LTC1726IS8-2.5

LTC1726 Triple Supply Monitor and µP Supervisor with Adjustable Reset and Watchdog Timer FEATURES ■ DESCRIPTIO ■ ■ ■ ■ ■ ■ ■ ■ 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 VCC3 ≥ 1V or VCC25 /VCC5 ≥ 1V 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. 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. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. APPLICATIO S ■ ■ ■ ■ ■ Desktop Computers Notebook Computers Intelligent Instruments Portable Battery-Powered Equipment Network Servers TYPICAL APPLICATIONS A 3.3V, 5V and 1.8V Monitor 1.8V (VTRIP = 1.665V) 3.3V 0.1µF 5V 0.1µF CRT 47nF 8 CWT 47nF 7 WT GND tRT = 155ms tWT= 1s 4 1726 TA01 A 3.3V, 2.5V and 1.8V Monitor 1.8V (VTRIP = 1.665V) 3.3V 0.1µF 2.5V 0.1µF RESET µP R1 66.5k 1% 2 1 3 6 R2 100k 1% VCC5 VCC3 VCCA RT RST LTC1726-5 5 WDI CRT 47nF 8 CWT 47nF 7 I/O tRT = 155ms tWT= 1s U R1 66.5k 1% 2 1 3 6 R2 100k 1% RESET µP 5 WT GND 4 1726 TA02 U U VCC25 VCC3 VCCA RT RST LTC1726-2.5 WDI I/O 1726fb 1 LTC1726 ABSOLUTE AXI U RATI GS Terminal Voltage VCC3, VCC5/VCC25, VCCA ......................... – 0.3V to 7V RST ....................................................... – 0.3V to 7V WDI ....................................................... – 0.3V to 7V PACKAGE/ORDER I FOR ATIO ORDER PART NUMBER TOP VIEW VCC3 VCC25 /VCC5 VCCA GND 1 2 3 4 8 7 6 5 RT WT RST WDI LTC1726EMS8-2.5 LTC1726EMS8-5 MS8 PACKAGE 8-LEAD PLASTIC MSOP MS8 PART MARKING LTKZ LTLA TJMAX = 125°C, θJA = 200°C/W Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: http://www.linear.com/leadfree/ Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS SYMBOL VRT3 VRT5 VRT25 VRTA VCC IVCC3 IVCC5 IVCC25 IVCCA PARAMETER Reset Threshold VCC3 Reset Threshold VCC5 Reset Threshold VCC25 Reset Threshold VCCA VCC3 or VCC5 Operating Voltage VCC3 Supply Current VCC5 Supply Current VCC25 Supply Current VCCA Input Current RT Charge Current Out WT Charge Current Out RT Discharge Current Out WT Discharge Current Out ∆tRT tUV Reset Time-Out Period Variation VCC Undervoltage Detect to RST The ● denotes specifications which apply over the full operating temperature range, otherwise specificaitons are at TA = 25°C. VCC3 = 3.3V, VCC5 = 5V, VCC25 = 2.5V, VCCA = VCC3 unless otherwise noted. CONDITIONS VCC3 Input Threshold VCC5 Input Threshold (5V Version) VCC25 Input Threshold (2.5V Version) VCCA Input Threshold RST in Correct Logic State VCC5/VCC25 > VCC3 VCC5/VCC25 < VCC3, VCC3 = 3.3V VCC5 = 5V VCC25 < VCC3, VCC25 = 2.5V (Note 4) VCCA = 1V VRT = 0V VWT = 0V VRT = 1.3V VWT = 1.3V CRT = 1500pF Deviation from tRT = 5ms (Note 5) VCC25/VCC5, VCC3 or VCCA Less Than Reset Threshold VRT by More Than 1% ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● 2 U U W WW U W (Notes 1, 2) RT, WT .................................................. – 0.3V to 7V Operating Temperature Range (Note 3) .. – 40°C to 85°C Storage Temperature Range ................ – 65°C to 150°C Lead Temperature (Soldering, 10 sec)................ 