4

LTC1235

PARAMETER

CONDITONS

MIN

TYP

MAX

UNITS

RESET and WDO Output Voltage

0.4

V

(Note 6)

3.5

RESET, RESET, WDO, LOW LINE

Output Source Current

1

3

25

µA

Output Short Circuit Current (Note 6)

Output Sink Current

25

mA

WDI Input Threshold

Logic Low

0.8

V

Logic High

2.0

WDI Input Current

q

450

µA

WDI = 0V

q

–50

–8

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 6)

0.4

V

3.5

PFO Short Circuit Source Current

PFI = HIGH, PFO = 0V

1

3

25

µA

(Note 6)

30

mA

PFI Comparator Response Time (falling)

2

µs

PFI Comparator Response Time (rising)

40

µs

(Note 6)

with 10k

Ω Pullup

8

Chip Enable Gating

CE IN Threshold

0.8

V

2.0

CE IN Pullup Current (Note 4)

3

µA

CE OUT Output Voltage

0.4

V

CE Propagation Delay

20

35

ns

q

20

45

CE OUT Output Short Circuit Current

Output Source Current

30

mA

Output Sink Current

35

ELECTRICAL C

C

HARA TERISTICS

range.

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, consult the factory.

Note 4: The input pins of PB RST, BACKUP and CE IN, have weak internal

pullups which pull to the supply when the input pins are floating.

Note 5: The LTC1235 can be programmed either to provide or not to

Note 6: The output pins of BATT ON, LOW LINE, PFO, WDO, RESET and

RESET have weak internal pullups of typically 3

µA. However, external

pullup resistors may be used when higher speed is required.

Note 7: The push-button reset input requires an active low signal.

Internally, this input signal is debounced and timed for a minimum of

40ms. When this condition is satisfied, the reset outputs go to the active

states. The reset outputs will remain in active states for a minimum of

140ms from the moment the push-button reset input is released from

logic low level.