STM6717 Datasheet, PDF (6/25 Pages) STMicroelectronics – Dual/Triple Ultra-Low Voltage Supervisors with Push-Button Reset (with Delay Option)

STM6717/6718/6719/6720/6777/6778/6779*/6780*
Pin Descriptions
Active-Low, Push-pull Reset Output (RST) -
STM6718/20/78/80. The RST pin is driven low
and stays low whenever V_CC1 or V_CC2 or RSTIN
falls below its factory-trimmed or adjustable reset
threshold or when MR goes to logic low. It remains
low for t_rec after ALL supply voltages being moni-
tored rise above their reset thresholds and MR
goes from low to high. (Push-pull outputs are ref-
erenced to V_CC1.)
Active-Low, Open Drain Reset Output (RST) -
STM6717/19/77/79. The RST pin is driven low
and stays low whenever V_CC1 or V_CC2 or RSTIN
falls below its factory-trimmed or adjustable reset
threshold or when MR goes to logic low. It remains
low for t_rec after ALL supply voltages being moni-
tored rise above their reset thresholds and MR
goes from low to high. Connect an external pull-up
resistor to V_CC1. A 10kΩ pull-up resistor should be
sufficient for most applications.
Push-Button Reset Input (MR). When MR goes
low the RST output is driven low. RST remains low
as long as MR is low and for t_rec after MR returns
to high. This active-low input has an internal 50kΩ
pull-up resistor to V_CC1. It can be driven from a
TTL or CMOS logic line, or with open drain/collec-
tor outputs, or connected to V_SS through a switch.
If unused, leave this pin open or connect it to V_CC1.
Connect a normally open momentary switch from
MR to V_SS; external debounce circuitry is not re-
quired. (If MR is driven from long cables or if the
device is used in noisy environments, connecting
a 0.1µF capacitor from MR to V_SS provides addi-
tional noise immunity.
Manual Reset Delay Input (MRC) - STM6777/78/
79/80). This pin is either left open or connected to
V_SS via a capacitor. By selecting the appropriate
capacitor, the manual reset process, initiated by
pressing the push-button Manual Reset Input, can
be delayed by any value from 6µs or more (see
Table 7., page 19).
Primary Supply Voltage Monitoring Input
(V_CC1). It also is the input for the primary reset
threshold monitor. Available fixed (customer-se-
lectable, factory-programmed) reset thresholds in-
clude 4.63V to 1.58V.
Secondary Supply Voltage Monitoring Input
(V_CC2). This function is available on the
STM6717/18/19/20/77/78. Fixed (customer-se-
lectable, factory-programmed) reset thresholds in-
clude 3.08V to 0.79V.
Adjustable Reset Comparator Input (RSTIN;
STM6719/20/79/80). This is a high impedance in-
put. RST is driven low when the voltage at the
RSTIN pin falls below 0.626V (internal reference
voltage at this comparator). The monitored voltage
reset threshold is set with an external resistor-di-
vider network.
Table 3. Pin Functions
Pin
STM6717 STM6719 STM6777
STM6718 STM6720 STM6778
1
1
1
3
3
3
–
–
5
5
6
6
4
4
4
–
5
–
2
2
2
STM6779
STM6780
1
3
4
6
–
5
2
Name
Function
RST Active-low Reset Output
MR Push-button Reset Input
MRC Manual Reset Delay Input
V_CC1 Primary Supply Voltage Input
V_CC2 Secondary Supply Voltage Input
RSTIN Adjustable Reset Comparator Input
V_SS Ground
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