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Monolithic Power Systems Inc. MP9942GJ-Z
- Part No.:
- MP9942GJ-Z
- Manufacturer:
- Monolithic Power Systems Inc.
- Package:
- SOT-23-8 Thin, TSOT-23-8
- Datasheet:
-
MP9942GJ-Z.pdf
- Description:
- IC REG BUCK ADJ 2A TSOT23-8
- Quantity:
- Payment:
- Shipping:
Inventory:3,237
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Product details
Overview
MP9942GJ-Z from Monolithic Power Systems is a synchronous step-down DC-DC converter IC delivering 2A continuous output current with 4V–36V input range, 410kHz fixed switching frequency, and integrated 90mΩ/55mΩ MOSFETs. It features power good (PG) indication, internal soft-start, thermal shutdown, and hiccup-mode over-current protection-designed for automotive cold-crank and industrial power rail regulation.
For engineers reviewing the MP9942GJ-Z datasheet, MP9942GJ-Z pinout, MP9942GJ-Z application, or MP9942GJ-Z equivalent, this device supports precise output voltage setting via resistor divider (0.792V FB reference), external clock synchronization (200kHz–2.2MHz), and AAM light-load efficiency mode-critical for battery-powered and wide-input industrial systems.
Technical Context
The MP9942GJ-Z employs peak-current-mode control with internal compensation, enabling fast transient response and stable loop behavior without external compensation components. Its 410kHz oscillator operates in fixed-frequency PWM mode but supports external synchronization to suppress EMI through frequency alignment.
It integrates a 5V internal VCC regulator powered from VIN, bootstrap circuitry with BST pin requiring external capacitor and optional 20Ω series resistor, and a dedicated open-drain PG output with 90μs delay and 6% hysteresis relative to the 0.792V reference-enabling reliable system power sequencing and fault reporting.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 36V - supports automotive battery systems including cold-crank (down to 4V) and industrial 24V rails. |
| Output Current | 2A continuous - sufficient for powering microcontrollers, sensors, and interface ICs in compact embedded systems. |
| Switching Frequency | 410kHz (typ.) - balances efficiency, size, and EMI; adjustable via EN/SYNC pin from 200kHz to 2.2MHz. |
| Feedback Reference | 0.792V ±12mV - enables accurate output voltage setting down to 0.8V using standard resistor dividers. |
| Power Good Threshold | 90% of VFB rising / 84% falling - provides clean power sequencing signal with 6% hysteresis to avoid chatter. |
| Thermal Shutdown | 170°C activation / 140°C recovery - protects against sustained overload while allowing automatic recovery after cooling. |
| Current Limit | 4.2A (typ.) - ensures robust short-circuit protection with hiccup mode to limit average fault current and die temperature. |
Pinout & Package
MP9942GJ-Z is housed in an 8-pin TSOT23 package (3.0mm × 3.0mm × 0.9mm), optimized for high-density PCB layouts with exposed thermal pad (not electrically connected). The package supports reflow soldering per JEDEC J-STD-020 and achieves θJA = 100°C/W on a 4-layer board.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - PG | Open-drain power good indicator | Pulled low at startup and during faults; pulled high when VOUT ≥ 90% × 0.792V, with 90μs delay - used for system enable sequencing. |
| 2 - IN | Main input supply connection | Accepts 4V–36V; requires local 22µF + 0.1µF ceramic decoupling; routed with wide trace to minimize impedance and noise coupling. |
| 3 - SW | Switch node | Connects to inductor; carries high di/dt square wave; must be kept short and away from analog traces (e.g., FB) to reduce noise. |
| 4 - GND | System ground reference | Primary return path for power and feedback; requires solid copper pour and multiple vias to inner ground plane for low-impedance return. |
| 5 - BST | Bootstrap supply for high-side gate driver | Requires 0.1µF–1µF capacitor between BST and SW; 20Ω resistor recommended to damp ringing and reduce SW spike voltage. |
| 6 - EN/SYNC | Enable input / external clock sync | Logic-high (>1.4V) enables operation; external 200kHz–2.2MHz clock applied here synchronizes switching edge - critical for multi-rail EMI reduction. |
| 7 - VCC | Bias supply output | Internally regulated ~5V output; requires 0.1µF–0.22µF ceramic decoupling close to pin; powers internal circuitry except gate drivers. |
