Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsPMICsPMIC - system monitor Dual voltage detector TSOT 23 5

LTC1727/LTC1728

17278fb

Typical applicaTion

DescripTion

Micropower Precision

Triple Supply Monitors

in 8-Lead MSOP and

5-Lead SOT-23 Packages

The LTC

1727 is a triple supply monitor intended for

systems with multiple supply voltages. Each supply moni-

tor has its own open-drain output for individual supply

monitoring. A common open-drain reset output remains

low until all three supplies have been in compliance for

200ms. Tight 1.5% accuracy speciﬁcations and glitch

immunity ensure reliable reset operation without false

triggering.

The LTC1728 is functionally identical to the LTC1727

without the individual monitor outputs.

The RST output is guaranteed to be in the correct state

for V

CC5

CC25

CC18

or V

CC3

down to 1V. The LTC1727/

LTC1728 may also be conﬁgured to monitor any one or

two V

inputs instead of three, depending on system

requirements.

Very low (10µA typical) supply current makes the LTC1727/

LTC1728 ideal for power conscious systems.

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

age and the LTC1728 is available in a 5-lead SOT-23

package.

Triple Supply Monitor with Power Good Output

(3.3V, 2.5V and Adjustable)

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

All other trademarks are the property of their respective owners.

FeaTures

applicaTions

Monitors Three Inputs Simultaneously

LTC1727-5: 5V, 3.3V and ADJ

LTC1727-2.5: 2.5V, 3.3V and ADJ

LTC1728-5: 5V, 3.3V and ADJ

LTC1728-2.5: 2.5V, 3.3V and ADJ

LTC1728-1.8: 3V, 1.8V and ADJ

LTC1728-3.3: 3.3V, 1.8V and ADJ

±1.5% Threshold Accuracy Over Temperature

Very Low Supply Current: 10µA Typ

200ms Reset Time Delay

Active Low RESET Output

Power Supply Glitch Immunity

Guaranteed RESET for V

CC3

≥ 1V

or V

CC5

CC25

CC18

≥ 1V

LTC1727 Includes Monitor Output for Each Supply

LTC1727: 8-Lead MSOP and SO Packages

LTC1728: 5-Lead SOT-23 Package

Desktop Computers

Notebook Computers

Intelligent Instruments

Portable Battery-Powered Equipment

Network Servers

CC3

CC5

CCA

RST

GND

LTC1728-5

1727/28 TA01

3.3V

1.8V

0.1µF

5 1

61.9k

100k

DC/DC

CONVERTER

SYSTEM

LOGIC

0.1µF

LTC1727-2.5

1727/28 TA08

ADJUSTABLE

SUPPLY

3.3V

2.5V

10k

POWER

GOOD

SYSTEM

RESET

10k

CC3

CC25

CCA

GND

COMP3

COMP25

RST

COMPA

Summary of content (16 pages)

