APX823/APX824/APX825A
PROCESSOR SUPERVISORY CIRCUITS
Description Pin Assignments
(Top View)
The APX823/APX824/APX825A family of supervisors
provides circuit initialization and timing supervision, primarily
for DSP and processor-based systems. 5
1 V
CC
RESET
During power-on, is asserted when supply voltage
RESET
22 APX823
V becomes higher than 1.1V. Thereafter, the supply GND
CC
voltage supervisor monitors V and keeps active as
RESET
CC
3 4
WDI
MR
long as V remains below the threshold voltage V . An
CC TH-
internal timer delays the return of the output to the inactive
SOT25
state (high) to ensure proper system reset. The delay time, t
d
starts after V has risen above the threshold voltage V .
CC TH-
(Top View)
When the supply voltage drops below the threshold voltage
V , the output becomes active (low) again. No external
TH-
1 5 V
RESET CC
components are required. All the devices of this family have a
fixed-sense threshold voltage V set by an internal voltage
TH-
22
GND APX824
divider.
The APX823/APX825A devices incorporate a manual reset
3 4
WDI
RESET
input, MR . A low level at MR causes to become
RESET
active. The APX824/APX825A devices include a high-level
SOT25
output RESET. APX823/APX824/APX825A have a watchdog
timer that is periodically triggered by a positive or negative
(Top View)
transition at WDI. When the supervising system fails to
retrigger the watchdog circuit within the time-out interval,
6
1 V
ttout, becomes active for the time period td. This RESET CC
RESET
event also reinitializes the watchdog timer. Leaving WDI
22 APX825A 5
GND WDI
unconnected disables the watchdog.
In applications where the input to the WDI pin may be active
3 4
RESET MR
(transitioning high and low) when the APX823/APX824/APX8
25A asserting the APX823/APX824/APX825A does
RESET
SOT26
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
o o
operation over a temperature range of -40 C to 105 C.
Applications
Features
Applications Using DSPs, Microcontrollers, or
Power-on reset generator with fixed delay time of 200ms
Microprocessors
Typ
Industrial Equipment
Manual reset input (APX823/APX825A)
Programmable Controls
Reset output available in active-low
Automotive Systems
(APX823/APX824/APX825A), active-high
Portable/Battery-Powered Equipment
(APX824/APX825A)
Intelligent Instruments
Supply voltage supervision range 2.5V, 3V, 3.3V, 5V
Wireless Communications Systems
Watchdog timer
Notebook/Desktop Computers
Supply current of 30A (Typ.)
Temperature range: -40C to 85C
SOT25 and SOT26: Available in Green Molding
Compound (No Br, Sb)
Lead Free Finish/RoHS Compliant (Note 1)
Note: 1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied, see EU Directive 2002/95/EC Annex Notes.
1 of 12 May 2011
APX823/APX824/APX825A
Diodes Incorporated
www.diodes.com
Document number: DS31323 Rev. 4 - 2
APX823/APX824/APX825A
PROCESSOR SUPERVISORY CIRCUITS
Typical Application Circuit
V
CC
C
IN
100nF
V V
CC CC
RESET RESET
APX8XX Microprocessor
MR WDI I/O
GND GND
Pin Descriptions
Pin Name Description
GND Ground
RESET
Reset output pin
(RESET)
V Operating voltage input
CC
WDI Watchdog input
Manual reset
MR
Functional Block Diagram
2 of 12 May 2011
APX823/APX824/APX825A
Diodes Incorporated
www.diodes.com
Document number: DS31323 Rev. 4 - 2