Monolithic Power Systems Inc. MP8736DL-LF-P

Overview

MP8736DL-LF-P from Monolithic Power Systems is a fully integrated synchronous buck converter with 4.5V–19V input range, 6A continuous output current, and proprietary Constant-On-Time (COT) control enabling fast transient response in networking and point-of-load systems. It integrates 30mΩ high-side and 12mΩ low-side MOSFETs, supports 100kHz–2.5MHz programmable switching frequency via external resistor, and delivers 1% reference voltage accuracy with PGOOD monitoring.

For engineers reviewing the MP8736DL-LF-P datasheet, MP8736DL-LF-P pinout, MP8736DL-LF-P application, or MP8736DL-LF-P equivalent, this device serves as a space-constrained, high-efficiency DC/DC solution requiring precise soft-start timing, thermal shutdown, and robust OCP/SCP/OVP/UVP protection in distributed power architectures.

Technical Context

The MP8736DL-LF-P employs Constant-On-Time (COT) control with line feed-forward via the FREQ pin, where ON-time scales inversely with input voltage to maintain stable frequency across 4.5V–19V input. Its internal 5V VCC LDO powers gate drivers, while BST capacitor enables high-side FET bootstrap operation.

Protection logic includes cycle-by-cycle over-current detection with 40μs hold-off timer for latch-off, immediate short-circuit latch-off when FB drops below 50% of 0.815V reference, and non-latching thermal shutdown at 150°C with 25°C hysteresis. PGOOD asserts after SS delay plus 0.5ms once FB reaches 90% of reference.

Key Specifications

Pinout & Package

MP8736DL-LF-P uses a QFN20 (3mm × 4mm, 0.5mm pitch) package with exposed thermal pad on underside for enhanced heat dissipation. Pin numbering follows top-view layout per MPS Rev. 1.34 datasheet.

Key Features

Applications

Equivalent & Alternatives

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

Compared with RTQ2132B-QT and TPS546B24A, the MP8736DL-LF-P offers superior transient response via COT control and smallest footprint, but lacks digital interface or sub-12mΩ RDS(on); best suited for cost-sensitive, space-constrained analog-regulated systems.

Availability

MP8736DL-LF-P is available at Aetrix Electronics and suitable for networking systems, broadband communication equipment, and distributed power architectures requiring stable component supply, RoHS-compliant packaging, and long-term production continuity.

Supply support for MP8736DL-LF-P 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 core expertise in DC/DC conversion, motor drivers, and LED lighting controllers.

The MP8736 belongs to MPS's high-density synchronous buck converter product line, designed specifically for space-constrained, high-efficiency point-of-load applications in telecom infrastructure and enterprise networking gear.

FAQ

What is the minimum recommended SS capacitor value for MP8736DL-LF-P?

The minimum SS capacitor is 4.7nF when output capacitance exceeds 330μF to prevent current-limit triggering during startup. For lower output capacitance, values as low as 1nF may be used. The soft-start time is calculated as T_SS(ms) = C_SS(nF) × 0.815V / 8.5μA, yielding ~0.4ms per nF.

How does the MP8736DL-LF-P handle light-load efficiency?

It enters skip mode below the critical current threshold, where the low-side FET driver goes high-Z and a current modulator limits inductor current to <−1mA. This eliminates reverse conduction loss and maintains >85% efficiency at 10mA load, unlike forced PWM converters that suffer diode conduction losses.

Can the FREQ pin be left unconnected?

No - the FREQ pin must be connected to IN through a resistor to set switching frequency. Leaving it floating causes undefined ON-time and unstable operation. A 301kΩ resistor yields ~600kHz at 12V input; values from 100kΩ to 1MΩ support 100kHz–2.5MHz range.

What is the thermal resistance (θJA) of the QFN20 package?

θJA is 48°C/W measured on a 4-layer JEDEC-standard PCB (JESD51-7). With 2.6W maximum continuous power dissipation at 25°C ambient, junction temperature rises ~125°C above ambient at full load - requiring adequate copper pour and thermal vias under the exposed pad to stay within 125°C limit.

Does MP8736DL-LF-P support output voltages below 0.815V?

No - the internal reference is fixed at 0.815V. Output voltage is set by R1/R2 divider as V_OUT = 0.815V × (1 + R1/R2). To achieve 0.6V, R1/R2 ratio must be 0.74, but accuracy degrades due to FB current (10–50nA) error contribution at very low R2 values.

How is short-circuit protection triggered?

SCP activates immediately when FB falls below 50% of 0.815V (i.e., <0.4075V) *and* current limit is detected - indicating a hard short. Unlike OCP, which requires 40μs of consecutive current-limit hits, SCP forces immediate latch-off without delay to protect MOSFETs and inductor.

Is an external bootstrap capacitor required?

Yes - a 0.1μF to 1μF ceramic capacitor must be placed between BST and SW pins. This forms the floating supply for the high-side gate driver. Use X7R/X5R dielectric, place as close as possible to BST/SW pins, and ensure low-ESL layout to sustain 5V gate drive under 6A load.