42V Input Window Voltage Detector

August 1, 2018

Voltage Detectors are widely used to monitor a specific supply voltage and are available in many shapes and sizes. Its general function is to detect a drop in the supply voltage, which may disrupt the proper operation of an application. For certain high reliability applications, this kind of supervision is not sufficient. The R3152 consists of two high accuracy voltage detectors (±0.5% @ 25°C), each with built-in hysteresis that makes the device less sensitive to supply voltage noise and ensures a stable operation. The R3152 monitors whether the supply voltage operates within a specific safe area and provides a reset signal when the supply voltage exceeds an overvoltage or undervoltage threshold.

Conventional voltage detectors are usually supervising a low-voltage power supply and its power source (LDO or DC/DC Converter) is commonly shared with the MCU application processor. In case this power source fails or starts up slowly, the voltage detector may fail to operate or has an unstable output.

Wide operating voltage range:

The R3152 has a wide operation voltage range from 3.0 to 42V and therefore tolerates a fluctuation in its power supply even during a severe cranking condition. Additionally, it can be powered directly from the primary power supply or battery and is functioning independent from the power source for the processor. Also note that the Vdd pin and sense pin of the R3152 are separated; so the output remains stable even if the sense pin voltage falls to 0V. It already operates before the external LDO or DC/DC Converter has started up, providing a more secure supervision and guarantees a proper reset signal.

Pin layout:

The R3152 has a very robust design; a short between adjacent pins will not lead to any damage of the chip. In particular, the Cd pin has a high voltage rating of 50V in order to tolerate a short with the adjacent Vdd pin.

Output reset time:

As for the output delay time, it can be specified by using an external capacitor connected to the Cd pin. In this way one can set the delay time long enough to reset the processor properly. The R3152 has an N-channel open drain output that needs a pull-up resistor to specify the logical high signal.

High detection accuracy:

The detection and release threshold for overvoltage and undervoltage are internally set, currently we have product versions available to monitor popular supply voltages 5.0V and 3.3V but other threshold settings can be specified on request as well.