ams AS1909C20-T Low-voltage microprocessor reset circuit Datasheet

AS1907, AS1908 , AS1909
D a ta S he e t
L o w - Vo l ta g e M i c r o p r o c e s s o r R e s e t C i r c u i ts
1 General Description
2 Key Features
!
3 Output Types: Push/Pull RESET, Push Pull
RESETN, and Open Drain RESETN
!
Reset Threshold Range: 1.6 to 2.5V (~100mV increments)
!
RESET/RESETN:
- Valid to VCC = 0.7V (AS1907 and AS1908)
- Valid to VCC = 1.0V (AS1909)
The devices are available as the standard products
listed in Table 1.
!
Reset Pulse Widths: 1, 20, and 100ms
Table 1. Standard Products
!
Supply Voltage Range: +0.7 to +3.6V
!
Supply Current Range: 2.6 to 7.0µA
!
Power Supply Transient Immunity
!
Requires No External Components
!
Operating Temperature Range: -40 to +125ºC
!
3-pin SOT23 Package
The AS1907/AS1908/AS1909 microprocessor supervisory circuits are ideal for monitoring the supply voltage
of digital systems and microprocessors.
The devices are designed to initiate a reset if the supply
voltage goes below a predefined threshold. The duration
of the reset is either 1.5, 30, or 150ms (typ.) after the
supply voltage has risen above the pre-set threshold
(see Ordering Information on page 9).
Model
Output Type
Reset Type
AS1907
Push/Pull
Active-Low
AS1908
Push/Pull
Active-High
AS1909
Open-Drain
Active-Low
The reset thresholds are factory-set between 1.6 and
2.5V in steps of approximately 100mV (see Table 5 on
page 7).
The devices exhibit excellent reliability, and can reduce
system costs by eliminating the need for external components. The extremely low current consumption makes
the devices ideal for use in portable applications.
The integrated reset comparator was specifically
designed to ignore fast transients on VCC.
The devices are available in a 3-pin SOT23 package.
3 Applications
The devices are ideal for use in cordless and mobile
phones, MP3 players, CD and DVD players, PDAs,
handheld computers, digital cameras, hard drives, and
any other application where power supply supervisory
control is required.
Figure 1. Application Diagrams
VCC
VCC
VCC
VCC
3
3
VCC
VCC
3
VCC
Microprocessor
AS1907
GND
1
RESETN
2
RESET I/O
GND
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1
3
VCC
3
VCC
Microprocessor
AS1908
GND
1
2
RESET
RESET I/O
GND
Revision 1.02
1
3
Microprocessor
AS1909
GND
1
2
RESETN
RESET I/O
GND
1
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AS1907/AS1908/AS1909
Data Sheet - P i n o u t
4 Pinout
Pin Assignments
Figure 2. Pin Assignments (Top View)
GND
1
AS1908/
AS1907/
AS1909
RESET,
RESETN
3
VCC
2
Pin Descriptions
Table 2. Pin Descriptions
Pin Number
Pin Name
1
GND
RESET
Active-High Reset Output (AS1908). This pin stays high whenever VCC is
below the RESET threshold VTH (see page 7), and for tTP (see page 4) after VCC
rises above VTH.
RESETN
Active-Low Reset Output (AS1907, AS1909). This pin remains low while VCC
is below the RESET threshold VTH (see page 7), and for tTP (see page 4) after
VCC rises above VTH.
Note: This pin is open-drain on the AS1909.
2
3
Description
Ground
VCC
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Positive Supply Voltage. Connect to +0.7 to +3.6V supply.
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AS1907/AS1908/AS1909
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 3 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 Section 6 Electrical
Characteristics on page 4 is not implied. Exposure to absolute maximum rating conditions for extended periods may
affect device reliability.
Table 3. Absolute Maximum Ratings
Parameter
Min
Max
Units
VCC
-0.3
+5
V
RESET, RESETN Push/Pull
-0.3
VCC + 0.3
V
RESETN Open Drain
-0.3
+6
V
Input Current (VCC)
20
mA
Output Current (RESET, RESETN)
20
mA
Continuous Power Dissipation
(TAMB = +70ºC)
320
mW
Operating Temperature Range
-40
+125
ºC
Storage Temperature Range
-65
+160
ºC
Package Body Temperature
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+260
Revision 1.02
ºC
Comments
3-pin SOT23 derate 4mW/ºC above +70ºC
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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AS1907/AS1908/AS1909
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
VCC = Full Range, TAMB = -40 to +125ºC (unless otherwise specified). Typ values are at VCC = +3.0V, TAMB = +25ºC.