300°C ORDER PART NUMBER TOP VIEW VCC3 1 VCC25/ 2 VCC5 VCCA 3 GND 4 8 7 6 5 RT WT RST WDI LTC1726ES8-2.5 LTC1726ES8-5 LTC1726IS8-2.5 LTC1726IS8-5 S8 PART MARKING 172625 17265 726I25 1726I5 S8 PACKAGE 8-LEAD PLASTIC SO TJMAX = 125°C, θJA = 150°C/W MIN 3.036 4.600 2.300 0.985 1 TYP 3.085 4.675 2.337 1.000 1 16 16 1 MAX 3.135 4.750 2.375 1.015 7 2 30 30 2 15 2.6 2.6 26 26 30 UNITS V V V V V µA µA µA µA nA µA µA µA µA % µs 1726fb – 15 1.4 1.4 14 14 –30 0 2 2 20 20 0 130 LTC1726 The ● denotes specifications which apply over the full operating temperature range, otherwise specificaitons are at TA = 25°C. VCC3 = 3.3V, VCC5 = 5V, VCC25 = 2.5V, VCCA = VCC3 unless otherwise noted. SYMBOL VOH VOL PARAMETER RST Output Voltage High (Note 6) RST Output Voltage Low CONDITIONS ISOURCE = 1µA 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 ● ● ● ● ● ● ● ● ELECTRICAL CHARACTERISTICS MIN VCC3 – 1 TYP 0.15 0.05 0.05 0.05 MAX 0.4 0.3 0.3 0.3 0.7 • VCC3 UNITS V V V V V V V ns VIH VIL tWP ∆tWT WDI Input Threshold High WDI Input Threshold Low WDI Pulse Width Watchdog Time-Out Period Variation WDI Leakage Current 0.3 • VCC3 40 –30 0 30 ±1 VCC3 ± 0.025 CWT = 1500pF Deviation from tWT = 33ms (Note 5) ● ● % µA V LTC1726-5 Only VOVR VCC5 Reset Override Voltage (Note 7) Override VCC5 Ability to Assert RST 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 PERFOR A CE CHARACTERISTICS VCC5 Threshold Voltage vs Temperature (LTC1726-5) 4.750 VCC5 THRESHOLD VOLTAGE, VRT5 (V) 4.725 4.700 4.675 4.650 4.625 4.600 –60 –40 –20 0 20 40 60 TEMPERATURE (°C) VCC3 THRESHOLD VOLTAGE, VRT3 (V) VCCA THRESHOLD VOLTAGE, VRTA (V) UW 80 VCC3 Threshold Voltage vs Temperature 3.135 3.125 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 1.015 1.010 1.005 1.000 0.995 0.990 VCCA Threshold Voltage vs Temperature 100 0.985 20 –60 –40 –20 0 40 60 TEMPERATURE (°C) 80 100 1726 G03 1726 G01 1726 G02 1726fb 3 LTC1726 TYPICAL PERFOR A CE CHARACTERISTICS VCC25 Threshold Voltage vs Temperature (LTC1726-2.5) 2.375 VCC25 THRESHOLD VOLTAGE, VRT25 (V) 2.360 IVCC5 (µA) 15 14 13 IVCC3 (µA) 2.345 2.330 2.315 2.300 20 40 60 –60 –40 –20 0 TEMPERATURE (°C) IVCC25 vs Temperature (LTC1726-2.5) 1.5 VCC3 = 3.3V 1.4 VCC25 = 2.5V 1.3 1.2 IVCC25 (µA) IVCC3 (µA) TYPICAL TRANSIENT DURATION (µs) 1.1 1.0 0.9 0.8 0.7 0.6 0.5 –60 –40 –20 0 20 40 60 TEMPERATURE (°C) 80 100 VCCA Input Current vs Input Voltage 2.0 1.5 INPUT CURRENT (nA) TA = 25°C WATCHDOG TIME PERIOD, tWT (ms) RESET PULSE WIDTH, tRT (ms) 1.0 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) 1726 G14 4 UW IVCC5 vs Temperature (LTC1726-5) VCC5 = 5V 19 VCC3 = 3.3V 18 17 16 20 1.5 IVCC3 vs Temperature (LTC1726-5) VCC5 = 5V 1.4 VCC3 = 3.3V 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6 12 11 80 100 1726 G04 10 –60 –40 –20 0 20 40 60 TEMPERATURE (°C) 80 100 0.5 –60 –40 –20 0 20 40 60 TEMPERATURE (°C) 80 100 1726 G05 1726 G06 IVCC3 vs Temperature (LTC1726-2.5) 20 VCC3 = 3.3V 19 VCC25 = 2.5V 18 17 16 15 14 13 12 11 10 –60 –40 –20 0 20 40 60 TEMPERATURE (°C) 80 100 700 600 500 400 300 200 100 Typical Transient Duration vs Comparator Overdrive TA = 25°C RESET OCCURS ABOVE CURVE 0 0.1 1 10 100 RESET COMPARATOR OVERDRIVE VOLTAGE (% OF VCC) 1726 G09 1726 G07 