AS1907_01 Datasheet, PDF (1/10 Pages) ams AG – Low-Voltage Microprocessor Reset Circuits

AS1907, AS1908, AS1909
Low-Voltage Microprocessor Reset Circuits
Data Sheet
1 General Description
The AS1907/AS1908/AS1909 microprocessor supervi-
sory 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 com-
ponents. 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 incre-
ments)
! 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
VCC
VCC 3
VCC 3
AS1907
RESETN
2
Micro-
processor
RESET I/O
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
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