3
LTC1727/LTC1728
Note 5: Measured from when input passes through the input threshold
(V
RTX
) until RST or COMPX passes through 1.5V.
Note 6: The output pins RST and COMPX have internal pull-ups to V
CC3
of
typically 6µA. However, external pull-up resistors may be used when faster
rise times are required or for V
OH
voltages greater than V
CC3
.
Note 7: The V
CC5
reset override voltage is valid for an operating range less
than approximately 4.15V. Above this point the override is turned off and
the V
CC5
pin functions normally.
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 LTC1727E/LTC1728E are guaranteed to meet specified
performance from 0°C to 70°C and are designed, characterized and
assured to meet the extended temperature limits of –40°C to 85°C
but are not tested at these temperatures.
Note 4: Both V
CC3
and V
CC5
/V
CC25
/V
CC18
can act as the supply depending
on which pin has the greatest potential.
All except LTC1728-1.8. The ● denotes specifications which apply over the
full operating temperature range, otherwise specifications are at T
A
= 25°C. V
CC3
= 3.3V, V
CC5
= 5V, V
CC25
= 2.5V, V
CCA
= V
CC3
unless
otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
t
UV
V
CC
Undervoltage Detect to RST V
CC5
, V
CC25
, V
CC3
or V
CCA
Less Than Reset 110 µs
or COMPX Threshold V
RT
by More Than 1% (Note 5)
V
OL
Output Voltage Low, RST, COMPX I
SINK
= 2.5mA, V
CC3
= 3V, V
CC5
/V
CC25
= 0V ● 0.15 0.4 V
I
SINK
= 100µA, V
CC3
= 1V, V
CC5
/V
CC25
= 0V ● 0.05 0.3 V
I
SINK
= 100µA, V
CC3
= 0V, V
CC5
/V
CC25
= 1V ● 0.05 0.3 V
I
SINK
= 100µA, V
CC3
= 1V, V
CC5
/V
CC25
= 1V ● 0.05 0.3 V
V
OH
Output Voltage High, RST, COMPX (Note 6) I
SOURCE
= 1µA ● V
CC3
– 1 V
LTC1727-5/LTC1728-5 Only
V
OVR
V
CC5
Reset Override Voltage (Note 7) Override V
CC5
Ability to Assert RST V
CC3
±0.025 V
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
RT3
Reset Threshold V
CC3
V
CC3
Input Threshold ● 2.760 2.805 2.850 V
V
RT18
Reset Threshold V
CC18
V
CC18
Input Threshold ● 1.656 1.683 1.710 V
V
RTA
Reset Threshold V
CCA
V
CCA
Input Threshold ● 0.985 1.000 1.015 V
V
CCOP
V
CC3
, V
CC18
Operating Voltage RST in Correct Logic State ● 17V
I
VCC3
V
CC3
Supply Current V
CC18
> V
CC3
● 12 µA
V
CC18
< V
CC3
, V
CC3
= 3V (Note 4) ● 10 20 µA
I
VCC18
V
CC18
Supply Current V
CC18
< V
CC3
, V
CC18
= 1.8V (Note 4) ● 12 µA
I
VCCA
V
CCA
Input Current V
CCA
= 1V ● –15 0 15 nA
t
RST
Reset Pulse Width RST Low (Note 5) ● 140 200 280 ms
t
UV
V
CC
Undervoltage Detect to RST V
CC18
, V
CC3
or V
CCA
Less Than Reset (Note 5) 110 µs
Threshold V
RT
by More Than 1%
V
OL
Output Voltage Low, RST I
SINK
= 2.5mA, V
CC3
= 3V, V
CC18
= 0V ● 0.15 0.4 V
I
SINK
= 100µA, V
CC3
= 1V, V
CC18
= 0V ● 0.05 0.3 V
I
SINK
= 100µA, V
CC3
= 0V, V
CC18
= 1V ● 0.05 0.3 V
I
SINK
= 100µA, V
CC3
= 1V, V
CC18
= 1V ● 0.05 0.3 V
V
OH
Output Voltage High, RST I
SOURCE
= 1µA (Note 6) ● V
CC3
– 1 V
LTC1728-1.8 The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at
T
A
= 25°C. V
CC3
= 3V, V
CC18
= 1.8V, V
CCA
= V
CC3
unless otherwise noted.
