Diodes APX823/APX824/APX825A User Manual
Processor supervisory circuits, Description, Features
APX823/APX824/APX825A
PROCESSOR SUPERVISORY CIRCUITS
APX823/APX824/APX825A
Document number: DS31323 Rev. 4 - 2
1 of 12
May 2011
© Diodes Incorporated
Description
The APX823/APX824/APX825A family of supervisors
provides circuit initialization and timing supervision, primarily
for DSP and processor-based systems.
During power-on,
RESET
is asserted when supply voltage
V
CC
becomes higher than 1.1V. Thereafter, the supply
voltage supervisor monitors V
CC
and keeps
RESET
active as
long as V
CC
remains below the threshold voltage V
TH-
. An
internal timer delays the return of the output to the inactive
state (high) to ensure proper system reset. The delay time, t
d
starts after V
CC
has risen above the threshold voltage V
TH-
.
When the supply voltage drops below the threshold voltage
V
TH-
, the output becomes active (low) again. No external
components are required. All the devices of this family have a
fixed-sense threshold voltage V
TH-
set by an internal voltage
divider.
The APX823/APX825A devices incorporate a manual reset
input,
MR
. A low level at
MR
causes
RESET
to become
active. The APX824/APX825A devices include a high-level
output RESET. APX823/APX824/APX825A have a watchdog
timer that is periodically triggered by a positive or negative
transition at WDI. When the supervising system fails to
retrigger the watchdog circuit within the time-out interval,
ttout,
RESET
becomes active for the time period td. This
event also reinitializes the watchdog timer. Leaving WDI
unconnected disables the watchdog.
In applications where the input to the WDI pin may be active
(transitioning high and low) when the APX823/APX824/APX8
25A asserting
RESET
the APX823/APX824/APX825A does
not return to a non-reset state when the input voltage is
above Vt. The product spectrum is designed for supply
voltage of 2.5V, 3V, 3.3V and 5V. The circuits are available in
a SOT25 and SOT26 packages. The
APX823/APX824/APX825A devices are characterized for
operation over a temperature range of -40
o
C to 105
o
C.
Features
•
Power-on reset generator with fixed delay time of 200ms
Typ
•
Manual reset input (APX823/APX825A)
•
Reset output available in active-low
(APX823/APX824/APX825A), active-high
(APX824/APX825A)
•
Supply voltage supervision range 2.5V, 3V, 3.3V, 5V
•
Watchdog timer
•
Supply current of 30
μA (Typ.)
•
Temperature range: -40°C to 85°C
•
SOT25 and SOT26: Available in “Green” Molding
Compound (No Br, Sb)
•
Lead Free Finish/RoHS Compliant (Note 1)
Pin Assignments
SOT25
(Top View)
1
2
V
CC
APX823
2
5
3
4
RESET
GND
WDI
MR
(Top View)
1
2
V
CC
APX824
2
5
RESET
GND
SOT25
3
4
RESET
WDI
SOT26
(Top View)
1
2
V
CC
APX825A
2
6
3
4
RESET
RESET
GND
MR
5 WDI
Applications
•
Applications Using DSPs, Microcontrollers, or
Microprocessors
•
Industrial Equipment
•
Programmable Controls
•
Automotive Systems
•
Portable/Battery-Powered Equipment
•
Intelligent Instruments
•
Wireless Communications Systems
•
Notebook/Desktop Computers
Note:
1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied, see EU Directive 2002/95/EC Annex Notes.