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Electrification of automobile by RICOH power management IC

Functional Safety

Implementation of Safety Mechanisms

Functional Safety

Functional Safety

Functional safety is generally defined as "to ensure safety at an acceptable level by introducing functions to ensure safety against harm." In other words, it is "to prepare for risk" for failure as "failure occurs at a certain probability".

In automobiles, for example, it is not acceptable that a part A failure leads a catastrophic failure immediately like uncontrollable engine or steering.
In order to cope with such a failure, it is necessary to prepare for risk by "monitoring abnormality of component A (sign of failure) with component B".

Safety Mechanisms

Safety mechanism is a risk assessment system to ensure functional safety.

Many MCUs are being used in the car for controlling its operation.
When assuming abnormality in the power supply, adding a voltage detector (reset IC) that monitors MCU failure due to overvoltage is a risk preparation, that is, a safety mechanism.

Safety Mechanisms

Implementation of safety mechanisms with RICOH power management IC

Ricoh enhance safety and reliability of automobiles by offering products that can be useful for constructing safety mechanisms of customers' systems, such as window type voltage detectors (reset ICs) and system power management ICs with watchdog timer function.

R3152 / R1524

With R3152, OV / UV detection accuracy is -1.25% to 0.75%, hysteresis accuracy Max 1.5%, high precision detection is possible. It is a window voltage detector best suited for functional safety requirements to prevent the MCU from operating at abnormal voltage.

Furthermore, a simple system configuration can be realized by combining the voltage regulator R1524 with the maximum input voltage of 36V. The R1524 achieves both low current consumption of 2.2 µA and excellent transient response characteristics, making it ideal for backup system constant voltage source.

R5114 / R5115

R5114/R5115 is a system power supply integrating an LDO regulator, a voltage detector, and a watchdog timer.

The IC monitors the output current of the LDO regulator while supplying power to the MCU, and at light load, the watchdog timer can automatically stop monitoring clock pulses.
As a result, even if the MCU clock pulse output is stopped during standby, the reset signal is not output from the watchdog timer.

Reset ICs (Voltage Detectors)

Product Name VDD VUVSET VOVSET ISS Features
R3152 3.0 V to 42.0 V 1.0 V to 4.8 V 1.1 V to 5.9 V Typ. 1.5 µA  
R3154 3.0 V to 42.0 V 0.55 V to 3.3 V 0.75 V to 3.7 V Typ. 2.0 µA Diagnostic Function

Watchdog Timer with Reset IC (VD) and LDO Regulator (Linear Regulator)

Product Name VIN VOUT VDET ISS Features
R5114 3.5 V to 42.0 V 3.3 V to 5.0 V 2.5 V to 4.8 V Typ. 8.5 µA  
R5115 3.5 V to 42.0 V 3.3 V to 5.0 V 2.5 V to 4.8 V Typ. 8.5 µA Window WDT

LDO Regulators (Linear Regulators)

Product Name VIN VOUT ISS Output Voltage Accuracy
R1524 3.5 V to 36.0 V 1.8 V to 9.0 V Typ. 2.2 µA ±0.6% (Ta=25°C)

Products for Automotive

Ricoh offers a wide range of innovative technologies for automotive applications from on-vehicle electrical equipment to in-vehicle accessory.
A severe quality control, which varies from the consumer products, is performed for automotive products including a reliability test of AEC-Q100 qualification and a traceability system.