LTC1726IS8-5#TRPBF

LTC1726 Triple Supply Monitor and µP Supervisor with Adjustable Reset and Watchdog Timer Features Description Monitors Three Inputs Simultaneously LTC1726-5: 5V, 3.3V and ADJ LTC1726-2.5: 2.5V, 3.3V and ADJ n ±1.5% Threshold Accuracy Over Temperature n Low Supply Current: 16µA Typ n Adjustable Reset Timeout n Adjustable Watchdog Timeout n Active Low Open-Drain Reset Output n Power Supply Glitch Immunity n Guaranteed RESET for V CC3 ≥ 1V or VCC25/VCC5 ≥ 1V n MS8 and SO-8 Packages The LTC®1726 is a triple supply monitor and microprocessor supervisory circuit with adjustable reset and watchdog functions intended for systems with multiple supply voltages. 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. n Applications n n n n n 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 VCC5/VCC25 or VCC3 down to 1V. The LTC1726 may also be configured to monitor any one or two VCC inputs instead of three, depending on system requirements. The low (16µA typical) supply current makes the LTC1726 ideal for power-conscious systems. Desktop Computers Notebook Computers Intelligent Instruments Portable Battery-Powered Equipment Network Servers L, LT, LTC, LTM, 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. Typical Application A 3.3V, 5V and 1.8V Monitor A 3.3V, 2.5V and 1.8V Monitor 1.8V (VTRIP = 1.665V) 3.3V 0.1µF 5V 0.1µF CRT 47nF CWT 47nF 2 8 1 3 VCC5 VCC3 VCCA RST RT LTC1726-5 7 WT WDI 6 5 1.8V (VTRIP = 1.665V) R1 66.5k 1% 3.3V R2 100k 1% 2.5V R1 66.5k 1% 0.1µF 0.1µF CRT 47nF RESET µP I/O CWT 47nF 2 8 tRT = 155ms tWT= 1s VCC25 VCC3 VCCA RST RT WT R2 100k 1% 3 LTC1726-2.5 7 WDI 6 5 RESET µP I/O GND GND 4 1 1726 TA01 tRT = 155ms tWT= 1s 4 1726 TA02 1726fd For more information www.linear.com/LTC1726 1 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........................................... –40°C to 125°C Storage Temperature Range................... –65°C to 150°C Lead Temperature (Soldering, 10 sec).................... 300°C Pin Configuration TOP VIEW TOP VIEW VCC3 VCC25 /VCC5 VCCA GND 1 2 3 4 8 7 6 5 RT WT RST WDI VCC3 1 8 RT VCC25/VCC5 2 7 WT VCCA 3 6 RST GND 4 5 WDI MS8 PACKAGE 8-LEAD PLASTIC MSOP TJMAX = 125°C, θJA = 200°C/W S8 PACKAGE 8-LEAD PLASTIC SO TJMAX = 125°C, θJA = 150°C/W Order Information LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC1726EMS8-2.5#PBF LTC1726EMS8-2.5#TRPBF LTKZ 8-Lead Plastic MSOP –40°C to 85°C LTC1726EMS8-5#PBF LTC1726EMS8-5#TRPBF LTLA 8-Lead Plastic MSOP –40°C to 85°C LTC1726HMS8-5#PBF LTC1726HMS8-5#TRPBF LTLA 8-Lead Plastic MSOP –40°C to 125°C LTC1726ES8-2.5#PBF LTC1726ES8-2.5#TRPBF 172625 8-Lead Plastic SO –40°C to 85°C LTC1726ES8-5#PBF LTC1726ES8-5#TRPBF 17265 8-Lead Plastic SO –40°C to 85°C LTC1726IS8-2.5#PBF LTC1726IS8-2.5#TRPBF 726I25 8-Lead Plastic SO –40°C to 85°C LTC1726IS8-5#PBF LTC1726IS8-5#TRPBF 1726I5 8-Lead Plastic SO –40°C to 85°C Consult LTC Marketing for parts specified with wider operating temperature ranges. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ 1726fd 2 For more information www.linear.com/LTC1726 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 1.000 1.015 1.022 V V 1 H-Grade VRT5 Reset Threshold VCC5 VCC5 Input Threshold (5V Version) VRT25 Reset Threshold VCC25 VCC25 Input Threshold (2.5V Version), VRTA Reset Threshold VCCA VCCA Input Threshold VCC VCC3 or VCC5 Operating Voltage RST in Correct Logic State l 7 V IVCC3 VCC3 Supply Current VCC5/VCC25 > VCC3 VCC5/VCC25 < VCC3, VCC3 = 3.3V l l 1 16 2 30 µA µA IVCC5 VCC5 Supply Current VCC5 = 5V l 16 30 µA IVCC25 VCC25 Supply Current VCC25 < VCC3, VCC25 = 2.5V (Note 4) l 1 2 µA IVCCA VCCA Input Current VCCA = 1V l –15 0 15 nA RT Charge Current Out VRT = 0V l l 1.4 1.3 2 2 2.6 2.6 µA µA l l 1.4 1.3 2 2 2.6 2.6 µA µA l l 14 13 20 20 26 28 µA µA l l 14 13 20 20 26 28 µA µA l l –30 –45 0 0 30 45 % % H-Grade WT Charge Current Out VWT = 0V H-Grade RT Discharge Current Out VRT = 1.3V H-Grade