Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsPMICsPMIC - system monitor Dual voltage detector SOIC 8

LTC1726

1726fd

For more information www.linear.com/LTC1726

Typical applicaTion

FeaTures DescripTion

Triple Supply Monitor and

µP Supervisor with Adjustable

Reset and Watchdog Timer

The LT C

1726 is a triple supply monitor and microproces-

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

CC5

CC25

or V

CC3

down to 1V. The LTC1726 may also be

configured to monitor any one or two V

inputs instead

of three, depending on system requirements.

The low (16µA typical) supply current makes the LTC1726

ideal for power-conscious systems.

L, LT , LT C , LT M , Linear Technology and the Linear logo are registered trademarks and

ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property

of their respective owners.

applicaTions

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

Guaranteed RESET for V

CC3

≥ 1V or V

CC25

CC5

≥ 1V

MS8 and SO-8 Packages

Desktop Computers

Notebook Computers

Intelligent Instruments

Portable Battery-Powered Equipment

Network Servers

A 3.3V, 5V and 1.8V Monitor A 3.3V, 2.5V and 1.8V Monitor

CC5

47nF

2 1

66.5k

= 155ms

= 1s

100k

0.1µF

1726 TA01

LTC1726-5

RST

WDI

CC3

3.3V

1.8V

TRIP

= 1.665V)

GND

CCA

µP

RESET

I/O

0.1µF

CC25

47nF

2 1

= 155ms

= 1s

100k

0.1µF

1726 TA02

LTC1726-2.5

RST

WDI

CC3

2.5V

3.3V

1.8V

TRIP

= 1.665V)

GND

CCA

µP

RESET

I/O

0.1µF

66.5k

Downloaded from Arrow.com.

Summary of content (14 pages)

