Monolithic Power Systems Inc. MP2151GQFU-15-Z

Overview

MP2151GQFU-15-Z from Monolithic Power Systems is a fixed-output 1.5V, 1A synchronous step-down DC/DC converter with 25μA quiescent current, constant-on-time (COT) control, and integrated 80mΩ/50mΩ MOSFETs. It operates from 2.5V–5.5V input, delivers ±1.5% output accuracy over temperature, and includes output discharge, OVP, SCP, and thermal shutdown-designed for space-constrained battery-powered I/O rails in portable instrumentation.

For engineers reviewing the MP2151GQFU-15-Z datasheet, MP2151GQFU-15-Z pinout, MP2151GQFU-15-Z application, or MP2151GQFU-15-Z equivalent, key selection criteria include ultra-low IQ for standby efficiency, fixed 1.5V output with no external feedback resistors, UTQFN (1.2mm×1.6mm) footprint for high-density PCBs, and hiccup-mode short-circuit protection for robust load handling.

Technical Context

The MP2151GQFU-15-Z implements a constant-on-time (COT) control architecture with input voltage feed-forward, enabling stable 1.1MHz switching across its 2.5V–5.5V input range and delivering fast transient response without external compensation. Its internal power stage integrates complementary P-channel and N-channel MOSFETs with 80mΩ high-side and 50mΩ low-side R_DS(ON), supporting up to 1A continuous output current at 1.5V.

It features dedicated output discharge via an internal NMOS switch (R_DIS = 200Ω), fixed 1.5V regulation (±1.5% over –40°C to +125°C), and a power-good (PG) open-drain output that asserts when V_OUT is within 85–115% of nominal-enabling reliable system power sequencing in portable devices.

Key Specifications

Pinout & Package

MP2151GQFU-15-Z uses a 6-pin UTQFN package (1.2mm × 1.6mm, 0.4mm pitch) with wettable flanks for automated optical inspection. The exposed thermal pad must be soldered to a PCB copper pour for optimal thermal performance (θ_JC = 30°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS62231DRYR and ADP2119ACPZ-R7, MP2151GQFU-15-Z offers the smallest footprint, lowest IQ, and unique combination of output discharge + VIN OVP-making it optimal for ultra-compact, battery-sensitive, and surge-prone industrial edge applications.

Availability

MP2151GQFU-15-Z is available at Aetrix Electronics and suitable for portable instrumentation, wireless sensor networks, multi-function printers, and industrial edge controllers requiring stable component supply with guaranteed long-term availability.

Supply support for MP2151GQFU-15-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 power management ICs, with design centers in the US, China, and Taiwan.

The MP2151 product line targets ultra-compact, low-IQ DC/DC conversion for battery-powered and space-constrained applications-including wearables, IoT endpoints, and portable medical devices-emphasizing integration, thermal efficiency, and ease of layout.

FAQ

What is the purpose of the FB pin on MP2151GQFU-15-Z?

The FB pin is internally connected to the 1.5V reference in fixed-output versions like MP2151GQFU-15-Z and must be left unconnected (NC). It is not used for external feedback; doing so will disrupt regulation. The datasheet explicitly states FB is "not connected" for -12, -15, -18, -25, and -33 variants.

Does MP2151GQFU-15-Z require an external pull-up resistor on the PG pin?

Yes. The PG pin is an open-drain output and requires an external pull-up resistor (100kΩ to 500kΩ) to VIN or VOUT to generate a valid logic-high signal. Without this resistor, PG remains floating and cannot indicate power-good status to downstream logic or microcontrollers.

Can MP2151GQFU-15-Z operate with a 2.4V input?

No. The absolute minimum input voltage is 2.5V, and the under-voltage lockout (UVLO) rising threshold is 2.45V typical. At 2.4V, the device remains disabled and draws only 1μA shutdown current. Operation below 2.5V violates the recommended operating conditions and risks unstable regulation.

How does output discharge work during EN deactivation?

When EN is pulled low, the internal 200Ω NMOS discharge switch activates between OUT and GND, discharging the output capacitor to <100mV within 1ms. This prevents back-powering of upstream circuitry and ensures clean power-down sequencing in multi-rail systems.

Is thermal pad soldering required for MP2151GQFU-15-Z?

Yes. The UTQFN package includes an exposed thermal pad that must be soldered to a PCB copper pour using ≥6 thermal vias (0.3mm diameter) to an inner ground plane. Omitting this compromises thermal performance: θ_JA degrades from 65°C/W to >170°C/W, risking thermal shutdown above 400mA load at +85°C ambient.

What is the maximum allowable output capacitance?

No hard upper limit is specified, but the soft-start time scales linearly with output capacitance. With the fixed 0.5ms soft-start, C_OUT > 100μF may cause excessive inrush current or overshoot. For 10μF–47μF ceramic capacitors (X5R/X7R), regulation is stable; larger values require verification of startup behavior in the target application.

Does MP2151GQFU-15-Z support forced PWM mode?

No. MP2151GQFU-15-Z operates exclusively in automatic pulse-frequency modulation (PFM) / COT mode. It transitions between continuous conduction mode (CCM), discontinuous conduction mode (DCM), and sleep mode based on load-there is no pin or register to force fixed-frequency PWM operation.