ltc1726-5 Linear Technology Corporation, ltc1726-5 Datasheet

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ltc1726-5

Manufacturer Part Number
ltc1726-5
Description
Triple Supply Monitor And ?p Supervisor With Adjustable Reset And Watchdog Timer
Manufacturer
Linear Technology Corporation
Datasheet
FEATURES
APPLICATIO S
TYPICAL APPLICATIONS
3.3V
Monitors Three Inputs Simultaneously
±1.5% Threshold Accuracy Over Temperature
Low Supply Current: 16µA Typ
Adjustable Reset Timeout
Adjustable Watchdog Timeout
Active Low Open-Drain Reset Output
Power Supply Glitch Immunity
Guaranteed RESET for V
MS8 and SO-8 Packages
Desktop Computers
Notebook Computers
Intelligent Instruments
Portable Battery-Powered Equipment
Network Servers
5V
LTC1726-5: 5V, 3.3V and ADJ
LTC1726-2.5: 2.5V, 3.3V and ADJ
0.1µF
0.1µF
47nF
t
t
C
RT
WT
WT
A 3.3V, 5V and 1.8V Monitor
= 155ms
= 1s
47nF
C
RT
U
8
7
V
RT
WT
CC5
2
LTC1726-5
V
GND
CC3
CC3
1
4
V
≥ 1V or V
WDI
RST
CCA
3
U
(V
TRIP
6
5
1.8V
= 1.665V)
R1
66.5k
1%
R2
100k
1%
CC25
/V
RESET
I/O
CC5
µP
1726 TA01
≥ 1V
µP Supervisor with Adjustable
Reset and Watchdog Timer
DESCRIPTIO
The LTC
sor supervisory circuit with adjustable reset and watchdog
functions intended for systems with multiple supply volt-
ages. The part has a common open-drain reset output with
an adjustable delay. The reset and watchdog time-out
periods are both adjustable using external capacitors.
Tight 1.5% accuracy specifications and glitch immunity
ensure reliable reset operation without false triggering.
The RST output is guaranteed to be in the correct state for
V
configured to monitor any one or two V
of three, depending on system requirements.
The low (16µA typical) supply current makes the LTC1726
ideal for power-conscious systems.
All other trademarks are the property of their respective owners.
CC5
3.3V
2.5V
Triple Supply Monitor and
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
/V
0.1µF
0.1µF
CC25
®
1726 is a triple supply monitor and microproces-
or V
47nF
t
t
C
RT
WT
WT
A 3.3V, 2.5V and 1.8V Monitor
CC3
= 155ms
= 1s
47nF
C
RT
down to 1V. The LTC1726 may also be
U
8
7
V
RT
WT
CC25
LTC1726-2.5
2
V
GND
CC3
1
4
V
WDI
RST
CCA
3
(V
TRIP
6
5
1.8V
= 1.665V)
CC
R1
66.5k
1%
R2
100k
1%
LTC1726
inputs instead
RESET
I/O
µP
1726 TA02
1726fb
1

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ltc1726-5 Summary of contents

Page 1

... FEATURES Monitors Three Inputs Simultaneously ■ LTC1726-5: 5V, 3.3V and ADJ LTC1726-2.5: 2.5V, 3.3V and ADJ ±1.5% Threshold Accuracy Over Temperature ■ ■ Low Supply Current: 16µA Typ ■ Adjustable Reset Timeout ■ Adjustable Watchdog Timeout ■ Active Low Open-Drain Reset Output ■ Power Supply Glitch Immunity ≥ ...

Page 2

... Less Than Reset CC25 CC5 CC3 CCA Threshold V by More Than 1% RT ORDER PART NUMBER LTC1726ES8-2.5 TOP VIEW LTC1726ES8 LTC1726IS8-2 LTC1726IS8-5 RST PART MARKING 4 5 WDI 172625 S8 PACKAGE 8-LEAD PLASTIC SO 17265 = 125°C, θ = 150°C/W ...

Page 3

... Specifications over the –40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls TYPICAL PERFOR A CE CHARACTERISTICS V Threshold Voltage CC5 vs Temperature (LTC1726-5) 4.750 4.725 4.700 4.675 4.650 4.625 4.600 –60 – ...

Page 4

... TEMPERATURE (°C) Watchdog Time-Out Period vs Temperature 1500pF WT (SILVER MICA –60 –40 – TEMPERATURE (° Temperature (LTC1726-5) VCC3 1 CC5 1 3.3V CC3 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 80 100 –60 –40 – TEMPERATURE (°C) 1726 G05 Typical Transient Duration ...

Page 5

... Bypass this pin to ground CC25 CC5 with a 0.1µF or larger ceramic capacitor. V (Pin 2): 5V Sense Input (LTC1726-5). This pin also CC5 supplies power to the part when the voltage on this pin is greater than the voltage on V CC3 ground with a 0.1µF or larger ceramic capacitor. ...

Page 6

... LTC1726 CTIO S RT (Pin 8): Reset Time-Out Input. Place a capacitor between this pin and ground to adjust the reset time-out period. To determine the reset time-out period 3.30 • BLOCK DIAGRA WDI CC3 CC5 CC25 V 3 CCA GND ...

Page 7

... The V input trip point is disabled if its voltage is equal CC5 ±25mV and the voltage the voltage on V CC3 less than 4.15V. In this manner the LTC1726-5 behaves as a 3.3V monitor and the 5V reset function is disabled. The V trip point is re-enabled when the voltage on CC5 V ...

Page 8

... Figure 3 contains a simple circuit for 5V systems that can’t risk the RST output going high in the 3.1V to 4.15V range (possibly due to very slow rise time on the 5V supply). Diode D1 powers the LTC1726-5 while dropping ≈ 0.6V from the V pin to the V pin. This prevents the part’s ...

Page 9

... RST SYSTEM RESET 5 WDI WDI 1726 TA04 LTC1726 , is adjusted between the WT pin and WT /21 µs (i.e., 1500pF ⇒ 32.7ms). The in pF and t WT CCA LTC1726 3. CC3 CC5 3 6 SYSTEM RESET V RST CCA 4 5 WDI ...

Page 10

... V RT CC3 CC25 R1 RST CCA 4 5 R2* GND WDI *TO PRESERVE THRESHOLD ACCURACY, SET PARALLEL COMBINATION OF R1 AND R2 ≤ 66.5k Using V Tied to DC/DC Feedback Divider CCA 2.9V 35.7k LTC1726 3. CC3 OSENSE CC5 RST CCA 4 5 22.1k GND ...

Page 11

... TYP .016 – .050 .014 – .019 (0.406 – 1.270) (0.355 – 0.483) TYP INCHES (MILLIMETERS) LTC1726 0.52 (.206 REF 3.00 ± 0.102 (.118 ± .004) NOTE ...

Page 12

... Precision Six Supply Monitor LTC2910 Octal Positive/Negative Voltage Monitor Linear Technology Corporation 12 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 ● 12V (± 5 11.2V TRIP (± 0.17V) 5V 3.3V V CC3 100nF LTC1726 R3* CC5 1.07M 100nF 0.1% V CCA R2 105k 0.1% GND V CCA V = (R1 + R2) ...

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