Renesas EL7554IREZ-T7

Overview

EL7554IREZ-T7 from Intersil is a monolithic synchronous 4A step-down DC/DC regulator with integrated CMOS power FETs, operating from 3V to 6V input and delivering adjustable output down to 0.8V. It achieves up to 96% efficiency at 4A load, supports 1MHz switching frequency, and includes junction temperature monitoring, ±5% voltage margining, and power-good indication - deployed in FPGA core supplies and portable equipment power rails.

For engineers reviewing the EL7554IREZ-T7 datasheet, EL7554IREZ-T7 pinout, EL7554IREZ-T7 application, or EL7554IREZ-T7 equivalent, key selection considerations include its 28-lead HTSSOP package with exposed thermal pad, constant-frequency PWM operation with external synchronization capability, soft-start control for multi-rail sequencing, and integrated over-temperature protection with 135°C shutdown threshold.

Technical Context

The EL7554IREZ-T7 implements current-mode PWM control using patented resistorless on-chip current sensing derived from the high-side PMOS switch, enabling fast transient response and precise over-current protection. Its architecture supports 100% duty cycle operation via complementary CMOS power switches (PMOS high-side, NMOS low-side), eliminating boot capacitor requirements and enabling output voltages approaching VIN minus RDSON1 and inductor IR drop.

Start-up is managed by a dedicated comparator front-end with STP/STN tracking inputs, supporting cascaded, offset, linear, and adjustable soft-start configurations. The VTJ pin provides a calibrated analog voltage (1.2V – 0.00384 × (TJ – 75)) directly proportional to junction temperature, while the PG pin delivers a window-comparator-based power-good signal with ±10% threshold relative to target VOUT.

Key Specifications

Pinout & Package

The EL7554IREZ-T7 is housed in a thermally enhanced 28-lead HTSSOP package (MDP0048) with an exposed thermal pad requiring solder connection to PCB ground plane for effective heat dissipation. Thermal resistance θJA is as low as 26°C/W on a 2-layer board with optimized copper area and thermal vias.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS544B20RTWR and ISL85415IRZ-T7, the EL7554IREZ-T7 uniquely combines analog voltage margining, direct junction temperature readout, and 3V–6V optimization - making it optimal for cost-sensitive, analog-controlled portable and FPGA power applications where thermal validation and production test flexibility are critical.

Availability

EL7554IREZ-T7 is available at Aetrix Electronics and suitable for FPGA core supplies, DSP I/O rails, and portable equipment power conversion requiring stable component supply, RoHS-compliant packaging, and long-term industrial temperature support (–40°C to +85°C).

Supply support for EL7554IREZ-T7 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

Intersil Corporation (now part of Renesas Electronics) is a U.S.-based analog and power management IC designer known for high-performance DC/DC regulators, precision references, and interface solutions.

The EL7554 product line was engineered for high-density, high-efficiency point-of-load regulation in FPGA, DSP, and CPU subsystems - emphasizing thermal intelligence, analog margining, and seamless multi-rail sequencing without digital controllers.

FAQ

What is the maximum output current rating of the EL7554IREZ-T7?

The EL7554IREZ-T7 is rated for 4A continuous output current under specified thermal conditions (TA = +25°C, 2-layer PCB with thermal vias). Peak current limit is 6A, and thermal shutdown activates at 135°C junction temperature to protect against sustained overload. Derating is required above +85°C ambient per Figure 10 in the FN7360 datasheet. The EL7554IREZ-T7 maintains regulation across its full 0.8V–VIN output range at this current level when properly heatsinked.

Does the EL7554IREZ-T7 support external synchronization of its switching frequency?

Yes, the EL7554IREZ-T7 operates in constant-frequency PWM mode and supports external synchronization via its COSC pin. To synchronize, apply a clean square wave to COSC through a series resistor (typically 10kΩ), with amplitude matching the internal oscillator ramp (0.2V–1.2V). The self-oscillation frequency must be set ~20% lower than the sync source to accommodate component tolerances. This capability enables noise-sensitive systems to avoid EMI peaks by locking multiple EL7554IREZ-T7 converters to a common clock.

How is voltage margining implemented on the EL7554IREZ-T7?

Voltage margining on the EL7554IREZ-T7 is implemented using two dedicated pins: TM (stress test enable) and SEL (margin polarity select). Pulling TM high and setting SEL high yields +5% output offset; pulling SEL low gives –5%. Both pins require pull-down resistors (1kΩ–100kΩ) when unused. This analog feature allows rapid functional testing of downstream logic under over/under-voltage stress without modifying feedback resistors or firmware - a key advantage for high-volume manufacturing validation of the EL7554IREZ-T7.

What is the function of the VTJ pin on the EL7554IREZ-T7?

The VTJ pin on the EL7554IREZ-T7 provides an analog voltage output directly proportional to silicon junction temperature: VTJ = 1.2 – 0.00384 × (TJ – 75). Measured with a high-impedance voltmeter or ADC, it eliminates need for external thermal sensors during design validation. This enables real-time thermal profiling, dynamic derating algorithms, and simplified qualification testing - all without adding components or layout area. The EL7554IREZ-T7's VTJ output is factory-calibrated and stable across process and temperature.

Can the EL7554IREZ-T7 operate with 100% duty cycle, and what does that enable?

Yes, the EL7554IREZ-T7 supports true 100% duty cycle operation due to its CMOS synchronous architecture (PMOS high-side, NMOS low-side). This allows the output voltage to reach nearly VIN minus IR drops across RDSON1 and the inductor DCR - critical for applications like powering 3.3V rails from a 3.6V Li-ion cell near end-of-discharge. Unlike N-channel-only buck controllers requiring bootstrapping, the EL7554IREZ-T7 sustains regulation without dropout, extending usable battery life and simplifying power tree design.