STM6780 STMicroelectronics, STM6780 Datasheet - Page 10

• Manufacturer Part Number: STM6780
• Description: Dual/triple ultra-low voltage supervisors with push-button reset (with delay option)
• Manufacturer: STMicroelectronics

Specifications of STM6780

• Primary Supply (vcc1) Monitor. Fixed (factory-programmed) Reset Thresholds: 4.63 V to 1.58 V
• Fixed (factory-programmed) Reset Thresholds: 3.08 V to 0.79 V
• Tertiary Supply Monitor (using Externally Adjustable Rstin): 0.626 V internal reference
• Reset Delay Time (trec) On Power-up: 13.2 ms, 210 ms, 900 ms (typ)
• Operating Temperature: –40 °C to 85 °C (industrial grade)

Operation
2
2.1
10/30
Operation
Applications information
1.
2.
Figure 11. STM67xx interface to processor with bi-directional reset pins
Figure 12. Ensuring RST valid to V
Interfacing to processors with bi-directional reset pins
Most processors with bi-directional reset pins can interface directly to the open drain
RST outputs (STM6717/19/77/79). Systems simultaneously requiring a push-pull RST
output and a bi-directional reset interface can be in logic contention. To prevent this
contention, connect a 4.7 kΩ resistor between RST and the processor’s reset I/O as
shown in
Ensuring a valid RST output down to V
The STM67xx supervisors are guaranteed to be in the correct RST output logic state
when V
levels down to V
Figure
sink or source current. This scheme does NOT work with the open drain outputs of the
STM6717/19/77/79.
The resistor value used is not critical, but it must be large enough not to load the reset
output when V
adequate.
12) will ensure that the reset line is valid while the reset output can no longer
CC1
Figure
V CC2
and/or V
CC
CC
11.
V CC1
is above the reset threshold. For most applications, 100 kΩ is
= 0, a pull-down resistor to active-low outputs (push-pull only, see
CC2
is greater than 0.8 V. In applications which require valid reset
V CC1
V CC2
Doc ID 11469 Rev 8
STM67xx
V SS
STM6717/6718/6719/6720/STM6777/6778/6779/6780
CC
RST
V SS
= 0 (active-low, push-pull outputs)
STM67xx
components
CC
To other
system
= 0 V
V CC1
4.7kΩ
RST
V CC1
RESET
Processor
R1
V SS
AI10425
AI10426