LTC2917 Datasheet, PDF (1/16 Pages) Linear Technology – Low Voltage Supervisorwith 27 Selectable Thresholds and Watchdog Timer

FEATURES
■ _{9 Selectable Supply Voltages}
12V, 5V, 3.3V, 2.5V, 1.8V
1.5V, 1.2V, 1V, +ADJ (0.5V)
■ _{3 Selectable Tolerances}
–5%, –10%, –15% (LTC2917)
■ _{Manual Reset Input (LTC2918)}
■ _{1.5V to 5.5V Supply Operation}
■ _{Adjustable Watchdog Timeout}
■ _{Windowed Watchdog Timeout for Higher Reliability}
Applications (LTC2917-B, LTC2918-B)
■ _{6.2V Shunt Regulator for High Voltage Operation}
■ _{Guaranteed to 125˚C}
■ _{Guaranteed Threshold Accuracy: ±1.5%}
■ _{Low Quiescent Current: 30μA Typical}
■ _{Power Supply Glitch Immunity}
■ _Guaranteed ⎯_R⎯_S⎯_{T for VCC ≥ 0.8V}
■ _{10-Lead MSOP Packages and (3mm × 2mm) DFN}
Packages
APPLICATIONS
■ _{Handheld Devices}
■ _{Cell Phone Base Stations}
■ _{Automotive Control Systems}
■ _{Network Servers}
■ _{Optical Networking Systems}
LTC2917/LTC2918
Low Voltage Supervisor
with 27 Selectable Thresh-
olds and Watchdog Timer
DESCRIPTION
The LTC^®2917-A/LTC2917-B and LTC2918-A/LTC2918-B
are low voltage single-supply monitors with selectable
thresholds and an adjustable watchdog timer. The parts
operate from 1.5V to 5.5V and consume a quiescent cur-
rent of only 30μA.
Two three state inputs select one of nine internally pro-
grammed thresholds without the need for external resistors.
For the LTC2917, an additional three state input determines
the tolerance (–5%, –10%, –15%). The tolerance for the
LTC2918 is fixed at –5%. Threshold accuracy is guaranteed
at ±1.5% over the entire operating temperature range.
Glitch filtering ensures reliable reset operation without
false triggering.
The reset timeout and the watchdog timeout may be set
with no external components, or adjusted using an exter-
nal capacitor. A windowed watchdog feature is available
for high-reliability applications (B1 versions). A separate
manual reset input on the LTC2918-A/LTC2918-B allows
a simple push button interface.
Operation to 125°C makes the LTC2917-A/LTC2917-B
and LTC2918-A/LTC2918-B suitable for automotive ap-
plications.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
1.8V Supply Monitor with Manual
Reset and Internal Timers Selected
1.8V
0.1μF
10k
V_CC
LTC2918-A
VM
RST
RT
WDI
WT
SEL1
MR
SEL2
GND
μP
RST
I/O
29178 TA01
t_WDU = 1.6s
t_RST = 200ms
Monitor Selection Table
NOMINAL VOLTAGE
SEL1
12V
V_CC
5V
V_CC
3.3V
V_CC
2.5V
Open
1.8V
Open
1.5V
Open
1.2V
GND
1V
GND
ADJ (0.5V)
GND
SEL2
V_CC
Open
GND
V_CC
Open
GND
V_CC
Open
GND
29178f
1