APX823 Datasheet, PDF (1/12 Pages) Diodes Incorporated – PROCESSOR SUPERVISORY CIRCUITS

APX823/APX824/APX825A
PROCESSOR SUPERVISORY CIRCUITS
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 30μA (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)
General 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 VCC becomes higher than 1.1V. Thereafter, the supply voltage supervisor
monitors VCC and keeps RESET active as long as VCC remains below the threshold voltage VTH-. An internal timer delays the return of
the output to the inactive state (high) to ensure proper system reset. The delay time ,td, starts after VCC has risen above the threshold
voltage VTH-. When the supply voltage drops below the threshold voltage VTH-, the output becomes active (low) again. No external
components are required. All the devices of this family have a fixed-sense threshold voltage VTH- 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/APX825A 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^oC to 105^oC.
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
APX823/APX824/APX825A Rev. 3
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FEBRUARY 2009
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