| 8 - FB | Feedback input | Compares output voltage (via resistor divider) to 0.792V reference; sensitive analog node - must be routed short and shielded from SW and GND noise. |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous rectification | Integrated 90mΩ HS / 55mΩ LS MOSFETs eliminate external diode losses - improves full-load efficiency by up to 8% vs. asynchronous designs. |
| Advanced Asynchronous Modulation (AAM) | Automatic PFM mode below ~200mA load - reduces quiescent current to 0.7mA and maintains >85% efficiency at 10mA output. |
| Internal soft-start | 1.45ms ramp time - prevents output overshoot and inrush current during startup, eliminating need for external soft-start circuitry. |
| Wide UVLO hysteresis | 3.5V rising / 3.3V falling threshold with 200mV hysteresis - ensures clean turn-on/turn-off during brown-out conditions in automotive environments. |
| Hiccup-mode over-current protection | Enters periodic restart cycle under sustained short-circuit - limits average power dissipation to <1W, preventing thermal runaway without latching off. |
Applications
| Automotive Body Control Module | Industrial PLC I/O Power Rail |
|---|---|
Use Scenario: Regulating 3.3V or 5V from 12V/24V vehicle battery for MCU, CAN transceivers, and sensor interfaces under cold-crank (4.5V min) and load-dump conditions. IC Role / Device Role / Timing Role: Primary buck regulator providing stable, sequenced power with PG signal for microcontroller reset coordination and fault reporting. Use Value: 95% maximum duty cycle and 4V minimum input ensure uninterrupted operation during engine cranking; PG output enables safe boot sequencing. |
Use Scenario: Generating isolated 5V/3.3V rails for digital I/O modules in programmable logic controllers operating in harsh factory environments with 24V DC supply. IC Role / Device Role / Timing Role: Compact, thermally robust DC-DC stage replacing linear regulators to reduce heat buildup and improve system efficiency. Use Value: TSOT23-8 footprint saves board space; thermal shutdown and hiccup protection prevent field failures due to wiring faults or overloads. |
| Distributed Telecom Power Supply | Medical Sensor Hub Power Management |
Use Scenario: Point-of-load conversion in remote radio units or base station submodules where 48V or 24V backplane supplies require local 3.3V/5V generation. IC Role / Device Role / Timing Role: High-efficiency synchronous buck converter synchronized to system clock to minimize conducted EMI across shared power planes. Use Value: External clock sync (200kHz–2.2MHz) allows EMI frequency shifting to avoid sensitive RF bands; 410kHz default simplifies filter design. |
Use Scenario: Powering low-noise analog front-ends, ADCs, and Bluetooth LE radios in portable diagnostic devices with Li-ion or USB input (5V). IC Role / Device Role / Timing Role: Low-quiescent, high-PSRR DC-DC stage delivering clean, regulated voltage with minimal ripple for precision analog circuits. Use Value: AAM mode reduces no-load current to <1µA; FB reference accuracy (±1.5%) ensures stable sensor biasing across temperature. |
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 | 36V input, 0.6A output, 2MHz switching, no PG pin, smaller 6-pin SOT563 package | Targeted at space-constrained, lower-current applications where power sequencing is not required | Select when board area is critical and load current ≤600mA; omit if PG signaling or 2A capability is mandatory. |
| TPS54202DRCT | 6V–18V input, 2A output, 400kHz–2.5MHz sync, integrated PG, but lacks cold-crank support below 6V | Suitable for 12V-only industrial systems; not rated for automotive battery transients | Choose only for non-automotive 12V applications; reject if 4V–36V range or cold-crank operation is needed. |
Compared with MP2451DT-LF-Z and TPS54202DRCT, MP9942GJ-Z uniquely combines 36V max input, 4V min start-up, integrated PG, and 2A capability in an 8-pin TSOT23-making it the only option qualified for automotive body electronics and wide-input industrial converters requiring full-feature power monitoring.
Availability
MP9942GJ-Z is available at Aetrix Electronics and suitable for automotive body control modules, industrial PLC I/O power rails, distributed telecom power supplies, and medical sensor hub power management requiring stable component supply across extended temperature and voltage ranges.
