ASM811, ASM812
October 2003
rev 1.0
Pin Diagram:
Block Diagram
SOT143
VCC
4
3
VCC
GND
1
20kΩ
ASM811
(ASM812)
MR
RESET Generator
RESET
VCC
+
(RESET)
-
4.63V
2
(RESET)
MR
RESET
4.38V
4.3080V
3.08V
2.93V
2.63V
+
-
ASM811
(ASM812)
Pin Description
GND
Pin #
Pin
Function
Name
ASM811
ASM812
1
1
-
GND
Ground.
RESET is asserted LOW if VCC falls below VTH and remains LOW for TRST after VCC exceeds
the Threshold. In addition, RESET is active LOW as long as the manual reset is low.
2
-
RESET
RESET is asserted HIGH if VCC falls below VTH and remains HIGH for TRST after VCC exceeds
the threshold. In addition, RESET is active HIGH as long as the manual reset is low.
2
RESET
Manual Reset Input. A logic LOW on MR asserts reset. Reset remains active as long as MR is
LOW and for TMRST after MR returns HIGH. The active low input has an internal 20kΩ pull-up
3
4
3
4
MR
resistor. The input should be left open if not used. It can be driven by TTL or CMOS logic or
shorted to ground by a switch.
VCC
Power supply input voltage (3.0V, 3.3V, 5.0V)
Detailed Description
Manual Reset (MR) Input
A logic low on MR assserts RESET LOW on the ASM811 and
A
proper reset input enables
a
microprocessor
/
RESET HIGH on the ASM812. MR is internally pulled high
through a 20kΩ resistor and can be driven by TTL/CMOS gates
or with open collector/drain outputs. MR can be left open if not
used. MR may be connected to ground through a normally-
open momentary switch without an external debounce circuit.
microcontroller to start in a known state. ASM811/812 assert
reset to prevent code execution errors during power-up, power-
down and brown-out conditions.
Reset Timing
The reset signal is asserted- LOW for the ASM811 and HIGH
for the ASM812- when the VCC supply voltage falls below the
A 0.1µF capacitor from MR to ground can be added for
additional noise immunity.
threshold trip voltage and remains asserted for 140ms
minimum after the VCC has risen above the threshold.
2 of 10
4 Pin µP Voltage Supervisor with Manual Reset
Notice: The information in this document is subject to change without notice
ALSC [ ALLIANCE SEMICONDUCTOR CORPORATION ]
