DS1831BS 查看數據表（PDF） - Maxim Integrated

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DS1831BS

Multisupply Micromonitor

Maxim Integrated 

NON-MASKABLE INTERRUPT CIRCUIT EXAMPLE Figure 9

VSENSE2

VSENSE1

VCC

DS1831/A/B

R1

PBRST5V

PBRST3.3V

R3

R2

IN1

DS1831

IN2

NMI1

NMI2

R4

GND

MPBRST

10 KW

Example:

VSENSE1 = 11.50V trip point VSENSE1 =

R1 + R2

R2

X 1.25V

Therefore:

R1 + 100 kW

11.50V =

X 1.25V

100 kW

Resulting In: R1 = 820kW

Repeat the same steps to solve for R3 and R4 with VSENSE2.

OPERATION - WATCHDOG TIMER

The watchdog timer function (DS1831A only) forces the WDS signal active (low) when the ST input

does not have a transition (high-to-low or low-to-high) within the predetermined time period. The time-

out period is determined by the condition of the TDWD pin (see Table 1). If TDWD is connected to ground

the minimum watchdog time-out would be 10ms, TD floating would yield a minimum time-out of 100ms,

and TDWD connected to VCC would provide a time-out of 1000ms minimum. Time-out of the watchdog

starts when at least one of the RST outputs becomes inactive (high). If a transition occurs on the ST input

pin prior to time-out, the watchdog timer is reset and begins to time-out again. If the watchdog timer is

allowed to time-out, then the WDS output is pulsed active for a minimum of 100µs.

The WDS output is an open-drain output and must be pulled up externally. In most applications this

output would be connected to one of the Pushbutton inputs and would not require an external 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 a WDS output is connected to a pushbutton input

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

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