HV9918 Datasheet, PDF (1/7 Pages) Supertex, Inc – Hysteretic, Buck, High Brightness LED Driver with High-Side Current Sensing

Supertex inc.
HV9918
Hysteretic, Buck, High Brightness LED Driver
with High-Side Current Sensing
Features
► Hysteretic control with high-side current sensing
► Integrated 40V 1.0Ω MOSFET
► >90% Efficiency
► Wide input voltage range: 4.5 to 40V
► ±5% LED current accuracy
► Up to 2.0MHz switching frequency
► Adjustable constant LED current
► Analog or PWM control signal for PWM dimming
► Over-temperature protection
► -40ºC to +125ºC operating 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 to 40VDC and employs hysteretic control with a
high-side current sense resistor to set the constant output current
up to 700mA. 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.
Dedicated pulse-width modulation (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 2.0V 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 thus providing 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 2.0MHz permits the use of
small inductors and capacitors, minimizing space and cost in the
overall system.
The HV9918 comes in a small 8-Lead DFN package and is ideal
for industrial and general lighting applications.
Typical Application Circuit
R_SENSE
L
C_IN
0 - 2.0V
VIN
RAMP
CS
SW
ADIM
VDD
DIM
GND
HV9918
Supertex inc. ● 1235 Bordeaux Drive, Sunnyvale, CA 94089 ● Tel: [phone] ● www.supertex.com