AEC-Q100 qualified A6274 and A6284 are pwm dimmable and include a driver circuit that can control an optional external p-channel mosfet which extends output power capability by dropping any voltage headroom not required for led regulation.
“This eliminates the need for a dc-dc switching solution and its associated inductor, diode and higher EMI.” said Allegro.
The A6274 sinks up to 60mA from each of six LED pins, and the A6284 handles 120mA. Paralleling outputs increases drive to up to 720mA, and for more current multiple ICs can be paralleled.
The six output can operate all at the same current, or with three outputs at one current and the other three at another current. Current settings are typically accurate to 2%, while typical matching between LED strings is 0.8%.
An internal pwm generator is included for dimming, with two resistors setting frequency and ratio, or an external pwm signal can be applied.
A last dimming option is to change between full and dim modes for bi-level operation, as often needed for stop/tail lamps or daytime running lights.
Because of the high-reliability application, fault detection is more than usually thorough. The fault outputs are asserted when the faults is active, or for applications that demand latched fault indication there are -1 versions of the two chips.
Most faults are protected against as well as indicated. The optional external p-mosfet is required if protection against led-string-short-to-ground is needed.
All devices some in a 20 lead exposed heat pad eTSSOP package.