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LINEAR LTC1727 1728 User's Manual

Summary

These micropower precision monitors are essential voltage supervision circuits designed to ensure system stability across multiple power rails (e.g., 5V, 3.3V, Adjustable). The manual details highly accurate, low-current monitoring capabilities that guarantee reliable reset operation even during severe power supply glitches. Ideal for battery-powered equipment, notebooks, and network servers, the monitor maintains precise voltage thresholds while minimizing quiescent current draw for power-conscious embedded systems.

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LTC1727/LTC1728 Micropower Precision Triple Supply Monitors in 8-Lead MSOP and

5-Lead SOT-23 Packages

FEATURES DESCRIPTIO Monitors Three Inputs Simultaneously The LTC®1727 is a triple supply monitor intended for LTC1727-5: 5V, 3.3V and ADJ systems with multiple supply voltages. Each supply moni-

LTC1727-2.5: 2.5V, 3.3V and ADJ tor has its own open-drain output for individual supply

LTC1728-5: 5V, 3.3V and ADJ monitoring. A common open-drain reset output remains LTC1728-2.5: 2.5V, 3.3V and ADJ low until all three supplies have been in compliance for

LTC1728-1.8: 3V, 1.8V and ADJ 200ms. Tight 1.5% accuracy specifications and glitch

LTC1728-3.3: 3.3V, 1.8V and ADJ immunity ensure reliable reset operation without false

±1.5% Threshold Accuracy Over Temperature triggering.

Very Low Supply Current: 10µA Typ

The LTC1728 is functionally identical to the LTC1727

200ms Reset Time Delay

without the individual monitor outputs.

Active Low RESET Output

Power Supply Glitch Immunity The RST output is guaranteed to be in the correct state for Guaranteed RESET for VCC3 ≥ 1V VCC5/VCC25/VCC18 or VCC3 down to 1V. The LTC1727/ or VCC5/VCC25/VCC18 ≥ 1V LTC1728 may also be configured to monitor any one or LTC1727 Includes Monitor Output for Each Supply two VCC inputs instead of three, depending on system

www.BDTIC.com/LINEAR requirements. LTC1727: 8-Lead MSOP and SO Packages

LTC1728: 5-Lead SOT-23 Package

Very low (10µA typical) supply current makes the LTC1727/ LTC1728 ideal for power conscious systems.

APPLICATIO S

The LTC1727 is available in an 8-lead MSOP or SO

Desktop Computers package and the LTC1728 is available in a 5-lead SOT-23 Notebook Computers package. Intelligent Instruments

, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.

Portable Battery-Powered Equipment All other trademarks are the property of their respective owners. Network Servers

TYPICAL APPLICATIO 3.3V

Triple Supply Monitor with Power Good Output

DC/DC 5V SYSTEM

CONVERTER LOGIC (3.3V, 2.5V and Adjustable)

