Analog Devices Inc. ADG3257BRQZ

Overview

ADG3257BRQZ from Analog Devices is a high-speed CMOS quad 2:1 bus switch (4-bit, 1-of-2 mux/demux) with bidirectional signal routing, 2 Ω on-resistance, 100 ps propagation delay, and single-supply operation at 3.3 V or 5 V. It enables level translation between 3.3 V/2.5 V and 5 V/3.3 V domains and is used in memory interleaving and bus isolation applications.

For engineers reviewing the ADG3257BRQZ datasheet, ADG3257BRQZ pinout, ADG3257BRQZ application, or ADG3257BRQZ equivalent, key selection criteria include its ultralow 1 nA quiescent current, 933 Mbps data rate capability, QSOP-16 package compatibility, and true bidirectional switching without added ground bounce noise.

Technical Context

The ADG3257BRQZ implements four independent 2:1 analog/digital bus switches controlled by two logic inputs: BE (active-low enable) and S (select). Each channel connects Port A to either B1 or B2 when enabled, with no directionality-signals pass identically in both directions.

Its CMOS process delivers low on-resistance matching (ΔRON ≤ 0.2 Ω), sub-nanosecond propagation delay matching (≤ 0.04 ns), and rail-to-rail blocking in the off state up to VCC. Power-off isolation ensures Port A and Port B remain disconnected when VCC = 0 V.

Key Specifications

Pinout & Package

ADG3257BRQZ is housed in a 16-lead QSOP (RQ-16) package with standard 3257-type pinout and 0.635 mm lead pitch. The package supports reflow soldering per JEDEC MO-137-AB and is RoHS compliant (Z suffix).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar bus switch applications.

Compared with SN74CBT3257PWR and TS3L501EPE4, ADG3257BRQZ uniquely supports dual-supply operation (3.3 V/5 V), offers 933 Mbps performance with 0.1 ns delay, and guarantees power-off isolation-making it the only option for mixed-voltage, high-speed, fail-safe bus switching.

Availability

ADG3257BRQZ is available at Aetrix Electronics and suitable for memory interleaving, processor-peripheral isolation, DDR bus multiplexing, and mixed-voltage test access requiring stable component supply across industrial temperature ranges.

Supply support for ADG3257BRQZ 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, communications, and aerospace markets.

The ADG3257BRQZ belongs to Analog Devices' high-speed bus switch product line, engineered specifically for low-latency, bidirectional signal routing in mixed-voltage digital systems with strict timing and isolation requirements.

FAQ

What is the maximum data rate supported by the ADG3257BRQZ?

The ADG3257BRQZ supports a maximum data rate of 933 Mbps, confirmed through eye diagram testing at both 3.3 V and 5 V supply voltages. This performance is achievable due to its 2 Ω on-resistance, 11 pF on-capacitance, and 0.1 ns propagation delay-enabling reliable operation in DDR2/3 memory interfaces and high-speed serial bus applications. The ADG3257BRQZ maintains signal integrity without requiring external termination or equalization.

Does the ADG3257BRQZ support level translation between 3.3 V and 2.5 V logic domains?

Yes, the ADG3257BRQZ supports bidirectional 3.3 V to 2.5 V level translation without external components when powered from 3.3 V. Its internal threshold limits output voltage to VCC − 1 V = 2.3 V (within 2.5 V logic high margin), as documented in Figure 17 of the Rev. E datasheet. This behavior is inherent to the device's CMOS architecture and requires no configuration-making the ADG3257BRQZ suitable for interfacing modern low-voltage peripherals with legacy 3.3 V controllers.

Can the ADG3257BRQZ be used with a 5 V supply to translate signals to a 3.3 V domain?

Yes, the ADG3257BRQZ can perform 5 V to 3.3 V level translation when powered from 5 V, but requires an external diode in series with the VCC pin to clamp internal gate voltage. As shown in Figure 15, a 0.7 V diode drops VCC to ~4.3 V, limiting output high voltage to approximately 3.3 V. This configuration is validated for bidirectional use and preserves the ADG3257BRQZ's 933 Mbps capability-enabling safe interfacing between 5 V FPGAs and 3.3 V microcontrollers.

What happens to the ADG3257BRQZ switches when VCC is removed?

When VCC is removed, the ADG3257BRQZ switches remain in the off state, providing guaranteed isolation between Port A and Port B. This power-off isolation prevents backfeeding, eliminates leakage paths, and avoids latch-up risk in hot-swap or power-sequencing scenarios. The behavior is intrinsic to the device's CMOS design and does not require external pull-downs or control logic-ensuring fail-safe operation even during brownout or uncontrolled power loss events involving the ADG3257BRQZ.

Is the ADG3257BRQZ pin-compatible with other industry-standard quad 2:1 bus switches?

The ADG3257BRQZ uses the standard 3257-type pinout defined in the datasheet (Figure 2), matching pin-for-pin assignments for VCC, GND, BE, S, and all A/B port terminals in the QSOP-16 package. This allows direct PCB footprint reuse with devices like the SN74CBT3257 and TS3L501E-but functional equivalence requires verification of on-resistance, timing, and level translation capability, as electrical performance differs significantly across vendors. The ADG3257BRQZ's 2 Ω RON and 0.1 ns tPD exceed those of most alternatives.