LTC2935_15 Datasheet, PDF (1/12 Pages) Linear Technology – Ultra-Low Power Supervisor with Power-Fail Output, Selectable Thresholds

FEATURES
n _{500nA Quiescent Current}
n _{±1.5% (Max) Accuracy over Temperature}
n _{Integrated Precision Attenuators}
n _{Eight Pin-Selectable Reset Thresholds}
n _{Eight Pin-Selectable Power-Fail Thresholds}
n _{Early Warning Power-Fail Output}
n _{200ms Reset Timeout}
n _{Manual Reset Input}
n _{Compact 8-Lead, 2mm × 2mm DFN and}
TSOT-23 (ThinSOT™) Packages
APPLICATIONS
n _{Portable Equipment}
n _{Battery-Powered Equipment}
n _{Security Systems}
n _{Point-of-Sale Devices}
n _{Wireless Systems}
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
LTC2935
Ultra-Low Power Supervisor
with Power-Fail Output,
Selectable Thresholds
DESCRIPTION
The LTC^®2935 ultra-low power voltage monitor provides
system initialization, power-fail warning and reset gen-
eration functions. Low quiescent current (500nA typical)
makes the LTC2935 an ideal choice for battery-operated
applications.
Three binary threshold-select inputs configure one of
eight integrated reset thresholds, ranging from 1.6V to
3.45V in pre-determined increments. Early warning of an
impending low voltage condition is provided at the power-
fail output (PFO), whose threshold is above the configured
reset threshold. Supervisory circuits monitor V_CC and
pull RST low when V_CC drops below the configured reset
threshold. When V_CC is rising from an under-threshold
condition, an internal reset timer is started after exceeding
the reset threshold by 5%. A 200ms reset timeout delays
the return of the RST output to a high state. A pushbut-
ton switch connected to the MR input is typically used to
force a manual reset. Outputs RST and PFO are available
with open-drain (LTC2935-1/LTC2935-3) or active pull-up
(LTC2935-2/LTC2935-4) circuits. Operating temperature
range is from –40°C to 85°C.
TYPICAL APPLICATION
Configurable Low Power Voltage Monitor
V_IN
0.1μF
V_CC
S2
PFO
S1
LTC2935-2
S0
MR
RST
GND
BATTERY
POWERED
SYSTEM
LOGIC
2935 TA01a
Falling Threshold Selection Table
LTC2935-1/LTC2935-2
LTC2935-3/LTC2935-4
RESET POWER-FAIL RESET POWER-FAIL
THRESHOLD THRESHOLD THRESHOLD THRESHOLD
(V)
(V)
(V)
(V)
S2 S1 S0
3.30
3.45
2.44
2.56
Low Low Low
3.15
3.30
2.32
2.44
Low Low High
3.00
3.15
2.20
2.32
Low High High
2.85
3.00
2.08
2.20
Low High Low
2.70
2.85
1.96
2.08 High High Low
2.55
2.70
1.84
1.96 High Low Low
2.40
2.55
1.72
1.84 High Low High
2.25
2.40
1.60
1.72 High High High
2935fa
1