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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Voltage Regulators - DC DC Switching Regulators

Monolithic Power Systems Inc. MP9943GQ-P

Name: MP9943GQ-P
Brand: Monolithic Power Systems Inc.
SKU: MP9943GQ-P
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MP9943GQ-P

Manufacturer:: Monolithic Power Systems Inc.

Category:: Voltage Regulators - DC DC Switching Regulators

Package:: 8-VDFN

Datasheet:: MP9943GQ-P.pdf

Description:: IC REG BUCK ADJ 3A 8QFN

Quantity:: RFQ Add To RFQ list

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Product details

Overview

MP9943GQ-P from Monolithic Power Systems is a synchronous step-down DC/DC converter IC with integrated 85mΩ/55mΩ MOSFETs, delivering up to 3A peak output current across a 4V–36V input range. It features 410kHz fixed switching frequency, internal soft-start, power-good (PG) indicator, and operates in AAM light-load mode for high efficiency. Used in multi-function printers and distributed power systems where compact 36V-rated buck regulation is required.

For engineers reviewing the MP9943GQ-P datasheet, MP9943GQ-P pinout, MP9943GQ-P application, or MP9943GQ-P equivalent, this page delivers verified technical context, validated pin functions, confirmed thermal and protection behavior, and real-world design constraints including BST resistor requirements, PG timing thresholds (90% V_FB rising), and UVLO hysteresis (200mV).

Technical Context

The MP9943GQ-P employs peak-current-mode control with internal compensation, enabling stable regulation without external loop components. Its 410kHz oscillator supports external synchronization from 200kHz to 2.2MHz, and the 95% maximum duty cycle supports automotive cold-crank operation down to 4V input.

It integrates a 5V internal LDO for biasing, bootstrap charging circuitry with 2.2V UVLO on the floating driver, and AAM (Advanced Asynchronous Modulation) for PFM operation below ~100mA load. Over-current protection uses cycle-by-cycle limiting with hiccup recovery, while thermal shutdown activates at 170°C with 30°C hysteresis.

Key Specifications

Parameter	Value and Actual Design Meaning
Input Voltage Range	4V to 36V continuous - supports wide industrial and automotive supply rails, including cold-crank conditions.
Output Current	3A peak - enables single-chip 5V/3A or 3.3V/3A conversion without external MOSFETs.
Switching Frequency	410kHz typical (320–500kHz) - balances EMI, inductor size, and efficiency; synchronizable to 200kHz–2.2MHz.
Feedback Reference	792mV ±14mV - sets output voltage via external resistor divider; enables precise 0.8V–36V adjustable outputs.
Power Good Threshold	Rising at 90% V_FB, falling at 84% V_FB - provides accurate output monitoring with 6% hysteresis and 90μs delay.
Thermal Shutdown	170°C activation, 140°C recovery - protects die during overload or poor PCB thermal design; 30°C hysteresis prevents oscillation.
HS/LS R_DS(ON)	85mΩ / 55mΩ - reduces conduction loss at full load; enables >92% efficiency at 12V→5V/2A.

Pinout & Package

MP9943GQ-P is housed in a thermally enhanced QFN-8 (3mm × 3mm) package with exposed thermal pad. The package supports high-power density designs and requires proper PCB copper area and vias for thermal management.

Pin/Terminal	Circuit Role	Design Meaning
1 FB	Feedback Input	Connects to resistor divider tap; regulates output by comparing against 792mV reference; triggers fold-back at <660mV during fault.
2 VCC	Bias Supply Rail	Internal 5V LDO output; powers control circuitry; requires 0.1–0.22μF ceramic decoupling close to pin.
3 EN/SYNC	Enable & Clock Input	Digital enable (1.4V threshold); accepts external sync clock (200kHz–2.2MHz); includes 500kΩ pull-down and 6.5V Zener clamp.
4 BST	Bootstrap Supply	Drives high-side MOSFET gate; requires capacitor between BST and SW; 20Ω series resistor strongly recommended to suppress SW spikes.
5 GND	System Ground Reference	Primary ground return for output, feedback, and power stages; must be low-impedance with multiple vias to inner ground plane.
6 SW	Switch Node	High-frequency drain connection of internal HS/LS MOSFETs; routes high di/dt current; requires wide, short PCB trace.
7 IN	Main Input Supply	Accepts 4V–36V; requires bulk + high-frequency ceramic input capacitors placed adjacent to IN/GND pins.
8 PG	Open-Drain Power-Good Output	Asserts high when V_OUT ≥ 90% target; pulled low during startup, fault, or shutdown; requires external pull-up resistor (e.g., 100kΩ to VCC).

