The R1540 from Ricoh Electronic Devices is a voltage tracker IC designed for off-board sensors and modules. Widely used in automotive applications (such as new automotive vehicles), it is primarily intended as a power supply that provides an additional safety level to keep the main power supply and associated critical circuits operational. It has an input voltage range up from 3.5 to 42 V, which makes it possible to use the voltage tracker in many cases. In addition, the R1540 has superior immunity to EMI noise over a frequency band from 150 kHz to 1 GHz.
Moreover, it features a ripple rejection ratio of 80 dB, a fast response to transients on input and load and it delivers a tracking precision of ± 15 mV. The combined CE / ADJ pin lead provides the input voltage as a reference for the output and it can be pulled low to control the device in standby mode. To protect the voltage tracker as well as other parts of the application, the R1540 has over-current protection, short protection (detects a short circuit and decreases the output current to a safe level of 40 mA), thermal protection (can turn off the output voltage if the temperature exceeds 165°C), and a protected pin lay-out.