Rainbow Electronics DS1846 - Manual (Page 9)

DS1846
9 of 16
o
When the supply being monitored decays to the voltage sense point, the DS1846 pulses the NMI output
to the active state for a minimum 200 s. The NMI power-fail detection circuitry also has built-in
hysteresis of 100 V. The supply must be below the voltage sense point for approximately 5 s before a
low NMI will be generated. In this way, power supply noise is removed from the monitoring function,
preventing false interrupts. During a power-up, any detected IN pin levels below V
TP
by the comparator
are disabled from generating an interrupt until V
CC
rises to V
CCTP
. As a result, any potential NMI pulse
will not be initiated until V
CC
reaches V
CCTP
.
Connecting NMI to PBRST would allow the non-maskable interrupt to generate an automatic reset when
an out-of-tolerance condition occurred in a monitored supply. An example is shown in Figure 5.
2- Wire Protocol Data Transfer Protocol Figure 2
2-Wire AC CHARACTERISTICS Figure 3