Key Features

Feature	Design Value
Wide Input Range (4V–36V)	Enables direct integration into 12V/24V industrial rails and automotive battery systems without pre-regulation.
Synchronous Rectification	Eliminates external Schottky diode; achieves >93% efficiency at mid-load by replacing conduction loss with low R_DS(ON).
Internal Soft-Start (1.5ms)	Prevents output overshoot and inrush current during power-up; ramps internal reference from 0V to 1.2V before engaging regulation.
Power-Good Indicator	Provides system-level status signaling with precise 90%/84% V_FB thresholds and 90μs delay-critical for processor reset sequencing.
AAM Light-Load Mode	Reduces quiescent current to 0.7mA and enables PFM operation below ~100mA, maintaining >85% efficiency at 10mA load.

Applications

Multi-Function Printers (MFP)

Distributed Power Systems

Use Scenario: Powering logic, sensors, and motor drivers in compact office MFPs with 24V input bus.

IC Role / Device Role / Timing Role: Primary 5V/3A buck regulator supplying FPGA I/O banks and USB PHY; PG signal sequences main controller boot.

Use Value: Integrated MOSFETs eliminate layout complexity; 36V rating handles 24V rail transients; PG timing ensures deterministic firmware initialization.

Use Scenario: Local point-of-load conversion in telecom shelf systems with 48V backplane and isolated 12V intermediate bus.

IC Role / Device Role / Timing Role: Secondary 3.3V/3A regulator feeding DSPs and SerDes; synchronized to system clock to reduce beat-frequency EMI.

Use Value: 410kHz sync capability aligns switching noise with system clock harmonics; QFN-8 footprint saves board space in dense card layouts.

Industrial Control Panels

Automotive Infotainment Displays

Use Scenario: Converting 24V field power to 5V for PLC I/O modules operating in harsh temperature environments.

IC Role / Device Role / Timing Role: Main 5V supply with thermal shutdown (170°C) and -40°C to +125°C junction rating; PG confirms stable rail before enabling analog front-end.

Use Value: Wide VIN and robust protection suite ensure reliability under brownouts and overloads; internal compensation simplifies certification testing.

Use Scenario: Powering LCD backlight drivers and touch controllers in vehicle head units with cold-crank immunity.

IC Role / Device Role / Timing Role: 3.3V/3A buck stage supporting 4V minimum input; 95% max duty cycle maintains regulation during 6V cranking events.

Use Value: High-duty-cycle capability eliminates need for boost-pre-regulator; AAM mode extends battery runtime in standby display states.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MP2451DT-LF-Z	Lower 36V max input, 2A peak output, no PG pin, 340kHz fixed f_SW	Lacks power-good signaling and automotive cold-crank support; suitable only for non-critical 12V→5V/2A loads.	Select MP9943GQ-P when PG sequencing, 3A peak, or 4V–36V operation is required.
LM5164QPWPRQ1	42V max input, 1A output, external MOSFETs, 100kHz–2.2MHz sync, no internal soft-start	Requires external FETs and compensation; better for ultra-low IQ but higher BOM count and layout effort.	Choose MP9943GQ-P for integrated, space-constrained 3A designs; LM5164QPWPRQ1 fits high-reliability 42V systems needing external FET control.

Compared with MP2451DT-LF-Z, MP9943GQ-P adds PG signaling, 50% higher peak current, and cold-crank support; versus LM5164QPWPRQ1, it trades external FET flexibility for lower component count and guaranteed 3A performance in QFN-8.

Availability

MP9943GQ-P is available at Aetrix Electronics and suitable for multi-function printers, distributed power systems, industrial control panels, and automotive infotainment displays requiring stable component supply, long-lifecycle availability, and RoHS-compliant packaging.

Supply support for MP9943GQ-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, LED drivers, and motor control solutions.

The MP9943 belongs to MPS's high-voltage synchronous buck converter product line, designed specifically for compact, efficient point-of-load regulation in industrial, automotive, and consumer applications demanding wide input range and integrated protection.

FAQ

What is the exact function of the BST pin, and why is a 20Ω resistor recommended?

The BST pin supplies gate drive voltage to the internal high-side MOSFET via a bootstrap capacitor connected between BST and SW. A 20Ω resistor in series with the BST capacitor reduces ringing and voltage spikes at the SW node during switching transitions. This improves EMI performance and prevents false triggering of the internal over-voltage protection on the BST rail, especially under high-dV/dt conditions.

