Diodes Incorporated PI4ULS5V108LEX

Overview

PI4ULS5V108LEX from Diodes Incorporated is an 8-bit bidirectional voltage level shifter supporting open-drain and push-pull interfaces without a direction pin, operating across VREFA = 0.95–4.5 V and VREFB = 1.8–5.5 V, with ≤8 Ω ON-state resistance at 3.3 V VREFA/5 V VREFB, 100+ MHz down-translation at ≤30 pF, and −40°C to +125°C operation - used in I²C, SMBus, and MDIO bus interfacing between mixed-voltage SoCs and peripherals.

For engineers reviewing the PI4ULS5V108LEX datasheet, PI4ULS5V108LEX pinout, PI4ULS5V108LEX application, or PI4ULS5V108LEX equivalent, key selection criteria include bidirectional translation flexibility per channel, EN-controlled high-impedance isolation, flow-through TSSOP-20 pinout for routing efficiency, and 5 V-tolerant I/O compatibility with TTL logic in industrial telecom systems.

Technical Context

The PI4ULS5V108LEX implements passive MOSFET-based bidirectional translation with no DIR control: when either port is LOW, the internal pass switch turns ON, enabling low-R_ON conduction; when both ports are HIGH, the switch remains OFF, isolating domains. Translation direction is determined dynamically by relative voltage levels on A and B sides.

VREFA and VREFB independently set domain reference voltages, enabling per-channel configurations such as 1.2 V ↔ 3.3 V and 2.5 V ↔ 1.8 V simultaneously. EN is referenced to VREFB and must be pulled HIGH via 200 kΩ to enable translation; at EN = LOW, all I/O pins enter high-impedance state for hot insertion support.

Key Specifications

Pinout & Package

PI4ULS5V108LEX is packaged in a 20-pin TSSOP (173 mil width) with flow-through pin arrangement optimized for minimal PCB trace crossovers and signal integrity. Pin numbering follows JEDEC MO-153 standard.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar bidirectional level translation applications.

Compared with TXS0108E and PCA9306, PI4ULS5V108LEX delivers superior design flexibility through DIR-less operation, per-channel VREF programming, 5 V I/O tolerance, and guaranteed 125°C performance - reducing system validation effort and enabling single-device solutions for multi-rail industrial and telecom platforms.

Availability

PI4ULS5V108LEX is available at Aetrix Electronics and suitable for I²C bus bridging, SMBus PMIC interfacing, MDIO PHY-MAC linking, and industrial sensor hub aggregation requiring stable component supply across automotive-grade temperature and long-lifecycle programs.

Supply support for PI4ULS5V108LEX 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability interface, power management, and signal integrity solutions for industrial, computing, and communications markets.

The PI4ULS5V108LEX belongs to Diodes' Pericom® ultra-low-distortion level translation product line, engineered specifically for high-speed, mixed-voltage digital interconnects in telecom infrastructure, enterprise storage, and ruggedized embedded systems.

FAQ

Can PI4ULS5V108LEX translate between 0.95 V and 5 V in a single channel?

Yes - it supports bidirectional translation from 0.95 V to 5 V using VREFA = 0.95 V and VREFB = 5 V. The device's architecture allows the lower-voltage domain to swing from 0 V to VREFA while the higher domain swings from 0 V to VREFB, with automatic direction sensing. This configuration is validated in the datasheet's voltage translation matrix and operates reliably at up to 40 MHz with 50 pF load.

What happens to the A/B ports when EN is driven LOW?

When EN is LOW (≤0.8 V), the internal pass switches disable completely, placing all A3–A10 and B11–B18 pins into a true high-impedance state (C_IO(off) = 4 pF typical). This prevents current leakage or bus contention during power sequencing, hot-swap events, or system sleep modes. The EN input is internally referenced to VREFB, so VREFB must be stable before asserting EN.

Is external pull-up resistor sizing required on both A and B sides for open-drain use?

Yes - for open-drain operation, pull-up resistors are mandatory on both A and B sides to establish valid HIGH logic levels. The minimum values depend on driver sink current (3/10/15 mA), VREFA/VREFB, and bus capacitance. Tables in the datasheet provide exact R_PU guidance; undersized resistors cause excessive power draw and slow rise times, while oversized ones increase susceptibility to noise and violate VIH/VIL thresholds.

Does PI4ULS5V108LEX support push-pull drivers on both sides simultaneously?

No - simultaneous push-pull operation on both A and B sides risks bus contention unless external direction control or 3-state logic is implemented. The device is designed for open-drain-to-open-drain or open-drain-to-push-pull topologies. If both sides use push-pull outputs, data must be strictly unidirectional or externally gated to avoid HIGH-to-LOW conflicts that could damage I/O structures.