LTC1726
ELECTRICAL CHARACTERISTICS The q denotes specifications which apply over the full operating
temperature range, otherwise specificaitons are at TA = 25°C. VCC3 = 3.3V, VCC5 = 5V, VCC25 = 2.5V, VCCA = VCC3 unless
otherwise noted.
SYMBOL
tRT
tUV
PARAMETER
Reset Time-Out Period
VCC Undervoltage Detect to RST
VOH
RST Output Voltage High (Note 5)
VOL
RST Output Voltage Low
VIH
WDI Input Threshold High
VIL
WDI Input Threshold Low
tWP
WDI Pulse Width
tWT
Watchdog Time-Out Period
WDI Leakage Current
LTC1726-5 Only
VOVR
VCC5 Reset Override Voltage (Note 6)
CONDITIONS
CRT = 1500pF
VCC25/VCC5, VCC3 or VCCA Less Than Reset
Threshold VRT by More Than 1%
ISOURCE = 1µA
ISINK = 2.5mA, VCC5/VCC25 = 0V
ISINK = 100µA, VCC3 = 1V, VCC5/VCC25 = 0V
ISINK = 100µA, VCC3 = 0V, VCC5/VCC25 = 1V
ISINK = 100µA, VCC3 = 1V, VCC5/VCC25 = 1V
CWT = 1500pF
MIN TYP MAX UNITS
q 3.5
5
6.5
ms
130
µs
q VCC3 – 1
V
q
0.15
0.4
V
q
0.05
0.3
V
q
0.05
0.3
V
q
0.05
0.3
V
q
q 0.3 • VCC3
q
40
0.7 • VCC3
V
V
ns
q
23
33
43
ms
q
±1
µA
Override VCC5 Ability to Assert RST
VCC3 ±0.025
V
Note 1: Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.
Note 2: All voltage values are with respect to GND.
Note 3: The LTC1726E is guaranteed to meet performance specifications
from 0°C to 70°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
Note 4: Both VCC3 and VCC25/VCC5 can act as the supply depending on
which pin has the greatest potential.
Note 5: The output pin RST has weak internal pull-ups to VCC3 of typically
6µA. However, external pull-up resistors may be used when faster rise
times are required or for VOH voltages greater than VCC3.
Note 6: The VCC5 reset override voltage is valid for an operating range less
than approximately 4.15V. Above this point the override is turned off and
the VCC5 pin functions normally.
TYPICAL PERFOR A CE CHARACTERISTICS
VCC5 Threshold Voltage
vs Temperature
4.750
4.725
4.700
4.675
4.650
4.625
4.600
–60 –40 –20 0 20 40 60
TEMPERATURE (°C)
80 100
1726 G01
VCC3 Threshold Voltage
vs Temperature
3.135
3.125
3.115
3.105
3.095
3.085
3.075
3.065
3.055
3.045
3.035
– 60 –40 – 20 0 20 40 60 80 100
TEMPERATURE (°C)
1726 G02
VCCA Threshold Voltage
vs Temperature
1.015
1.010
1.005
1.000
0.995
0.990
0.985
–60 –40 –20 0 20 40 60
TEMPERATURE (°C)
80 100
1726 G03
3