LINEAR 100V Controller Drives High Power LED Strings - From Nearly Any Input - Design Note 461 by Keith Szolusha
Summary
This versatile high-voltage LED driver IC is an essential component for modern solid-state lighting systems, capable of powering hundreds of watts across extremely wide input ranges (10V–80V). Designed for professional LED lighting manufacturers, it provides unmatched performance features—including sophisticated PWM and analog dimming alongside comprehensive protection circuits. The manual details its adaptable boost, buck, and buck-boost topologies, offering a single-chip solution ideal for applications ranging from large stadium lights to indoor architectural designs.
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100V Controller Drives High Power LED Strings from Just about Any Input – Design Note 461 by Keith Szolusha Introduction range. Its 100V fl oating LED current sense inputs provide
Strings of high power solid-state LEDs are replacing accurate LED current sensing. Excellent PWM dimming traditional lighting technologies in large area and high architecture produces high dimming ratios.
lumens light sources because of their high quality light
A number of features protect the LEDs and surround-
output, unmatched durability, relatively low lifetime cost,
ing components. Shutdown and undervoltage lockout,
constant-color dimming and energy effi ciency. The list of
when combined with analog dimming derived from the
applications grows daily, including LCD backlights and
input, provide the standard ON/OFF feature as well as
projection, industrial and architectural lighting, automo-
a reduced LED current should the battery voltage drop
tive lights, streetlights, billboards and stadium lights.
to unacceptably low levels. Analog dimming is accurate As the list expands, so does the range of VIN for the LED and can be combined with PWM dimming for a wide drivers. LED drivers must be able to handle wide ranging range of brightness control. Soft-start prevents spiking inputs, including transient voltages of automotive batter- inrush currents. The OPENLED pin informs of open or ies, a wide range of other batteries and wall wart voltages. missing LEDs and the SYNC (LT3756-1) pin can be used For LED lighting manufacturers, applying a different LED to sync switching to an external clock. The FB voltage driver for each application means stocking, testing and loop limits the max VOUT to protect the converter in the designing with a number of controllers. It would be better case of open LEDs.
to use just one that can be applied to many solutions.
The 16-pin IC is available in a tiny QFN (3mm × 3mm) The LT3756 high voltage LED driver features a unique and an MSE package, both thermally enhanced. For lower topological versatility that allows it to be used in boost, input voltage requirements, the 40VIN, 75VOUT LT3755 buck-boost mode, buck mode, SEPIC, fl yback and other LED controller is a similar option. topologies. Its high power capability provides potentially L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.
hundreds of watts of LED power over a wide input voltage
VIN 10V TO 80V
196k VIN ISP 147k
22μH 2× PDS5100 100V 16V
VIN 40V TO 60V 120k
×2 SHDN/UVLO ILED
499k OVP= 1.8M
100V VIN 100V VREF ISN
×2 ×5 FB
SHDN/UVLO FB
VREF ISP FOR CTRL M2 12.4k
1M 0A–1A ILED
23.2k LT3756 ILED 51k 1 OR 2
CTRL 1.5A 1k LEDs
LT3756
ISN 3.5V OPTIONAL
PWMOUT M3 EACH
GATE Q1A, B
PWM PWM
SENSE L1
OPENLED 33μH
100k OPENLED
1N4448HWT
INTVCC PWM STRING
SS GATE M1
SS PWMOUT
RT 0.1μF D1: DIODES INC B2100
RT SENSE
0.1μF GNDVC INTVCC L1: SUMIDA CDRH8D38-330
42.2k GNDVC INTVCC
Si7322DN 0.05Ω M1: VISHAY SILICONIX Si4484EY
250k Hz 69.8k M2: VISHAY SILICONIX Si2307BDS
10k 150k Hz 4.7μF M3: VISHAY SILICONIX Si2328DS
4700p F Q1: MMBT5401
L1 = 2× SERIES SLF12575T-220M4R0 Q1 = 2× PARALLEL Si7322DN
Figure 1. A 125W, 83V at 1.5A, 97% Effi cient Boost LED Figure 2. An 80VIN Buck Mode LED Driver With Driver for Stadium Lighting PWM Dimming for Single or Double LEDs
Page Summary Contents For LINEAR 100V Controller Drives High Power LED Strings - From Nearly Any Input - Design Note 461 by Keith Szolusha
Manual Details
| Brand | High Power |
|---|---|
| Pages | 2 |
| File Size | 90.03 KB |
| Published | May 28, 2026 |
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Frequently Asked Questions
What protection features are built into the LED driver?
It includes undervoltage lockout, shutdown, soft-start functionality, and open/short circuit detection (OPENLED pin).
How does it handle varying LED strings over a wide input range?
The LT3756 controller can drive up to 100V LED strings from a wide input voltage range of 10V to 80V, simplifying inventory by using one IC for many solutions.
Can the driver be used with different types of dimming?
Yes, it supports both accurate analog dimming and PWM dimming. Analog dimming can be combined with PWM dimming for flexible brightness control.
What benefit does high switching frequency offer in dimming?
Higher switching frequencies increase the maximum PWM dimming ratio, allow for more fine-grained brightness control, and minimize the size of discrete components.