STMicroelectronics L4963D013TR

Overview

L4963D013TR from STMicroelectronics is a monolithic step-down switching regulator delivering 1.5A output current with adjustable output voltage from 5.1V to 36V, operating in discontinuous variable-frequency mode. It integrates a precise 5.1V on-chip reference (±2%), internal current limiting, thermal shutdown, open-collector reset and power-fail outputs, and TTL-level inhibit control - used in industrial power supplies for microprocessor supervision and stable DC-DC conversion.

For engineers reviewing the L4963D013TR datasheet, L4963D013TR pinout, L4963D013TR application, or L4963D013TR equivalent, key selection criteria include its 5.1–36V adjustable output range, 1.5A load capability, SO20 package thermal performance (R_{th j-amb} = 85°C/W), and integrated reset/power-fail signaling without external timing components.

Technical Context

The L4963D013TR implements a self-oscillating discontinuous conduction mode (DCM) buck topology, where switching frequency varies with input voltage, output voltage, inductance, and load - eliminating need for external frequency compensation. Regulation relies on two comparators comparing feedback voltage against a 5.1V internal reference, latched drive control, and zero-current detection via negative output voltage sensing (–0.1V threshold).

Its power-fail circuit monitors input supply via an external resistor divider at Pin 7 (threshold ~19V typical), while reset delay is set by a capacitor from Pin 9 to ground. Inhibit (Pin 16) accepts TTL logic low to disable switching; all protection functions - overcurrent (3.5–6.5A trip), thermal shutdown (145–150°C), and undervoltage lockout - are fully integrated.

Key Specifications

Pinout & Package

The L4963D013TR is housed in a 20-lead SOIC (SO20) plastic surface-mount package (body size 12.6 × 7.6 mm, lead pitch 1.27 mm), rated for 4W total power dissipation at T_pins ≤ 90°C with PCB copper area.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar adjustable buck regulator applications.

Compared with LM2596S-ADJ and TPS5430DDAR, the L4963D013TR uniquely integrates reset, power-fail, and inhibit functions in a single SO20 package - reducing system-level component count and simplifying compliance with IEC 61000-4-28 and ISO 16750-2 for voltage interruption immunity.

Availability

L4963D013TR is available at Aetrix Electronics and suitable for industrial PLC power supplies, automotive body control modules, telecom remote radio units, and medical diagnostic equipment requiring stable component supply and long-term lifecycle support.

Supply support for L4963D013TR 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, Switzerland, designing and manufacturing silicon solutions for automotive, industrial, and power management applications.

The L4963 series belongs to ST's legacy power management IC portfolio, developed specifically for robust, low-component-count DC-DC conversion in industrial and automotive environments where reliability, integrated supervision, and wide input range are critical.

FAQ

What is the minimum input voltage required for stable 5.1V output operation?

The L4963D013TR requires a minimum input voltage of 9V to maintain regulation at 5.1V output, as specified in the Absolute Maximum Ratings and Electrical Characteristics tables. Below 9V, the internal regulator cannot sustain logic and gate drive functionality, causing dropout or shutdown. The dropout voltage between Pin 3 and Pin 2 is typically 1.5–2V at 3A, but full 1.5A output is only guaranteed above 9V input.

Can the L4963D013TR be used for fixed 5.1V output without external resistors?

Yes - for fixed 5.1V operation, connect the feedback input (Pin 12) directly to the output (Pin 2). This configures the internal 5.1V reference as the regulation setpoint without any external divider. Figure 30 in the datasheet confirms this minimal configuration requires only the inductor, output capacitor, and input capacitor.

How is the power-fail threshold adjusted, and what is its default value?

The power-fail threshold is set by an external resistor divider from Pin 3 (input voltage) to Pin 8 (PF input) to ground. With Pin 8 left open, the internal threshold is approximately 19V (typical), with rising and falling thresholds of 17.5–20.5V and 14.25–15.75V respectively. Adding a divider scales this threshold linearly - e.g., a 2:1 divider reduces it to ~9.5V.

Does the L4963D013TR support synchronization to an external clock?

No - the L4963D013TR uses an internal self-oscillating architecture with frequency determined by inductance, input/output voltage, and load current. It does not provide an external sync input or clock output; oscillator frequency is programmable only via external R (Pin 18) and C (Pin 17), and operates in discontinuous mode without fixed timing.