1726 G08 Watchdog Time-Out Period vs Temperature 40 38 36 34 32 30 28 26 20 40 60 –60 –40 –20 0 TEMPERATURE (°C) CWT = 1500pF (SILVER MICA) 6.0 Reset Pulse Width vs Temperature CRT = 1500pF 5.8 (SILVER MICA) 5.6 5.4 5.2 5.0 4.8 4.6 4.4 4.2 80 100 4.0 –60 –40 –20 0 20 40 60 TEMPERATURE (°C) 80 100 1726 G10 1726 G11 1726fb LTC1726 TYPICAL PERFOR A CE CHARACTERISTICS Watchdog Time-Out Period vs Capacitance 1000 WATCHDOG TIME-OUT PERIOD, t WT (sec) TA = 25°C RESET TIME-OUT PERIOD, tRT (sec) 100 10 1 100m 10m 1m 100µ 1p 10p 100p 1 100m 10m 1m 100µ 10µ 1p 10p 100p 1µ 10µ RST OUTPUT VOLTAGE (V) 10n 100n CWT (FARAD) 1n PI FU CTIO S 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. UW 1µ Reset Time-Out Period vs Capacitance 100 TA = 25°C RST Output Voltage vs Supply Voltage (LTC1726-2.5) VCC3 = VCC25 = VCCA 10k PULL-UP FROM VCC3 TO RST 3 T = 25°C A 10 2 1 10µ 10n 100n CRT (FARAD) 1n 0 0 1 2 VCC3 (V) 3 1726 F13 1726 G12 1726 G15 U U U 1726fb 5 LTC1726 PI FU CTIO S 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. BLOCK DIAGRA WDI 5 VCC3 1 VCC5/VCC25 2 VCCA 3 1V GND 4 TI I G DIAGRA S VCC Monitor Timing Watchdog Timing Diagram VCCX VRTX tUV tRT 1.5V 1726 TD01 RST 6 + + + – – – W W U U UW U 2µA TRANSITION DETECT WATCHDOG TIMER 7 WT + CWT 22µA VCC3 POWER DETECT VCC INTERNAL VCC5 /VCC25 VCC3 6µA ADJUSTABLE RESET PULSE GENERATOR 6 RST 2µA 22µA BANDGAP REFERENCE 8 + RT CRT 1726 BD WDI tWP tWT tRT tWT tRT RST 1.5V 1726 TD02 1726fb LTC1726 APPLICATIO S I FOR ATIO 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. Override Functions (5V Versions Only) RST OUTPUT VOLTAGE (V) The VCCA pin, if unused, can be tied to either VCC3 or VCC5. This is an obvious solution since the trip points for VCC3 and VCC5 will always be greater than the trip point for VCCA. The VCC5 input trip point is disabled if its voltage is equal to the voltage on VCC3 ± 25mV and the voltage on VCC5 is less than 4.15V. In this manner the LTC1726-5 behaves as a 3.3V monitor and the 5V reset function is disabled. The VCC5 trip point is re-enabled when the voltage on VCC5 is equal to the voltage on VCC3 ± 25mV and the two inputs are greater than approximately 4.15V. In this U 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 < 200ms during power-up, and the RST output will behave as desired. Table 1 summarizes the state of RST at various operating voltages with VCC3 = VCC5. Table 1. Override Truth Table (VCC3 = VCC5) INPUTS (VCC3 = VCC5 = VCC) 0V ≤ VCC ≤ 1V 1V ≤ VCC ≤ VRT3 VRT3 ≤ VCC ≤ 4.15V 4.15V ≤ VCC ≤ VRT5 VRT5 ≤ VCC VCC 3.3V OR 5V 1 2 3 4 W UU RST — 0 1 0 1 LTC1726-5 VCC3 VCC5 VCCA GND RST 6 TO SYSTEM RESET 1726 F01 R1 10k PINS 5, 7 AND 8 NOT SHOWN FOR CLARITY Figure 1. Single Supply Monitor with Others Disabled 5 VCC3 = VCC5 = VCCA = 0V TO 5V 10k PULL-UP FROM RST TO VCC3 TA = 25°C 4 3 2 1 0 0 1 3 4 2 SUPPLY VOLTAGE (V) 5 1726 F02 Figure 2. RST Voltage vs Supply Voltage 1726fb 7 LTC1726 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 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 LTC1726-5 1 2 3 VCC3 VCC5 VCCA GND RST 6 TO SYSTEM RESET 1726 F03 R1 10k 0.1µF 4 D1: MMBD914 OR EQUIVALENT PINS 5, 7 AND 8 NOT SHOWN FOR CLARITY Figure 3. LTC1726-5 Monitoring a Single 5V Supply. D1 Used to Avoid RST High Near 3.1V to 4V (See Figure 2). 