stm1404c STMicroelectronics, stm1404c Datasheet - Page 13

• Manufacturer Part Number: stm1404c
• Description: Security Supervisor With Battery Switchover
• Manufacturer: STMicroelectronics

BLD, V
Active-low RST output (open drain)
MR, Manual reset input
PFO, Power-fail output (open drain)
PFI, Power-fail input
V
REF
, Reference voltage output (1.237, typ)
BAT
If a Security Alarm (SAL) is issued on Tamper, then the state of the Vccsw pin is as follows:
1.
2.
3.
This is an internally loaded test of the battery, activated only during a power-up sequence to
insure that the battery is good either prior to or after encapsulation of the module. There are
three customer options for V
●
●
●
This output pin will go active-low when it detects a voltage on the V
will be released when V
Goes low and stays low when V
customer), or when MR is logic low. It remains low for t
above V
A logic low on MR asserts the RST output. The RST output remains asserted as long as MR
is low and for t
(typical) pull-up resistor. It can be driven from a TTL or CMOS Logic line or shorted to
Ground with a switch. Leave it open if unused.
When PFI is less than V
(battery switchover threshold ~ 2.4V), PFO goes low, otherwise, PFO remains high. Leave
this pin open if unused.
When PFI is less than V
active-low. If this function is unused, connect this pin to V
This is valid only when V
V
on the STM1404A. On the STM1404B/C, this pin is V
If unused, this pin should float.
low voltage detect output (open drain)
REF
STM1404A (V
operate in normal mode;
STM1404B (V
High when this occurs; and
STM1404C (V
High when this occurs.
2.3V (2.5V – external diode drop of about 0.2V) for a 3V lithium cell;
2.5V (2.7V – 0.2V) for a 3V lithium cell; or
3.2V (3.4V – 0.2V) for a 3.68V lithium “AA” battery.
is pulled to Ground with an internal 100kΩ resistor. This is an optional feature available
RST
and MR goes from low to high.
rec
after MR returns to high. This active low input has an internal 40kΩ
OUT
OUT
OUT
remains ON when SAL is active-low): Vccsw pin will continue to
is taken to High-Z when SAL is active-low): Vccsw pin will be set to
is driven to Ground when SAL is active-low): Vccsw pin will be set to
CC
PFI
PFI
CC
, or when V
drops below V
(Power-fail Input Threshold Voltage) or V
is between 2.4V and 3.6V. When V
DET
CC
:
drops below V
CC
RST
falls below V
.
RST
TPU
(Reset Threshold selected by the
rec
SW
(200ms, typical) AFTER V
SS
(internally switched V
(see PFO, above), PFO goes
.
CC
falls below 2.4V (V
BAT
CC
pin below V
falls below V
CC
DET
or V
CC
SW
SW
. BLD
rises
BAT
13/36
),
).