Monolithic Power Systems Inc. MP18021HQ-A-LF-P

Overview

MP18021HQ-A-LF-P from Monolithic Power Systems is a high-frequency, 100V half-bridge N-channel MOSFET gate driver in QFN8 (3×3 mm) package, delivering matched 16 ns propagation delay and <5 ns high-side/low-side drive skew. It integrates a bootstrap diode, supports 9–18 V VDD, and drives 1 nF loads with 12 ns/9 ns rise/fall times-used in telecom DC-DC converters requiring precise timing and shoot-through prevention.

For engineers reviewing the MP18021HQ-A-LF-P datasheet, MP18021HQ-A-LF-P pinout, MP18021HQ-A-LF-P application, or MP18021HQ-A-LF-P equivalent, key selection criteria include bootstrap voltage range (100 V), UVLO thresholds (7.7 V / 6.7 V), independent INH/INL control for dead-time management, and thermal performance in QFN8 at 125 °C junction temperature.

Technical Context

The MP18021HQ-A-LF-P implements dual independent drivers: a low-side channel referenced to VSS and a floating high-side channel level-shifted via bootstrap architecture. Its internal UVLO monitors both VDD and BST–SW rails, forcing outputs low below threshold-preventing partial turn-on during supply ramp-up.

Timing precision is achieved through matched propagation paths (TDLRR/TDHRR = 16 ns typ.) and sub-5 ns inter-channel skew (TMON/TMOFF ≤ 5 ns). The integrated bootstrap diode (VF = 0.5 V @ 100 µA, RD = 2.5 Ω @ 100 mA) enables compact layout while maintaining 100 V BST voltage capability and supporting >50 V/ns SW slew rates.

Key Specifications

Pinout & Package

MP18021HQ-A-LF-P uses a thermally enhanced QFN8 (3×3 mm) package with exposed pad on underside for PCB-level heat dissipation. Package meets JEDEC MO-229 VEEC-2 standard and supports reflow soldering per IPC/JEDEC J-STD-020.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-frequency half-bridge gate driver applications.

Compared with IRS21844STRPBF and LM5109BMAX/NOPB, MP18021HQ-A-LF-P uniquely combines 100 V BST capability, integrated bootstrap diode, <5 ns drive matching, and dual-rail UVLO-making it optimal for compact, high-frequency telecom and avionics DC-DC designs where timing integrity and component count are decisive.

Availability

MP18021HQ-A-LF-P is available at Aetrix Electronics and suitable for telecom power supplies, avionics DC-DC converters, and two-switch forward converters requiring stable component supply, RoHS-compliant packaging, and guaranteed long-term lifecycle support.

Supply support for MP18021HQ-A-LF-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 design centers in the US, China, and Taiwan, and global manufacturing partnerships.

The MP18021 series belongs to MPS's high-frequency gate driver product line, engineered specifically for isolated DC-DC topologies demanding precise timing, high bus voltage tolerance, and minimal external components in space-constrained environments.

FAQ

What is the maximum allowable SW node slew rate for reliable operation?

The MP18021HQ-A-LF-P is characterized for SW slew rates up to 50 V/ns per datasheet Section "Recommended Operating Conditions." Exceeding this may cause false triggering of internal level shifters or premature UVLO activation due to coupling into BST or VDD rails. Layout best practices-short SW traces, minimized parasitic inductance, and proper gate resistor selection-are essential to stay within this limit.

Can INH and INL be tied together for synchronous operation?

Yes, INH and INL can be connected to a single PWM signal for synchronous two-switch forward operation. However, doing so eliminates independent dead-time control. For half-bridge or active-clamp topologies, separate INH/INL routing is mandatory to prevent shoot-through-internal logic does not enforce interlock or blanking.

Is the exposed thermal pad electrically connected to VSS internally?

Yes, Pin 7 (VSS) and the exposed pad are internally shorted within the die assembly. The pad must be soldered to a dedicated VSS copper pour on the PCB to ensure both electrical grounding and thermal conduction. Floating or isolated pad connection violates JEDEC MO-229 compliance and degrades thermal performance beyond θ_JA = 50 °C/W.

Does the integrated bootstrap diode support bidirectional current flow?

No-the internal bootstrap diode is unidirectional, conducting only from VDD to BST during charging. It does not conduct from BST to VDD. During high-side conduction, BST discharges into the high-side gate and SW node; recharge occurs only when the low-side FET is on and SW ≈ VSS. Reverse conduction is not supported or characterized.

What is the minimum recommended bootstrap capacitor value for 500 kHz operation?

For 500 kHz switching with 50% duty cycle and 2.5 A peak gate drive, a minimum 100 nF X7R ceramic capacitor (rated ≥16 V) is recommended between BST and SW. This ensures <100 mV ripple under worst-case charge loss, maintaining UVLO margin. Larger values (220–470 nF) improve margin in high-temperature or high-dV/dt environments.

How does the device behave during BST–SW UVLO condition?

When BST–SW falls below 6.7 V (typ.), the high-side driver (DRVH) is forced low and held inactive until BST–SW rises above 7.25 V (6.7 V + 0.55 V hysteresis). The low-side driver remains fully operational unless VDD also drops below its own UVLO threshold-enabling safe fallback to low-side-only operation during bootstrap fault.

Is there an internal pull-down on INH and INL, and what is its resistance?

Yes, both INH and INL feature internal 185 kΩ pull-down resistors to VSS, ensuring defined logic-low state when inputs are unconnected or high-impedance. This eliminates need for external pull-downs in most PWM controller interfaces, though external resistors may be added for noise immunity in high-EMI environments.