Diodes Incorporated ZR78L09GTA

Overview

ZR78L09GTA from Zetex Semiconductors (now Diodes Incorporated) is a fixed-output +9.0 V positive linear voltage regulator in SOT223 package, designed for local point-of-load regulation with 200 mA output current capability, ±2.5% initial output tolerance, and internal thermal shutdown and short-circuit current limiting. It operates across -55°C to +125°C and requires no external compensation components.

For engineers reviewing the ZR78L09GTA datasheet, ZR78L09GTA pinout, ZR78L09GTA application, or ZR78L09GTA equivalent, this device is selected for space-constrained industrial control modules, battery-powered instrumentation requiring stable 9 V bias, and embedded subsystems needing low-quiescent-current local regulation without external capacitors beyond input/output bypassing.

Technical Context

The ZR78L09GTA implements a monolithic three-terminal linear regulator architecture with built-in current-limiting transistor, thermal foldback circuitry, and precision bandgap reference. Its dropout voltage remains ≤1.3 V at 200 mA over temperature, enabling operation from as low as 10.7 V input while maintaining 9.0 V output.

It achieves 43–57 dB ripple rejection at 120 Hz and delivers 150 µV_rms output noise (10 Hz–10 kHz), with load regulation of ≤30 mV across 1–200 mA and line regulation of ≤40 mV over input range 11–20 V - performance exceeding legacy 78Lxx series regulators in thermal stability and transient response.

Key Specifications

Pinout & Package

SOT223 package (suffix G): 4-pin thermally enhanced surface-mount outline with exposed thermal pad (pin 4). Pin 4 is internally connected to the die substrate and may be tied to ground or left floating per layout requirements.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM78L09ACZ/NOPB, ZR78L09GTA offers tighter tolerance, lower IQ, and robust thermal/current protection; versus MCP1703T-9002E/MB, it trades ultra-low IQ for integrated fault resilience and higher output current headroom.

Availability

ZR78L09GTA is available at Aetrix Electronics and suitable for industrial sensor interfaces, portable test equipment, automotive body control modules, and IoT edge gateways requiring stable component supply with guaranteed long-term manufacturability.

Supply support for ZR78L09GTA 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 Semiconductors, acquired by Diodes Incorporated in 2008, specialized in high-performance analog and discrete semiconductors for demanding industrial and automotive applications.

The ZR78L Series was engineered specifically for local voltage regulation in space-constrained, thermally aggressive environments where legacy 78Lxx regulators failed to meet reliability or accuracy targets.

FAQ

What is the minimum input voltage required for ZR78L09GTA to maintain regulation?

The absolute minimum input voltage is 10.7 V at 100 mA load and 25°C, per datasheet specification. At full 200 mA load or elevated temperature, input must be ≥11 V to guarantee 9.0 V output within tolerance. Below this threshold, dropout behavior occurs with proportional output sag.

Can ZR78L09GTA be used without an input bypass capacitor?

No - a minimum 1 µF ceramic capacitor (X7R, 10 V rating) must be placed within 5 mm of the input pin to prevent high-frequency oscillation and ensure stability under dynamic load conditions. Omission risks output overshoot, ringing, or thermal shutdown during transients.

Is pin 4 (thermal tab) electrically connected to any internal node?

Pin 4 is the exposed thermal pad connected to the silicon substrate - not to ground, input, or output. It is electrically isolated but thermally coupled. Diodes Incorporated recommends connecting it to a large copper pour tied to ground for optimal thermal performance, though floating is permissible if thermal limits are not exceeded.

How does ZR78L09GTA behave during thermal shutdown?

When junction temperature exceeds ~165°C, internal thermal protection disables the pass element, dropping output to near zero volts. Regulation automatically resumes once junction cools below ~145°C hysteresis threshold - no manual reset or power cycle is needed, enabling self-recovering operation in intermittent overload scenarios.