Monolithic Power Systems Inc. MP5505AGL-P

Overview

MP5505AGL-P from Monolithic Power Systems is a 7V-input, 4A integrated energy storage and management unit with lossless bi-directional buck/boost architecture for SSD/HDD power hold-up. It features programmable input current limit (up to 4.6A), 6V bus clamping, adjustable storage/release voltages (e.g., 12V/4.2V), and thermal protection in a QFN-20 (3mm × 4mm) package.

For engineers reviewing the MP5505AGL-P datasheet, MP5505AGL-P pinout, MP5505AGL-P application, or MP5505AGL-P equivalent, key selection criteria include input-current-limit resistor programming (ILIM), storage-voltage feedback divider (FBS), release-voltage feedback (FBB), dv/dt slew-rate control (DVDT), and power-good indicator timing (PGIN/PGS).

Technical Context

The MP5505AGL-P integrates two independent power paths: an input-current-limiting hot-swap FET (50mΩ) with dv/dt-controlled soft-start, and a bi-directional energy management core using shared inductor SW and internal 70mΩ/60mΩ switches. Its patented architecture enables lossless charge (boost mode) and regulated discharge (buck-release mode at 500kHz fixed-frequency COT control).

It implements dual feedback loops - FBB senses VB for bus regulation and release triggering (UVLO threshold 2.2V), while FBS senses STRG for storage voltage regulation (reference 0.79V). ENCH enables/disables only the charge/release circuitry, decoupling it from the input limiter controlled by EN.

Key Specifications

Pinout & Package

MP5505AGL-P is housed in a thermally enhanced QFN-20 (3mm × 4mm) package with exposed thermal pad (PGND-connected). Pin 13 is NC; all other pins are functionally assigned per the manufacturer's top-view layout.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar energy storage and management applications.

Compared with MP5504AGL-Z, MP5505AGL-P delivers higher current capability and extended efficiency at low voltage differentials via CST; versus TPS65023BRSBR, it provides dedicated, high-efficiency capacitor-based hold-up without battery dependency or complex charging algorithms.

Availability

MP5505AGL-P is available at Aetrix Electronics and suitable for solid-state drive power hold-up, hard-disk drive crash protection, and industrial PLC I/O module backup requiring stable component supply, full production traceability, and long-term lifecycle support.

Supply support for MP5505AGL-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 over 20 years of leadership in DC/DC conversion, motor drivers, and energy management solutions.

The MP5505A product line was designed specifically for ultra-compact, high-efficiency power hold-up in storage subsystems - addressing the growing need for lossless, programmable, and thermally robust energy buffering in SSDs, HDDs, and industrial edge controllers.

FAQ

What is the minimum recommended storage capacitance for 20ms hold-up at 1A with 12V storage and 4.2V release?

The required storage capacitance is calculated as Cs = (V²STORAGE − V²RELEASE) × τDASP / (2 × IRELEASE × VRELEASE) × 1.1 for efficiency margin. Substituting values yields Cs ≈ 1500μF. A 2200μF/16V POSCAP or low-ESR electrolytic capacitor is recommended to ensure margin and reliability across temperature.

Can MP5505AGL-P operate with VIN = 3.3V and still charge a 12V storage capacitor?

Yes. The integrated boost converter raises STRG above VIN - up to 30V - regardless of input voltage. With VIN = 3.3V, the device enters boost mode once STRG exceeds VB and uses the internal 70mΩ HS-FET and 60mΩ LS-FET to pump energy, achieving full 12V storage with appropriate inductor (e.g., 4.7μH) and feedback divider.

How does reverse-current protection work during energy release?

Reverse-current protection is enforced by the input hot-swap FET, which turns off when VIN falls below VB (or below the PGIN threshold of ~0.79V). This blocks backflow from STRG → VB → VIN, ensuring stored energy flows only to the bus rail and downstream loads - critical for system isolation during brownouts.

Is the TPOR pin required to be used, or can it be left floating?

TPOR can be left floating to use the default 0.4ms power-on-reset delay. However, for systems requiring precise sequencing - such as enabling ENCH only after VB has fully settled - a capacitor (e.g., 100nF for 1ms delay) must be connected to TPOR and GND to avoid accidental release-mode entry during startup.

What is the purpose of the CST pin, and what happens if it is left unconnected?

CST stores charge to drive the high-side switch gate when STRG voltage approaches VB, enabling efficient charge transfer near voltage crossover. If left unconnected, the device still operates but with reduced efficiency in the 10–20% ΔV range (e.g., 12V→11V), increasing conduction loss and thermal stress on internal switches.

Does MP5505AGL-P support automatic transition between charge and release modes without external intervention?

Yes. The device continuously monitors FBB and FBS voltages. When VB drops below the release threshold (set by FBB), it automatically disables boost mode and initiates buck-release - no external control signal or microcontroller action is needed. This autonomous behavior ensures deterministic hold-up response within microseconds.

What is the maximum allowable storage voltage, and what failure mode occurs if exceeded?

The absolute maximum storage voltage (VSTRG) is 35V. Exceeding this risks permanent damage to the internal 70mΩ/60mΩ switches and BST driver circuitry. Operation above 30V is outside recommended conditions and voids parametric guarantees - sustained overvoltage may trigger immediate thermal shutdown or latent die degradation.