Monolithic Power Systems Inc. MP8718EN-LF-Z

Overview

MP8718EN-LF-Z from Monolithic Power Systems is a synchronous step-down DC/DC converter with integrated 120mΩ high-side and 20mΩ low-side MOSFETs, delivering 4A continuous output current across a 4.5V–21V input range, fixed 500kHz switching frequency, and adjustable 0.8V–21V output voltage-used in notebook I/O power and flat-panel display bias rails.

For engineers reviewing the MP8718EN-LF-Z datasheet, MP8718EN-LF-Z pinout, MP8718EN-LF-Z application, or MP8718EN-LF-Z equivalent, key selection criteria include internal MOSFET R_DS(on), thermal shutdown at 150°C, EN/SYNC dual-function pin behavior, and SOIC8E exposed-pad thermal performance under 4A load conditions.

Technical Context

The MP8718EN-LF-Z operates in peak-current-mode control with internal compensation, enabling stable regulation without external loop components. Its proprietary bootstrap charging circuit maintains gate drive for the high-side MOSFET across duty cycles up to 90%, while the 1.5ms internal soft-start prevents output overshoot during startup.

It integrates an under-voltage lockout (UVLO) with 4.0V rising / 3.2V falling thresholds on VCC, cycle-by-cycle overcurrent protection triggering at 6.1A, and hiccup-mode recovery during sustained short-circuit faults-ensuring robust operation in distributed power systems with variable line conditions.

Key Specifications

Pinout & Package

MP8718EN-LF-Z is housed in a thermally enhanced 8-pin SOIC package (SOIC8E) with an exposed pad soldered to PCB ground for improved heat dissipation (θ_JA = 50°C/W, θ_JC = 10°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous step-down converter applications.

Compared with RT6220AGQW and TPS54340DDAR, MP8718EN-LF-Z offers optimal balance of 21V input capability, 4A output, integrated compensation, and SYNC flexibility-making it ideal for consumer electronics where size, efficiency, and EMI control are prioritized.

Availability

MP8718EN-LF-Z is available at Aetrix Electronics and suitable for notebook I/O power, flat panel display bias, and distributed telecom power requiring stable component supply, RoHS compliance, and long-term lifecycle assurance.

Supply support for MP8718EN-LF-Z 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

Monolithic Power Systems (MPS) is a fabless semiconductor company specializing in high-performance analog and power ICs, with design centers in the US, China, and Taiwan.

The MP8718 belongs to MPS's high-efficiency DC/DC converter product line, engineered for space-constrained computing and consumer electronics needing integrated power stages and minimal external components.

FAQ

What is the minimum recommended input capacitance for MP8718EN-LF-Z?

A 22μF X5R/X7R ceramic capacitor is recommended at the IN pin, placed as close as possible to pins 1 and 8. This value ensures adequate RMS current handling (≥2A) and limits input voltage ripple to <100mV under 4A load, based on worst-case VIN = 2×VOUT condition per datasheet Section 11.

Can MP8718EN-LF-Z operate with an output voltage below 0.8V?

No. The internal reference is fixed at 0.805V, and the feedback amplifier is not designed for sub-0.8V regulation. Attempting to set VOUT < 0.8V results in loss of regulation and uncontrolled output collapse, as confirmed by the absolute minimum FB voltage specification (789mV) and typical application circuit constraints.

Is an external bootstrap diode required for reliable operation?

An external diode (e.g., IN4148) from VCC to BST is optional and only beneficial when duty cycle exceeds 65% (i.e., VOUT > 0.65×VIN). At 12V_IN/3.3V_OUT, duty cycle is ~28%, so the internal bootstrap circuit suffices; the diode adds cost and board area without measurable benefit.

How does the EN/SYNC pin behave during external clock synchronization?

When an external clock (300kHz–2MHz) is applied to EN/SYNC, the internal oscillator locks to its rising edge within 2ms. During sync, the EN function remains active: pulling EN/SYNC < 0.4V disables the part regardless of external clock presence, preserving safe shutdown capability.

What is the maximum achievable output voltage accuracy over temperature?

Over –20°C to +85°C, FB voltage is specified as 789mV to 821mV (±1.6% of 0.805V nominal), resulting in ±2% total output error for a 1.2V rail using standard 1% resistors-verified by Figure 3 in the datasheet and confirmed in Electrical Characteristics Table on page 3.

Does MP8718EN-LF-Z support forced PWM mode at light loads?

No. The device operates exclusively in synchronous continuous conduction mode (CCM) and lacks a dedicated pulse-skipping or forced-PWM control pin. Light-load efficiency relies on reduced switching losses from low R_DS(on) MOSFETs, not mode switching-confirmed by absence of MODE or PFM pins and functional block diagram.

What PCB layout practices are critical for thermal performance?

Direct connection of the exposed pad to a ≥250mm² internal or bottom-layer GND copper pour using ≥6 thermal vias (0.3mm diameter) is mandatory. Per datasheet Section 12, failure to implement this reduces θ_JA from 50°C/W to >75°C/W, risking thermal shutdown at 3A+ loads in still air.