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ams AG
The technical content of this austriamicrosystems datasheet is still valid.
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8141 Unterpremstaetten, Austria
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AS1904, AS1905, AS1906
1 General Description
The AS1904/5/6 family is an ultra low-power supervisory
circuit device.
The device can be used to monitor the supply voltage of
digital systems and microprocessors and initiate a reset
when the voltage goes below a predefined threshold.
The duration of the reset is 5/20/100/500ms (typ.) after
the supply voltage has risen above the threshold.
The device exhibits excellent reliability and can reduce
application costs by eliminating all external components.
The device is available with different output drivers:
!
Ultra Low-Power µP Supervisory Circuit
Wor
ld's
L
Pow owest
Con
sum er
2 Key Features
ptio
n!
Low 150nA (typical) Supply Current
!
!
Data Sheet
!
!
!
Supply Voltage Range 1.0 to 3.6V
Reset Threshold Available from 2.2 to 3.1V
Available in three Versions
- AS1904 Push-Pull RESETN
- AS1905 Push-Pull RESET
- AS1906 Open Drain RESETN
!
!
!
!
!
!
The AS1905 uses the same output stage as the
AS1904, but has an active high reset.
!
The AS1906 has an open drain output with active low
reset.
All devices operate down to a voltage of 1V.
The reset thresholds are factory-trimmable between
2.2V and 3.08V in steps of approximately 100mV.
Each device of the AS1904/5/6 family is offered with four
time-out periods of 5/20/100/500ms.
The extremely low current consumption of only 150nA
(typ) at 3.3V makes the device ideal for use in portable
applications.
All devices are available in a 3-pin SOT23 package.
Figure 1. Functional Block Diagrams
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Detection Voltage Accuracy: ±1.5%
Temperature Range: -40 to +85°C
SOT23-3 Package
Superior Upgrade to austriamicrosystems
AS1901/2/3 Device Family
The AS1904 has a push-pull driver with an active low
reset.
4 Time-Out Periods Ranging from 5 to 500ms
3 Applications
The devices are ideal for computers, intelligent instru-
ments, controllers, critical microprocessor and micro-
controller, power monitoring and portable/battery-
powered equipment.
V
CC
3
3
V
DD
V
CC
V
DD
AS1904
AS1905
RESET,
RESETN
2
Microprocessor
AS1906
RESETN
2
RESET
GND
1
GND
GND
1
Revision 1.41
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Precision Monitoring of 2.5-, 3-, and 3.3V-Power
Supplies
AS1904, AS1905, AS1906
Data Sheet - P i n o u t
4 Pinout
Pin Assignments
Figure 2. Pin Assignments (Top View)
Top View
GND
1
SOT23-3
Pin Descriptions
Table 1. Pin Descriptions
AS1904/AS1906
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Pin Number
AS1905
1
-
Pin Name
GND
Description
Ground
2
RESETN
-
2
RESET
V
DD
3
3
Supply voltage.
Revision 1.41
Active-low reset output. RESETN remains low while V
DD
is
below the reset threshold and for t
TP
after V
DD
rises above
the reset threshold. RESETN is open-drain on the AS1906
and push-pull on the AS1904.
Active-high reset output. RESET remains high while V
DD
is
below the reset threshold and for t
TP
after V
DD
rises above
the reset threshold.
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RESET
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AS1904
AS1905
AS1906
3
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DD
id
AS1904, AS1905, AS1906
Data Sheet - A b s o l u t e M a x i m u m R a t i n g s
5 Absolute Maximum Ratings
Stresses beyond those listed in Table 2 may cause permanent damage to the device. These are stress ratings only,
and functional operation of the device at these or any other conditions beyond those indicated in the operational sec-
tions of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may
affect device reliability.
Table 2. Absolute Maximum Ratings
(
T
A
= 25°C Unless Otherwise Noted)
V
DD
to GND
RESET/RESETN to GND
Input Current (V
DD
)
Output Current (RESET, RESETN)
Rate of Rise (V
DD
)
Operating Temperature Range (T
A
)
Storage Temperature Range
-0.3 to +5
-0.3 to V
DD
+ 0.3
20
20
100
-40 to +85
-65 to +150
V
V
mA
mA
V/µs
°C
°C
Parameter
Limits
Units
Notes
Package-Body Peak Temperature
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+260
°C
Revision 1.41
The reflow peak soldering temperature (body
temperature) specified is in accordance with
IPC/JEDEC J-STD-020C “Moisture/Reflow
Sensitivity Classification for non-hermetic
Solid State Surface Mount Devices”
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Data Sheet - E l e c t r i c a l C h a r a c t e r i s t i c s
6 Electrical Characteristics
V
DD
= Full Range; T
A
= -40º to +85°C; Unless Otherwise Specified
Table 3. Electrical Characteristics
Parameter
V
DD
Range
Supply Current
RESET Threshold Voltage
1
V
DD
to Reset Delay
2
RESET Active Time-Out Period
3
RESETN Output Voltage
(AS1904/AS1906)
Symbol
V
DD
I
DD
V
TH
T
A
= -40 to +85°C
t
RD
t
TP
I
SINK
= 1.2mA, V
DD
= 2.1V,
reset asserted
V
DD
= V
TH
to (V
TH
- 100mV)
t
TP
-
40%
Conditions
T
A
= 0 to +70°C
T
A
= -40 to +85°C
V
DD
= 3.3V, No Load
T
A
= +25°C
V
TH
-
1.5%
V
TH
-
2.5%
Min
1.0
1.2
150
V
TH
V
TH
20
Typ
Max
3.6
3.6
290
V
TH
+
1.5%
V
TH
+
2.5%
50
t
TP
+
60%
0.4
Unit
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V
OL
I
SINK
= 400µA, V
DD
= 1.2V,
reset asserted
0.4
V
OH
I
SOURCE
= 1.2mA, V
DD
= 3.2V
0.8 x
V
DD
V
OH
I
SOURCE
= 500µA, V
DD
= 2.1V,
reset asserted
I
SOURCE
= 100µA, V
DD
= 1.2V,
reset asserted
I
SINK
= 1.2mA, V
DD
= 3.2V,
reset not asserted
0.8 x
V
DD
0.8 x
V
DD
V
OL
0.4
V
HYST
I
LEAK
10
0.1
Revision 1.41
RESETN Output Voltage (AS1904)
RESET Output Voltage (AS1905)
RESET Threshold Hysteresis
Open-Drain RESETN Output
Leakage Current (AS1906)
Notes:
1
2
3
See Table 6, “Coding of Factory-Trimmed Reset Threshold Voltages,” on page 6.
Guaranteed by design.
See Table 4, “Coding of Factory-trimmed Reset Active Time-Out Period,” on page 6.
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TP
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µA
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