Renesas IDTQS3800QG

Overview

IDTQS3800QG from Integrated Device Technology (IDT) is a 10-bit high-speed CMOS bus switch with precharged outputs, designed for live-insertion VME bus applications. It features 5 Ω bidirectional ON resistance, zero propagation delay, TTL-compatible I/O, and user-selectable VBIAS for B-port precharge. Operates across –40°C to +85°C industrial temperature range.

For engineers reviewing the IDTQS3800QG datasheet, IDTQS3800QG pinout, IDTQS3800QG application, or IDTQS3800QG equivalent, key selection criteria include precharge-enabled live insertion noise suppression, sub-1 ns turn-on/turn-off timing, 50 pF load switching performance, and QSOP-24 package compatibility with legacy VME backplane interfaces.

Technical Context

The IDTQS3800QG implements a single-enable-controlled 10-channel analog bus switch with independent A↔B bidirectional conduction when ON = LOW. Its internal architecture integrates undershoot clamp diodes on all I/O and control pins and supports external bias voltage (VBIAS) applied to precharge B-port lines during OFF state.

Switching behavior is defined by two distinct operational modes: conductive mode (RON ≈ 5 Ω at VIN = 0 V) and high-impedance precharge mode (B-port pulled to VBIAS). Timing parameters-including tPZL ≤ 7.5 ns and tPLZ ≤ 6.5 ns-are specified at C_L = 50 pF and R_L = 500 Ω under VCC = 5 V ±10%.

Key Specifications

Pinout & Package

Package: 24-pin Quarter Size Outline Package (QSOP), gull-wing leads, RoHS-compliant "QG" variant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with NB3N551DR2G and SN74CBT3384APW, the IDTQS3800QG uniquely delivers VBIAS-configurable B-port precharge-critical for minimizing transient noise during VME card insertion-while maintaining 5 V TTL compatibility and sub-1 ns propagation delay.

Availability

IDTQS3800QG is available at Aetrix Electronics and suitable for VME backplane interfaces, industrial PLC I/O modules, and automated test equipment signal routing requiring stable component supply over extended product lifecycles.

Supply support for IDTQS3800QG 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

Integrated Device Technology (IDT), now part of Renesas Electronics, is a fabless semiconductor company specializing in timing, memory interface, RF, and high-performance interconnect solutions.

The IDTQS3800QG belongs to IDT's QUICKSWITCH® family of high-speed bus switches, engineered specifically for live-insertion and hot-swap applications in industrial and military computing systems.

FAQ

What is the primary function of the VBIAS pin on the IDTQS3800QG?

The VBIAS pin on the IDTQS3800QG sets the precharge voltage level applied to the B-port lines during the OFF state. When the ON input is HIGH, the B-port is disconnected from A-port and actively pulled to the externally supplied VBIAS voltage (–0.5 V to VCC), minimizing signal transients during live insertion. This feature is essential for VME bus compliance and is not present in standard bus switches like the SN74CBT3384APW. The IDTQS3800QG requires a stable, low-noise VBIAS source to maintain clean precharge behavior.

Does the IDTQS3800QG support 3.3 V logic levels?

No, the IDTQS3800QG is specified for 5 V ±10% operation only and requires VCC = 4.5 V to 5.5 V. Its VIH (≥2 V) and VIL (≤0.8 V) thresholds are TTL-compatible, not LVTTL or LVCMOS. Driving the ON input or interpreting A/B port signals at 3.3 V violates absolute maximum ratings and may cause unreliable switching or latch-up. For 3.3 V systems, consider alternatives such as the SN74CBTD3384, but note that none replicate the IDTQS3800QG's VBIAS precharge functionality.

How does the IDTQS3800QG achieve zero propagation delay?

The IDTQS3800QG achieves effectively zero propagation delay because its 5 Ω ON resistance forms an RC network with typical load capacitance (e.g., 50 pF), yielding a time constant of ~0.25 ns-far shorter than standard logic edge rates. As confirmed in the datasheet, the device adds no measurable delay beyond inherent board trace and driver limitations. This behavior is verified under tPLH/tPHL = 0.25 ns typical conditions and distinguishes the IDTQS3800QG from conventional logic buffers or translators that introduce fixed gate delays. The IDTQS3800QG maintains signal integrity without timing compensation.

Can the IDTQS3800QG be used in place of a mechanical relay for signal switching?

Yes, the IDTQS3800QG serves as a solid-state replacement for mechanical relays in low-voltage (≤5 V), low-current (≤120 mA per pin) signal routing applications. Its 5 Ω RON, nanosecond switching, and absence of contact wear or bounce make it superior for high-cycle-count digital bus switching. However, it cannot handle AC signals, high voltages, or currents exceeding its absolute maximum ratings. Unlike relays, the IDTQS3800QG requires power (VCC) and control logic, and its bidirectional nature means signal direction is not enforced-designers must ensure external logic prevents bus contention. The IDTQS3800QG is not a drop-in relay substitute but a purpose-built high-speed digital bus switch.

Is the IDTQS3800QG pin-compatible with other QSOP-24 bus switches?

No, the IDTQS3800QG has a unique pinout optimized for VME backplane routing: A0–A9 occupy pins 1–10 and 13–14; B0–B9 span pins 12, 15–22; ON is pin 11; VBIAS is pin 24; VCC is pin 23; GND is pin 1. This layout differs from generic 10-bit switches like the SN74CBT3384APW (which places VCC/GND centrally and interleaves A/B pairs). Attempting PCB reuse without verification will result in misrouted signals and nonfunctional precharge. Always validate against the IDTQS3800QG top-view diagram-not generic QSOP footprints-when designing or reusing layouts.