5 VCC5 = VCCA = 0V TO 5V 10k PULL-UP FROM RST TO VCC5 TA = 25°C RST OUTPUT VOLTAGE (V) 4 3 2 1 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 VCC5 (V) 1726 F04 Figure 4. RST Output Voltage Characteristics of the Circuit in Figure 3 8 U LTC1726-2.5 Override Functions The VCCA pin, if unused, can be tied to either VCC3 or VCC25. This is an obvious solution since the trip points for VCC3 and VCC25 will always be greater than the trip point for VCCA. Likewise, the VCC25, if unused, can be tied to VCC3. VCC3 must always be used. Tying VCC3 to VCC25 and operating off of a 2.5V supply will result in the continuous assertion of RST. Watchdog Timer The watchdog circuit monitors a µP’s activity. The µP is required to change the logic state of the WDI pin on a periodic basis in order to clear the watchdog timer and prevent the LTC1726 from issuing a reset. During power-up, the watchdog timer remains cleared while reset is asserted. As soon as the reset timer times out, the watchdog timer is started. The watchdog timer will continue to run until a transition is detected on the WDI input or until the watchdog timer times out. Once the watchdog timer times out, the internal circuitry asserts the reset and starts the reset timer. When the reset timer times out and reset is deasserted, the watchdog timer is again started. If no WDI transition is received within the watchdog time-out period, the reset will be reasserted at the end of the watchdog time-out period. If a transition is received on the WDI input during the watchdog time-out period, the watchdog timer will be restarted and reset will remain deasserted. 1726fb W UU LTC1726 APPLICATIO S I FOR ATIO Selecting the Reset and Watchdog Time-Out Capacitors The reset time-out period is adjustable in order to accommodate a variety of µP applications. The reset time-out period, tRT, is adjusted by connecting a capacitor, CRT, between the RT pin and ground. The value of this capacitor is determined as follows: CRT = tRT/3.30 with CRT in pF and tRT in µs (i.e., 1500pF ⇒ 4.95ms). The capacitor should be a low leakage type. A ceramic capacitor is recommended. TYPICAL APPLICATIO S Disabling the Watchdog Timer LTC1726-5/2.5 3.3V R1* 5V/2.5V 1 VCC3 2V / CC5 VCC25 3 VCCA 4 GND RT WT RST WDI 8 7 6 5 SYSTEM RESET CRT ADJUSTABLE SUPPLY *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 Triple Supply Monitor (3.3V, 5V and Adjustable) LTC1726-5 3.3V ADJUSTABLE SUPPLY OR DC/DC FEEDBACK DIVIDER R1* 5V 1 2 3 R2* 4 VCC3 VCC5 VCCA GND RT WT RST WDI 8 7 6 5 CWT SYSTEM RESET WDI 1726 TA04 CRT *TO PRESERVE THRESHOLD ACCURACY, SET PARALLEL COMBINATION OF R1 AND R2 ≤ 66.5k U The watchdog period is also adjustable so that the watchdog time-out period can be optimized for software execution. The watchdog time-out period, tWT, is adjusted by connecting a capacitor, CWT, between the WT pin and ground. Once the optimum watchdog time-out period (tWT) is