Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsPMICsPMIC - system monitor Dual voltage detector SOIC 8

LTC1326/LTC1326-2.5

132625fc

TYPICAL APPLICATIO

APPLICATIO S

FEATURES

DESCRIPTIO

Micropower Precision

Triple Supply Monitors

RST Output Voltage vs Supply Voltage (LTC1326-2.5)

■

Simultaneously Monitors Three Supplies

LTC1326: 5V, 3.3V and ADJ

LTC1326-2.5: 2.5V, 3.3V and ADJ

■

Guaranteed Threshold Accuracy: ±0.75%

■

Low Supply Current: 20µA

■

Internal Reset Time Delay: 200ms

■

Manual Push-Button Reset Input

■

Active Low and Active High Reset Outputs

■

Active Low “Soft” Reset Output

■

Power Supply Glitch Immunity

■

Guaranteed RESET for V

CC3

≥ 1V or V

CC5

≥ 1V

or V

CC25

≥ 1V

■

8-Pin SO and MSOP Packages

The LTC

1326/LTC1326-2.5 are triple supply monitors

intended for systems with multiple supply voltages. They

provide micropower operation, small size and high accu-

racy supply monitoring.

Tight 0.75% threshold accuracy and glitch immunity

ensure reliable reset operation without false triggering.

The 20µA typical supply current makes the LTC1326/

LTC1326-2.5 ideal for power-conscious systems.

The RST output is guaranteed to be in the correct state for

CC3

CC5

or V

CC25

down to 1V. The LTC1326/LTC1326-2.5

can be configured to monitor one, two or three inputs,

depending on system requirements.

A manual push-button reset input provides the ability to

generate a very narrow “soft” reset pulse (100µs typ) or a

200ms reset pulse equivalent to a power-on reset. Both

SRST and RST outputs are open-drain and can be OR-tied

with other reset sources.

■

Desktop Computers

■

Notebook Computers

■

Intelligent Instruments

■

Portable Battery-Powered Equipment

CC3

(V)

2.0

2.5

3.5

1.5 2.5

1326/2.5 TA02

1.5

1.0

0.5 1.0

2.0 3.0 3.5

0.5

3.0

RST OUTPUT VOLTAGE (V)

CC25

= V

CCA

= V

CC3

4.7k PULL-UP FROM RST TO V

CC3

= 25°C

PUSH-BUTTON

RESET

1326/2.5 TA01

CC3

CC25

0.1µF

CCA

GND

RST

PBR

SRST

LTC1326-2.5

CORE

3.3V

2.5V

DC/DC

CONVERTER

SYSTEM

LOGIC

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

All other trademarks are the property of their respective owners.

Protected by U.S. Patents, including 4843302.

Summary of content (16 pages)

