STMicroelectronics DA108S1RL

Overview

DA108S1RL from STMicroelectronics is an 8-diode ESD protection array in SO-8 package, configured as four dual-diode cells for bidirectional transient clamping on digital I/O lines. It delivers 15 kV air/8 kV contact ESD immunity per IEC 61000-4-2 Level 4, 18 V repetitive peak reverse voltage, and 12 A 8/20 µs surge current handling - deployed in ISDN S-interface logic-side protection and microcontroller I/O port safeguarding.

For engineers reviewing the DA108S1RL datasheet, DA108S1RL pinout, DA108S1RL application, or DA108S1RL equivalent, key selection criteria include its dual-reference (REF1/REF2) biasing architecture, low 9 V peak forward voltage at 12 A surge, sub-2 µA reverse leakage at 15 V, and SO-8 thermal resistance of 170 °C/W - critical for compact, high-reliability signal-line protection designs.

Technical Context

The DA108S1RL implements a quad-cell diode array where each cell consists of two back-to-back diodes tied between I/O and dual reference rails (REF1, REF2), enabling symmetrical clamping to either 0–18 V or ±9 V operating windows. Its low 22–36 pF input capacitance at 5 V DC bias ensures minimal signal distortion on high-speed digital lines up to 1 MHz.

Clamping action occurs when transients exceed the diode's 18 V V_RRM, diverting surge current away from protected circuitry while maintaining <9 V peak forward voltage under full 12 A 8/20 µs stress. Thermal design relies on SO-8 package's 170 °C/W junction-to-ambient resistance and 0.73 W power dissipation limit.

Key Specifications

Pinout & Package

DA108S1RL is housed in a standard SO-8 surface-mount package with gull-wing leads, UL94 V0 epoxy molding, and lead-free second-level interconnect compliant with JEDEC JESD97. Dimensions conform to Table 4: D = 4.80–5.00 mm, E = 5.80–6.20 mm, e = 1.27 mm pitch.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ESD protection array applications.

Compared with DA112S1RL and ESDA6V1SC6, DA108S1RL uniquely balances 4-channel protection, dual-reference configurability, and 12 A surge rating in SO-8 - making it optimal for ISDN and mid-density MCU I/O protection where layout simplicity and ±9 V compatibility are prioritized over channel count or ultra-low capacitance.

Availability

DA108S1RL is available at Aetrix Electronics and suitable for ISDN interface protection, microcontroller I/O safeguarding, and industrial digital bus conditioning requiring stable component supply and long-term lifecycle support.

Supply support for DA108S1RL 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, designing and manufacturing analog, digital, and mixed-signal ICs for automotive, industrial, and consumer markets.

DA108S1RL belongs to ST's ESD protection array product line, engineered specifically for high-immunity, low-distortion signal-line safeguarding in telecom and embedded control systems.

FAQ

What is the correct bias configuration for DA108S1RL in a 0–18 V system?

For 0–18 V operation, connect REF1 to system ground (0 V) and REF2 to +18 V supply. This configures all eight diodes to clamp positive transients to +18 V and negative transients to 0 V. Ensure REF1 and REF2 traces are low-inductance and decoupled with local 100 nF capacitors to maintain clamping integrity during fast transients.

Can DA108S1RL protect differential signals like RS-485 without signal degradation?

Yes - with input capacitance of 22–36 pF and <9 V clamping voltage, DA108S1RL preserves edge rates on RS-485 lines up to 10 Mbps. Place one DA108S1RL per differential pair: connect I/O1/I/O2 to A/B lines, REF1 to GND, REF2 to V_CC, ensuring common-mode voltage stays within the ±9 V or 0–18 V window.

Why does DA108S1RL have unused pins 7 and 8?

Pins 7 and 8 are I/O5 and I/O6 - functional in the 12-diode DA112S1RL variant but internally unconnected in DA108S1RL. This shared SO-8 footprint allows PCB design reuse across both part numbers, reducing layout complexity when migrating between 4- and 6-channel protection requirements.

How does thermal performance impact surge handling in repeated ESD events?

With R_th(j-a) = 170 °C/W and P_DISS = 0.73 W, DA108S1RL can sustain ≤12 A surges only if ambient temperature remains ≤25 °C and pulses are spaced to allow full junction cooling. For burst-mode testing (e.g., IEC 61000-4-2), derate peak current by 20% above 50 °C ambient to avoid thermal runaway.