Datasheet

austriamicrosystems AG
is now
ams AG
The technical content of this austriamicrosystems datasheet is still valid.
Contact information:
Headquarters:
ams AG
Tobelbaderstrasse 30
8141 Unterpremstaetten, Austria
Tel: +43 (0) 3136 500 0
e-Mail: [email protected]
Please visit our website at www.ams.com
AS1920, AS1922
D a ta S h e e t
Tri p l e - Vo l ta g e , M i c r o - P o w e r M i c r o p r o c e s s o r
Supervi s ory Ci rcuits
2 Key Features
These very-low-current (6.2µA, typ) devices maintain
reset for a minimum timeout period after all supplies
have stabilized. Guaranteed to be in the correct state for
VCC > +1.0V, these devices are perfect for multiple-voltage systems with low current requirements and strict
monitoring requirements.
Simultaneous Triple-Voltage Monitoring
!
Very-Low Supply Current: 6.2µA
!
±1.5% Accuracy Over Temperature
!
Reset Time Delay: 200ms
!
Power Supply Transient Immunity
!
Guaranteed Reset for VCC3 ≥ 1V or VCC18 ≥ 1V
!
Active-Low Push/Pull Reset Output (AS1920)
!
Active-Low Open-Drain Reset Output (AS1922)
!
5-pin SOT23 Package
am
lc s
on A
te G
nt
st
il
The devices are available as the standard products
listed in Table 1.
!
al
id
The AS1920 and AS1922 microprocessor supervisory
circuits were designed to generate a reset when at least
one of the three monitored supply voltages falls below
its respective trip threshold.
lv
1 General Description
Table 1. Standard Products
Model
Output Type
Supervisory Voltages
AS1920-18
Push/Pull
3V, 1.8V, Adjustable
AS1922-18
Open-Drain
3V, 1.8V, Adjustable
All devices monitor primary and secondary factorytrimmed voltages. Additionally, a third monitoring voltage
can be selected via an external resistor divider.
The AS1920 has an active-low push/pull reset output,
whereas the AS1922 has an active-low open-drain reset
output.
3 Applications
The AS1920 and AS1922 are available in a 5-pin
SOT23 package.
The devices are ideal for personal computers, notebooks, battery-powered systems, embedded controllers,
intelligent instruments, automotive systems, critical CPU
monitoring, and any multi-supply monitoring application.
ca
Figure 1. Typical Application Diagram
3V
System
Logic
ni
1.8V
Te
ch
2.5V
0.1µF
www.austriamicrosystems.com
5
VCC3
4
R1
130kΩ
1%
0.1µF
R2
100kΩ
1%
VCC18
AS1920/
AS1922
3
VCCA
Revision 1.00
1
RESETN
2
GND
1 - 14
AS1920/AS1922
Datasheet - P i n o u t
4 Pinout
Pin Assignments
Figure 2. Pin Assignments (Top View)
AS1920/
AS1922
VCCA 3
am
lc s
on A
te G
nt
st
il
Pin Descriptions
4 VCC18
lv
GND 2
5 VCC3
al
id
RESETN 1
Table 2. Pin Descriptions
Pin Number
Pin Name
Description
1
RESETN
Reset Logic Output. This active-low pin serves as the 3V push/pull reset
output. A reset is asserted when any one of the supplies are below its
respective trip threshold and the reset is held for 200ms after all power supplies
have stabilized.
2
GND
Ground.
VCCA
VCCA. 1V sense, high-impedance input.
Note: If this pin is not used it should be tied to VCC3 or VCC18.
VCC18
VCC18. 1.8V sense input and power detect pin (AS1920-18, AS1922-18). This
pin provides power to the output reset stage of the device in order to assert a
valid reset when the voltage on the primary input is down.
Note: Bypass this pin to GND with a ≥0.1µF ceramic capacitor.
VCC3
VCC3. 3V sense input and power supply pin (AS1920-18, AS1922-18). This pin
provides power to the device.
Note: Bypass this pin to GND with a ≥0.1µF ceramic capacitor.
3
4
Te
ch
ni
ca
5
www.austriamicrosystems.com
Revision 1.00
2 - 14
AS1920/AS1922
Datasheet - 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 Electrical Characteristics on page 4 is not implied. Exposure to absolute maximum rating conditions for extended periods may affect
device reliability.
Min
Max
Units
-0.3V
+5
V
RESETN Open-Drain
-0.3
+7
V
RESETN to GND
-0.3
VCC3 +
0.3
V
-40
+85
ºC
Guaranteed to meet specified performance from
0 to 70ºC and is designed, characterized and
assured to meet the extended temperature limits
of -40 to 85ºC but are not tested at these
temperatures.
am
lc s
on A
te G
nt
st
il
Operating Temperature Range
Comments
lv
Parameter
VCC18, VCC3, VCCA to GND
al
id
Table 3. Absolute Maximum Ratings
Storage Temperature Range
-65
+260
ºC
ºC
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”.
