Monolithic Power Systems Inc. MP3900DK-LF

Overview

MP3900DK-LF from Monolithic Power Systems is a high-efficiency constant-frequency peak current mode boost controller driving external N-channel MOSFETs up to 10A, featuring 330kHz switching, 0.816V feedback reference, 10V gate drive, and lossless current sensing for V_ISENSE < 30V. It supports telecom isolated power, off-line controllers, and CCFL backlighting with 97% efficiency at 25V/2A output.

For engineers reviewing the MP3900DK-LF datasheet, MP3900DK-LF pinout, MP3900DK-LF application, or MP3900DK-LF equivalent, key selection criteria include its 180µA quiescent current, 200mV current limit threshold, 8.9V V_CC UVLO turn-on, 77–83% max duty cycle, and MSOP-8 thermal resistance of 150°C/W.

Technical Context

The MP3900DK-LF implements a fixed-frequency (270–390kHz) peak current mode control architecture with internal slope compensation and cycle-by-cycle current limiting. Its transconductance error amplifier (0.36mA/V typ) interfaces with a 0.816V internal reference and COMP/RUN node to regulate output voltage via external resistor divider.

It integrates a 10V gate driver with 4Ω sink/16Ω source impedance, enabling low-loss drive of standard-threshold MOSFETs. The ISENSE pin accepts direct drain-sensing below 30V, eliminating external sense resistors, while PGND/SGND separation supports clean current path routing in high-noise boost topologies.

Key Specifications

Pinout & Package

The MP3900DK-LF is housed in an 8-pin MSOP package with exposed thermal pad (JEDEC MO-187 AA), optimized for high-power density and thermal performance in space-constrained DC-DC modules.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar boost controller applications.

Compared with LM5022MM/NOPB and UCC28064DR, the MP3900DK-LF delivers superior efficiency in mid-voltage boost (25V output) due to lossless sensing and 10V gate drive, while its 330kHz frequency balances size and EMI-making it optimal for telecom and display power where thermal density and component count are constrained.

Availability

MP3900DK-LF is available at Aetrix Electronics and suitable for TV backlight power generation, telecom isolated DC-DC modules, and off-line AC-DC controller designs requiring stable component supply, RoHS-compliant packaging, and long-term lifecycle continuity.

Supply support for MP3900DK-LF 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 MP3900 product line targets high-efficiency, low-quiescent-current DC-DC controllers for telecom, industrial, and consumer power applications-emphasizing integration, thermal robustness, and ease of layout in space-constrained modules.

FAQ

What is the maximum output voltage achievable with MP3900DK-LF in boost configuration?

The MP3900DK-LF itself does not impose a hard upper limit on output voltage; instead, the practical maximum is determined by the voltage rating of the external MOSFET and output diode. For example, with a 100V MOSFET (e.g., FDS6630A) and 150V Schottky diode, outputs up to 80–100V are feasible. However, lossless current sensing is restricted to V_ISENSE < 30V, so above that threshold, an external sense resistor must be used, adding conduction loss and complexity.

Can MP3900DK-LF operate in discontinuous conduction mode (DCM)?

Yes, the MP3900DK-LF supports both continuous and discontinuous conduction modes. Its peak current mode architecture and internal slope compensation ensure stable operation across DCM, especially at light loads or high V_OUT/V_IN ratios. The 330kHz fixed frequency remains active in DCM, unlike some hysteretic controllers, enabling predictable EMI filter design and consistent transient response.

Why does the datasheet specify two ground pins (PGND and SGND), and how should they be routed?

PGND carries high di/dt gate driver return current, while SGND serves as the quiet reference for FB, COMP/RUN, and ISENSE. They must be tied together at a single point-preferably the negative terminal of the output capacitor-to avoid noise coupling into the feedback path. Routing PGND as a wide, low-inductance copper pour separate from SGND traces prevents switching noise from modulating the error amplifier and causing instability or output ripple.

Is the MP3900DK-LF compatible with synchronous rectification in boost topology?

No, the MP3900DK-LF is a controller-only device designed to drive a single external N-channel MOSFET as the main switch; it does not provide complementary gate drive signals required for synchronous rectification. To implement synchronous boost, an additional gate driver IC or discrete logic would be needed to generate the inverted, delayed signal for the synchronous rectifier MOSFET-adding complexity and potential shoot-through risk.

What is the purpose of the NC pin (Pin 6), and can it be grounded or left floating?

Pin 6 is a no-connect (NC) pin with no internal bond wire or circuit connection. It must be left electrically floating-neither grounded nor tied to any voltage rail-as grounding it could introduce parasitic capacitance or leakage paths affecting adjacent pins (e.g., ISENSE or COMP/RUN). The MSOP-8 package drawing confirms this pin is unpopulated, and the datasheet explicitly states "must remain floating."

How does the MP3900DK-LF handle input voltage brownout conditions?

The MP3900DK-LF uses an internal undervoltage lockout (UVLO) with 8.9V turn-on threshold and 2.3V hysteresis. When V_CC drops below 6.6V (8.9V – 2.3V), the IC shuts down, reducing supply current to 10µA. Upon recovery, the internal 0.5µA current charges the external COMP/RUN capacitor, providing controlled soft-start to prevent inrush current and output overshoot-critical for reliable operation in unstable 12V telecom or automotive supplies.