Monolithic Power Systems Inc. MP9485GN-Z

Overview

MP9485GN-Z from Monolithic Power Systems is a 100V-input, 500mA synchronous step-down converter with integrated 1.0A high-side MOSFET, hysteretic voltage-mode control, and 170µA quiescent current-designed for automotive power supplies, solar energy systems, and high-power LED drivers where wide VIN range and fast transient response are critical.

For engineers reviewing the MP9485GN-Z datasheet, MP9485GN-Z pinout, MP9485GN-Z application, or MP9485GN-Z equivalent, key selection factors include its 4.5–100V input range, SOIC-8 EP package with exposed pad, 215mV/185mV FB threshold hysteresis, PWM dimming capability on DIM pin, and thermal shutdown + short-circuit protection.

Technical Context

The MP9485GN-Z employs hysteretic voltage-mode control with adaptive FB threshold adjustment (215mV high / 185mV low), eliminating external compensation components. Its internal high-side MOSFET features 500mΩ R_DS(ON) and integrated current limiting at 0.75A typical.

Operation includes dedicated EN pin with 1.55V rising threshold and 320mV hysteresis, DIM pin supporting up to 20kHz PWM dimming for LED applications, and bootstrap circuitry regulated to ~5V for gate drive-enabling stable operation up to 2MHz switching frequency.

Key Specifications

Pinout & Package

MP9485GN-Z is housed in an SOIC-8 package with exposed pad for enhanced thermal dissipation (θ_JA = 50°C/W, θ_JC = 10°C/W on 4-layer board). The exposed pad must be soldered to a GND plane using thermal vias for reliable 2.5W power handling.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage buck converter applications.

Compared with LM5164QWRGERQ1 and MAX20006AATP+T, MP9485GN-Z uniquely combines 100V input tolerance, hysteretic simplicity, and native PWM dimming-making it optimal for cost-sensitive, high-input-voltage LED and industrial power applications where minimal external components are critical.

Availability

MP9485GN-Z is available at Aetrix Electronics and suitable for automotive system power, solar energy systems, e-bike control power supplies, and high-power LED drivers requiring stable component supply across extended temperature and voltage ranges.

Supply support for MP9485GN-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 core expertise in DC-DC conversion, motor drivers, and LED lighting solutions.

The MP9485 belongs to MPS's high-voltage buck converter product line, engineered specifically for rugged industrial and automotive applications demanding wide input range, integrated protection, and minimal external components.

FAQ

What is the maximum recommended input voltage for continuous operation?

The MP9485GN-Z is rated for continuous operation up to 95V input per Recommended Operating Conditions. While Absolute Maximum Rating allows 100V, sustained operation above 95V risks reduced reliability and thermal margin-especially at high ambient temperatures or full load. Designers should maintain ≤95V for production systems unless derated per thermal analysis.

Can the DIM pin be left unconnected in non-LED applications?

Yes-the DIM pin can be left floating or tied to EN in standard buck configurations. When unused, connecting DIM to EN ensures consistent enable behavior and avoids unintended dimming activation. No pull-up or pull-down resistor is required, as DIM has high-impedance input (±1µA leakage) and does not affect regulation when inactive.

How does the hysteretic control affect output voltage accuracy?

Hysteretic control delivers ±1.5% typical output voltage accuracy over line, load, and temperature-achieved through adaptive 215mV/185mV FB thresholds that compensate for propagation delays. Unlike fixed-frequency controllers, it does not require external compensation but trades off tighter DC accuracy for faster transient response and simpler design.

Is an external bootstrap diode necessary for reliable operation?

An external bootstrap diode (e.g., BAT54) is recommended when VIN exceeds 5V and duty cycle >65%, or when operating above 1.5MHz. It improves BST capacitor charging efficiency and prevents under-voltage lockout of the high-side driver during high-duty-cycle conditions-particularly critical in 5V-output applications from 36V+ inputs.

What thermal management practices are essential for SOIC-8 EP package?

For reliable 500mA operation at elevated ambient temperatures, the exposed pad must be soldered to a minimum 100mm² GND copper area with ≥6 thermal vias (15mil barrel, 40mil pitch). Avoid placing signal traces under the pad. Thermal resistance drops from 50°C/W to ≤35°C/W with proper layout-preventing thermal shutdown at 125°C ambient.

Does the MP9485GN-Z support synchronous rectification?

No-the MP9485GN-Z uses an integrated high-side MOSFET but requires an external Schottky diode for low-side conduction. It is not a synchronous buck converter. The datasheet specifies "low forward voltage Schottky rectifier" and provides D1 part recommendations (e.g., B1100); no internal low-side FET or gate drive for sync rectification is present.

How is short-circuit protection implemented and what is the recovery behavior?

SCP triggers when FB remains <185mV for >10µs-indicating output short or severe overload. The IC shuts off the high-side switch, waits ~300µs, then attempts restart. This auto-retry continues indefinitely until fault clears. Unlike latch-off protection, this preserves system availability in intermittent fault environments like vibrating industrial wiring.