PAGE 1
LTC1326/LTC1326-2.5 Micropower Precision Triple Supply Monitors U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO Simultaneously Monitors Three Supplies LTC1326: 5V, 3.3V and ADJ LTC1326-2.5: 2.5V, 3.3V and ADJ Guaranteed Threshold Accuracy: ±0.
PAGE 2
LTC1326/LTC1326-2.5 W W W AXI U U ABSOLUTE RATI GS (Notes 1, 2) Terminal Voltage VCC3, VCC5, VCC25, VCCA ......................... – 0.5V to 7V RST, SRST ............................................ – 0.5V to 7V RST ...................................... – 0.5V to (VCC3 + 0.3V) PBR .......................................................... – 7V to 7V Operating Temperature Range LTC1326C/LTC1326C-2.5 ....................... 0°C to 70°C LTC1326I/LTC1326I-2.5 .....................
PAGE 3
LTC1326/LTC1326-2.5 ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC3 = 3.3V, VCC5 = 5V (for LTC1326),VCC25 = 2.5V (for LTC1326-2.5), VCCA = VCC3, TA = 25°C unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VRT3 Reset Threshold VCC3 0°C ≤ TA ≤ 70°C –40°C ≤ TA ≤ 85°C ● ● 3.094 3.052 3.118 3.118 3.135 3.
PAGE 4
LTC1326/LTC1326-2.5 ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. LTC1326 Only VCC3 = 3.3V, VCC5 = 5V, VCCA = VCC3, TA = 25°C unless otherwise noted.
PAGE 5
LTC1326/LTC1326-2.5 U W TYPICAL PERFOR A CE CHARACTERISTICS VCC5 Transient Immunity (LTC1326) VCCA Input Current vs Input Voltage 50 TRANSIENT DURATION (µs) 2 INPUT CURRENT (nA) 45 RESET OCCURS ABOVE CURVE TA = 25°C 45 1 0 –1 –2 –3 0.8 0.85 0.9 0.95 1.0 1.05 1.1 1.15 1.2 INPUT VOLTAGE (V) 40 35 30 25 20 15 10 25 20 15 10 0 0.001 0.01 0.1 1 VCC5 RESET COMPARATOR OVERDRIVE (V) 0 0.01 0.1 1 0.001 VCC25 RESET COMPARATOR OVERDRIVE (V) 1326/2.5 G05 1326/2.
PAGE 6
LTC1326/LTC1326-2.5 U W TYPICAL PERFOR A CE CHARACTERISTICS Reset Pulse Width vs Temperature SOFT RESET PULSE WIDTH, tSRST (µs) 220 215 210 205 200 195 190 – 60 – 40 – 20 0 20 40 60 TEMPERATURE (°C) 80 100 PBR ASSERTION TIME TO RESET, tPB (SEC) 112.5 225 RESET PULSE WIDTH, tRST (ms) PBR Assertion Time to Reset vs Temperature “Soft” Reset Pulse Width vs Temperature 110.0 107.5 105.0 102.5 100.0 97.5 95.0 – 60 – 40 – 20 0 20 40 60 TEMPERATURE (°C) 1326/2.5 G13 80 100 1326/2.5 G14 2.25 2.20 2.
PAGE 7
LTC1326/LTC1326-2.5 W BLOCK DIAGRA S LTC1326 VCC3 VCC3 6µA 7µA 7 SRST 6 RST 5 RST SOFT RESET PBR TIMER PBR 8 – RESET 4.15V TO POWER DETECT + – VCC5 2 + 25mV – VCC3 – 25mV VCC3 INTERNAL + + VCC3 1 VCC3 VCC3 6µA – 200ms RESET GENERATOR + POWER DETECT/ GATE DRIVE – VCCA 3 VCC5 + GND 4 VCC3 REF 1326 BD LTC1326-2.
PAGE 8
LTC1326/LTC1326-2.5 WU W TI I G DIAGRA S VCC Monitor Timing VCCX Push-Button Reset Function Timing PBR VRTX t < tPB tRST tPB tRST tDB RST RST tSRST 1326/2.5 TD01 SRST 1326/2.5 TD02 U W U U APPLICATIO S I FOR ATIO Operation The LTC1326/LTC1326-2.5 are micropower, high accuracy triple supply monitoring circuits. The parts have two basic functions: generation of a reset when power supplies are out of range, and generation of reset or a “soft” reset when the PBR pin is pulled low.
PAGE 9
