Monolithic Power Systems Inc. MP2305DS-LF-Z

Overview

MP2305DS-LF-Z from Monolithic Power Systems is a monolithic synchronous buck regulator integrating 130mΩ high- and low-side N-channel MOSFETs, delivering 2A continuous output current across a 4.75V–23V input range with adjustable 0.923V–20V output voltage, fixed 340kHz switching frequency, and cycle-by-cycle overcurrent protection-used in FPGA/DSP power supplies and notebook DC-DC conversion.

For engineers reviewing the MP2305DS-LF-Z datasheet, MP2305DS-LF-Z pinout, MP2305DS-LF-Z application, or MP2305DS-LF-Z equivalent, key selection considerations include its SOIC8 package thermal resistance (θJA = 90°C/W), 1μA shutdown current, 0.923V feedback reference, soft-start programmability via external capacitor, and input UVLO threshold of 4.10V.

Technical Context

The MP2305DS-LF-Z implements current-mode control with an internal transconductance error amplifier (GEA = 800μA/V) and COMP pin-based loop compensation, enabling fast transient response and stable regulation with ceramic output capacitors. Its functional block includes integrated 130mΩ MOSFETs, a bootstrap circuit requiring SW-to-BS 0.01μF capacitor, and dual-level enable logic with 1.5V EN rising threshold and 2.5V lockout threshold.

It features fixed 340kHz oscillator frequency, 90% maximum duty cycle, 220ns minimum on-time, and thermal shutdown at 160°C. The device supports adjustable soft-start (15ms with 0.1μF SS-to-GND capacitor) and provides cycle-by-cycle current limiting with 3.4A typical upper switch limit and 1.1A lower switch limit under fault conditions.

Key Specifications

Pinout & Package

MP2305DS-LF-Z is housed in an 8-pin SOIC package (JEDEC MS-012 AA, 150mil width) with exposed pad not electrically connected. Thermal performance: θJA = 90°C/W, θJC = 45°C/W on 4-layer PCB per JESD51-7.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP2314S, MP2305DS-LF-Z offers proven SOIC8 integration and 2A capability but lacks the 0.8V reference and 3A headroom needed for next-gen processors; versus LM2678-ADJ, it delivers superior efficiency and smaller footprint but requires careful bootstrap design and has no pin compatibility.

Availability

MP2305DS-LF-Z is available at Aetrix Electronics and suitable for FPGA power supplies, notebook system rail conversion, networking ASIC bias generation, and green appliance control modules requiring stable component supply and long-term obsolescence management.

Supply support for MP2305DS-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, and global manufacturing partnerships.

The MP2305 belongs to MPS's mainstream synchronous buck regulator product line, engineered for cost-sensitive, space-constrained DC-DC applications in computing, networking, and consumer electronics where integration, efficiency, and reliability are prioritized.

FAQ

What is the recommended input capacitor configuration for MP2305DS-LF-Z?

Use a low-ESR ceramic capacitor (X5R/X7R dielectric) rated ≥25V, with minimum 10µF value placed as close as possible to the IN and GND pins. For high-RMS input current applications, add a 0.1µF ceramic in parallel. The RMS current rating should exceed half the maximum load current (≥1A for 2A output), and total capacitance must suppress input ripple below 100mVpp at 340kHz.

Can MP2305DS-LF-Z operate with a 3.3V input?

No. MP2305DS-LF-Z has a minimum input voltage of 4.75V per datasheet specifications. Operation below this threshold will trigger input under-voltage lockout (UVLO), disabling the regulator. It is unsuitable for 3.3V or 5V input rails unless boosted externally; for such cases, consider the MP2314S or other lower-VIN buck regulators.

How is output voltage accuracy affected by resistor tolerance in the FB divider?

Output voltage error is directly proportional to resistor tolerance: a 1% R1 and R2 combination contributes up to ±2% VOUT error, dominated by the ratio mismatch. To achieve ≤1% total output error, use 0.5% tolerance resistors and ensure layout symmetry to minimize thermal drift and parasitic coupling at the high-impedance FB node.

Is an external Schottky diode required for MP2305DS-LF-Z operation?

No - the MP2305DS-LF-Z uses synchronous rectification with integrated low-side MOSFET, eliminating the need for an external Schottky diode. However, adding one (e.g., B130 or SK13) between SW and GND may improve light-load efficiency by reducing body-diode conduction losses during dead time, though it adds cost and board area.

What is the purpose of the BS-to-SW capacitor, and what value is recommended?

The BS-to-SW capacitor (≥0.01µF, 16V X7R ceramic) forms a flying capacitor that charges during low-side conduction and supplies gate drive voltage >VIN to the high-side MOSFET. It must be placed within 2mm of BS/SW pins with short, wide traces to minimize impedance; insufficient capacitance causes high-side drive collapse and erratic switching or thermal failure.

Does MP2305DS-LF-Z support forced PWM or PFM mode selection?

No - MP2305DS-LF-Z operates exclusively in forced continuous conduction mode (CCM) with fixed 340kHz frequency. It does not feature pulse-frequency modulation (PFM) or mode-select pins. Light-load efficiency is maintained via low quiescent current (1.5mA active, 1μA shutdown), not variable-frequency operation.

What is the maximum achievable output voltage with MP2305DS-LF-Z?

The maximum regulated output voltage is 20V, limited by internal circuitry and absolute maximum ratings (e.g., SW pin withstands ≤26.3V). Attempting >20V via external divider violates specification and risks instability or damage; for higher outputs, use a different topology (e.g., flyback) or a dedicated high-VOUT buck controller.