PAGE 1
LTC1727/LTC1728 Micropower Precision Triple Supply Monitors in 8-Lead MSOP and 5-Lead SOT-23 Packages Description Features Monitors Three Inputs Simultaneously LTC1727-5: 5V, 3.3V and ADJ LTC1727-2.5: 2.5V, 3.3V and ADJ LTC1728-5: 5V, 3.3V and ADJ LTC1728-2.5: 2.5V, 3.3V and ADJ LTC1728-1.8: 3V, 1.8V and ADJ LTC1728-3.3: 3.3V, 1.8V and ADJ n ±1.
PAGE 2
LTC1727/LTC1728 Absolute Maximum Ratings (Notes 1. 2) VCC3, VCC5 /VCC25/VCC18, VCCA ......................... – 0.3V to 7V RST.............................................................. – 0.3V to 7V COMPA, COMP3, COMP25/COMP5 (MS8 and SO-8 Only).............................. – 0.3V to 7V Operating Temperature Range LTC1727/LTC1728E (Note 3)................ – 40°C to 85°C LTC1728H...........................................– 40°C to 125°C LTC1727I..............................................
PAGE 3
LTC1727/LTC1728 Electrical Characteristics All except LTC1728-1.8/LTC1728-3.3. The l denotes 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 IVCC3 VCC3 Supply Current VCC5/VCC25 > VCC3 VCC5/VCC25 < VCC3, VCC3 = 3.3V (Note 4) l l 1 10 2 20 µA µA IVCC25 VCC25 Supply Current VCC25 < VCC3, VCC25 = 2.
PAGE 4
LTC1727/LTC1728 Electrical Characteristics LTC1728-3.3 The l denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC3 = 3.3V, VCC18 = 1.8V, VCCA = VCC3 unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VRT3 Reset Threshold VCC3 VCC3 Input Threshold l 3.036 3.086 3.135 V VRT18 Reset Threshold VCC18 VCC18 Input Threshold l 1.656 1.683 1.710 V VRTA Reset Threshold VCCA VCCA Input Threshold l 0.
PAGE 5
LTC1727/LTC1728 Typical Performance Characteristics VCCA Input Current vs Input Voltage 450 0.5 0 –0.5 –1.0 –1.5 –2.0 0.80 0.85 0.90 0.95 1 1.05 1.10 1.15 1.20 INPUT VOLTAGE (V) TYPICAL TRANSIENT DIRATION (µs) 1.0 1.010 1.005 1.000 0.995 0.990 0.985 20 40 60 –60 –40 –20 0 TEMPERATURE (°C) Reset Pulse Width vs Temperature 10 9 260 180 40 60 80 100 IVCC25 (µA) 1.1 1.0 0.9 0.8 0.7 1 0.6 0 0.
PAGE 6
LTC1727/LTC1728 Typical Performance Characteristics VCC3 Threshold Voltage vs Temperature (All But LTC1728-1.8) 3.135 2.3675 3.125 2.3600 2.3525 2.3450 2.3375 2.3300 2.3225 2.3150 2.3075 2.3000 –60 –40 –20 0 20 40 60 TEMPERATURE (°C) 80 100 4.750 4.725 3.115 3.105 4.700 3.095 3.085 4.675 3.075 4.650 3.065 3.055 4.625 3.045 3.035 –60 –40 –20 0 20 40 60 TEMPERATURE (°C) 1727/28 G10 1.4 100 4.600 20 40 60 –60 –40 –20 0 TEMPERATURE (°C) VCC3 = 3V 14 VCC18 = 1.8V VCCA = 3V 13 1.2 12 1.
PAGE 7
LTC1727/LTC1728 Pin Functions (LTC1727/LTC1728) VCC3 (Pin 1/Pin 5): 3.3V Sense Input and Power Supply Pin. (3V Sense Input and Power Supply Pin for LTC17281.8.) This pin provides power to the part when the voltage on VCC3 is greater than the voltage on VCC5/VCC25/VCC18. Bypass to ground with a ≥ 0.1µF ceramic capacitor. VCC5 (Pin 2/Pin 4): 5V Sense Input and Power Supply Pin.
PAGE 8
LTC1727/LTC1728 Block DiagramS LTC1727-5/LTC1727-2.
PAGE 9
LTC1727/LTC1728 Block DiagramS LTC1728-5/LTC1728-2.5/LTC1728-1.8/LTC1728-3.3 – VCC3 5 + POWER DETECT VCC INTERNAL VCC3 VCC5/ VCC25/ 4 VCC18 6µA – 200ms PULSE GENERATOR 1 RST 200ms DELAY + – VCCA 3 + GND 2 BANDGAP REFERENCE 1727 BD2 TIMING Diagram VCC Monitor Timing VCCX VRTX tUV RST tRST 1.