Supply support for MP9942GJ-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 MP9942 belongs to MPS's high-voltage synchronous buck converter product line, engineered specifically for automotive and industrial applications demanding wide input range, robust protection, and compact footprint without sacrificing efficiency or reliability.
FAQ
What is the minimum input voltage required for MP9942GJ-Z to start switching?
The MP9942GJ-Z has an under-voltage lockout (UVLO) rising threshold of 3.5V, meaning it begins switching once the input voltage exceeds 3.5V. However, stable 2A operation requires ≥4V per datasheet specifications, and the device maintains regulation down to 4V even under full load-critical for automotive cold-crank scenarios.
Can MP9942GJ-Z synchronize to an external clock, and what is the valid frequency range?
Yes, the EN/SYNC pin accepts an external clock signal for synchronization. Valid frequencies range from 200kHz to 2.2MHz, with pulse width limited to <2μs. The internal oscillator locks to the rising edge of the external clock, enabling EMI reduction in multi-rail systems and compliance with strict spectral emission requirements.
How does the Power Good (PG) pin behave during startup and fault conditions?
The PG pin is open-drain and pulls low during startup, thermal shutdown, EN deactivation, or when VOUT drops below 84% of the FB reference (≈0.669V). It transitions high only after VOUT reaches ≥90% of the reference (≈0.713V), with a typical 90μs delay-ensuring reliable power sequencing and avoiding false assertions during transient recovery.
What is the purpose of the BST pin, and what external components are required?
The BST pin supplies the floating gate drive voltage for the high-side MOSFET. A 0.1µF–1µF ceramic capacitor must be placed between BST and SW pins. A 20Ω resistor in series with the BST capacitor is strongly recommended to damp SW node ringing and reduce voltage spikes that could compromise gate oxide integrity or EMI performance.
Does MP9942GJ-Z support adjustable output voltage, and what is the feedback reference voltage?
Yes, output voltage is set externally using a resistor divider from VOUT to GND connected to the FB pin. The internal reference is 0.792V ±12mV (780–804mV), enabling precise output regulation from 0.8V up to near VIN. For example, a 3.3V output uses R1 = 41.2kΩ and R2 = 13kΩ per the datasheet's T-network recommendation.
What thermal protection mechanisms does MP9942GJ-Z implement?
The device features two-tier thermal protection: first, internal thermal shutdown activates at 170°C junction temperature, halting switching until die cools to ~140°C; second, the bootstrap driver includes independent UVLO (2.2V rising threshold) to prevent high-side FET misfire during thermal stress-ensuring graceful degradation rather than latch-up or parametric shift.
Is MP9942GJ-Z RoHS-compliant and lead-free?
Yes, MP9942GJ-Z is fully RoHS-compliant and lead-free per EU Directive 2011/65/EU. All MPS products adhere to green packaging standards, and the TSOT23-8 package uses matte tin plating on leads. Full compliance documentation, including substance declarations and test reports, is available on the MPS Quality Assurance website.
MP9942GJ-Z Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Monolithic Power Systems Inc.
- Series:
- -
- Package/Case:
- SOT-23-8 Thin, TSOT-23-8
- 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):
- 30V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 28.5V
- Current - Output:
- 2A
- Frequency - Switching:
- 410kHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- TSOT-23-8
MP9942GJ-Z FAQ
1.How can I place an order for MP9942GJ-Z through Aetrix?
Please submit a Request for Quotation (RFQ) for MP9942GJ-Z 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 MP9942GJ-Z reliable?
The price and inventory of MP9942GJ-Z are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MP9942GJ-Z is usually 5 days.
3.What payment methods are accepted for MP9942GJ-Z?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MP9942GJ-Z transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MP9942GJ-Z?
MP9942GJ-Z orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MP9942GJ-Z 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 MP9942GJ-Z?
For technical support, including MP9942GJ-Z datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MP9942GJ-Z requirements.
6.How does Aetrix verify that MP9942GJ-Z is sourced from the original manufacturer or authorized distributors?
All MP9942GJ-Z 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 MP9942GJ-Z meets industry standards.
7.What is the process for return or replacement of MP9942GJ-Z?
All MP9942GJ-Z units undergo pre-shipment inspection (PSI). If there is an issue with MP9942GJ-Z, 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 MP9942GJ-Z part is unused and in its original packaging.
Return procedure for MP9942GJ-Z:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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