ASM811JEUS-T ALSC [Alliance Semiconductor Corporation], ASM811JEUS-T Datasheet - Page 2

• Manufacturer Part Number: ASM811JEUS-T
• Description: 4 Pin P Voltage Supervisor with Manual Reset
• Manufacturer: ALSC [Alliance Semiconductor Corporation]

October 2003
rev 1.0
Pin Diagram:
Detailed Description
A
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 V
threshold trip voltage and remains asserted for 140ms
minimum after the V
Pin Description
ASM811
proper
1
2
3
4
-
Pin #
reset
ASM812
(RESET)
1
2
3
4
-
CC
input
RESET
has risen above the threshold.
GND
RESET
RESET
Name
GND
V
Pin
MR
enables
CC
CC
2
1
supply voltage falls below the
SOT143
(ASM812)
ASM811
Notice: The information in this document is subject to change without notice
4 Pin µP Voltage Supervisor with Manual Reset
Ground.
RESET is asserted LOW if V
the Threshold. In addition, RESET is active LOW as long as the manual reset is low.
RESET is asserted HIGH if V
the threshold. In addition, RESET is active HIGH as long as the manual reset is low.
Manual Reset Input. A logic LOW on MR asserts reset. Reset remains active as long as MR is
LOW and for T
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.
Power supply input voltage (3.0V, 3.3V, 5.0V)
a
microprocessor
4
3
V
MR
CC
MRST
after MR returns HIGH. The active low input has an internal 20kΩ pull-up
/
CC
CC
Block Diagram
A logic low on MR assserts RESET LOW on the ASM811 and
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.
A 0.1µF capacitor from MR to ground can be added for
additional noise immunity.
MR
V
Manual Reset (MR) Input
CC
falls below V
falls below V
+
-
Function
+
-
V
TH
20kΩ
TH
CC
GND
and remains LOW for T
4.38V
4.00V
4.38V
3.08V
2.93V
2.63V
4.63V
and remains HIGH for T
RESET Generator
ASM811, ASM812
(ASM812)
RST
ASM811
RST
after V
after V
CC
CC
exceeds
exceeds
(RESET)
2 of 10
RESET