Analog Devices Inc. AD4685BCPZ-RL

Overview

AD4685BCPZ-RL from Analog Devices is a 16-bit, dual simultaneous sampling SAR ADC with 4 single-ended analog inputs, 500 kSPS throughput, ±1.5 LSB INL (typ), and integrated 2.5 V reference (10 ppm/°C max) in a 3 mm × 3 mm LFCSP package - used for high-precision motor current sensing and position feedback in industrial servo drives.

For engineers reviewing the AD4685BCPZ-RL datasheet, AD4685BCPZ-RL pinout, AD4685BCPZ-RL application, or AD4685BCPZ-RL equivalent, this page delivers verified specifications, real-world timing behavior, channel isolation performance, oversampling configuration impact on SNR, and validated alternative options for dual-channel precision data acquisition systems.

Technical Context

The AD4685BCPZ-RL implements two independent SAR cores with shared 4:2 multiplexer and hardware sequencer, enabling true simultaneous sampling of two channel pairs (AINA0/AINA1 and AINB0/AINB1). Its internal 2.5 V reference buffer supports external use via REFIO, while the separate VLOGIC supply (1.65 V–3.6 V) ensures compatibility with 1.8 V/2.5 V/3.3 V digital interfaces.

Oversampling is implemented via on-chip rolling average logic (OSR_MODE = 1), configurable up to OSR = 8, delivering 93 dB SNR at 100 kHz input with RES = 1 and internal 2.5 V reference - without requiring external DSP resources. Aperture jitter is specified at 20 ps, and channel-to-channel isolation reaches −109.7 dB.

Key Specifications

Pinout & Package

AD4685BCPZ-RL is housed in a 16-lead, 3 mm × 3 mm lead frame chip scale package (LFCSP) with exposed pad (EPAD) requiring GND connection for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-channel simultaneous sampling ADC applications.

Compared with AD4685BCPZ-RL, AD4684BCPZ-RL offers double throughput in same footprint for latency-critical control, while AD7616BSTZ trades dual-pair simultaneity for higher channel density and simpler register mapping - making AD4685BCPZ-RL optimal for compact, precision dual-signal acquisition where timing alignment is non-negotiable.

Availability

AD4685BCPZ-RL is available at Aetrix Electronics and suitable for motor control position feedback, sonar time-of-flight measurement, and power quality monitoring requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AD4685BCPZ-RL includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, founded in 1965 and headquartered in Wilmington, MA.

The AD468x family targets high-accuracy, low-latency industrial data acquisition - specifically engineered for simultaneous dual-channel sampling in motor control, energy metering, and test equipment where timing integrity and thermal stability are critical.

FAQ

What is the maximum sampling rate supported by the AD4685BCPZ-RL?

The AD4685BCPZ-RL supports a maximum throughput rate of 500 kSPS in single-channel-pair mode (SEQ = 0) and 250 kSPS in alternating-channel mode (SEQ = 1). This is confirmed in Table 1 of the Rev. A datasheet under "THROUGHPUT" with test condition AD4685. The device achieves this rate while maintaining 16-bit resolution, ±1.5 LSB INL, and 93 dB SNR with oversampling enabled - making it suitable for demanding closed-loop control applications where timing alignment between dual channels is essential.

Does the AD4685BCPZ-RL include an internal voltage reference?

Yes, the AD4685BCPZ-RL integrates a buffered 2.5 V internal reference with a maximum temperature coefficient of 10 ppm/°C and 7 µV_rms noise. This reference is accessible via the REFIO pin and can be used externally when configured correctly via the REFSEL bit in CONFIGURATION1. When using the internal reference, a 0.1 µF capacitor must be placed on REFIO, and the REFIO pin must be decoupled with a 1 µF capacitor to GND - as specified in Table 6 and Figure 33 of the datasheet.

Can the AD4685BCPZ-RL operate with a 1.8 V digital interface?

Yes, the AD4685BCPZ-RL supports 1.8 V digital interfaces through its dedicated VLOGIC supply pin (Pin 2), which accepts voltages from 1.65 V to 3.6 V. Logic levels are defined as VIL = 0.2 × VLOGIC and VIH = 0.8 × VLOGIC, ensuring reliable operation at 1.8 V. This eliminates the need for external level shifters when interfacing with 1.8 V FPGAs or microcontrollers - a key advantage confirmed in the "DIGITAL INPUTS" section of the Rev. A datasheet.

How does the oversampling feature improve performance in the AD4685BCPZ-RL?

The AD4685BCPZ-RL's on-chip oversampling block implements rolling average with configurable OSR up to 8, improving SNR by up to 5.5 dB (from 87.5 dB to 93 dB) and increasing effective resolution to 18 bits when OSR = 8 and RES = 1. This reduces post-processing load on host processors and lowers required SCLK frequency - directly easing timing constraints in resource-constrained embedded systems, as validated in Figure 11 and Table 1 of the datasheet.

What is the operating temperature range for the AD4685BCPZ-RL?

The AD4685BCPZ-RL is rated for operation from −40°C to +125°C, as stated in the General Description and Absolute Maximum Ratings sections of the Rev. A datasheet. This extended temperature range is fully characterized for all key parameters including INL (±1.5 LSB typ), gain error drift (±1 ppm/°C), and reference voltage stability (2.496 V to 2.505 V over temperature), making it suitable for under-hood automotive, industrial motor drives, and outdoor power electronics.