Analog Devices Inc. AD8561ARZ

Overview

AD8561ARZ from Analog Devices is a single ultrafast 7 ns rail-to-rail input comparator with latch function, operating from 3 V to 10 V single supply or ±5 V dual supply. It delivers matched rising/falling propagation delay (ΔtP ≤ 2.0 ns), 0.25 V low output voltage at 3.2 mA sink, and input common-mode range extending to ground. It is used in clock recovery circuits where duty-cycle preservation is critical.

For engineers reviewing the AD8561ARZ datasheet, AD8561ARZ pinout, AD8561ARZ application, or AD8561ARZ equivalent, key selection criteria include propagation delay matching over temperature, latch enable timing (tS = 1.0 ns, tH = 1.2 ns), input common-mode range (0 V to +3.0 V on single supply), and SOIC-8 package compatibility with LT1016 footprints.

Technical Context

The AD8561ARZ uses a PNP differential input stage enabling rail-to-rail common-mode operation down to ground, with typical input bias current of –3 μA flowing out of both inputs. Its latch circuit accepts TTL/CMOS-compatible logic thresholds (VIH ≥ 2.0 V, VIL ≤ 0.8 V) and provides data hold with 1 ns setup and 1.2 ns hold time.

Propagation delay is specified at 6.75–9.8 ns (200 mV step, 100 mV overdrive) and remains stable across –40°C to +85°C. Output drive capability supports 3.2 mA sink with VOL ≤ 0.25 V and 3.2 mA source with VOH ≥ 2.4 V, enabling direct interfacing with TTL and CMOS logic without pull-up resistors.

Key Specifications

Pinout & Package

AD8561ARZ is housed in an 8-lead narrow-body SOIC (R-8) package per JEDEC MS-012-AA, with 1.27 mm lead pitch and 5.00 mm × 4.00 mm body dimensions.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-speed comparator applications.

Compared with LT1016CN8#PBF and TLV3501CDR, AD8561ARZ uniquely combines sub-10 ns delay, integrated latch with nanosecond timing, and ground-sensing input in SOIC-8-enabling simpler, more deterministic clock recovery designs without external logic or level shifters.

Availability

AD8561ARZ is available at Aetrix Electronics and suitable for high-speed timing, clock distribution, and digital communications applications requiring stable component supply and industrial temperature support (–40°C to +85°C).

Supply support for AD8561ARZ 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, serving precision instrumentation, industrial automation, and communications markets.

The AD8561ARZ belongs to Analog Devices' high-speed comparator product line, designed specifically for timing-critical applications including clock recovery, line reception, and phase detection where propagation delay matching and latch synchronization are essential.

FAQ

What is the maximum input common-mode voltage for AD8561ARZ on a +5 V single supply?

The AD8561ARZ supports an input common-mode voltage range of 0 V to +3.0 V when operated on a +5 V single supply. Exceeding +3.0 V may increase input bias current and degrade propagation delay performance, as confirmed in Figure 8 of the datasheet. This limit is independent of the V+ supply voltage and applies strictly to the differential input pins (IN+ and IN−) referenced to GND.

Does AD8561ARZ require external pull-up resistors on its output pins?

AD8561ARZ does not require external pull-up resistors on its true output (Pin 7) because it features a push-pull output stage capable of sourcing 3.2 mA with VOH ≥ 2.4 V at +5 V. However, the complementary output (Pin 6) is open-collector–like and may need a pull-up if active-high logic is required. The datasheet confirms VOH and VOL specifications are guaranteed without external components under defined load conditions.

Can AD8561ARZ operate from a 3.3 V supply, and what are the output voltage levels?

Yes, AD8561ARZ operates from 3 V to 10 V single supply. At +3.3 V, the output low voltage (VOL) is guaranteed ≤ 0.3 V at 3.2 mA sink, and output high voltage (VOH) is ≥ 1.21 V at 3.2 mA source (per Rev. D datasheet, page 4). For improved VOH, a 5 kΩ pull-up to V+ is recommended per the "Increasing Output Swing" section, but it is not required for basic TTL/CMOS interfacing.

How does the latch function of AD8561ARZ behave during power-up or brownout conditions?

The AD8561ARZ latch input (Pin 5) has no internal power-on reset; its state is undefined until a valid logic high (≥2.0 V) or low (≤0.8 V) is applied. During brownout, if V+ drops below 3 V, the latch may release unpredictably due to degraded noise margins. The datasheet cautions that proper bypassing (1 μF + 10 nF per supply pin) is mandatory to maintain latch integrity during transient supply events.

Is AD8561ARZ pin-compatible with LT1016, and what layout changes are needed for replacement?

Yes, AD8561ARZ is pin-compatible with LT1016 in SOIC-8 (R-8) packaging. Layout changes are minimal: no PCB modifications are required. However, the wider input common-mode range (0 V to +3.0 V vs. +1.25 V to +3.5 V) and lower supply current (6.5 mA vs. 25 mA) allow removal of input level-shifters and reduction of thermal relief on power traces, as documented in the "Replacing the LT1016" application note.