1 Features
• Window-watchdog with programmable delay and
window ratio
• 6-Pin SOT-23 package
• Supply current of 9μA (typical)
• Power-on reset generator with a fixed delay time of
25ms
• Precision supply voltage monitor (VIT):
2.5V, 3V, 3.3V, and 5V
• Open-drain reset output
• Temperature range: –40°C to 85°C

2 Applications
• Active Antenna System mMIMO (AAS)
• Storage area network
• Electricity meters
• Safety critical systems
• Infustion pump
• HVAC controller

3 Description
The TPS3813xxx family of supervisory circuits provide
circuit initialization and timing supervision, primarily
for DSPs and processor-based systems.
During power on, RESET is asserted when supply
voltage (VDD) becomes higher than 1.1V. Thereafter,
the supervisory circuit monitors VDD and keeps
RESET active as long as VDD remains below the
threshold voltage (VIT). An internal timer delays the
return of the output to the inactive state (high) to
ensure proper system reset. The delay time,
td = 25ms typical, starts after VDD has risen above
the threshold voltage (VIT). When the supply voltage
drops below the threshold voltage (VIT), the output
becomes active (low) again. No external components
are required. All the devices of this family have a
fixed-sense threshold voltage (VIT) set by an internal
voltage divider.
For safety critical applications the TPS3813xxx
family incorporates a so-called window-watchdog
with programmable delay and window ratio. The
upper limit of the watchdog time-out can be set
by either connecting WDT to GND, VDD, or using
an external capacitor. The lower limit and thus the
window ratio is set by connecting WDR to GND or
VDD. The supervised processor now needs to trigger
the TPS3813xxx within this window not to assert a
RESET.
The product spectrum is designed for supply voltages
of 2.5V, 3V, 3.3V, and 5V. The circuits are available in
a 6-pin SOT-23 package.
The TPS3813xxx devices are characterized for
operation over a temperature range of –40°C to 85°C.