The lead finish for Pb-free leaded packages is
matte tin (100% Sn).
Te
ch
ni
ca
Package Body Temperature
+150
www.austriamicrosystems.com
Revision 1.00
3 - 14
AS1920/AS1922
Datasheet - 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
VCC18 = 1.8V, VCC3 = 3V, VCCA = VCC3, TAMB = -40 to +85ºC (unless otherwise specified).
Table 4. Electrical Characteristics
VRT18
Min
Typ
Max
Unit
Reset Threshold VCC18
1.653
1.683
1.713
V
VRT3
Reset Threshold VCC3
2.763
2.805
2.847
V
VRTA
Reset Threshold VCCA
0.982
1.00
1.018
V
VCC3, VCC18
Operating Voltage
RESETN in Correct Logic State
3.3
V
IVCC18
VCC18 Supply Current
VCC18 < VCC3, VCC18 = 1.8V
0.7
2
µA
IVCC3
VCC3 Supply Current
VCC18 < VCC3, VCC3 = 3V
6.2
15
µA
VCCA Input Current
VCCA = 1V
-15
0
15
nA
IOUT
Open-Drain RESETN
Output Current
Reset Not Asserted, Forced to 0V
2
4
13
µA
ILEAK
Open-Drain RESETN Output
Leakage Current
Reset Not Asserted, RESETN
Forced to 5.5V, TAMB = 25ºC
-0.1
tRST
Reset Pulse Width
RESETN Low, TAMB = 25ºC
2
140
tUV
VCC Undervoltage
Detect to RESETN
VCC18, VCC3, or VCCA <
2
Reset Threshold by > 1%
TAMB = 25ºC
130
ISINK = 2.5mA, VCC3 = 3V,
VCC18 = 0V
0.15
0.4
ISINK = 100µA, VCC3 = 1V,
VCC18 = 0V
0.05
0.3
ISINK = 100µA, VCC3 = 0V,
VCC18 = 1V
0.05
0.3
ISINK = 100µA, VCC3 = 1V,
VCC18 = 1V
0.05
0.3
1
am
lc s
on A
te G
nt
st
il
IVCCA
1
Conditions
al
id
Parameter
lv
Symbol
VOL
Output Voltage Low, RESETN
VOH
Output Voltage High, RESETN
ISOURCE = 1µA (AS1922-xx)
VCC3 1
200
0.1
µA
280
ms
VCC3 0.65
µs
V
V
Te
ch
ni
ca
1. Guaranteed by design.
2. Measured from the time (t1) when the input passes through the input threshold voltage (VRTX) to the time (t2)
when RESETN passes through 1.5V.
www.austriamicrosystems.com
Revision 1.00
4 - 14
AS1920/AS1922
Datasheet - 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 3. IVCC18 vs. Temperature
Figure 4. IVCC3 vs. Temperature; VCC3 = 3V
6.5
0.7
0.6
0.5
-100
-50
6.2
6.1
6
5.9
5.8
5.7
5.6
0
50
5.5
-100
100
Temperature (°C)
-50
9
Figure 6. VOH/RST vs. Temperature; VCC3 = 3V
Output Voltage High e
7
6
5
4
3
2
1
0
-100
-50
0
50
2.4
2.35
2.3
2.25
2.2
-100
100
-50
ca
Temperature (°C)
Figure 7. tRST vs. Temperature; VCC3 = VCCA = 3V
220
Te
200
180
160
-50
0
50
100
50
100
Figure 8. tUV vs. Temperature; VCC3 = VCCA = 3V
150
125
100
75
50
-100
-50
0
50
100
Temperature (°C)
Temperature (°C)
www.austriamicrosystems.com
0
Temperature (°C)
VCC Undervoltage Detect [µs] e
ni
ch
Reset Pulse Width (ms) e
280
140
-100
100
2.45
8
240
50
2.5
10
260
0
Temperature (°C)
Figure 5. Supply Current VCCA vs. Temperature
VCCA Supply Current (nA) e
al
id
0.8
6.3
lv
VCC3 Supply Current (µA) e
6.4
0.9
am
lc s
on A
te G
nt
st
il
VCC18 Supply Current (µA) e
1
Revision 1.00
5 - 14
AS1920/AS1922
Datasheet - D e t a i l e d D e s c r i p t i o n
8 Detailed Description
The AS1920/AS1922 microprocessor supervisory circuits were designed to generate a reset when at least one of the
three monitored supply voltages falls below its respective trip threshold.
al
id
These very-low-current (6.5µA, typ) devices maintain reset for a minimum timeout period after all supplies have stabilized. Guaranteed to be in the correct state for VCC > +1.0V, these devices are perfect for multiple-voltage systems with
low current requirements and strict monitoring requirements.
