Microchip HV9918 Handleiding

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 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 2-1for pin information.

1

2

3

4

CS

VIN

RAMP

ADIM

SW

GND

VDD

DIM

GND

8

7

6

5

EP

Hysteretic Buck High-Brightness LED Driver with High-Side Current Sensing

Product specificaties