September 2005
rev
1.5
ASM6381 - ASM6390
Single/Dual Low Voltage, Low Power Microcontroller Power Supply Supervisor
General Description
The ASM6381 - ASM6390 are cost effective +1.8V to +5V
power supply supervisor circuits optimized for low-power
microprocessor (µP), microcontroller (µC) and digital systems.
They provide a reset output during power-up, power-down and
brown-out conditions. They provide excellent reliability by
eliminating external components and adjustments.
A reset signal is issued if the power supply voltage drops below
a preset reset threshold and is asserted for a minimum reset
timeout period after the supply has risen above the reset
threshold. The reset timeout periods are available from 1ms to
1200ms. The ASM6381, ASM6384 and ASM6387 have a push-
pull active-low reset output. The ASM6382, ASM6385 and
ASM6388 have a push-pull active-high reset output, and the
ASM6383, ASM6386, ASM6389 and ASM6390 have an open-
drain active-low reset output. The ASM6384, ASM6385 and
ASM6386 also feature a manual reset input.
The ASM6387, ASM6388, ASM6389 have an auxiliary input
RESET IN for monitoring a second voltage. The ASM6390
offers a manual reset input with a longer V
CC
reset timeout
period and a shorter manual reset timeout.
The reset output state is guaranteed to be in the correct logic
state for V
CC
down to 1V. The reset comparator is designed to
ignore fast transients on V
CC
.
• Factory-set Reset Threshold Voltages ranging from +1.58V
to 4.63V.
• Monitor 1.8V to 5V supplies.
• Push-Pull Active-low reset valid with 1.0V supply.
• Small 3-pin SC-70, 4-pin SC-70, 3-pin and 5-pin SOT23
packages.
• No external components.
• Specified over full temperature range: -40°C to 125°C
• Seven Reset Timeout periods: 1ms, 20ms, 140ms, 280ms,
560ms, 1120ms, 1200ms (min).
• Low power consumption: 3µA at +1.8V.
• Auxiliary RESET IN
• Manual Reset input.
Low supply current makes the ASM6381 - ASM6390 ideal for
use in portable and battery operated equipments. The
ASM6381 - ASM6383 are available in a compact, industry
standard 3-pin SC70 package and the ASM6384 - ASM6390
are available in a compact, industry standard 4-pin SC70
package. The ASM63811, ASM63812,
3-pin and 5-pin SOT23 package.
Reset thresholds are available from +1.58V to 4.63V in
approximately 100mV increments to support +1.8V to +5V
systems.
ASM63832 are
available in 3-pin SOT23 package. ASM63813 is available in
Features:
Typical Operating Circuit
Applications
•
•
•
•
•
•
Embedded controllers
Portable/Battery operated systems
Intelligent instruments
Wireless communication systems
PDAs and handheld equipment
Computers
MR
R2
V
CC
R1
V
CC
RESET IN
V
CC
µP
RESET
Input
(RESET)
RESET
(RESET)
GND
GND
Alliance Semiconductor
2575 Augustine Drive . Santa Clara, CA 95054 . Tel: 408.855.4900 . Fax: 408.855.4999 . www.alsc.com
Notice: The information in this document is subject to change without notice
September 2005
rev 1.5
Pin Diagram
3SOT23
RESET
1
ASM63811
3
V
CC
ASM6381 - ASM6390
Top View
3SC-70
GND
1
ASM6381
(ASM6382)
ASM6383
3
V
CC
GND
2
(RESET) RESET
2
4SC-70
GND
4SC-70
GND
1
ASM6384
(ASM6385)
ASM6386
ASM6390
4
V
CC
1
ASM6387
(ASM6388)
ASM6389
4
V
CC
(RESET) RESET
2
3
MR
(RESET) RESET
2
3
RESET IN
3SOT23
GND
1
RESET
1
3SOT23
ASM63812
ASM63832UR
3
RESET
2
V
CC
ASM63813UR
3
GND
V
CC
2
5SOT23
RESET
1
V
CC
2
ASM63813UK
GND
3
4
5
NC
NC
2 of 15
Single/Dual Low Voltage, Low Power Microcontroller Power Supply Supervisor
Notice: The information in this document is subject to change without notice
September 2005
rev 1.5
Pin Description
Pin #
ASM63813UR
ASM63813UK
ASM63812
ASM63832
ASM63811
ASM6384/
ASM6386/
ASM6390
ASM6387/
ASM6389
ASM6381
ASM6383
ASM6382
ASM6385
ASM6381 - ASM6390
ASM6388
Pin Name
Function
5SOT23
3
3SOT23
3
3SOT23
1
3SOT23
2
3SOT23
1
3SC-70
1
1
1
4SC-70
1
1
1
GND
Ground.
RESET is asserted
LOW if V
CC
falls below
1
1
2
1
2
2
-
2
-
2
-
RESET
V
TH
and remains LOW
for T
RST
after V
CC
exceeds the threshold.