Figure 9. AS1920 Block Diagram
5
–
VCC3
VCC
Internal
+
lv
Power
Detect
VCC3
4
am
lc s
on A
te G
nt
st
il
VCC18
200ms Pulse Generator
–
RESETN
200ms
Delay
+
3
1
–
VCCA
+
2
AS1920
Bandgap
Reference
ca
GND
ch
ni
Figure 10. VCC Monitor Timing Diagram
VCCX
VRTX
tRST
tUV
RESETN
Te
1.5V
www.austriamicrosystems.com
Revision 1.00
6 - 14
AS1920/AS1922
Datasheet - D e t a i l e d D e s c r i p t i o n
Figure 11. AS1922 Block Diagram
5
–
VCC3
VCC
Internal
+
VCC3
4
IOUT
VCC18
200ms Pulse Generator
–
al
id
Power
Detect
1
RESETN
200ms
Delay
am
lc s
on A
te G
nt
st
il
lv
+
3
–
VCCA
+
2
Bandgap
Reference
AS1922
Te
ch
ni
ca
GND
www.austriamicrosystems.com
Revision 1.00
7 - 14
AS1920/AS1922
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
9 Application Information
Supply Monitoring
The AS1920/AS1922 are low-power, high-accuracy triple-supply monitoring circuits with a single 200ms microprocessor reset output.
al
id
All VCC inputs (VCC18, VCC3, and VCCA) must be above their thresholds to prevent a reset from being asserted. The
AS1920/AS1922 will assert a reset during powerup, powerdown and brownout conditions on one or all of the VCC
inputs.
Power Detect
lv
The AS1920/AS1922 is powered from the 3V input pin (VCC3). The power detect circuitry ensures that the device pulls
pin RESETN low as soon as the primary input pin is ≥1V or the secondary input pin is ≥1V.
Powerup
Powerdown
am
lc s
on A
te G
nt
st
il
The power detect circuitry ensures that RESETN will be low when either VCC18 or VCC3 ≥1V. As long as any one of the
VCC inputs is below its reset threshold, RESETN will stay at a logic low. When all VCC inputs have stabilized, an internal timer will be started and RESETN will be driven high after 200ms.
On powerdown, if any of the VCC inputs drop below its threshold, RESETN is held at a logic low (0.3V) and is guaranteed until VCC3 and VCC18 < 1V.
Override Functions
As the trip points for VCC3 and VCC18 will always be greater than the trip point for VCCA, if pin VCCA is not used, it
should be tied to VCC3 or VCC18. In a similar manner if pin VCC18 is not used it should be tied to VCC3. Tying VCC3 to
VCC18 and operating from a 1.8V supply will assure the continuous assertion of RESETN.
Note: Pin VCC3 must be used in all configurations.
Ensuring RESETN Valid for Supply Voltages < 1V
When the supplies drops below 1V the RESETN output current sink capability is greatly reduced. Stray currents and
stray capacitance to signals other than GND can cause the RESETN output to float. This is not relevant for most applications since most microprocessors and other circuits do not operate with a supply voltage < 1V.
ca
In applications where the RESETN output must be valid down to 0V, a pulldown resistor from pin RESETN to ground
will ensure RESETN is held low (see Figure 12).
ch
ni
Figure 12. Typical Application w/Resistor on RESETN Output to GND
Te
Adjustable
Supply
5
3V
1.8V
VCC3
4
VCC18
AS1920/
AS1922
3
R1
1
RESETN
2
VCCA
R3
100kΩ
GND
R2
The value of the pulldown resistor (R3) is a trade-off between pulldown strength and loading of the RESETN pin. If the
value of R3 is too large RESETN may still float, and if the value of R3 is too small it may load RESETN and also use
excess supply current, therefore a value of 100kΩ is recommended for the pulldown resistor.