Table 4. Electrical Characteristics
Parameter
Symbol
Conditions
TAMB = 0 to +85ºC
Supply Voltage Range
VCC
TAMB = -40 to +85ºC
Min
AS1907, AS1908
1
RESET Threshold Voltage
ICC
tRD
RESET Active
Time-Out Period
tTP
RESETN Output Low Voltage;
RESET asserted
(AS1907/AS1909)
VOL
RESETN Output High Voltage;
RESET Not Asserted (AS1907)
VOH
RESET Output Voltage; RESET
Asserted (AS1908)
VOH
RESET Output Voltage; RESET
Not Asserted (AS1908)
VOL
RESETN Output Leakage
Current; RESETN
Deasserted (AS1909)
ILEAK
Unit
3.6
AS1909
1.0
3.6
0.78
3.6
AS1909
1.2
3.6
1.2
V
3.6
VCC = 1.8V, no load
2.4
6.0
VCC = 2.5V, no load
2.6
7.0
µA
TAMB = +25ºC
VTH 0.9%
VTH
VTH +
0.9%
V
TAMB = -40 to +125ºC
VTH 3%
VTH
VTH +
3%
V
VTH
VCC Falling Reset Delay
0.7
Max
AS1907, AS1908
TAMB = -40 to +125ºC
Supply Current
Typ
VCC falling at 10V/ms
33
µs
AS190x-Azz-T
1
1.5
2
AS190x-Bzz-T
20
30
40
AS190x-Czz-T
100
150
200
ISINK = 50µA, VCC ≥ 1.0V
0.4
ISINK = 500µA, VCC ≥ 1.8V
0.3
ISOURCE = 200µA, VCC ≥ 1.8V
0.8 x
VCC
ISOURCE = 500µA, VCC ≥ 2.7V
0.8 x
VCC
ISOURCE = 1µA, VCC ≥ 1.0V
0.8 x
VCC
ISOURCE = 200µA, VCC ≥ 1.8V
0.8 x
VCC
ms
V
V
V
ISINK = 500µA, VCC ≥ 1.8V
0.3
ISINK = 1.2mA, VCC ≥ 2.7V
0.3
VCC > VTH
0.5
V
µA
1. Not valid if VCC = VTH.
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AS1907/AS1908/AS1909
Data Sheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s
7 Typical Operating Characteristics
TAMB = +25ºC (unless otherwise specified).
Figure 4. Supply Current vs. Supply Voltage
3.2
6
3
5
Supply Current (µA) .
Supply Current (µA) .
Figure 3. Supply Current vs. Temperature
VCC = 2.5V
2.8
2.6
VCC = 1.8V
2.4
4
3
2
1
2.2
2
-50
0
-25
0
25
50
75
100
1.4
125
1.8
2.2
2.6
3
3.4
3.8
Supply Voltage (V)
Temperature (°C)
Figure 5. Normalized Reset Timeout Period vs.
Temperature, VTH = 2.3V
Figure 6. Output Voltage Low vs. Temperature
Reset Asserted
1.3
Output Voltage Low (mV)
Norm. Reset Timeout Period
.
.
75
1.2
1.1
1
0.9
-50
-25
0
25
50
75
100
65
55
45
VCC = 2.2V
ISINK = 500µA
35
25
15
5
-50
125
VCC = 1.8V
ISINK = 500µA
VCC = 0.7V
ISINK = 50µA
VCC = 1.0V
ISINK = 50µA
-25
Temperature (°C)
0
25
50
75
100
125
Temperature (°C)
Figure 8. VCC falling Propagation Delay vs.
Temperature
Figure 7. Max. Transient Duration vs.
Reset Comparator Overdrive
140
600
120
.
Propagation Delay (µs)
Max. Transient Duration (µs)
.
700
500
400
Reset Occurs
300
Reset does
not Occur
200
100
0
0.1
1
10
100
1000
80
60
40
VCC falling at 10V/ms
20
0
-50
Reset Comparator Overdrive (mV)
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VCC falling at 1V/ms
100
-25
0
25
50
75
100 125
Temperature (°C)
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AS1907/AS1908/AS1909
Data Sheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s
Figure 9. Output Voltage Low vs. VCC, ISINK = 50µA
60
80
Output Voltage Low (mV)
50
.
