LDO regulators with the lowest dark current

Paul Boughton
ROHM Semiconductor GmbH has developed the BD7xxL2EFJ-C series of high-voltage (50V) LDO regulators for automotive applications featuring the industry’s lowest dark current (6μA) – 80% lower than conventional LDO regulators – utilising a proprietary circuit design, reducing power consumption significantly.
 
Dark current is the current expended when a car is idling (eg stopped). The number of microcontrollers used in automotive systems has grown dramatically due to the greater demand for functionality and sophistication, leading to a rapid rise in current consumption.

In particular, currents consumed when the engine is on but not running is becoming increasingly problematic, such as standby energy for the remote controller (keyless entry) and security block as well as power for maintaining memory in the audio system, ECUs, and clock.

The larger the standby battery current consumption the greater the drain on the battery and the shorter the battery life. Similarly, parking the car over an extended period of time without driving it, for example during export at sea, will also prematurely drain the battery.

Generally, in order to reduce current consumption the impedance of the internal circuit needs to be increased. However, high impedance not only causes the circuit to become susceptible to noise, it makes miniaturization more difficult and slows down the circuit during start-up, leading to additional problems.
 
In response to these challenges, ROHM developed a compact, high reliability, low-dark-current LDO designed for automotive use that combines decades of expertise in automotive power technologies with a proprietary noise-proof circuit design.

The result is 80 peer cent lower dark current than conventional low IQ LDO regulators, reducing battery load and protecting against premature drainage due to extended periods of non-use. Power consumption during normal operation is also reduced, conserving total system energy.
Future plans are to extend the low IQ LDO line-up with other packages and higher output currents.
 
For more information, visit www.rohm.com/eu