4
LTC 690/LTC 691
LTC 694/LTC 695
ELECTRICAL C
range, otherwise specifications are at T
A
= 25
°
C. V
CC
= full operating range, V
BATT
= 2.8V, unless otherwise noted.
HARC
The
G
denotes specifications which apply over the operating temperature
PARAMETER
RESET, RESET, WDO, LOW LINE
Output Short-Circuit Current (Note 4)
CONDITONS
Output Source Current
Output Sink Current
Logic Low
Logic High
WDI = V
OUT
WDI = 0V
MIN
1
TYP
3
25
MAX
25
UNITS
μ
A
mA
WDI Input Threshold
0.8
V
3.5
WDI Input Current
G
G
4
50
μ
A
–50
–8
Power-Fail Detector
PFI Input Threshold
PFI Input Threshold PSRR
PFI Input Current
PFO Output Voltage (Note 4)
V
CC
= 5V
G
1.25
1.3
0.3
±
0.01
1.35
V
mV/V
±
25
0.4
nA
V
I
SINK
= 3.2mA
I
SOURCE
= 1
μ
A
PFI = HIGH, PFO = 0V
PFI = LOW, PFO = V
OUT
V
IN
= –20mV, V
OD
= 15mV
V
IN
= 20mV, V
OD
= 15mV
with 10k
Pull-Up
3.5
1
PFO Short-Circuit Source Current (Note 4)
3
25
2
40
8
25
μ
A
mA
μ
s
μ
s
PFI Comparator Response Time (Falling)
PFI Comparator Response Time (Rising) (Note 4)
Chip Enable Gating
CE IN Threshold
V
IL
V
IH
0.8
V
2.0
CE IN Pull-Up Current (Note 7)
CE OUT Output Voltage
3
μ
A
V
I
SINK
= 3.2mA
I
SOURCE
= 3.0mA
I
SOURCE
= 1
μ
A, V
CC
= 0V
V
CC
= 5V, C
L
= 20pF
0.4
V
OUT
– 1.50
V
OUT
– 0.05
CE Propagation Delay
20
20
30
35
35
45
ns
G
CE OUT Output Short-Circuit Current
Output Source Current
Output Sink Current
mA
Oscillator
OSC IN Input Current (Note 7)
OSC SEL Input Pull-Up Current (Note 7)
OSC IN Frequency Range
OSC IN Frequency with External Capacitor
±
2
5
μ
A
μ
A
kHz
kHz
OSC SEL = 0V
OSC SEL = 0V, C
OSC
= 47pF
G
0
250
4
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of device may be impaired.
Note 2:
All voltage values are with respect to GND.
Note 3:
For military temperature range parts or for the LTC692 and
LTC693, consult the factory.
Note 4:
The output pins of BATT ON, LOW LINE, PFO, WDO, RESET and
RESET have weak internal pull-ups of typically 3
μ
A. However, external
pull-up resistors may be used when higher speed is required.
Note 5:
The LTC690 and LTC691 have minimum reset active time of 35ms
(50ms typically) while the LTC694 and LTC695 have longer minimum
reset active time of 140ms (200ms typically). The reset active time of the
LTC691 and LTC695 can be adjusted (see Table 2 in Applications
Information section).
Note 6:
The external clock feeding into the circuit passes through the
oscillator before clocking the watchdog timer (See Block Diagram).
Variation in the time-out period is caused by phase errors which occur
when the oscillator divides the external clock by 64. The resulting variation
in the time-out period is 64 clocks plus one clock of jitter.
Note 7:
The input pins of CE IN, OSC IN and OSC SEL have weak internal
pullups which pull to the supply when the input pins are floating.