LTC1326/LTC1326-2.5 U W U U APPLICATIO S I FOR ATIO During a supply induced reset condition, the ability of the PBR pin to force a soft reset condition on the SRST pin is disabled. In other words SRST will remain high. If the PBR pin is held low, both during and after a supply induced reset (low RST), the RST pin will remain low until 200ms after the PBR goes high. Power Detect/Gate Drive The LTC1326/LTC1326-2.5 for the most part are powered internally from the VCC3 pin.
PAGE 10
LTC1326/LTC1326-2.5 U U W U APPLICATIO S I FOR ATIO 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 LTC1326 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 ≅ 4.725V (See Figure 4). 1 2 5V 3 0.
PAGE 11
LTC1326/LTC1326-2.5 U TYPICAL APPLICATIONS N Triple Supply Monitor (3.3V, 5V and Adjustable) LTC1326 1 3.3V ADJUSTABLE SUPPLY OR DC/DC FEEDBACK DIVIDER 2 5V R1 3 4 R2 VCC3 PBR VCC5 SRST VCCA RST GND 8 7 6 SYSTEM RESET 5 RST 1326/2.5 TA03 Dual Supply Monitor (3.3V and 5V, Defeat VCCA Input) LTC1326 1 3.3V 2 5V 3 4 VCC3 PBR VCC5 SRST VCCA RST GND RST 8 7 6 SYSTEM RESET 5 1326/2.5 TA05 Dual Supply Monitor (3.3V or 5V Plus Adj) 3.
PAGE 12
LTC1326/LTC1326-2.5 U TYPICAL APPLICATIONS N SRST Tied to RST and OR-Tying Other Sources to RST to Generate Reset and Reset LTC1326/ LTC1326-2.5 PUSHBUTTON 8 PBR 3.3V 4.7k 6µA RESET SRST 7 6µA RST 6 OTHER OPEN DRAIN RESET SOURCES OR-TIED TO RESET VCC3 RST 5 RESET 1326/2.5 TA08 Using VCCA Tied to DC/DC Feedback Divider 2.9V 35.7k 1% 3.3V 2.8k 5V 1% LTC1435 6 VOSENSE LTC1326 1 2 3 4 22.1k 1% ADJUSTABLE RESET TRIP THRESHOLD 2.
PAGE 13
LTC1326/LTC1326-2.5 U TYPICAL APPLICATIONS N Monitoring a Negative Supply 3.3V C1 0.1µF LTC1326 1 2 5V R2 150k 1% R1 150k 1% Q1 2N3906 C2 0.1µF 3 4 VCC3 PBR VCC5 SRST VCCA RST GND RST 8 7 6 SYSTEM RESET 5 Q2 2N3906 VCCA R3 100k 1% Q3 2N3904 R4 392k 1% –5V R4 ≈ (100k)(0.98)(VTRIP + 0.55)(–1) SUPPLY VTRIP R4 – 5V – 4.6V 392k – 3.3V – 3V 237k – 12V – 10.8V 1M 1326/2.5 TA12 Reset Valid for VCC3 Down to 0V 3.3V 3.5 LTC1326-2.5 ADJUSTABLE SUPPLY R1 2.
PAGE 14
LTC1326/LTC1326-2.5 U PACKAGE DESCRIPTIO MS8 Package 8-Lead Plastic MSOP (Reference LTC DWG # 05-08-1660) 0.889 ± 0.127 (.035 ± .005) 5.23 (.206) MIN 3.20 – 3.45 (.126 – .136) 0.42 ± 0.038 (.0165 ± .0015) TYP 3.00 ± 0.102 (.118 ± .004) (NOTE 3) 0.65 (.0256) BSC 8 7 6 5 0.52 (.0205) REF RECOMMENDED SOLDER PAD LAYOUT 0.254 (.010) 3.00 ± 0.102 (.118 ± .004) (NOTE 4) 4.90 ± 0.152 (.193 ± .006) DETAIL “A” 0° – 6° TYP GAUGE PLANE 0.53 ± 0.152 (.021 ± .006) DETAIL “A” 1 2 3 4 1.10 (.
PAGE 15
LTC1326/LTC1326-2.5 U PACKAGE DESCRIPTIO S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch) (Reference LTC DWG # 05-08-1610) .189 – .197 (4.801 – 5.004) NOTE 3 .045 ±.005 .050 BSC 8 .245 MIN 7 6 5 .160 ±.005 .150 – .157 (3.810 – 3.988) NOTE 3 .228 – .244 (5.791 – 6.197) .030 ±.005 TYP 1 RECOMMENDED SOLDER PAD LAYOUT .010 – .020 × 45° (0.254 – 0.508) .008 – .010 (0.203 – 0.254) 0°– 8° TYP .016 – .050 (0.406 – 1.270) NOTE: 1. DIMENSIONS IN .053 – .069 (1.346 – 1.752) .014 – .019 (0.
PAGE 16
LTC1326/LTC1326-2.5 U TYPICAL APPLICATIO Triple Supply Monitor with 3.3V and 5V System Resets 3.3V 5V LTC1326 ADJUSTABLE SUPPLY OR DC/DC FEEDBACK DIVIDER R1 R2 VCC3 PBR VCC5 SRST VCCA RST GND RST 10k 10k TO 3.3V SYSTEM RESET TO 5V SYSTEM RESET Q1 2N7002 1326/2.5 TA14 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC690 5V Supply Monitor, Watchdog Timer and Battery Backup 4.65V Threshold LTC694-3.3 3.3V Supply Monitor, Watchdog Timer and Battery Backup 2.