AS1907_04 Datasheet, PDF (1/10 Pages) ams AG – Low-Voltage Microprocessor Reset Circuits

AS1907, AS1908 , AS1909
Low-Voltage Microprocessor Reset Circuits
1 General Description
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).
The devices are available as the standard products listed in Table 1.
Table 1. Standard Products
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.
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)
Reset Pulse Widths: 1, 20, and 100ms
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
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 3
VCC 3
AS1907
RESETN
2
Micro-
processor
RESET I/O
VCC
VCC 3
VCC 3
AS1908
2
RESET
Micro-
processor
RESET I/O
VCC
VCC 3
VCC 3
AS1909
2
RESETN
Micro-
processor
RESET I/O
GND 1
GND 1
GND 1
GND 1
GND 1
GND 1
www.ams.com/Supervisors/AS1907-09
Revision 1.8
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