Does MP9943GQ-P support external synchronization, and what are the valid frequency limits?

Yes, MP9943GQ-P supports external synchronization via the EN/SYNC pin. It accepts TTL/CMOS-compatible clock signals from 200kHz to 2.2MHz. Synchronization begins 2ms after output regulation is established, and the external clock pulse width must remain below 2μs to avoid interference with internal timing. This feature enables EMI reduction through frequency dithering or alignment with system clocks.

How does the Power Good (PG) pin behave during startup and fault conditions?

The PG pin is an open-drain output that remains low until V_FB reaches 90% of the nominal reference (792mV), then asserts high after a 90μs delay. It pulls low again if V_FB drops to 84% of reference, or immediately upon EN/SYNC deactivation, thermal shutdown, or output short-circuit causing hiccup mode. An external pull-up resistor (e.g., 100kΩ to VCC) is mandatory for proper logic-level signaling.

What is the purpose of the AAM (Advanced Asynchronous Modulation) mode, and how is it triggered?

AAM mode is an automatic light-load efficiency optimization that switches the regulator from PWM to PFM operation. It activates when the COMP voltage falls below the internal VAAM threshold (~0.4V), typically below ~100mA load. During AAM, the internal clock is gated, allowing variable off-time to reduce switching losses while maintaining regulation-achieving quiescent current as low as 0.7mA and >85% efficiency at 10mA.

Can MP9943GQ-P operate with input voltage below 5V, and what limitations apply?

Yes, MP9943GQ-P operates down to 4V input, but bootstrap charging becomes marginal below 5V due to reduced VIN–VSW headroom. At low VIN (<5V) combined with high duty cycle (>65%), BST voltage may sag, increasing high-side FET conduction loss and output ripple. In such cases, adding an external bootstrap diode (e.g., 1N4148) from VCC or VOUT to BST is recommended to maintain gate drive integrity.

What are the absolute maximum ratings for the EN/SYNC pin, and how should it be interfaced?

The EN/SYNC pin has an absolute maximum rating of 6.5V, enforced by an internal Zener clamp. It must be driven with a voltage ≤6V if connected directly, or via a pull-up resistor to VIN (≥36.7kΩ for 12V VIN) to limit current to <150μA. Floating the pin disables the device via its internal 500kΩ pull-down. Exceeding 6.5V risks permanent damage to the clamp structure.

Is the MP9943GQ-P RoHS-compliant and lead-free?

Yes, MP9943GQ-P is fully RoHS-compliant and lead-free per EU Directive 2011/65/EU. All MPS products adhere to green manufacturing standards, and the device uses matte tin (Sn) plating on QFN-8 terminals. Full compliance documentation, including substance declarations and test reports, is available on the Monolithic Power Systems website under Quality Assurance.

MP9943GQ-P Specifications

Product attributes: Attribute value

Manufacturer:: Monolithic Power Systems Inc.

Series:: -

Package/Case:: 8-VDFN

Packaging:: Tape & Reel (TR)

Product Status:: Active

Function:: Step-Down

Output Configuration:: Positive

Topology:: Buck

Output Type:: Adjustable

Number of Outputs:: 1

Voltage - Input (Min):: 4V

Voltage - Input (Max):: 36V

Voltage - Output (Min/Fixed):: 0.8V

Voltage - Output (Max):: 28.5V

Current - Output:: 3A

Frequency - Switching:: 410kHz

Synchronous Rectifier:: Yes

Operating Temperature:: -40°C ~ 125°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 8-QFN (3x3)

MP9943GQ-P FAQ

1.How can I place an order for MP9943GQ-P through Aetrix?

Please submit a Request for Quotation (RFQ) for MP9943GQ-P on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for MP9943GQ-P reliable?

The price and inventory of MP9943GQ-P are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MP9943GQ-P is usually 5 days.

3.What payment methods are accepted for MP9943GQ-P?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MP9943GQ-P transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MP9943GQ-P?

MP9943GQ-P orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MP9943GQ-P order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for MP9943GQ-P?

For technical support, including MP9943GQ-P datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MP9943GQ-P requirements.

6.How does Aetrix verify that MP9943GQ-P is sourced from the original manufacturer or authorized distributors?

All MP9943GQ-P products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that MP9943GQ-P meets industry standards.

7.What is the process for return or replacement of MP9943GQ-P?

All MP9943GQ-P units undergo pre-shipment inspection (PSI). If there is an issue with MP9943GQ-P, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The MP9943GQ-P part is unused and in its original packaging.

Return procedure for MP9943GQ-P:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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