Specifications

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The LM3464 and LM3464A from National
Semiconductor are high-voltage, 4-channel
LED drivers that support dimming for
thermal-management purposes in addition to
conventional brightness adjustment. They also
feature Dynamic Headroom Control (DHC),
which optimises the voltage supplied to the
LED strings for minimum losses.
The LM3464 has an input-voltage range from
12V to 80V, while the LM3464A can accept input
voltages up to 95V. As a feature of each device,
high-speed PWM dimming allows flexible
brightness control while minimising any
variations in colour temperature. The
PWM frequency is programmed using an
external resistor.
An analogue dimming input is provided,
which can be connected to a sensor such
as an ambient light sensor for brightness
control. Alternatively a temperature
sensor such as a PTC or NTC device can be
connected directly to the analogue input.
This allows LEDs to be dimmed in order
to manage the temperature of the heatsink or
the system chassis. When analogue dimming is
used, the driver maintains minimum-duty-cycle
control. The duty cycle is programmed by an
external resistor.
The built-in DHC feature provides an output
that can be used to adjust the voltage of the
FEATURES:
 98% peak eciency
 Highchannel-to-channelaccuracy
 Fault detection
 LED open- or short-circuit protection
 Over-temperature protection
 Thermal shutdown
APPLICATIONS:
 Street lights
 General solid-state lighting solutions
 Display backlighting
LED drivers support thermal dimming feedback and dynamic efficiency
optimisation
National
Semiconductor
The MIC3202 is a hysteretic, step-down,
constant-current, High-Brightness LED (HB
LED) driver. It provides an ideal
solution for interior/exterior
lighting, architectural and
ambient lighting, LED
bulbs, and other general
illumination applications.
The MIC3202 is well
suited for lighting
applications requiring
a wide-input voltage
range. The hysteretic control gives good
supply rejection and fast response during
load transients and PWM dimming. The high-
High-BrightnessLEDDriverwithIntegratedMOSFETandHigh-Side
Current Sense
side current sensing and on-chip current-
sense amplifier delivers LED current with ±5%
accuracy. An external high-side current-sense
resistor is used to set the output current.
The MIC3202 offers a dedicated PWM
input (DIM) which enables a wide range
of pulsed dimming. High-frequency
switching operation of up to 1MHz allows
the use of smaller external components,
minimizing space and cost. The MIC3202
offers a frequency dither feature for low-EMI
applications.
The MIC3202 operates over a junction
temperature from -40ºC to -125ºC and is
available in an 8-pin e-PAD SOIC
package. A dither disabled
version MIC3202-1 is also
available in the same package
as the MIC3202.
Datasheets
and support
documentation can
be found on Micrel’s
web site at: www.micrel.com.
FEATURES:
 6V to 37V input voltage range
 Higheciency(>90%)
 ±5% LED current accuracy
 MIC3202: Dither enabled for low EMI
 MIC3202-1: Dither disabled
 High-sidecurrentsense(upto1A)
 Dedicated dimming control input
 Hystereticcontrol(nocompensation
required)
 Upto1MHzswitchingfrequency
 Adjustable constant LED current
 Over-temperature protection
 -40ºC to +125ºC junction temperature
range
APPLICATIONS:
 Architectural, industrial, and ambient
lighting
 LED bulbs
 Indicators and emergency lighting
 Street lighting
 Channel letters
 12V lighting systems (MR-16 bulbs, under-
cabinet lighting, garden/pathway lighting)
Micrel
Semiconductor
external power supply dynamically. This allows
the system to supply the minimum voltage
needed to maintain every string current in
regulation, thereby optimising efficiency
and reliability as LED forward voltage varies
according to temperature or process-related
factors.