Temp = -40°C
Temp = +25°C
Temp = +85°C
Temp = +125°C
.
Output Voltage Low (mV)
Figure 10. Output Voltage Low vs. VCC, ISINK = 100µA
40
30
20
10
0
Temp = -40°C
Temp = +25°C
Temp = +85°C
Temp = +125°C
70
60
50
40
30
20
10
0
0.7
1
1.3
1.6
1.9
2.2
0.7
VCC (V)
1
1.3
1.6
1.9
2.2
VCC (V)
Figure 11. Output Voltage Low vs. VCC, ISINK = 500µA
250
Output Voltage Low (mV)
.
Temp = -40°C
Temp = +25°C
Temp = +85°C
Temp = +125°C
200
150
100
50
0
0.7
1
1.3
1.6
1.9
2.2
VCC (V)
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AS1907/AS1908/AS1909
Data Sheet - A p p l i c a t i o n I n f o r m a t i o n
8 Application Information
Negative Going VCC Transients
All devices are effectively immune to short-duration, negative-going VCC transients (glitches). The Maximum Transient
Duration vs. Reset Comparator Overdrive graph (see page 5) shows the maximum pulse width that a negative-going
VCC transient may typically have without issuing a reset signal. As the amplitude of the transient increases, the maximum allowable pulse width decreases.
Valid Reset Output
If VCC falls below 1V and approaches the minimum operating voltage of 0.7V, push/pull-type reset sinking/sourcing
capabilities greatly decrease. High-impedance CMOS-logic inputs connected to RESET can drift to indeterminate voltages, although this is normally not a problem since most microprocessors do not operate at VCC < 1V.
For the AS1908, where RESET must be valid to VCC = 0, a 100kΩ pull-up resistor between RESET and VCC (see Figure 1 on page 1) will hold RESET high if VCC falls below 0.7V.
For the AS1907, where RESET must be valid down to 0V, add a pull-down resistor between RESET and GND (see
Figure 1 on page 1) to eliminate stray leakage currents and hold RESET low. A pull-down resistor of 100kΩ is large
enough not to load RESET yet small enough to pull it low.
Since the AS1909 has an open-drain, active-low output, it typically uses a pull-up resistor. With this device, RESET will
most likely not maintain an active condition, but will drift to a non-active level due to the pull-up resistor and the
reduced sinking capability of the open drain device. Therefore, this device is not recommended for applications where
the RESET pin is required to be valid down to VCC = 0.
Table 5. Reset Thresholds
Reset Thresholds
TAMB = +25ºC
TAMB = -40 to +125ºC
Suffix
Min
Typ
Max
Min
Max
25
2.478
2.50
2.523
2.43
2.58
24
2.378
2.40
2.422
2.33
2.47
23
2.279
2.30
2.321
2.23
2.37
22
2.180
2.20
2.220
2.13
2.27
21
2.081
2.10
2.119
2.04
2.18
20
1.982
2.00
2.018
1.94
2.06
19
1.883
1.90
1.917
1.84
1.96
18
1.784
1.80
1.816
1.75
1.85
17
1.685
1.70
1.715
1.65
1.75
16
1.586
1.60
1.614
1.55
1.65
Bi-Directional Microprocessor Interface
The RESET output on the AS1909 is open-drain, thus this device can interface easily with microprocessors that have
bi-directional reset pins, such as the Motorola 68HC11.
Connect the RESET output of this device directly to the microprocessor’s RESET I/O pin with a single pull-up resistor
to allow either device to assert reset (see Figure 1 on page 1).
Layout Considerations
The devices require proper layout and design procedures for optimum performance.
!
Short, wide traces should be used to reduce stray inductance and capacitance.
!
Bypass capacitors should be as close to the device as possible.
!
Large ground planes should be used wherever possible.
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AS1907/AS1908/AS1909
Data Sheet - P a c k a g e D r a w i n g s a n d M a r k i n g s
9 Package Drawings and Markings
The devices are available in an 3-pin SOT23 package.
