2019 Microchip Technology Inc. DS20005722A-page 1
HV9918
Features
• Hysteretic Control with High-Side Current
Sensing
• Integrated 40V1Ω MOSFET
• >90% Efficiency
• 4.5V to 40V Wide Input Voltage Range
• ±5% LED Current Accuracy
• Up to 2 MHz Switching Frequency
• Adjustable Constant LED Current
• Analog or Pulse-With Modulation (PWM) Control
Signal for PWM Dimming
• Overtemperature Protection
• –40ºC to +125ºC Operating Ambient Temperature
Range
Applications
• Low-Voltage Industrial and Architectural Lighting
• General Purpose Constant Current Source
• Signage and Decorative LED Lighting
• Indicator and Emergency Lighting
General Description
The HV9918 is a PWM controller IC designed to drive
high-brightness LEDs using a buck topology. It
operates from an input voltage of 4.5 VDC to 40 VDC
and employs hysteretic control with a high-side current
sense resistor to set the constant output current up to
700 mA. The device is well suited for applications
requiring a wide input voltage range. The high-side
current sensing and an integrated current-setting
circuitry minimize the number of external components
while delivering an accurate average output.
A dedicated PWM input enables pulsed LED dimming
over a wide range of brightness levels. A hysteretic
control method ensures excellent input supply rejection
and fast response during load transients and PWM
dimming.
The HV9918 offers an analog-controlled PWM
dimming feature that reduces the output current by
applying an external DC voltage below the internal 2V
threshold voltage from ADIM to GND. ADIM can also
accept input from a resistor divider including a negative
temperature coefficient (NTC) thermistor connected
between ADIM and GND or a positive temperature
coefficient (PTC) thermistor connected between ADIM
and VDD. This provides a PWM thermal foldback
feature that reduces the LED current when the
temperature of the LED string exceeds a specified
temperature point. Additional features include
thermal-shutdown protection.
The high-switching frequency up to 2 MHz permits the
use of small inductors and capacitors, minimizing
space and cost in the overall system.
Package Type
8-lead DFN
(Top View)
See Table 2-1 for pin information.
