Analog Devices Inc. AD8643ACPZ-REEL7

Overview

AD8643ACPZ-REEL7 from Analog Devices is a quad-channel, rail-to-rail output, precision JFET-input operational amplifier optimized for low-power, high-impedance signal conditioning. It delivers 250 µA max supply current per amplifier, 1 pA max input bias current, and 750 µV max offset voltage at 25°C, enabling accurate amplification in photodiode interfaces and precision current sensing circuits operating from 5 V to 26 V single supply or ±2.5 V to ±13 V dual supply.

For engineers reviewing the AD8643ACPZ-REEL7 datasheet, AD8643ACPZ-REEL7 pinout, AD8643ACPZ-REEL7 application, or AD8643ACPZ-REEL7 equivalent, key selection considerations include its 2.5 MHz gain bandwidth, unity-gain stability with >500 pF capacitive load drive, −40°C to +125°C extended industrial temperature rating, and LFCSP-16 (3 mm × 3 mm) package with exposed pad connected to V+.

Technical Context

The AD8643ACPZ-REEL7 implements a JFET-input stage delivering ultra-low input bias current (≤1 pA) and high input impedance (>10¹² Ω), critical for sensor front-ends where leakage must be minimized. Its rail-to-rail output swing (within 50 mV of rails at 1 mA load) and wide input common-mode range (0 V to 3 V on 5 V supply) support direct interfacing with CMOS DACs and ASICs in single-supply systems.

Designed for multichannel, thermally constrained environments, it maintains DC precision across temperature: offset voltage drift ≤2.5 µV/°C and guaranteed operation up to +125°C. The amplifier remains stable without phase reversal and exhibits robust PSRR (≥90 dB) and CMRR (≥74 dB) over frequency.

Key Specifications

Pinout & Package

The AD8643ACPZ-REEL7 is housed in a 16-lead, 3 mm × 3 mm LFCSP (CP-16-27) with exposed thermal pad that must be soldered to V+. Pin 1 is marked by a dot; the exposed pad is electrically connected to V+ and improves thermal performance (θ_JA = 81°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar precision op-amp applications.

Compared with OPA2182IDR and ADA4625-2ARZ, the AD8643ACPZ-REEL7 uniquely balances ultra-low input bias current, quad integration, and sub-1 mA total quiescent current - making it optimal for compact, thermally sensitive, multichannel precision analog front-ends where leakage and power are primary constraints.

Availability

AD8643ACPZ-REEL7 is available at Aetrix Electronics and suitable for photodiode amplification, precision current sensing, and medical instrumentation requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AD8643ACPZ-REEL7 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 R&D and manufacturing operations worldwide.

The AD864x family was designed specifically for low-power, high-precision signal conditioning in space- and energy-constrained systems - emphasizing JFET input performance, rail-to-rail output, and extended temperature reliability for industrial, medical, and test equipment.

FAQ

What is the maximum capacitive load the AD8643ACPZ-REEL7 can drive while remaining stable?

The AD8643ACPZ-REEL7 is specified to remain stable with capacitive loads exceeding 500 pF, as confirmed in the datasheet's "Typical Performance Characteristics" section (Figure 24–25). This eliminates the need for series isolation resistors in many ADC driver and filter applications. Stability is maintained across the full −40°C to +125°C temperature range and for supply voltages from 5 V to 26 V. No external compensation is required for loads ≤500 pF.

Does the AD8643ACPZ-REEL7 support true rail-to-rail input operation?

The AD8643ACPZ-REEL7 features rail-to-rail *output* swing but does not provide rail-to-rail *input* common-mode range. On a 5 V supply, its input common-mode voltage range is 0 V to 3 V (i.e., up to 2.5 V below V+). This allows direct interfacing with 0–3.3 V logic and DAC outputs but requires level-shifting for signals extending to V+. Input bias current remains ≤1 pA across this full range, preserving accuracy.

How is the exposed thermal pad on the AD8643ACPZ-REEL7 LFCSP package connected?

The exposed pad on the AD8643ACPZ-REEL7 (CP-16-27 package) is electrically connected to the V+ supply pin and must be soldered to a PCB copper plane tied to V+. This connection is mandatory for thermal performance (θ_JA = 81°C/W) and electrical stability. The datasheet explicitly states in Figure 6 notes: "EXPOSED PAD SHOULD BE CONNECTED TO V+". Leaving it floating or grounding it degrades thermal resistance and may cause parametric shift.

What is the guaranteed offset voltage specification for the AD8643ACPZ-REEL7 over temperature?

The AD8643ACPZ-REEL7 guarantees a maximum offset voltage of 1.5 mV over the full −40°C to +125°C operating temperature range, as stated in Table 1 (Electrical Characteristics, "−40°C < T_A < +125°C" row). At 25°C, the limit is tighter: 750 µV max. Offset voltage drift is further bounded at 2.5 µV/°C, ensuring predictable, linear drift behavior critical for calibration-reduced systems.

Can the AD8643ACPZ-REEL7 be used in single-supply 3.3 V systems?

The AD8643ACPZ-REEL7 is not characterized for reliable operation at 3.3 V supply. Its absolute minimum single-supply voltage is 5 V, per the "Single-supply operation: 5 V to 26 V" specification in the General Description. Attempting 3.3 V operation risks degraded parameters including reduced output swing, increased distortion, and potential failure to meet AC/DC specifications. For 3.3 V systems, consider the AD8605/AD8606/AD8607 family instead.