LTC2935 Datasheet, PDF (1/12 Pages) Linear Technology – Ultra-Low Power Supervisor with Power-Fail Output, Selectable Thresholds

LTC2935
Ultra-Low Power Supervisor
with Power-Fail Output,
Selectable Thresholds
FEATURES
DESCRIPTION
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}
, LT, LTC, LTM 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.
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, available from 3.3V to 2.25V
in 150mV increments. Early warning of an impending
low voltage condition is provided at the power-fail output
(PFO), whose threshold is 150mV 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 exceed-
ing the reset threshold by 5%. A 200ms reset timeout
delays the return of the RST output to a high state. A
pushbutton 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) or active pull-up
(LTC2935-2) circuits. Operating temperature range is from
–40ºC to 85ºC.
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
RESET POWER-FAIL
THRESHOLD THRESHOLD
(V)
(V)
S2
S1
3.30
3.45
Low
Low
3.15
3.30
Low
Low
3.00
3.15
Low
High
2.85
3.00
Low
High
2.70
2.85
High
High
2.55
2.70
High
Low
2.40
2.55
High
Low
2.25
2.40
High
High
S0
Low
High
High
Low
Low
Low
High
High
2935f
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