Part A
AD7685BRMZ
Công ty Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 1331 PCS
- Package
- TFSOP-10
- Series
- Data Acquisition - Analog to Digital Converters (ADC)
Replacement verdict
Compatible functional replacement candidate
The AD7685BRMZ and AD7688BRMRL7 are both 16-bit successive-approximation ADCs from Analog Devices in the same MSOP-10 package, sharing a compatible serial interface and reference architecture. The AD7688BRMRL7 offers a higher throughput rate and a wider analog supply range, making it a viable functional upgrade candidate for the AD7685BRMZ in most designs, provided the system timing and supply rails are validated against the higher sample rate and VDD requirements.
Resolution
High match
Package Type
High match
Sampling Rate
Validation required
Supply Voltage Range
Validation required
Parts at a glance
Part B
AD7688BRMRL7
Công ty Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 17 PCS
- Package
- MSOP-10
- Series
- Data Acquisition - 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 | AD7685BRMZ | AD7688BRMRL7 | Why it matters |
|---|---|---|---|
| Resolution (bits) | 16 | 16 | Both are 16-bit ADCs, so resolution is equivalent and does not affect substitutability. |
| Sampling Rate (max) | 250 kSPS | 500 kSPS | The AD7688 offers twice the throughput, which matters for higher-bandwidth signal acquisition. |
| Number of Input Channels | 1 (single-ended) | 1 (differential) | Single-ended vs differential input topology changes signal conditioning and noise performance requirements. |
| Input Type | Single-ended | Differential (pseudo-differential) | Differential inputs reject common-mode noise, so the two parts are not directly interchangeable in circuit design. |
| Supply Voltage (analog) | 2.7 V to 5.5 V | 4.5 V to 5.5 V | The AD7685 supports lower supply voltages, enabling 3.3 V operation that the AD7688 cannot. |
| Interface | SPI / QSPI / MICROWIRE / DSP compatible | SPI / QSPI / MICROWIRE / DSP compatible | Both use the same serial interface, so digital host compatibility is equivalent. |
| Package | 10-lead MSOP | 10-lead MSOP | Identical package and pinout simplify board-level substitution. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Same temperature range means environmental suitability is equivalent. |
| Power Consumption (typical) | 3.5 mW at 5 V, 250 kSPS | 15 mW at 5 V, 500 kSPS | The AD7688 consumes more power, which affects thermal and energy budget considerations. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7685BRMZ | AD7688BRMRL7 |
|---|---|---|
| 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 AD7688BRMRL7?
The AD7685BRMZ is a 16-bit, 250 kSPS PulSAR analog-to-digital converter, while the AD7688BRMRL7 is a 16-bit, 500 kSPS PulSAR ADC. Both are pin-compatible in the 10-lead MSOP package, but the AD7688 offers twice the throughput of the AD7685. The AD7685BRMZ is supplied in a tube, whereas the AD7688BRMRL7 is supplied in a 7-inch tape-and-reel format.
Are the AD7685BRMZ and AD7688BRMRL7 pin-compatible?
Yes. Both devices are offered in the same 10-lead MSOP (RM) package with identical pin functions, allowing the AD7688BRMRL7 to be used as a drop-in replacement for the AD7685BRMZ when the higher 500 kSPS throughput is required and the surrounding circuit is validated accordingly.
What is the maximum sampling rate of each device?
The AD7685BRMZ supports a maximum throughput of 250 kSPS, while the AD7688BRMRL7 supports up to 500 kSPS. Both are 16-bit successive-approximation PulSAR ADCs.
Do both parts support the same analog input range and supply voltage?
Yes. Both the AD7685BRMZ and AD7688BRMRL7 operate from a single 2.7 V to 5.5 V supply (VDD) with a separate VIO supply of 1.8 V to VDD for the digital interface, and both provide a differential analog input range of 0 V to VREF with a reference voltage from 0.5 V to VDD.
What digital interface do the AD7685BRMZ and AD7688BRMRL7 use?
Both devices use a SPI-compatible serial interface (CS and SCLK) with a serial data output (SDO) and a busy indicator (SDO or optional BUSY), supporting daisy-chain and cascaded operation. The interface logic level is set by the VIO supply.
How do the power consumption figures compare?
Both parts are specified for low power operation from a 2.7 V to 5.5 V supply. Because the AD7688BRMRL7 runs at up to 500 kSPS, its power consumption at full throughput is higher than that of the AD7685BRMZ at 250 kSPS; the AD7685BRMZ consumes proportionally less power at its lower maximum rate. Refer to the respective datasheets for exact mW figures at specific supply voltages and sample rates.
What are the package and ordering differences between the two part numbers?
Both are in the 10-lead MSOP (RM) package. The AD7685BRMZ suffix "Z" denotes RoHS-compliant lead-free construction and is supplied in tubes. The AD7688BRMRL7 suffix "RL7" denotes a 7-inch tape-and-reel packaging option, also RoHS-compliant. The core silicon and pinout are otherwise compatible.
Can the AD7688BRMRL7 replace the AD7685BRMZ in an existing design?
In most cases yes, because the devices are pin-compatible and share the same supply, reference, and interface architecture. However, the higher 500 kSPS throughput of the AD7688BRMRL7 requires that the digital host, reference drive, and analog front-end be capable of supporting the faster conversion timing. The replacement should be validated against the AD7688 datasheet timing specifications before production use.