DS1831C 查看數據表（PDF） - Maxim Integrated

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DS1831C

3.3V/2.5V Multisupply MicroMonitor

Maxim Integrated 

APPLICATION DIAGRAM—OPEN DRAIN OUTPUTS Figure 7

2.5V Supply

3.3V Supply

10 KW

IN2.5V

RST2.5V

TOL2.5V

TD2.5V

PBRST2.5V

1

16

2

15

DS1831C

3

14

4

13

5

12

IN3.3v

RST3.3V

TOL3.3V

TD3.3V

PBRST3.3V

GND

10 KW

DS1831C/D/E

NOTE: If outputs are at different voltages the outputs can not be connected to form a wired AND.

OPERATION—NON-MASKABLE INTERRUPT

The DS1831 has two referenced comparators (DS1831D has only one referenced comparator) that can be

used to monitor upstream voltages or other system specific voltages. Each comparator is referenced to the

1.25V internal band gap reference and controls an open-drain output. When a voltage being monitored

decays to the voltage sense point, the DS1831 pulses the NMI output to the active state for a minimum

10µs. The comparator detection circuitry also has built-in hysteresis of 100µV. The supply must be below

the voltage sense point for approximately 2µs before a low NMI will be generated. In this way, power

supply noise is minimized in the monitoring function, reducing false interrupts. See Figure 8 for the non-

maskable timing diagram.

Versatile trip voltages can be configured by the use of an external resistor divider to divide the voltage at

a sense point to the 1.25V trip levels of the referenced comparators. See Figure 9 for an example circuit

diagram and sample equations. The equations demonstrate a design process to determine the resistor

values to use.

Connecting one or both NMI outputs to one of the reset specific PBRST s allows the non-maskable

interrupt to generate an automatic reset for the reset time period when an out-of-tolerance condition

occurs in a monitored supply. An example is shown in Figure 9.

The output associated with the specific input will be held low if the voltage on the input pin is less than

1.25V. If the voltage is above 1.25V the output will not sink current and will be pulled up by the required

pull-up resistor. The value of the resistors is not critical in most cases but must be set low enough to pull

the output to a high state. A common value used is 10kW. If an NMI output is connected to a pushbutton

input an additional pull-up resistor can be used (to improve speed of transitions) but is not required.

During a power-up, any detected IN pin levels above VTP by the comparator are disabled from generating

an inactive (high) interrupt until at least one supply on the VIN inputs rises above 1.5V. All NMI outputs

will be held active (low) until at least one VIN reaches 1.5V at which point the NMI outputs will be based

on the value of the associated IN input.

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