PAGE 10
LTC1727/LTC1728 applications information Supply Monitoring Power-Down The LTC1727 is a low power, high accuracy triple supply monitoring circuit with three monitor outputs and a 200ms microprocessor reset output. On power-down, once any of the VCC inputs drop below its threshold, RST is held at a logic low. A logic low of 0.3V is guaranteed until both VCC3 and VCC5/VCC25/VCC18 drop below 1V. All three VCC inputs must be above predetermined thresholds for reset not to be invoked.
PAGE 11
LTC1727/LTC1728 Applications Information Override Functions (5V Versions Only) When monitoring either 3.3V or 5V with VCC3 strapped to VCC5 (see Figure 2), the part determines which is the appropriate range. The part handles this situation as shown in Figure 3. Above 1V and below VRT3, RST is held low. From VRT3 to approximately 4.15V the part assumes 3.3V supply monitoring and RST is deasserted. Above approximately 4.15V the part operates as a 5V monitor.
PAGE 12
LTC1727/LTC1728 applications information LTC1727-2.5/LTC1728-2.5/LTC1728-1.8/LTC1728-3.3 Override Functions Figure 4 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 LTC1728-5 while dropping ≈ 0.6V from the VCC5 pin to the VCC3 pin. This prevents the part’s internal override circuit from being activated.
PAGE 13
LTC1727/LTC1728 typical Applications Dual Supply Monitor (3.3V and 5V, Defeat VCCA Input) LTC1728-5 5 3.3V 4 5V 3 2 RST VCC3 1 SYSTEM RESET VCC5 VCCA GND 1727/28 TA04 Dual Supply Monitor (3.3V or 5V Plus Adjustable) 3.3V OR 5V LTC1728-5 5 4 R1* ADJUSTABLE SUPPLY 3 R2* 2 RST VCC3 10k 1 SYSTEM RESET VCC5 VCCA GND 1727/28 TA05 *TO PRESERVE THRESHOLD ACCURACY, SET PARALLEL COMBINATION OF R1 AND R2 ≤ 66.
PAGE 14
LTC1727/LTC1728 Package Description MS8 Package 8-Lead Plastic MSOP (Reference LTC DWG # 05-08-1660) 3.00 ± 0.102 (.118 ± .004) (NOTE 3) 0.889 ± 0.127 (.035 ± .005) 7 6 5 0.52 (.0205) REF 3.00 ± 0.102 (.118 ± .004) (NOTE 4) 4.90 ± 0.152 (.193 ± .006) DETAIL “A” 0.254 (.010) 8 0° – 6° TYP GAUGE PLANE 5.23 (.206) MIN 3.20 – 3.45 (.126 – .136) 1 0.53 ± 0.152 (.021 ± .006) DETAIL “A” 4 0.86 (.034) REF 0.18 (.007) 0.65 (.0256) BSC 0.42 ± 0.038 (.0165 ± .0015) TYP 2 3 1.10 (.
PAGE 15
LTC1727/LTC1728 Package Description 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) A SOT-23 (Original) .90 – 1.45 (.035 – .057) SOT-23 (ThinSOT) 1.00 MAX (.039 MAX) A1 .00 – .15 (.00 – .006) .01 – .10 (.0004 – .004) A2 .90 – 1.30 (.035 – .051) .80 – .90 (.031 – .035) L .35 – .55 (.014 – .021) .30 – .50 REF (.012 – .019 REF) 2.60 – 3.00 (.102 – .118) 1.50 – 1.75 (.059 – .069) (NOTE 3) PIN ONE .95 (.
PAGE 16
LTC1727/LTC1728 Typical Application Triple Supply Monitor with Manual Reset Button 12V (±5%) VTRIP = 11.2V (±0.17V) 5V 3.3V 5 100nF R3* 10k 5% R1 1.07M 0.1% MANUAL RESET BUTTON (NORMALLY OPEN) 100nF *OPTIONAL RESISTOR RECOMMENDED TO EXTEND ESD TOLERANCE RST 1 LTC1728-5 4 R2 105k 0.1% VCC3 3 VCC5 VCCA GND 2 1727/28 TA02 V VTRIP = CCA (R1 + R2) R2 V R1 = R2 TRIP – 1 VCCA ( ) Related Parts PART NUMBER DESCRIPTION COMMENTS LTC690 5V Supply Monitor, Watchdog Timer and Battery Backup 4.