LED driver supports exponential scale dimming

It is available at distributor Anglia Components.

The device contains a DMOS switch with 1.5A peak current @ 60V and can support an external PWM dimming PMOS.

It also features spread spectrum frequency modulation (SSFM) and a well-controlled switch node for low emissions.

The device has an internal PWM generator for dimming that maps an analogue control signal to an exponential scale used to define PWM dimming duty ratio.

Using this exponential scale approach, allows the device to define the duty ratio preserving dimming resolution across a wide range of LED currents.

In addition to operating as a constant current source, the LED driver also has provision for output voltage regulation, this feature can be used to protect the device against damage in the case of an open circuit LED event.

A programmable switching frequency from 300kHz to 2MHz offers design flexibility allowing configuration for higher efficiency or reduced component size.

An integrated high-side PWM-dimming MOSFET makes this a very versatile IC, that can be used for boost, buck-boost mode and buck mode LED driver applications.

The integrated MOSFET not only provides high PWM dimming ratio capability, but it also serves as a short-circuit protection device, the device also has a FAULT flag to indicate when there is either a short-circuit or open-LED fault at the output.

The device also permits use of spread spectrum frequency modulation, reducing EMI and enabling designs to meet the CISPR25 Class 5 standard.

And the switching frequency can also easily be synchronized by driving the SYNC/SPRD pin with an external clock.

The desired output LED current can be programmed using a single external sense resistor and can be adjusted from zero to full-scale by an analogue signal at the CTRL pin allowing ease of control.

High voltage operation, 3V input voltage operation, multiple topologies, small-and-compact size, fault protection, low EMI, and multiple brightness control options make the LT3950 flexible and powerful for compact, noise-sensitive LED driver solutions.

The device is supplied in a compact 16 lead MSOP package and is offered in a choice of operating temperature ranges, -40°C to +125°C (LT3950E) and -40°C to 150°C (LT3950J).