DS1836 데이터 시트보기 (PDF) - Dallas Semiconductor -> Maxim Integrated

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DS1836

3.3V/5V Micro Manager

Dallas Semiconductor -> Maxim Integrated 

Non-Maskable Interrupt

DS1836A/B/C/D

The DS1836 generates a non-maskable interrupt ( NMI ) for early warning of a power failure. A precision

comparator monitors the voltage level at the IN pin relative to an on-chip reference generated by an

internal band gap. The IN pin is a high impedance input allowing for a user-defined sense point. An

external resistor voltage divider network (Figure 3) is used to interface with high voltage signals. This

sense point may be derived from a regulated supply or from a higher DC voltage level closer to the main

system power input. Since the IN trip point VTP is 1.25V, the proper values for R1 and R2 can be

determined by the equation as shown in Figure 3. Proper operation of the DS1836 requires that the

maximum voltage at the IN pin be limited to the active supply (VCC or VBAT). Therefore, the maximum

allowable voltage at the supply being monitored (VMAX) can also be derived as shown in Figure 3. A

simple approach to solving the equation is to select a value for R2 high enough to keep power

consumption low and solve for R1. The flexibility of the IN input pin allows for detection of power loss

at the earliest point in a power supply system, maximizing the amount of time for system shutdown

between NMI and RST (or RST ).

A pull-up resistor is required for proper operation of the NMI open-drain output. A 10kW resistor would

be a typical value for the pull-up resistor.

TYPICAL APPLICATION Figure 2

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