LTC2938/LTC2939
4
293839ff
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
I
WDI
WDI Input Current V
WDI
= GND
V
WDI
= 0.7V
V
WDI
= 1.1V
V
WDI
= 5V
l
l
l
l
–10
10
–30
30
μA
μA
μA
μA
t
WP
WDI Input Pulse Width V
CC
= 3.3V or 5.5V
l
2μs
ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T
A
= 25°C, V
CC
= 5V unless otherwise specifi ed. (Note 3)
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: All currents into pins are positive, all voltages are referenced to
GND unless otherwise noted.
Note 3: The greater of V1, V2 is the internal supply voltage (V
CC
).
Note 4: Under static no-fault conditions, V1 will necessarily supply
quiescent current. If at any time V2 is larger than V1, V2 must be capable
of supplying the quiescent current, programming (transient) current and
reference load current.
Note 5: The outputs RST and WDO have internal pull-ups to V2 of typically
6μA. However, external pull-up resistors may be used when faster rise
times are required or for V
OH
voltages greater than V2. For V2 confi gured
to monitor 1.2V, 1.5V, 1.8V and 2.5V supplies, external pull-up resistors
are required to ensure that the output voltage, high, is above the V
IH
input
threshold of the external circuit.
TYPICAL PERFORMANCE CHARACTERISTICS
Normalized Threshold Voltages
vs Temperature
–ADJ Threshold Voltage
vs Temperature
V
REF
vs Temperature
TEMPERATURE (°C)
–50
NORMALIZED THRESHOLD VOLTAGES (V/V)
1.005
1.010
1.015
25 75
29389 G01
1.000
0.995
–25 0
50 100 125
0.990
0.985
TEMPERATURE (°C)
–50
THRESHOLD VOLTAGE, V
RTAN
(mV)
6
12
18
25 75
29389 G02
0
–6
–25 0
50 100 125
–12
–18
TEMPERATURE (°C)
–50
V
REF
(V)
1.216
1.222
1.228
25 75
29389 G03
1.210
1.204
–25 0
50 100 125
1.198
1.192
