Diodes Incorporated ZSR850N8TA

Overview

ZSR850N8TA from Zetex plc is a fixed-output, three-terminal positive voltage regulator delivering 8.5 V ±1.5% over load (1–200 mA) and line (10.5–20 V) variations, with 115 µV_rms output noise and 44–60 dB ripple rejection at 120 Hz. It features internal thermal shutdown and short-circuit current limiting, operates across –55°C to +125°C, and requires no external compensation components - ideal for space-constrained local regulation in industrial control modules and embedded power rails.

For engineers reviewing the ZSR850N8TA datasheet, ZSR850N8TA pinout, ZSR850N8TA application, or ZSR850N8TA equivalent, key selection considerations include its SO8 package thermal resistance (780 mW @ 25°C), input voltage headroom requirement (≥10.5 V), low 350 µA typical quiescent current, and stable operation without output capacitance.

Technical Context

The ZSR850N8TA implements a monolithic bandgap-referenced series pass architecture with integrated error amplifier, current-limit foldback, and thermal foldback protection. Its output voltage is trimmed during final test to achieve ±1.5% initial accuracy at 100 mA load and 25°C junction temperature.

It maintains regulation under transient conditions: line transients (dV_in/dt = 5 V/µs) induce ≤±0.2 V output deviation, and load transients (dI_o/dt = 1 A/µs) produce ≤±0.2 V deviation with zero output capacitance - confirming inherent stability and fast internal loop response.

Key Specifications

Pinout & Package

The ZSR850N8TA is housed in an SO8 surface-mount package (suffix N8), with exposed thermal pad for enhanced heat dissipation. Maximum power dissipation is 780 mW at 25°C ambient, derating linearly to zero at 125°C.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fixed-output linear regulator applications.

Compared with TL78L08ACD and MC78L08ACDR2G, the ZSR850N8TA offers superior output accuracy (±1.5% vs ±3–4%), lower quiescent current (350 µA vs 3.5–3.8 mA), and tighter thermal regulation - making it optimal for high-stability, low-power, wide-temperature applications where 8.5 V is required.

Availability

ZSR850N8TA is available at Aetrix Electronics and suitable for industrial PLC I/O modules, automotive body control units, medical patient monitor front-ends, and test & measurement signal sources requiring stable component supply and long-term lifecycle support.

Supply support for ZSR850N8TA 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

Zetex plc (now part of Diodes Incorporated) is a UK-based semiconductor company specializing in high-performance analog and power management ICs for industrial, automotive, and communications markets.

The ZSR Series was designed specifically for rugged, space-constrained local voltage regulation - emphasizing intrinsic stability, wide temperature operation, and fault resilience without external components.

FAQ

Is the ZSR850N8TA stable without an output capacitor?

Yes. The ZSR850N8TA is internally compensated and remains stable with zero output capacitance, as confirmed by transient response testing (≤±0.2 V deviation under 1 A/µs load steps). An output capacitor (e.g., 1–10 µF ceramic) is optional and improves transient recovery time but is not required for stability.

What is the maximum safe input voltage for continuous operation?

The absolute maximum input voltage is 20 V, but continuous operation must respect power dissipation limits. At 100 mA load and 25°C ambient, the SO8 package dissipates ~0.75 W (10.5 V_in − 8.5 V_out) × 0.1 A. Derating applies above 25°C: max power drops linearly to zero at 125°C ambient.

Can Pin 4 (NC) be used as a thermal pad connection?

No. Pin 4 is electrically isolated and unconnected internally. Thermal performance relies solely on the exposed pad (Pins 5–8), which is internally bonded to GND. Pin 4 should remain floating or be grounded only for mechanical anchoring - connecting it to any signal risks unintended coupling.

How does the ZSR850N8TA behave during thermal shutdown?

When junction temperature exceeds ~150°C, the device shuts down output and reduces quiescent current. It automatically resumes regulation once junction temperature falls below the hysteresis threshold (~135°C). During shutdown, input-to-output isolation is maintained, but input transients may exceed 20 V unless clamped externally (e.g., with a 1 µF input capacitor).