The BD18336NUF-M is an LED driver developed for socket-type LED lamps, adoption of which has been increasing recently for use in the daytime running lamps (DRLs), position lamps, rear lamps, and the like for automobiles. Using linear step-down constant-current driving, in essence up to three series LED lamps can be driven with the 12 V battery of the vehicle as input. First the features of the device are indicated.
- ・High-voltage specs for onboard 12-V battery input: Rated up to 42 V, maximum operating voltage 20 V
- ・Compact but with high output current: 400 mA (DC), 600 mA (50% PWM) from a 3x3 mm package
- ・Footprint is reduced by approx. 30% compared with previous products; mounting on 10x10 mm boards required for microminiature socket-type LED lamps is possible
- ・Single-chip implementation of a bypass function to bypass one among three series LEDs and keep the remaining lamps lit when the battery voltage is low
- ・High-brightness white LEDs also supported through an output current derating function that uses an external thermistor to suppress heat generation
- ・Extensive protection functions, including open LED detection and output ground fault protection
A Single Chip Ensures Safe Lighting when the Onboard Battery Voltage is Low
The BD18336NUF-M is equipped with a low-voltage current bypass function, so that a single chip can enable safe lighting when the onboard battery voltage has dropped. This is an industry first. (ROHM survey, March 31 2020)
Microminiature Socket-type LED Lamps Made Possible by Reducing the Footprint Roughly 30% Compared with Previous Products
The BD18336NUF-M implements the low-voltage current bypass function in a single chip, and so it is possible to eliminate seven external components from circuits that use conventional products which require comparators, transistors, and the like, and consequently the footprint can be decreased by about 30%, including external circuits. As a result, mounting on a 10x10 mm LED module board is possible, paving the way for the microminiature socket-type LED lamps that has been sought in recent years.
Compatible with Diverse LED Lamps, Including High-brightness White LEDs
Functional Block Diagram of the BD18336NUF-M and Application Circuit Example
Below are shown a functional block diagram and a basic application circuit example, as well as the main specifications. For further details, please refer to the data sheet.
＜Main Features and Functions＞