Running off a 2 volt (V) to 44 V input voltage, the NCV8876 non-synchronous boost controller with automatic wake up and shutdown functions is designed to supply a minimum output voltage during start-stop conditions in order to counteract any sag in the vehicle's battery voltage. The NCV8876 is enabled when the supply voltage drops below 7.2 V, then boost operation is initiated once this voltage goes under 6.8 V, with the IC driving an external N-channel MOSFET. A quiescent current of just 11 µA is drawn when the device is in sleep mode so that power consumption is minimised. Among its array of protection features are cycle-by-cycle current limiting, thermal shutdown (with a 170⁰C threshold) and hiccup-mode over-current protection. Its peak current mode control with internal slope compensation ensures device stability over the entire voltage range. This also ensures that it is protected during a current fault condition by turning off the power switch for the remainder of the cycle if the current limit is exceeded.
The NCV896530 2.1 MHz switching frequency dual channel step-down DC-DC converter is targeted at the sophisticated driver assistance systems now being incorporated into modern vehicles. Both of its channels are externally adjustable (covering 0.9 V to 3.3 V) and can source currents up to 1600 mA. Synchronous rectification enables the device to offer enhanced system efficiency. Inclusion of features such as integrated soft-start, cycle-by-cycle current limit and thermal shutdown protection mean that this device is highly optimized for deployment in harsh automotive environments. The NCV8876 and NCV896530 both support a junction temperature range of−40 °C to 150 °C.
“The NCV8876 is an off-the-shelf device with the ability to react to low battery conditions automatically, whereas alternative solutions either require the expense of designing a custom ASIC in order to get the required performance, or are based on discrete components but achieve far slower response times,” states Jim Alvernaz, director of the Automotive product division