www.austriamicrosystems.com
Revision 1.00
8 - 14
AS1920/AS1922
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
Figure 13. Triple-Supply Monitor (3V, 1.8V, Adjustable)
5
3V
RESETN
System
Reset
4
VCC18
AS1920-18
3
2
VCCA
R1
al
id
1.8V
GND
R2
To ensure threshold accuracy,
set the parallel combination of
R1 and R2 ≤ 66.5kΩ
lv
Adjustable Supply
or DC/DC Feedback Divider
1
VCC3
am
lc s
on A
te G
nt
st
il
Figure 14. Dual-Supply Monitor (3V and 1.8V; Disable VCCA Input)
5
3V
1
VCC3
RESETN
System
Reset
4
1.8V
VCC18
AS1920-18
3
2
VCCA
GND
Figure 15. Dual-Supply Monitor (3V and Adjustable)
ni
ca
3V
Adjustable Supply
or DC/DC Feedback Divider
1
RESETN
VCC3
4
VCC18
AS1920-18
3
VCCA
R1
System
Reset
2
GND
R2
Te
ch
To ensure threshold accuracy,
set the parallel combination of
R1 and R2 ≤ 66.5kΩ
5
www.austriamicrosystems.com
Revision 1.00
9 - 14
AS1920/AS1922
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
Figure 16. VCCA Tied to DC/DC Feedback Divider
2.5V
5
3V
1
RESETN
VCC3
Adjustable Reset
Trip Threshold
2.31V
4
1.8V
VCC18
2.26kΩ
1%
System
Reset
al
id
27.4kΩ
1%
AS1920-18
3
2
VCCA
GND
am
lc s
on A
te G
nt
st
il
lv
22.6kΩ
1%
Figure 17. Triple-Supply Monitor w/Manual Reset Switch
VTRIP = VCCA/R2 (R1 + R2)
2.5V
VTRIP = 2.3V
1.8V
3V
5
100nF
R1 = R2 ((VTRIP/VCCA) - 1)
†
R3
10kΩ
5%
R1
130kΩ
0.1%
4
100nF
VCC18
3
VCCA
RESETN
System
Reset
AS1920-18
2
GND
R2
100kΩ
0.1%
ca
Normally Open
Manual Reset
Switch
1
VCC3
Optional Resistor Recommended
to Extend ESD Tolerance
Te
ch
ni
†
www.austriamicrosystems.com
Revision 1.00
10 - 14
AS1920/AS1922
Datasheet - 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
10 Package Drawings and Markings
The devices are available in an 5-pin SOT23 package.
am
lc s
on A
te G
nt
st
il
lv
al
id
Figure 18. 5-pin SOT23 Package
Notes:
ch
All dimensions in millimeters.
Foot length measured at intercept point between datum A and lead surface.
Package outline exclusive of mold flash and metal burr.
Package outline inclusive of solder plating.
Complies with EIAJ SC74.
PKG ST 0003 Rev A supersedes SOT23-D-2005 Rev C.
Te
1.
2.
3.
4.
5.
6.
Min
Max
0.90
1.45
0.00
0.15
0.90
1.30
0.30
0.50
0.09
0.20
2.80
3.05
2.60
3.00
1.50
1.75
0.30
0.55
0.95 REF
1.90 REF
0º
8º
ni
ca
Symbol
A
A1
A2
b
C
D
E
E1
L
e
e1
α
www.austriamicrosystems.com
Revision 1.00
11 - 14
AS1920/AS1922
Datasheet - 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
Tape and Reel Pin1 Orientation
Figure 19. AS1920 Tape&Reel Pin1 Orientation
User direction of feed
SOT23-5
SOT23-5
SOT23-5
am
lc s
on A
te G
nt
st
il
SOT23-5
lv
al
id
Top, Through View
Figure 20. AS1922 Tape&Reel Pin1 Orientation
Top, Through View
User direction of feed
SOT23-5
SOT23-5
SOT23-5
Te
ch
ni
ca
SOT23-5
www.austriamicrosystems.com
Revision 1.00
12 - 14
AS1920/AS1922
Datasheet - O r d e r i n g I n f o r m a t i o n
11 Ordering Information
The devices are available as the standard products shown in Table 5.
Table 5. Ordering Information
Marking
Description
Reset Type
Delivery Form
Package
AS1920-18-T
ASI1
Triple-Voltage Supervisory Circuit:
3V, 1.8V, and Adjustable.
Push/Pull
Tape and Reel
5-pin SOT23
AS1922-18-T
ASI2
Triple-Voltage Supervisory Circuit:
3V, 1.8V, and Adjustable.
Open-Drain
Tape and Reel
al
id
Model
Te
ch
ni
ca
am
lc s
on A
te G
nt
st
il
lv
5-pin SOT23
www.austriamicrosystems.com
Revision 1.00
13 - 14
AS1920/AS1922
Datasheet
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.
al
id
Disclaimer
am
lc s
on A
te G
nt
st
il
lv
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.
ni
ca
The information furnished here by austriamicrosystems AG is believed to be correct and accurate. However,
austriamicrosystems AG shall not be liable to recipient or any third party for any damages, including but not limited to
personal injury, property damage, loss of profits, loss of use, interruption of business or indirect, special, incidental or
consequential damages, of any kind, in connection with or arising out of the furnishing, performance or use of the technical data herein. No obligation or liability to recipient or any third party shall arise or flow out of
austriamicrosystems AG rendering of technical or other services.
ch
Contact Information
Te
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:
http://www.austriamicrosystems.com/contact
www.austriamicrosystems.com
Revision 1.00
14 - 14
Similar pages