sp706rcu-tr Exar Corporation, sp706rcu-tr Datasheet - Page 13

• Manufacturer Part Number: sp706rcu-tr
• Description: Sp706r -low Power Microprocessor Supervisory Circuits
• Manufacturer: Exar Corporation

Figure 18. Monitoring a Negative Voltage Supply
output is driven HIGH and the µP wants to pull
it LOW, indeterminate logic levels may result.
To correct this, connect a 4.7kΩ resistor
between the RESET output and the µP reset
I/O, as shown if Figure 19.
RESET output to other system components.
Negative-Going V
While issuing resets to the µP during power-up,
power-down, and brownout conditions, these
supervisors are relatively immune to short-
duration negative-going V
It is usually undesirable to reset the µP when V
experiences only small glitches.
Figure 20 shows maximum transient dura-
tion vs. reset-comparator overdrive, for which
reset pulses are not generated. The data was gen-
erated using negative-going V
at 3.3V and ending below the reset threshold by
Date: 6-28-04
PFO
MR
100kΩ
2N3904
+3.3V
+3.3V
to µP
0V
0V
R
R
1
2
100kΩ
=
RESET
1.25 - V
V
CC
PFO
MR
CC
- 1.25
V
+3.3V/+3.0V
TRIP
TRIP
Transients
CC
, V
V
GND
transients (glitches).
CC
TRIP
0V
CC
< 0
PFI
pulses, starting
SP706 +3.0/ +3.3 Low Power Microprocessor Circuits
V-
Buffer the
R
R
V-
V-
2
1
CC
13
the magnitude indicated (reset comparator over-
drive). The graph shows the maximum pulse
width a negative-going V
typically have without causing a reset pulse to
be issued. As the amplitude of the transient
increases (i.e. goes farther below the reset
threshold), the maximum allowable pulse width
decreases. Typically, a V
100mV below the reset threshold and lasts for
40µs or less will not cause a reset pulse to be
issued. A 100nF bypass capacitor mounted close
to the V
immunity.
Applications
The SP706P/R/S/T-SP708R/S/T series offers
unmatched performance and the lowest power
consumption for these industry standard de-
vices. Refer to Figures 21 and 22 for supply
current performance characteristics rated against
temperature and supply voltages.
Figure 19. Interfacing to Microprocessors with
Bidirectional RESET I/O for the SP706
+3.3V/+3.0V
Buffered RESET connects to System Components
GND
V
CC
CC
RESET
pin provides additional transient
4.7KΩ
© Copyright 2004 Sipex Corporation
CC
RESET
transient that goes
CC
transient may
+3.3V/+3.0V
µP
GND
V
CC