WT Discharge Current Out VWT = 1.3V H-Grade ∆tRT Reset Time-Out Period Variation CRT = 1500pF Deviation from tRT = 5ms (Note 5) H-Grade tUV VCC Undervoltage Detect to RST VCC25/VCC5, VCC3 or VCCA Less Than Reset Threshold VRT by More Than 1% VOH RST Output Voltage High (Note 6) ISOURCE = 1µA l VOL RST Output Voltage Low ISINK = 2.5mA, VCC5/VCC25 = 0V ISINK = 100µA, VCC3 = 1V, VCC5/VCC25 = 0V ISINK = 100µA, VCC3 = 0V, VCC5/VCC25 = 1V ISINK = 100µA, VCC3 = 1V, VCC5/VCC25 = 1V l l l l VIH WDI Input Threshold High l VIL WDI Input Threshold Low l 0.3 • VCC3 tWP WDI Pulse Width l 40 ∆tWT Watchdog Time-Out Period Variation CWT = 1500pF Deviation from tWT = 33ms (Note 5) l l –30 –45 H-Grade WDI Leakage Current 130 µs VCC3 – 1 V 0.15 0.05 0.05 0.05 0.4 0.3 0.3 0.3 V V V V 0.7 • VCC3 V V ns 0 0 l 30 45 % % ±1 µA LTC1726-5 Only VOVR VCC5 Reset Override Voltage (Note 7) Override VCC5 Ability to Assert RST VCC3 ±0.025 V 1726fd For more information www.linear.com/LTC1726 3 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. Specifications over the –40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls. Note 4: Both VCC3 and VCC25/VCC5 can act as the supply depending on which pin has the greatest potential. Note 5: Timing measured with respect to RST passing through 1.5V. Note 6: The output pin RST has a weak internal pull-up to VCC3 of typically 6µA. However, external pull-up resistors may be used when faster rise times are required or for VOH voltages greater than VCC3. Note 7: The VCC5 reset override voltage is valid for an operating range less than approximately 4.15V. Above this point the override is turned off and the VCC5 pin functions normally. Typical Performance Characteristics VCC5 Threshold Voltage vs Temperature (LTC1726-5) VCC3 Threshold Voltage vs Temperature 3.135 4.725 4.700 4.675 4.650 4.625 80 100 1726 G01 3.115 3.105 3.095 3.085 3.075 3.065 3.055 3.045 3.035 – 60 –40 – 20 0 20 40 60 TEMPERATURE (°C) 80 100 1.010 1.005 1.000 0.995 0.990 0.985 20 40 60 –60 –40 –20 0 TEMPERATURE (°C) 1726 G02 VCC25 Threshold Voltage vs Temperature (LTC1726-2.5) IVCC5 vs Temperature (LTC1726-5) 2.375 IVCC5 (µA) 2.345 2.330 VCC5 = 5V 1.4 VCC3 = 3.3V 18 1.3 17 1.2 16 1.1 15 14 1.0 0.9 13 0.8 2.315 12 0.7 11 0.6 2.300 20 40 60 –60 –40 –20 0 TEMPERATURE (°C) 10 –60 –40 –20 0 20 40 60 TEMPERATURE (°C) 0.5 –60 –40 –20 0 20 40 60 TEMPERATURE (°C) 80 100 1726 G04 1726 G03 1.5 VCC5 = 5V 19 VCC3 = 3.3V 2.360 80 100 IVCC3 vs Temperature (LTC1726-5) 20 IVCC3 (µA) 4.600 20 40 60 –60 –40 –20 0 TEMPERATURE (°C) 1.015 3.125 VCCA THRESHOLD VOLTAGE, VRTA (V) VCC3 THRESHOLD VOLTAGE, VRT3 (V) VCC5 THRESHOLD VOLTAGE, VRT5 (V) 4.750 VCC25 THRESHOLD VOLTAGE, VRT25 (V) VCCA Threshold Voltage vs Temperature 80 100 1726 G05 80 100 1726 G06 1726fd 4 For more information www.linear.com/LTC1726 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 5.8 (SILVER MICA) 32 30 28 10 1 100m 10m 1m 1 5.6 5.4 5.2 5.0 4.8 4.6 4.4 4.2 80 4.0 –60 –40 –20 0 20 40 60 TEMPERATURE (°C) 100 1726 G10 10 1726 G12 80 100 1726 G11 RST Output Voltage vs Supply Voltage (LTC1726-2.5) VCC3 = VCC25 = VCCA 10k PULL-UP FROM VCC3 TO RST TA = 25°C TA = 25°C 3 10 RST OUTPUT VOLTAGE (V) 100 RESET TIME-OUT PERIOD, tRT (sec) WATCHDOG TIME-OUT PERIOD, t WT (sec) 0 1 10 100 0.1 RESET COMPARATOR OVERDRIVE VOLTAGE (% OF VCC) Reset Pulse Width vs Temperature 34 100 10n 100n CWT (FARAD) 100 Reset Time-Out Period vs Capacitance TA = 25°C 1n 200 1726 G09 36 Watchdog Time-Out Period vs Capacitance 10p 100p 300 6.0 1726 G14 1p RESET OCCURS ABOVE CURVE 400 CWT = 1500pF (SILVER MICA) 26 20 40 60 –60 –40 –20 0 TEMPERATURE (°C) – 2.0 0.80 0.85 0.90 0.95 1 1.05 1.10 1.15 1.20 INPUT VOLTAGE (V) 100 500 RESET PULSE WIDTH, tRT (ms) 40 TA = 25°C 1000 100 TA = 25°C 600 Watchdog Time-Out Period vs Temperature WATCHDOG TIME PERIOD, tWT (ms) INPUT CURRENT (nA) 1.5 80 1726 G08 VCCA Input Current vs Input Voltage 2.0 Typical Transient Duration vs Comparator Overdrive 1 100m 10m 1m 2 1 100 10 1p 10p 100p 10n 100n CRT (FARAD) 1n 1 10 1726 G15 0 0 1 2 VCC3 (V) 3 1726 F13 1726fd For more information www.linear.com/LTC1726 5 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). 