LTC2939_15 Datasheet, PDF (1/20 Pages) Linear Technology – Confi gurable 4- and 6-Supply Monitors with Watchdog Timer

LTC2938/LTC2939
Configurable 4- and 6-Supply
Monitors with Watchdog Timer
FEATURES
n _{Simultaneously Monitors Four (LTC2938) or Six}
Supplies (LTC2939)
n _{Sixteen User-Selectable Combinations of 5V, 3.3V,}
2.5V, 1.8V, 1.5V, 1.2V and/or ± Adjustable Voltage
Thresholds
n _{Guaranteed Threshold Accuracy: ±1.5%}
n _{Adjustable Reset and Watchdog Timeout}
n _{Low Supply Current: 80μA Typical}
n _{Power Supply Glitch Immunity}
n _{Guaranteed RST for VCC > 1V}
n _{High Temperature Operation to 125°C}
n _{12-Pin 4mm × 3mm DFN or 12-Lead MSOP}
(LTC2938) and 16-Lead MSOP Package (LTC2939)
APPLICATIONS
n _{Desktop and Notebook Computers}
n _{Multivoltage Systems}
n _{Telecom Equipment}
n _{Network Servers}
n _{Automotive Control Systems}
DESCRIPTION
The LTC^®2938/LTC2939 are configurable supply monitors
for systems with up to four or six supply voltages that need
watchdog supervision. One of sixteen preset or adjustable
voltage monitor combinations can be selected using an
external resistive divider connected to the program input.
The preset voltage thresholds are accurate to ±1.5% over
temperature. The LTC2938 and LTC2939 also feature ad-
justable inputs with a 0.5V nominal threshold.
The reset and watchdog timeout periods are adjustable
using external capacitors. Tight voltage threshold accuracy
and glitch immunity ensure reliable reset operation without
false triggering. The RST output is guaranteed to be in the
correct state for V_CC down to 1V. Each status output has
a weak internal pull-up and may be externally pulled up
to a user-defined voltage.
The 80μA supply current makes the LTC2938 and LTC2939
ideal for power conscious systems. The LTC2939 moni-
tors up to six supplies and the LTC2938 monitors up to
four supplies.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Protected by U.S. Patents, including 6967591, 7239251, 7119714.
TYPICAL APPLICATION
6-Supply Monitor 12V (ADJ), 5V, 3.3V, 2.5V, 1.8V, 1.2V (ADJ)
12V
5V
3.3V
SYSTEM
2.5V
LOGIC
1.8V
1.2V
0.1μF
0.1μF
2150k 124k
1% 1%
100k 100k
1% 1%
V1
V2
V3
V4
V5
V6
V_REF
R1
59k
1%
V_PG
GND
R2
40.2k
1%
LTC2939
WDI
WDO
RST
CWT
C_WT
47nF
t_RST = 94ms
CRT t_WD = 940ms
C_RT
47nF
293839 TA01
Voltage Configuration Table
V1 (V)
5
5
5
5
5
3.3
3.3
3.3
3.3
3.3
3.3
3.3
3.3
3.3
3.3
3.3
V2 (V)
3.3
3.3
3.3
3.3
3.3
2.5
2.5
1.8
1.8
1.8
2.5
2.5
1.8
1.8
1.5
1.2
V3 (V)
2.5
2.5
1.8
ADJ
ADJ
1.8
1.8
1.5
1.5
1.2
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
V4 (V)
1.8
ADJ
ADJ
ADJ
–ADJ
1.5
ADJ
1.2
ADJ
ADJ
ADJ
–ADJ
ADJ
–ADJ
ADJ
ADJ
V5 (V)
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
V6 (V)
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
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