ams AS1909C22-T Low-voltage microprocessor reset circuit Datasheet

AS1907, AS1908 , AS1909
L o w - Vo l t a 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 t s
1 General Description
2 Key Features
3 Output Types: Push/Pull
The AS1907/AS1908/AS1909 microprocessor supervisory circuits
are ideal for monitoring the supply voltage of digital systems and
microprocessors.
RESET, Push Pull RESETN, and
Open Drain RESETN
Reset Threshold Range: 1.6 to 2.5V (~100mV increments)
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 preset threshold (see Ordering Information on page 9).
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
Model
Output Type
Reset Type
Supply Current Range: 2.6 to 7.0µA
AS1907
Push/Pull
Active-Low
Power Supply Transient Immunity
AS1908
Push/Pull
Active-High
Requires No External Components
AS1909
Open-Drain
Active-Low
Operating Temperature Range: -40 to +125ºC
3-pin SOT23 Package
The reset thresholds are factory-set between 1.6 and 2.5V in steps
of approximately 100mV (see Table 5 on page 7).
3 Applications
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 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.
The integrated reset comparator was specifically designed to ignore
fast transients on VCC.
The devices are available in a 3-pin SOT23 package.
Figure 1. Application Diagrams
VCC
VCC
VCC 3
VCC 3
VCC
VCC 3
VCC 3
Microprocessor
AS1907
GND 1
RESETN
2
RESET I/O
GND 1
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VCC 3
VCC 3
Microprocessor
AS1908
GND 1
2
RESET
RESET I/O
GND 1
Revision 1.8
Microprocessor
AS1909
GND 1
2
RESETN
RESET I/O
GND 1
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AS1907/AS1908/AS1909
Datasheet - P i n A s s i g n m e n t s
4 Pin Assignments
Figure 2. Pin Assignments (Top View)
GND
1
AS1908/
AS1907/
AS1909
RESET,
RESETN
3
VCC
2
4.1 Pin Descriptions
Table 2. Pin Descriptions
Pin Number
Pin Name
1
GND
Ground
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
VCC
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Positive Supply Voltage. Connect to +0.7 to +3.6V supply.
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AS1907/AS1908/AS1909
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.
Table 3. Absolute Maximum Ratings
Parameter
Min
Max
Units
Comments
Electrical Parameters
VCC to GND
-0.3
+5.0
V
Open-Drain RESETN
-0.3
+6.0
V
Push/Pull RESET, RESETN
-0.3
VCC +
0.3
V
Input Current (VCC)
20
mA
Output Current (RESET, RESETN)
20
mA
Electrostatic Discharge
Electrostatic Discharge HBM
±1
kV
Norm: MIL 883 E Method 3015
320
mW
3-pin SOT23 derate 4mW/ºC above +70ºC
+150
ºC
+150
ºC
Continuous Power Dissipation
Continuous Power Dissipation
(TAMB = +70ºC)
Temperature Ranges and Storage Conditions
Junction Temperature
Storage Temperature Range
-55
Package Body Temperature
Humidity non-condensing
Moisture Sensitive Level
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8
+260
ºC
85
%
1
The reflow peak soldering temperature (body temperature)
specified is in accordance with IPC/JEDEC J-STD-020
“Moisture/Reflow Sensitivity Classification for NonHermetic Solid State Surface Mount Devices”.
The lead finish for Pb-free leaded packages is matte tin
(100% Sn).
Represents a maximum floor life time of unlimited
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AS1907/AS1908/AS1909
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
VCC = Full Range, TAMB = -40 to +125ºC (unless otherwise specified). Typ values are at VCC = +3.0V, TAMB = +25ºC. All limits are guaranteed.
The parameters with min and max values are guaranteed with production tests or SQC (Statistical Quality Control) methods.
Table 4. Electrical Characteristics
Symbol
Parameter
Conditions
TAMB = 0 to +85ºC
VCC
Supply Voltage Range
TAMB = -40 to +85ºC
Min
VTH
tRD
tTP
Supply Current
1
RESET Threshold Voltage
VCC Falling Reset Delay
RESET Active
Time-Out Period
VOL
RESETN Output Low Voltage; RESET
asserted
(AS1907/AS1909)
VOH
RESETN Output High Voltage; RESET
Not Asserted (AS1907)
VOH
RESET Output Voltage; RESET
Asserted (AS1908)
VOL
RESET Output Voltage; RESET Not
Asserted (AS1908)
ILEAK
RESETN Output Leakage Current;
RESETN
Deasserted (AS1909)
Max
AS1907, AS1908
0.7
3.6
AS1909
1.0
3.6
AS1907, AS1908
0.78
3.6
AS1909
1.2
3.6
TAMB = -40 to +125ºC
ICC
Typ
1.2
Unit
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 = 0ºC to +50°C;
AS1909C17, AS1909C168, AS1909C188 only
VTH 1.2%
VTH
VTH +
1.2%
V
TAMB = -40 to +125ºC
VTH 3%
VTH
VTH +
3%
V
1
1.5
VCC falling at 10V/ms
AS190x-Azz-T
33
µs
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
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 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
3
2
1
2.2
2
-50
4
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 = 2.3VReset Asserted
Figure 6. Output Voltage Low vs. Temperature
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
125
65
55
45
VCC = 2.2V
ISINK = 500µA
35
25
15
5
-50
Temperature (°C)
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VCC = 1.8V
ISINK = 500µA
VCC = 0.7V
ISINK = 50µA
VCC = 1.0V
ISINK = 50µA
-25
0
25
50
75
100
125
Temperature (°C)
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AS1907/AS1908/AS1909
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
Figure 7. Max. Transient Duration vs.
Reset Comparator OverdriveTemperature
Figure 8. VCC falling Propagation Delay vs.
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
80
60
40
VCC falling at 10V/ms
20
0
-50
1000
VCC falling at 1V/ms
100
-25
Reset Comparator Overdrive (mV)
80
.
Output Voltage Low (mV)
.
Output Voltage Low (mV)
50
75
100 125
Figure 10. Output Voltage Low vs. VCC, ISINK = 100µA
Temp = -40°C
Temp = +25°C
Temp = +85°C
Temp = +125°C
50
25
Temperature (°C)
Figure 9. Output Voltage Low vs. VCC, ISINK = 50µA
60
0
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
Datasheet - 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
8.1 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.
8.2 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
8.3 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).
8.4 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
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
9 Package Drawings and Markings
Figure 12. 3-pin SOT23 Package
Top Marking
Bottom Marking
xxxx- encoded Datacode
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AS1907/AS1908/AS1909
Datasheet - 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 standard products shown in Table 6.
Table 6. Ordering Information
Ordering Code
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
AS1909C168-T
ASSB
Open Drain
1.68V
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
AS1909C188-T
ASTE
Open Drain
1.88V
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 ams 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*
A
tTP in Milliseconds
Min
Typ
Max
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.
Note: All products are RoHS compliant and ams green.
Buy our products or get free samples online at www.ams.com/ICdirect
Technical Support is available at www.ams.com/Technical-Support
For further information and requests, email us at [email protected]
(or) find your local distributor at www.ams.com/distributor
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AS1907/AS1908/AS1909
Datasheet
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warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the described
devices from patent infringement. ams 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 ams 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 life-sustaining equipment are specifically not recommended without additional processing
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production flow, such as test flow or test location.
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