PAGE 1
LTC1726 Triple Supply Monitor and µP Supervisor with Adjustable Reset and Watchdog Timer Features n n n n n n n n n Description Monitors Three Inputs Simultaneously LTC1726-5: 5V, 3.3V and ADJ LTC1726-2.5: 2.5V, 3.3V and ADJ ±1.
PAGE 2
LTC1726 Absolute Maximum Ratings (Notes 1, 2) Terminal Voltage VCC3, VCC5/VCC25, VCCA............................ –0.3V to 7V RST........................................................... –0.3V to 7V WDI.......................................................... –0.3V to 7V RT, WT...................................................... –0.3V to 7V Operating Temperature Range (Note 3) LTC1726E, LTC1726I.............................–40°C to 85°C LTC1726H...........................................
PAGE 3
LTC1726 Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC3 = 3.3V, VCC5 = 5V, VCC25 = 2.5V, VCCA = VCC3 unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VRT3 Reset Threshold VCC3 VCC3 Input Threshold l l 3.036 3.023 3.085 3.085 3.135 3.147 V V H-Grade l l 4.600 4.582 4.675 4.675 4.750 4.769 V V l 2.300 2.337 2.375 V H-Grade l l 0.985 0.978 1.000 1.
PAGE 4
LTC1726 Electrical Characteristics Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: All voltage values are with respect to GND. Note 3: The LTC1726E is guaranteed to meet performance specifications from 0°C to 70°C.
PAGE 5
LTC1726 Typical Performance Characteristics IVCC25 vs Temperature (LTC1726-2.5) IVCC3 vs Temperature (LTC1726-2.5) 1.5 20 700 1.3 18 1.2 17 1.1 16 1.0 0.9 15 14 0.8 13 0.7 12 0.6 11 0.5 –60 –40 –20 0 20 40 60 TEMPERATURE (°C) 80 TYPICAL TRANSIENT DURATION (µs) VCC3 = 3.3V 19 VCC25 = 2.5V IVCC3 (µA) IVCC25 (µA) VCC3 = 3.3V 1.4 VCC25 = 2.5V 10 –60 –40 –20 0 20 40 60 TEMPERATURE (°C) 100 1726 G07 1.0 0.5 0 – 0.5 –1.0 –1.5 38 CRT = 1500pF 5.
PAGE 6
LTC1726 Pin Functions VCC3 (Pin 1): 3.3V Sense Input. This pin also supplies power to the part when the voltage on this pin is greater than the voltage on VCC25/VCC5. Bypass this pin to ground with a 0.1µF or larger ceramic capacitor. VCC5 (Pin 2): 5V Sense Input (LTC1726-5). This pin also supplies power to the part when the voltage on this pin is greater than the voltage on VCC3. Bypass this pin to ground with a 0.1µF or larger ceramic capacitor. VCC25 (Pin 2): 2.5V Sense Input (LTC1726-2.5).
PAGE 7
LTC1726 Block Diagram 2µA WDI WATCHDOG TIMER TRANSITION DETECT 5 VCC3 7 – 1 WT + CWT 22µA VCC3 + POWER DETECT VCC5/VCC25 VCC INTERNAL – 2 VCC5 /VCC25 VCC3 + VCCA 6µA RST – 3 GND 1V 4 6 ADJUSTABLE RESET PULSE GENERATOR + 2µA 22µA BANDGAP REFERENCE 8 + RT 1726 BD CRT Timing Diagram VCC Monitor Timing VCCX Watchdog Timing Diagram VRTX WDI tUV RST tWP tRT 1.5V RST 1726 TD01 tWT tRT tWT tRT 1.5V 1726 TD02 1726fd For more information www.linear.
PAGE 8
LTC1726 Applications Information Supply Monitoring The LTC1726 is a low power, high accuracy triple supply monitor and watchdog timer. The watchdog and reset periods are both adjustable using external capacitors. All three VCC inputs must be above predetermined thresholds for reset not to be asserted. The LTC1726 will assert reset during power-up, power-down and brownout conditions on any one or all of the VCC inputs.
PAGE 9
LTC1726 Applications Information 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 VCC5 pin to the VCC3 pin. This prevents the part’s internal override circuit from being activated. Without the override circuit active, the RST pin stays low until VCC5 reaches VRT5 ≅ 4.675V. (See Figure 4.) 5V D1 1 2 3 4 0.
PAGE 10
LTC1726 Typical Applications Disabling the Watchdog Timer 3.3V R1* ADJUSTABLE SUPPLY 5V/2.5V R2* LTC1726-5/LTC1726-2.5 1 8 RT VCC3 2 7 VCC5/VCC25 WT 3 6 RST VCCA 4 5 GND WDI CRT SYSTEM RESET 1726 TA03 *TO PRESERVE THRESHOLD ACCURACY, SET PARALLEL COMBINATION OF R1 AND R2 ≤ 66.5k THE WATCHDOG TIMER CAN BE DISABLED BY CONNECTING THE WDI AND WT PINS TO GROUND. THE PART WILL ACT STRICTLY AS A TRIPLE SUPPLY MONITOR WITH AN ADJUSTABLE RESET TIME-OUT PERIOD Dual Supply Monitor (3.
PAGE 11
LTC1726 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. MS8 Package 8-Lead Plastic MSOP (Reference LTC DWG # 05-08-1660 Rev F) 3.00 ± 0.102 (.118 ± .004) (NOTE 3) 0.889 ± 0.127 (.035 ± .005) 5.23 (.206) MIN 0.254 (.010) 7 6 5 0.52 (.0205) REF 3.00 ± 0.102 (.118 ± .004) (NOTE 4) 4.90 ± 0.152 (.193 ± .006) DETAIL “A” 0° – 6° TYP GAUGE PLANE 3.20 – 3.45 (.126 – .136) 0.53 ± 0.152 (.021 ± .006) DETAIL “A” 0.42 ± 0.038 (.
PAGE 12
LTC1726 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch) S8 Package LTC DWG # 05-08-1610 G) Inch) 8-Lead (Reference Plastic Small Outline (NarrowRev .150 (Reference LTC DWG # 05-08-1610 Rev G) .189 – .197 (4.801 – 5.004) NOTE 3 .045 ±.005 .050 BSC 8 .245 MIN .160 ±.005 .010 – .020 × 45° (0.254 – 0.508) 2 .053 – .069 (1.346 – 1.752) 0°– 8° TYP .016 – .050 (0.406 – 1.
PAGE 13
LTC1726 Revision History (Revision history begins at Rev C) REV DATE DESCRIPTION C 10/10 Added H-grade to Absolute Maximum Ratings and Electrical Characteristics sections. PAGE NUMBER D 4/13 Clarified ∆tRT conditions. 2, 3 3 1726fd Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use.
PAGE 14
LTC1726 Typical Application Triple Supply Monitor with Watchdog Timer and Manual Reset Button 12V ( ±5%) VTRIP = 11.2V ( ±0.17V) 5V 3.3V 47nF 100nF R3* 10k 5% R1 1.07M 0.1% 100nF R2 105k 0.