Two 42 V Power Management ICs with a built-in Window or Battery Voltage Detector

Adding Functional Safety:

Microcontroller processors often require a precise power supply in order to operate properly. To improve the reliability of the application some additional monitoring circuits have been added to check if the power supply operates within the narrow safety margins. If the supply voltage exceeds the safety margins, the microcontroller must be reset to prevent its operation from working improperly.The R5116 and R5117 both have a 500mA voltage regulator and supervisory circuits embedded in a single package which saves valuable circuit board space and additional wiring between the components, providing the designer a cost effective solution with minimal external components.

The main differences between the R5116 and R5117 are the supervisory circuits:

• R5116: 500mA Voltage Regulator + monitors the output voltage for both over- and undervoltage
• R5117: 500mA Voltage Regulator + monitors both input voltage and output voltage for undervoltage

The integrated supervisory circuitry provides an active low reset signal when the regulator output falls out of regulation or when the input voltage falls below a minimum.

As for the circuit monitoring the output voltage, it has an independent sense pin which can be connected to the regulator output or directly to the microcontroller supply voltage pin for improving the measurement accuracy.

Robust Design:

The new CMOS-based R5116 and R5117 are robust enough to survive in harsh conditions; operating up to 42 V and even tolerates load dump surge peak voltages of 60 V with a duration of less than 200 ms. The minimum operating voltage starts at 3.5 V, which makes the products suitable to use even at severe cranking conditions. The product will be available in a version intended for the consumer, industrial and automotive application market and has customized operating temperature ranges, respectively -40 to 105°C, -50 to 125°C and -40 to 125°C.

All settings for the output voltage and supervisory thresholds are internally fixed by laser trimming and have a high accuracy level, making the product suitable as a power source with high reliability.

Excellent Performance:

The voltage regulator has an excellent transient response. A change on the input or load results in only a small signature on the output voltage and a false supervisory detection is prevented by these characteristics.

The ripple rejection ratio is in the range of 70dB at 1kHz, see above graph for details. Another important feature is to minimize current consumption for those applications that are continuously active, thereby extending the operational lifetime of the battery. The R5116 / R5117 contribute to reducing the total current consumption with respectively Typ. 25 µA / 35 µA in On-mode and 1.5 µA / 10 µA in Off-mode by controlling the chip disable pin.

The outputs have an N-Channel open drain and require an external pull-up resistor to define its logic high state. Each supervisory circuit has its own output and can be combined together or connected individually to the microcontroller.

An external capacitor is used to specify the active reset period and power on reset time. It should be set long enough in order to reset the processor properly.

Safety Circuits:

The R5116 and R5117 have an array of safety features, protecting the voltage regulator and other parts of the application from possible damage and defects.

• Over-current protection, reducing the output current when overloaded.
• Short protection, an embedded fold-back short current limit circuit, detects a short circuit and decreases the output current to a safe level of 105 mA. After removing the short the regulator resumes to normal operation automatically.
• hermal protection is incorporated and will turn off the regulator when an over-temperature of 175°C is detected and will resume to normal operation again as soon a temperature of 145°C is reached.