NCV8660B
http://onsemi.com
10
IN
OUT
RO
Reset Delay Time
Reset
Threshold
Plus
Hysteresis
Thermal
Shutdown
Voltage Dip
at Input
Secondary
Spike
Overload
at Output
Reset
Reaction
Time
t
t
t
OUT
Reset
Threshold
plus
Hysteresis
OUT
Reset
Threshold
Figure 25. Reset Timing
Thermal Shutdown
minus
Thermal Hysteresis
Reset Delay Time
Reset Delay Time t
<
Reset
Reaction
Time
During power−up (or restoring OUT voltage from a reset
event), the OUT voltage must be maintained above the Reset
threshold for the Reset Delay time before RO goes high. The
time for Reset Delay is determined by the choice of IC and
the state of the DT pin.
Reset Delay Time Select
Selection of the NCV8660B device and the state of the DT
pin determines the available Reset Delay times. The part is
designed for use with DT tied to ground or OUT, but may be
controlled by any logic signal which provides a threshold
between 0.8 V and 2 V. The default condition for an open DT
pin is the slower Reset time (DT = GND condition). Times
are in pairs and are highlighted in the chart below. Consult
factory for availability.
DT=GND DT=OUT
Reset Time Reset Time
NCV86601B 8 ms 128 ms
NCV86602B 8 ms 32 ms
NCV86603B 16 ms 64 ms
NCV86604B 32 ms 128 ms
The Delay Time select (DT) pin is logic level controlled
and provides Reset Delay time per the chart. Note the DT pin
is sampled only when RO is low, and changes to the DT pin
when RO is high will not effect the reset delay time.
Thermal Shutdown
When the die temperature exceeds the Thermal Shutdown
threshold, a Thermal Shutdown event is detected OUT is
turned off, and RO goes low. The IC will remain in this state
until the die temperature moves below the shutdown
threshold (175°C typical) minus the hysteresis factor (25°C
typical). The output will then turn back on and RO will go
high after the RESET Delay time.
