4

LTC692/LTC693

temperature range.

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: For military temperature range, 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

µA. However, external

pull-up resistors may be used when higher speed is required.

ELECTRICAL C

C

HARA TERISTICS

Note 5: The LTC692/LTC693 have minimum reset active times of 140ms

(200ms typically). The reset active time of the LTC693 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

pull-ups which pull to the supply when the input pins are floating.

PARAMETER

CONDITONS

MIN

TYP

MAX

UNITS

RESET, RESET, WDO, LOW LINE

Output Source Current

1

3

25

µA

Output Short-Circuit Current (Note 4)

Output Sink Current

25

mA

WDI Input Threshold

Logic Low

0.8

V

Logic High

3.5

V

WDI Input Current

q

450

µA

WDI = 0V

q

–50

– 8

µA

Power Fail Detector

PFI Input Threshold

q

1.25

1.3

1.35

V

PFI Input Threshold PSRR

0.3

mV/V

PFI Input Current

±0.01

±25

nA

PFO Output Voltage (Note 4)

0.4

V

3.5

V

PFO Short Circuit Source Current

PFI = HIGH, PFO = 0V

1

3

25

µA

(Note 4)

25

mA

PFI Comparator Response Time (falling)

2

µs

PFI Comparator Response Time (rising)

40

µs

(Note 4)

with 10k

Ω Pull-Up

8

µs

Chip Enable Gating

CE IN Threshold

0.8

V

2.0

V

CE IN Pullup Current (Note 7)

3

µA

CE OUT Output Voltage

0.4

V

V

V

CE Propagation Delay

20

35

ns

q

20

45

ns

CE OUT Output Short Circuit Current

Output Source Current

30

mA

Output Sink Current

35

mA

Oscillator

OSC IN Input Current (Note 7)

±2

µA

OSC SEL Input Pull-Up Current (Note 7)

5

µA

OSC IN Frequency Range

OSC SEL = 0V

q

0

250

kHz

OSC IN Frequency with External Capacitor

4

kHz