STM704T/S/R STMicroelectronics, STM704T/S/R Datasheet - Page 17

• Manufacturer Part Number: STM704T/S/R
• Description: 3V Supervisor
• Manufacturer: STMicroelectronics

Specifications of STM704T/S/R

• Operating Temperature: –40 °C to 85 °C (industrial grade)

STM690, STM704, STM795, STM802, STM804, STM805, STM806
Figure 12. Chip enable waveform (STM795)
2.8
2.9
E CON
RST
E
V CC
Power-fail input/output (NOT available on STM795)
The Power-Fail Input (PFI) is compared to an internal reference voltage (independent from
the V
Output (PFO) will go low. This function is intended for use as an undervoltage detector to
signal a failing power supply. Typically PFI is connected through an external voltage divider
(see
of the V
below V
804/805/806 or the microprocessor drops below the minimum operating voltage.
During battery backup, the power-fail comparator is turned off and PFO goes (or remains)
low (see
the power-fail comparator is enabled and PFO follows PFI. If the comparator is unused, PFI
should be connected to V
the STM704/806 so that a low voltage on PFI will generate a reset output.
Applications information
These supervisor circuits are not short-circuit protected. Shorting V
excluding power-up transients such as charging a decoupling capacitor - destroys the
device. Decouple both V
the device as possible.
V RST
V BAT
Figure
RST
CC
PFI
Figure
comparator). If PFI is less than the power-fail threshold (V
t rec
regulator. The voltage divider can be set up such that the voltage at PFI falls
several milliseconds before the regulated V
10) to either the unregulated DC input (if it is available) or the regulated output
½ tr ec
13). This occurs after V
CC
SS
½ t rec
10 µs
and V
and PFO left unconnected. PFO may be connected to MR on
Doc ID 10519 Rev 9
BAT
t rec
pins to ground by placing 0.1 µF capacitors as close to
CC
drops below V
CC
input to the STM690/704/795/802/
SW
(2.4 V). When power returns,
OUT
PFI
), the Power-Fail
to ground -
Operation
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