DS1831C Просмотр технического описания (PDF) - Dallas Semiconductor -> Maxim Integrated

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производитель

DS1831C

3.3V/2.5V Multi-Supply MicroMonitor

Dallas Semiconductor -> Maxim Integrated 

APPLICATION DIAGRAM - OPEN DRAIN OUTPUTS Figure 7

2.5V Supply

3.3V Supply

10 KΩ

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 KΩ

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 2 referenced comparator (DS1831D has only 1 referenced comparator) that can be used

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

1.25 volt 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

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

below the voltage sense point for approximately 2 µs 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 1.25 volt 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

1.25 volts. If the voltage is above 1.25 volts 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 10 kΩs. If a 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 1 supply on the VIN inputs rises above 1.5 volts. All NMI outputs

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

based on the value of the associated IN input.

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