to 5.5 V supply (VDD). The AD7686CRM operates from a single 5 V supply. The digital interface supply (VIO) on both devices supports 1.8 V to 5 V logic, allowing direct connection to a variety of host processors and FPGAs.
Do both parts support the same serial interface?
Yes. Both the AD7685BRMZ and AD7686CRM use a SPI-compatible serial interface with a 3-wire or 4-wire configuration (CNV, SCK, SDO, and optional SDI). The interface is compatible with SPI, QSPI, MICROWIRE, and DSP host interfaces, and both devices support daisy-chaining of multiple ADCs on a single serial bus.
What is the analog input configuration of these ADCs?
Both the AD7685BRMZ and AD7686CRM feature a differential analog input with a pseudo-differential configuration, where the IN+ and IN- inputs are sampled against each other. The input range is 0 V to VREF, with the reference voltage applied externally to the REF pin. Both devices support a reference voltage range of 0.5 V to VDD.
Can the AD7686CRM replace the AD7685BRMZ in an existing design?
In many cases yes, because the two devices are pin-compatible and share the same package and serial interface. However, the AD7686CRM requires a 5 V supply and supports a higher throughput of 500 kSPS, so the designer must verify that the system supply, reference, and digital timing (including CNV pulse width and SCK frequency) are compatible with the faster device before substituting it.
What are the typical applications for these PulSAR ADCs?
Both the AD7685BRMZ and AD7686CRM are suited for battery-powered instruments, data acquisition systems, medical instrumentation, process control, and portable spectrum analyzers. The AD7685BRMZ's lower 250 kSPS rate and wider 2.7 V to 5.5 V supply range favor low-power portable designs, while the AD7686CRM's 500 kSPS throughput suits higher-speed data acquisition and multiplexed channel scanning applications.