RESET is asserted
HIGH if V
CC
falls below
-
-
-
-
-
-
2
-
2
-
2
RESET
V
TH
and remains HIGH
for T
RST
after V
CC
exceeds the threshold.
Manual Reset Input. A
logic LOW on MR
asserts reset. Reset
remains active as long
as MR is LOW and for
T
MRST
after MR returns
HIGH. The active low
-
-
-
-
-
-
-
3
3
-
-
MR
input has an internal
20k. pull-up 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.
Auxiliary Reset input.
Reset asserts when
either V
CC
or RESET IN
falls below its threshold
voltage.
-
-
-
-
-
-
-
-
-
3
3
RESETIN
2
2
3
3
3
3
3
4
4
4
4
V
CC
Power supply input
voltage.
Single/Dual Low Voltage, Low Power Microcontroller Power Supply Supervisor
Notice: The information in this document is subject to change without notice
3 of 15
September 2005
rev 1.5
Detailed Description
A proper reset input enables a microprocessor or a
microcontroller
errors
during
to
start
in
a
known
and
state.
ASM6381 - ASM6390 assert reset to prevent code execution
power-up,
power-down
brown-out
V
IN
ASM6381 - ASM6390
1.27V, reset is asserted. The RESET IN can be used as a
secondary power supply monitor input by implementing a
resistor divider at RESET IN pin.
conditions.
Manual Reset (MR) Input
A logic low on MR asserts reset. MR is internally pulled high
through a 63kΩ resistor (for ASM6381-ASM6389, 1.35KΩ for
ASM6390) 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.
V
CC
R1
RESET IN RESET
R2
GND
Figure 1: RESET IN Comparator
Valid Reset with V
CC
under 1.0V
A 0.1µF capacitor from MR to ground can be added for
additional noise immunity.
Reset Output Operation
In µP / µC systems it is important to have the processor and
the system begin operation from a known state. A reset
output to a processor is provided to prevent improper
operations during power supply sequencing or low voltage
brown-out conditions.
The ASM6381-ASM6390 are designed to monitor the system
power supply voltages and issue a reset signal when the
levels are out of range. RESET outputs are guaranteed to be
active for V
CC
above 1.0V. When V
CC
exceeds the reset
threshold, an internal timer keeps RESET active for the reset
timeout period, after which RESET becomes inactive. If V
CC
drops below the reset threshold, RESET automatically
becomes active. Alternatively, external circuitry or an
operator
can
initiate
this
condition
using
the
Manual Reset (MR) pin. MR can be left open if it is not used.
MR can be driven by TTL/CMOS logic or even an external
switch.
RESET IN Comparator
Reset asserts when either V
CC
or RESET IN falls below its
respective threshold. RESET IN is compared to an internal
+1.27V reference. If the voltage at RESET IN is less than
To ensure logic inputs connected to the ASM6381 - ASM6390
are in a known state when V
CC
is under 1.0V, a 100kΩ pull-
down resistor at RESET is needed. The value is not critical. A
100kΩ pull-up resistor to V
CC
is needed with the RESET pin.
V
CC
V
CC
Power Supply
MR
ASM6381
ASM6384
ASM6387
RESET
GND
100kΩ
Power Supply
ASM6382
ASM6385
ASM6388
MR
RESET
GND
100kΩ
Figure 2: RESET valid with V
CC
under 1.0V
Application Information
Negative V
CC
Transients
The ASM6381 - ASM6390 protect µPs from brownouts and
low V
CC
. Short duration transients of 100mV amplitude and
35µs or less duration typically do not cause a false RESET.
Single/Dual Low Voltage, Low Power Microcontroller Power Supply Supervisor
Notice: The information in this document is subject to change without notice
4 of 15
September 2005
rev 1.5
Absolute Maximum Ratings Table 1:
ASM6381 - ASM6390
Parameter
Pin Terminal Voltage With Respect To Ground
V
CC
RESET, RESET
Input current at V
CC
Output current: RESET, RESET
Rate of Rise at V
CC
ESD rating
HBM
MM
Min
Max
Units
-0.3
-0.3
6.0
V
CC
+ 0.3
20
20
100
V
V
mA
mA
V/µs
2
200
KV
V
Note: These are stress ratings only and the functional operation is not implied. Exposure to absolute
maximum ratings for prolonged time periods may affect device reliability.
Absolute Maximum Ratings Table 2:
Parameter
Power Dissipation (T
A
= 70°C)
Operating temperature range
Storage temperature range
Lead temperature (Soldering, 10 sec)
Min
235
-40
-65
Max
245
125
150
300
Units
mW
°C
°C
°C
Note: These are stress ratings only and the functional operation is not implied. Exposure to absolute maximum rat-
ings for prolonged time periods may affect device reliability.
Single/Dual Low Voltage, Low Power Microcontroller Power Supply Supervisor
Notice: The information in this document is subject to change without notice
5 of 15
Analog electronics
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