Analog Devices Inc. AD7655ASTZRL

Overview

AD7655ASTZRL from Analog Devices is a low-cost, 4-channel, 16-bit, simultaneous-sampling SAR ADC with dual track-and-hold amplifiers, 500 kSPS throughput in normal mode, 0 V to 5 V analog input range, and parallel/serial (SPI/QSPI/MICROWIRE/DSP-compatible) interface - used in 3-phase power control and AC motor control systems requiring precise multichannel voltage/current acquisition.

For engineers reviewing the AD7655ASTZRL datasheet, AD7655ASTZRL pinout, AD7655ASTZRL application, or AD7655ASTZRL equivalent, key selection considerations include simultaneous dual-channel sampling capability, impulse-mode power scaling (2.6 mW at 10 kSPS), no pipeline delay, 48-lead LQFP package compatibility, and true differential input support via INA1/INB1 and INA2/INB2 pairs.

Technical Context

The AD7655ASTZRL implements a charge redistribution SAR architecture with two independent track-and-hold amplifiers enabling true simultaneous sampling across two differential input pairs. Its A0 multiplexer control selects between INA1/INB1 (A0 = LOW) or INA2/INB2 (A0 = HIGH), supporting 4-channel acquisition in one conversion cycle.

It features internal error correction, an integrated conversion clock, and dual interface modes: parallel 16-bit bus (with BYTESWAP and A/B channel select) and 2-wire serial (master/slave, configurable SYNC/SCLK/SDOUT timing). Power dissipation scales dynamically with throughput in impulse mode, dropping from 120 mW at 500 kSPS to 2.6 mW at 10 kSPS.

Key Specifications

Pinout & Package

AD7655ASTZRL is packaged in a 48-lead LQFP (Lead Quad Flat Package) with exposed pad grounded per datasheet Figure 4. Pin functions are validated per AD7655 Rev. E datasheet Table 6 and Figure 4 top-view layout.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7654ASTZ, AD7655ASTZRL adds 2 bits of resolution and 18 dB SFDR improvement at same speed; compared with AD7656ASTZ, it trades 2 channels and 250 kSPS for pin compatibility, 500 kSPS, and lower power - making AD7655ASTZRL optimal for cost-sensitive, space-constrained 4-channel industrial control upgrades.

Availability

AD7655ASTZRL is available at Aetrix Electronics and suitable for AC motor control, 3-phase power control, and uninterruptible power supplies requiring stable component supply, long-term industrial lifecycle support, and RoHS-compliant packaging.

Supply support for AD7655ASTZRL 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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA, with design centers worldwide and ISO 9001-certified manufacturing.

The AD7655ASTZRL belongs to Analog Devices' PulSAR® family of precision SAR ADCs, engineered specifically for industrial automation, motor control, and power quality monitoring where simultaneous sampling, low latency, and robust noise immunity are mandatory.

FAQ

What is the maximum sampling rate of the AD7655ASTZRL in normal mode?

The AD7655ASTZRL achieves a maximum throughput rate of 500 kSPS in normal mode, corresponding to a complete dual-channel conversion cycle every 2 µs. This specification is confirmed in the Rev. E datasheet Table 2 and applies to the AD7655ASTZRL in its specified operating conditions (AVDD = DVDD = 5 V, T = −40°C to +85°C). The part maintains full 16-bit accuracy and linearity at this rate.

Does the AD7655ASTZRL support true differential input configurations?

Yes, the AD7655ASTZRL supports true differential inputs via two independent pairs: INA1/INB1 and INA2/INB2. Each pair accepts a differential signal with 0 V to 5 V common-mode range and provides >92 dB channel-to-channel isolation at 100 kHz. The datasheet explicitly defines these as differential analog inputs (Table 6, Pin Descriptions), and the functional block diagram confirms dedicated front-end track-and-hold paths per pair.

How does impulse mode affect power consumption in the AD7655ASTZRL?

In impulse mode (IMPULSE = HIGH), the AD7655ASTZRL reduces power dissipation proportionally to throughput: 120 mW at 500 kSPS, 114 mW at 444 kSPS, and 2.6 mW at 10 kSPS. This behavior is measured and specified in Table 2 of the Rev. E datasheet under "Power Dissipation" and enables ultra-low-power operation during idle or diagnostic states without sacrificing resolution or accuracy.

Is the AD7655ASTZRL pin-to-pin compatible with any other Analog Devices ADCs?

Yes, the AD7655ASTZRL is pin-to-pin compatible with the AD7654ASTZ, as stated in the "Features" section and confirmed in the "Product Highlights" of the Rev. E datasheet. Both devices share identical 48-lead LQFP footprints, identical pin functions (including A0, SER/PAR, BUSY, EOC), and identical interface timing - enabling direct replacement to upgrade from 14-bit to 16-bit resolution without PCB modification.

What reference voltage options are supported by the AD7655ASTZRL?

The AD7655ASTZRL supports external reference voltages from 2.3 V to 2.5 V applied to the REF pin, with REFA and REFB allowing independent reference routing to Channel A and Channel B respectively. The datasheet specifies that VREF = 2.5 V is used for all AC/DC performance testing, and the reference current drain is 180 µA at 500 kSPS - confirming direct drive capability from precision references like ADR4525 or REF192.