Renesas EL7556DCMZ

Overview

EL7556DCMZ from Intersil is an adjustable synchronous DC/DC switching regulator optimized for 5V input and 1.0V–3.8V output, delivering up to 6A continuous current with integrated NMOS power FETs, internal 1% reference, and VCC2DET interface for Intel P54/P55 microprocessors. It operates over –40°C to +85°C in a 28-pin SO package and supports thermal shutdown via OT pin.

For engineers reviewing the EL7556DCMZ datasheet, EL7556DCMZ pinout, EL7556DCMZ application, or EL7556DCMZ equivalent, key selection criteria include its fused-lead thermal package (31°C/W), resistorless current sensing, adjustable oscillator (105–145 kHz), ±10% PWRGD window, and dual feedback mode (internal 3.5V or external 1.0–3.8V).

Technical Context

The EL7556DCMZ implements current-mode PWM control using a triple-input summing comparator that combines voltage feedback (FB1/FB2), inductor current sense, and user-adjustable slope compensation (via CSLOPE). Its fused-lead 28-pin SO package integrates seven high-current LX pins and six VSSP ground pins to minimize thermal resistance and support 6A continuous operation without external heatsinks.

It features dual feedback path selection via VCC2DET: logic high selects FB2 for fixed 3.5V output; logic low enables FB1 for externally programmed output (1.0V–3.8V) using R3/R4 divider. The on-chip temperature sensor triggers OT at 135°C with 40°C hysteresis, and PWRGD asserts high when output is within ±10% of programmed voltage.

Key Specifications

Pinout & Package

EL7556DCMZ uses a Pb-free 28-pin SOIC package (MDP0027) with fused-lead thermal construction: pins 7, 9–12, 18–19 serve as VSSP ground return paths for the synchronous buck stage, while pins 20–23 are paralleled LX switch-node outputs. This layout enables low thermal resistance (~31°C/W) when connected to PCB copper pour.

Key Features

Applications

Equivalent & Alternatives

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

Compared with EL7556DCMZ, EL7566 offers higher current capacity but sacrifices Intel interface and integrated current sensing, while ISL6208 provides VID programmability and multi-phase capability at lower per-phase current and different packaging-neither is pin-compatible nor drop-in, and both require layout and firmware changes.

Availability

EL7556DCMZ is available at Aetrix Electronics and suitable for PC motherboards, local high-power CPU supplies, and GTL+ bus power applications requiring stable component supply, RoHS compliance, and long-term industrial temperature support (–40°C to +85°C).

Supply support for EL7556DCMZ 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) designs high-performance analog and power management ICs for computing, industrial, and communications markets, with ISO9001-certified manufacturing.

The EL7556DCMZ belongs to Intersil's integrated synchronous buck regulator product line, engineered specifically for cost-sensitive, high-current CPU and core logic power delivery on PC motherboards and embedded platforms.

FAQ

What is the maximum continuous output current supported by the EL7556DCMZ?

The EL7556DCMZ supports up to 6A continuous output current under full -40°C to +85°C ambient conditions when implemented with proper PCB thermal design (≥2 in² copper pour connected to fused VSSP leads). Peak current capability is 9A, but sustained operation above 6A requires derating based on thermal performance curves in FN7339.

How does the VCC2DET pin affect the output voltage of the EL7556DCMZ?

The VCC2DET pin selects between two feedback modes: when pulled high (≥4V), EL7556DCMZ uses FB2 to deliver a factory-trimmed 3.500V output; when pulled low (≤0.8V), it uses FB1 with external R3/R4 resistors to set output from 1.0V to 3.8V. This dual-mode architecture enables direct compatibility with Intel P54/P55 processors while retaining flexibility for other applications.

Can the EL7556DCMZ be used without external slope compensation components?

No - the EL7556DCMZ requires an external CSLOPE capacitor (typically 470 pF) to generate the slope compensation ramp essential for stable current-mode operation above 50% duty cycle. Omitting CSLOPE risks subharmonic oscillation and poor load transient response, as confirmed in the oscillator and loop gain sections of FN7339.

What thermal resistance can be achieved with the EL7556DCMZ in a typical PCB layout?

With a minimum 2 in² copper pour connected to all fused VSSP pins (7,9–12,18–19), the EL7556DCMZ achieves ~31°C/W junction-to-ambient thermal resistance in still air - significantly lower than the ~78°C/W of a standard SO28 package. Adding 100 LFPM airflow further reduces θJA by ~15%, extending maximum ambient operating temperature.

Is the EL7556DCMZ RoHS compliant and what does the 'Z' suffix indicate?

Yes - the 'Z' suffix in EL7556DCMZ denotes Intersil's Pb-free plus anneal construction: 100% matte tin termination, RoHS-compliant molding compounds and die attach, qualified for both SnPb and lead-free reflow profiles. It meets IPC/JEDEC J-STD-020 MSL classification for Pb-free peak temperatures and is fully compatible with modern assembly processes.