Microchip Technology HV9918K7-G

Overview

HV9918K7-G from Microchip Technology is a hysteretic buck LED driver IC with integrated 40V/1Ω N-channel MOSFET, high-side current sensing, ±5% LED current accuracy, and support for analog/PWM dimming. It operates from 4.5V to 40V input and delivers up to 700 mA constant output current for industrial signage and architectural lighting.

For engineers reviewing the HV9918K7-G datasheet, HV9918K7-G pinout, HV9918K7-G application, or HV9918K7-G equivalent, key selection criteria include its 2 MHz max switching frequency, thermal shutdown at 140°C, ADIM-based thermal foldback capability, and compatibility with low-ESR ceramic input capacitors in compact DFN layouts.

Technical Context

The HV9918K7-G implements hysteretic control using a high-side current sense comparator with 213–246 mV upper and 158–182 mV lower thresholds, enabling fast transient response and high input supply rejection. Its internal 5V regulator (4.5–5.5V output) powers the logic and supports 8 mA load.

Dimming is implemented via dual paths: a dedicated DIM pin accepting 0.7V/2.2V logic thresholds for PWM, and an ADIM pin accepting 0–2V analog signals that modulate LED current through comparison with a programmable RAMP voltage (0.1–2.1 V range), with frequency set by an external capacitor.

Key Specifications

Pinout & Package

Package: 8-lead 3×3 mm WDFN (wettable flank), RoHS-compliant, exposed thermal pad (EP) tied to GND for enhanced thermal dissipation (θJA = 60°C/W on 25 mm² FR-4).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar constant-current LED driver applications.

Compared with AL8862SP-13 and MPQ4425AGU-AEC1-P, the HV9918K7-G uniquely combines integrated MOSFET, high-side sensing, and ADIM-based thermal foldback in a compact 3×3 mm DFN-making it optimal for space-constrained industrial and architectural LED modules requiring autonomous thermal protection.

Availability

HV9918K7-G is available at Aetrix Electronics and suitable for architectural LED strip lighting, industrial panel indicators, and emergency exit sign power supplies requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for HV9918K7-G 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

Microchip Technology is a U.S.-based semiconductor manufacturer specializing in microcontrollers, analog devices, and power management ICs, with global design, manufacturing, and support infrastructure.

The HV9918K7-G belongs to Microchip's high-brightness LED driver product line, engineered specifically for cost-sensitive, thermally demanding constant-current lighting applications where simplicity, reliability, and autonomous thermal management are critical.

FAQ

What is the maximum LED string voltage supported by the HV9918K7-G?

The HV9918K7-G is a buck converter with an integrated 40 V MOSFET, so the maximum allowable LED string forward voltage is VIN – (V_CS + V_SW,on). At 40 V input and 700 mA load, practical V_LED is limited to ≤32 V to maintain margin for sense voltage and MOSFET conduction loss. For higher V_LED, external high-voltage MOSFETs or boost/buck-boost topologies are required. The HV9918K7-G itself does not support direct 48 V LED strings.

Can the HV9918K7-G operate without an external current sense resistor?

No, the HV9918K7-G requires an external high-side current sense resistor (RSENSE) between VIN and CS to establish LED current regulation. The device measures the voltage drop across this resistor to trigger hysteretic switching. Omitting RSENSE disables current control and risks overcurrent damage to the internal MOSFET and LED load. Typical values range from 0.2 Ω to 2 Ω depending on desired I_LED.

How does the ADIM pin enable thermal foldback in the HV9918K7-G?

The ADIM pin accepts a 0–2 V analog signal that modulates the internal PWM dimming duty cycle. When connected to an NTC thermistor divider (NTC between ADIM and GND), rising temperature lowers ADIM voltage, reducing LED current proportionally. This provides passive, MCU-free thermal protection. The HV9918K7-G's ADIM offset voltage (±35 mV) ensures accurate tracking across temperature, and the RAMP pin allows tuning of dimming frequency to avoid audible noise.

What is the recommended PCB layout practice for the HV9918K7-G to ensure stable operation?

Key layout practices for the HV9918K7-G include: (1) placing RSENSE within 2 mm of VIN and CS pins with Kelvin connections; (2) connecting the exposed pad (EP) directly to a solid GND plane covering ≥80% of the pad area; (3) minimizing the high-di/dt loop formed by CIN, SW, and freewheeling diode; and (4) routing DIM/ADIM traces away from noisy SW and VIN nodes. These steps reduce EMI, improve thermal performance, and prevent false triggering of the current sense comparator in the HV9918K7-G.

Does the HV9918K7-G support synchronization to an external clock signal?

No, the HV9918K7-G does not support external clock synchronization. Its switching frequency is determined by input voltage, output voltage, inductor value, and internal hysteretic comparator propagation delays-resulting in variable frequency operation up to 2 MHz. There is no SYNC pin or frequency-locking feature. For applications requiring fixed-frequency operation or phase alignment, a different controller such as the MIC2289 or TPS92691 would be required instead of the HV9918K7-G.