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. VCCA (Pin 3): 1V Sense, High Impedance Input. If unused it can be tied to either VCC3, VCC5 or VCC25. GND (Pin 4): Ground. WDI (Pin 5): Watchdog Input. A logic input whose rising or falling edge must occur on this pin within the selected watchdog time-out period or a reset pulse will occur. The watchdog time-out period is set by the value of the capacitor that is placed on the WT pin. The rising or falling edge of this pin clears the voltage on the WT capacitor, preventing a reset pulse from occurring. If the watchdog timer is not cleared, a reset pulse will occur. The watchdog timer is cleared during a reset and restarts when the reset is deasserted. When disabling the watchdog function, this pin should be connected to either VCC3 or ground and WT must be grounded. RST (Pin 6): Reset Logic Output. Active low, open-drain logic output with weak pull-up to VCC3. Asserted when one or more of the supplies are below trip thresholds. After all supplies become valid, the reset remains asserted for the period set by the capacitor on the RT pin. The watchdog timer can also trigger the reset whenever the watchdog time-out period is exceeded. This pin can be pulled up greater than VCC3 when interfacing to 5V logic. WT (Pin 7): Watchdog Time-Out Input. Place a capacitor between this pin and ground to adjust the watchdog timeout period. To determine the watchdog time-out period: tWT = 21.8 • CWT with tWT in µs and CWT in pF. As an example, a 47nF capacitor will generate a 1s watchdog time-out period. The watchdog function can be disabled by connecting this pin to ground. 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: tRT = 3.30 • CRT with tRT in µs and CRT in pF. As an example, a 47nF capacitor will generate a 155ms reset time-out period. 1726fd 6 For more information www.linear.com/LTC1726 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 VRTX WDI tUV RST Watchdog Timing Diagram tWP tRT 1.5V RST 1726 TD01 tWT tRT tWT tRT 1.5V 1726 TD02 1726fd For more information www.linear.com/LTC1726 7 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. Upon power-up, either the VCC5 /VCC25 or VCC3 pin can power the drive circuits for the RST pin. This ensures that RST will be low when either VCC5/VCC25 or VCC3 reaches 1V. As long as any one of the VCC inputs is below its predetermined threshold, RST will stay a logic low. Once all of the VCC inputs rise above their thresholds, the adjustable reset timer is started and RST is released after the reset time-out period. On power-down, once any of the VCC inputs drops below its threshold, RST is held at a logic low. A logic low of 0.3V is guaranteed until both VCC3 and VCC5/VCC25 drop below 1V. 3V or 5V/2.5V Power Detect Since the LTC1726 is a multisupply monitor, it will be required to assert reset as soon as there is power on any one of the monitor inputs. Therefore, the part derives its power from either the VCC3 or VCC5/VCC25 input, whichever pin has the greatest potential. This ensures the part pulls the RST pin low as soon as either input pin is ≥1V. The adjustable input is excluded from being a potential supply pin because of its 1V nominal operating range. are greater than approximately 4.15V. In this manner, the part can function as a 5V monitor with the 3.3V monitor disabled. When monitoring either 3.3V or 5V with VCC3 strapped to VCC5, (see Figure 1) the part determines which is the appropriate range. The part handles this situation as shown in Figure 2. 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. In most systems, the 5V supply will pass through the 3.1V to 4.15V region in