Figure 12. 3-pin SOT23 Package
Symbol
A
A1
B
C
D
E
e
H
L
S
α
Min
0.787
0.025
0.356
0.086
2.667
1.194
1.778
2.083
0.102
0.432
0º
Max
1.194
0.127
0.559
0.152
3.048
1.397
2.032
2.489
0.305
0.559
8º
Notes:
1. Dimensions D and E do not include mold flash.
2. Mold flash protrusions not to exceed .15mm (.006”).
3. Controlling dimension: millimeter.
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AS1907/AS1908/AS1909
Data Sheet - O r d e r i n g I n f o r m a t i o n
10 Ordering Information
The devices are available as the following standard products.
Table 6. Ordering Information
Type
Marking
Reset Type
Reset
Threshold
Minimum Reset
Timeout
Delivery Form
AS1908C18-T
ASHU
Active High
1.8V
100ms
Tape and Reel
AS1908C20-T
ASHV
Active High
2.0V
100ms
Tape and Reel
AS1907C16-T
ASHP
Active Low
1.6V
100ms
Tape and Reel
AS1907C18-T
ASHQ
Active Low
1.8V
100ms
Tape and Reel
AS1907C20-T
ASHR
Active Low
2.0V
100ms
Tape and Reel
AS1907C22-T
ASNB
Active Low
2.2V
100ms
Tape and Reel
AS1907B23-T
ASHX
Active Low
2.3V
20ms
Tape and Reel
AS1909C16-T
ASHY
Open Drain
1.6V
100ms
Tape and Reel
AS1909C17-T
ASHZ
Open Drain
1.7V
100ms
Tape and Reel
AS1909C18-T
ASND
Open Drain
1.8V
100ms
Tape and Reel
AS1909C20-T
ASH1
Open Drain
2.0V
100ms
Tape and Reel
AS1909C22-T
ASNC
Open Drain
2.2V
100ms
Tape and Reel
AS1909C23-T
ASH2
Open Drain
2.3V
100ms
Tape and Reel
Non-standard versions require a minimum order of 30,000 units. Contact austriamicrosystems, AG for availability of
non-standard versions.
Table 7. Coding of Factory-Trimmed Reset Active Time-Out Period
Device
Suffix
AS1907xyy-T*
AS1908xyy-T*
AS1909xyy-T*
tTP in Milliseconds
Min
Typ
Max
A
1
1.5
2
B
20
30
40
C
100
150
200
* These devices are available in factory-set VCC reset thresholds from 1.6V to 2.5V, in approximately 100mV increments. Choose the desired reset threshold suffix from (see Table 5 on page 7) and insert it instead of “yy” in the part
number.
Factory-programmed reset timeout periods are also available. Insert the code corresponding to the desired nominal
reset timeout period (see Table 7) instead of “x” in the part number. All devices available in tape-and-reel only.
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AS1907/AS1908/AS1909
Data Sheet
Copyrights
Copyright © 1997-2007, austriamicrosystems AG, Schloss Premstaetten, 8141 Unterpremstaetten, Austria-Europe.
Trademarks Registered ®. All rights reserved. The material herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner.
All products and companies mentioned are trademarks or registered trademarks of their respective companies.
Disclaimer
Devices sold by austriamicrosystems AG are covered by the warranty and patent indemnification provisions appearing
in its Term of Sale. austriamicrosystems AG makes no warranty, express, statutory, implied, or by description regarding
the information set forth herein or regarding the freedom of the described devices from patent infringement. austriamicrosystems AG reserves the right to change specifications and prices at any time and without notice. Therefore, prior
to designing this product into a system, it is necessary to check with austriamicrosystems AG for current information.
This product is intended for use in normal commercial applications. Applications requiring extended temperature
range, unusual environmental requirements, or high reliability applications, such as military, medical life-support or lifesustaining equipment are specifically not recommended without additional processing by austriamicrosystems AG for
each application. For shipments of less than 100 parts the manufacturing flow might show deviations from the standard
production flow, such as test flow or test location.
The information furnished here by austriamicrosystems AG is believed to be correct and accurate. However,
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austriamicrosystems AG rendering of technical or other services.
Contact Information
Headquarters
austriamicrosystems AG
A-8141 Schloss Premstaetten, Austria
Tel: +43 (0) 3136 500 0
Fax: +43 (0) 3136 525 01
For Sales Offices, Distributors and Representatives, please visit:
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