LTC1727-2.5

VCC3 RST 10k 10k

3.3V VCC3 COMP3 POWER

LTC1728-5

VCC5 2.5V VCC25 COMP25

61.9k R1ADJUSTABLE SYSTEM

VCCA RST

1% SUPPLY RESET

0.1µF VCCA GND

R2 GND COMPA

100k 1727/28 TA01

1727/28 TA08

17278fb

Page Summary Contents For LINEAR LTC1727 1728 User's Manual

Page 1 LTC1727/LTC1728 Micropower Precision Triple Supply Monitors in 8-Lead MSOP and 5-Lead SOT-23 Packages FEATURES DESCRIPTIO Monitors Three Inputs Simultaneously The LTC®1727 is a triple supply monitor i...
Page 2 LTC1727/LTC1728 XI ARBSOLUTE TI (Notes 1, 2) VCC3, VCC5/VCC25/VCC18, VCCA –0.3V to 7V Operating Temperature Range RST –0.3V to 7V LTC1727/LTC1728E (Note 3) 40°C to 85°C COMPA, COMP3, COMP25/COMP5 LTC1...
Page 3 LTC1727/LTC1728 ELECTRICAL CHARACTERISTICS All except LTC1728-1.8/LTC1728-3.3. The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = ...
Page 4 LTC1727/LTC1728 ELECTRICAL CHARACTERISTICS LTC1728-3.3 The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC3 = 3.3V, VCC18...
Page 5 (µ A) RE SE PU LS ID TH , t RS (m s) IN PU CU RR EN (n A) LTC1727/LTC1728 TYPICAL PERFOR A CE CHARACTERISTICS VCCA Input Current VCCA Threshold Voltage Typical Transient Duration vs Input Voltage vs T...
Page 6 C2 TH RE SH OL VO LT AG E, RT (V LTC1727/LTC1728 TYPICAL PERFOR A CE CHARACTERISTICS VCC25 Threshold Voltage C1 TH RE SH OL VO LT AG E, RT (V VCC3 Threshold Voltage VCC5 Threshold Voltage CC (µ A) vs ...
Page 7 LTC1727/LTC1728 PI FU CTIO S (LTC1727/LTC1728) VCC3 (Pin 1/Pin 5): 3.3V Sense Input and Power COMPA (Pin 5): VCCA Comparator Output for the LTC1727. Supply Pin. (3V Sense Input and Power Supply Pin fo...
Page 8 LTC1727/LTC1728 BLOCK DIAGRA LTC1727-5/LTC1727-2.5 1VCC3 COMP3 POWER VCC INTERNAL 6µA DETECT COMP25/ 2VCC5/ VCC25 COMP5 200ms PULSE GENERATOR– RST 3VCCA 200ms www.BDTIC.com/ DELAY INEAR COMPA BANDGAP ...
Page 9 LTC1727/LTC1728 BLOCK DIAGRA LTC1728-5/LTC1728-2.5/LTC1728-1.8/LTC1728-3.3 5VCC3 POWER VCC INTERNAL DETECT VCC5/ VCC25/ 6µA VCC18 200ms PULSE GENERATOR RST 200ms DELAY 3VCCA www.BDTIC.com/LINEAR BANDG...
Page 10 LTC1727/LTC1728 APPLICATIO S I FOR ATIO Supply Monitoring Power-Down The LTC1727 is a low power, high accuracy triple supply On power-down, once any of the VCC inputs drop below monitoring circuit wit...
Page 11 LTC1727/LTC1728 APPLICATIO S I FOR ATIO When monitoring either 3.3V or 5V with VCC3 strapped to Override Functions (5V Versions Only) VCC5 (see Figure 2), the part determines which is the appropriate ...
Page 12 LTC1727/LTC1728 APPLICATIO S I FOR ATIO Figure 4 contains a simple circuit for 5V systems that can’t LTC1727-2.5/LTC1728-2.5/LTC1728-1.8/LTC1728-3.3 risk the RST output going high in the 3.1V to 4.15V...
Page 13 LTC1727/LTC1728 TYPICAL APPLICATIO S Dual Supply Monitor (3.3V and 5V, Defeat VCCA Input) LTC1728-5 3.3V VCC3 RST SYSTEM RESET 5V VCC5 1727/28 TA04 Dual Supply Monitor (3.3V or 5V Plus Adjustable) 3.3...
Page 14 LTC1727/LTC1728 PACKAGE DESCRIPTIO MS8 Package 8-Lead Plastic MSOP (LTC DWG # 05-08-1660) (.118 ± .004) 0.52 (NOTE 3) (.0205) REF DETAIL “A” (.118 ± .004) (NOTE 4) 0° – 6° TYP GAUGE PLANE MIN (.021 ± ...
Page 15 LTC1727/LTC1728 PACKAGE DESCRIPTIO S5 Package 5-Lead Plastic SOT-23 (Reference LTC DWG # 05-08-1633) (Reference LTC DWG # 05-08-1635) 2.80 – 3.10 (.110 – .118) (NOTE 3) SOT-23 SOT-23 (Original) (Thin ...
Page 16 LTC1727/LTC1728 TYPICAL APPLICATIO Triple Supply Monitor with Manual Reset Button 12V (± 5%) VTRIP = 11.2V VCC3 RST LTC1728-5 R3* R1 VCC5 VCCA GND MANUAL 1727/28 TA02 RESET BUTTON (NORMALLY OPEN) VCCA...

Manual Details

Brand Linear
Pages 16
File Size 316.25 KB
Published June 16, 2026
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Frequently Asked Questions

What is the supply current characteristic of this monitor?

It features a very low supply current, specified at 10µA typical, making it ideal for power conscious systems.

How low can the LTC monitors reliably detect voltage drops?

The RESET output guarantees proper signaling even when input voltages are down to 1V.

What is the required delay time before reset acknowledgment?

After a dip, a common open-drain reset output remains low until all three supplies have been stable and compliant for 200ms.

What packages are available for both the LTC1727 and LTC1728 parts?

The LTC1727 is available in an 8-lead MSOP or SO package, while the LTC1728 is housed in a 5-lead SOT-23 package.