determined, the value of the capacitor is calculated as follows: CWT = tWT/21.8 with CWT in pF and tWT in µs (i.e., 1500pF ⇒ 32.7ms). The capacitor should be a low leakage type. A ceramic capacitor is recommended. R2* 1726 TA03 W U UU Dual Supply Monitor (3.3V and 5V, Defeat VCCA Input) LTC1726-5 3.3V 5V 1 2 3 4 VCC3 VCC5 VCCA GND RT WT RST WDI 8 7 6 5 CWT SYSTEM RESET WDI 1726 TA05 CRT 1726fb 9 LTC1726 TYPICAL APPLICATIO S Dual Supply Monitor (3.3V or 5V Plus Adjustable) ADJUSTABLE SUPPLY ADJUSTABLE SUPPLY ADJUSTABLE RESET TRIP THRESHOLD 2.74V 10 U 3.3V OR 5V 1 2 R1* R2* 3 4 LTC1726-5 VCC3 VCC5 VCCA GND RT WT RST WDI 8 7 6 5 10k CRT REFER TO LTC1726-X OVERRIDE FUNCTIONS IN THE APPLICATIONS INFORMATION SECTION CWT SYSTEM RESET WDI 1726 TA06 *TO PRESERVE THRESHOLD ACCURACY, SET PARALLEL COMBINATION OF R1 AND R2 ≤ 66.5k Dual Supply Monitor (3.3V Plus Adjustable) 3.3V LTC1726-2.5 1 2 R1* R2* 3 4 VCC3 VCC25 VCCA GND RT WT RST WDI 8 7 6 5 CWT SYSTEM RESET WDI 1726 TA07 10k CRT *TO PRESERVE THRESHOLD ACCURACY, SET PARALLEL COMBINATION OF R1 AND R2 ≤ 66.5k Using VCCA Tied to DC/DC Feedback Divider 2.9V LTC1435 VOSENSE 6 35.7k 1% 3.3V 2.8k 5V 1% 22.1k 1% LTC1726-5 1 2 3 4 VCC3 VCC5 VCCA GND RT WT RST WDI 1726 TA08 CRT 8 7 6 5 CWT SYSTEM RESET WDI 1726fb LTC1726 PACKAGE DESCRIPTIO 5.23 (.206) MIN 0.42 ± 0.04 (.0165 ± .0015) TYP RECOMMENDED SOLDER PAD LAYOUT DETAIL “A” 0° – 6° TYP 4.90 ± 0.15 (1.93 ± .006) GAUGE PLANE 0.53 ± 0.015 (.021 ± .006) DETAIL “A” 0.18 (.077) SEATING PLANE 0.22 – 0.38 (.009 – .015) TYP 0.13 ± 0.076 (.005 ± .003) MSOP (MS8) 0802 NOTE: 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX .050 BSC 8 .245 MIN .030 ±.005 TYP RECOMMENDED SOLDER PAD LAYOUT .010 – .020 × 45° (0.254 – 0.508) .008 – .010 (0.203 – 0.254) 0°– 8° TYP NOTE: 1. DIMENSIONS IN INCHES (MILLIMETERS) 2. DRAWING NOT TO SCALE 3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm) Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. U MS8 Package 8-Lead Plastic MSOP (Reference LTC DWG # 05-08-1660) 0.889 ± 0.127 (.035 ± .005) 3.2 – 3.45 (.126 – .136) 0.65 (.0256) BSC 3.00 ± 0.102 (.118 ± .004) (NOTE 3) 8 7 65 0.52 (.206) REF 0.254 (.010) 3.00 ± 0.102 (.118 ± .004) NOTE 4 1 23 4 1.10 (.043) MAX 0.86 (.034) REF 0.65 (.0256) BSC S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch) (Reference LTC DWG # 05-08-1610) .045 ±.005 .189 – .197 (4.801 – 5.004) NOTE 3 7 6 5 .160 ±.005 .228 – .244 (5.791 – 6.197) .150 – .157 (3.810 – 3.988) NOTE 3 1 2 3 4 .053 – .069 (1.346 – 1.752) .004 – .010 (0.101 – 0.254) .016 – .050 (0.406 – 1.270) .014 – .019 (0.355 – 0.483) TYP .050 (1.270) BSC SO8 0303 1726fb 11 LTC1726 TYPICAL APPLICATIO Triple Supply Monitor with Watchdog Timer and Manual Reset Button MANUAL RESET BUTTON (NORMALLY OPEN) *OPTIONAL RESISTOR RECOMMENDED TO EXTEND ESD TOLERANCE RELATED PARTS PART NUMBER LTC690 LTC694-3.3 LTC699 LTC1232 LTC1326 LTC1326-2.5 LTC1536 LTC1727-5 LTC1727-2.5 LTC1728-5 LTC1728-2.5 LTC1728-1.8 LTC1985-1.8 LTC2900 LTC2901 LTC2902 LTC2903 LTC2908 LTC2910 DESCRIPTION 5V Supply Monitor, Watchdog Timer and Battery Backup 3.3V Supply Monitor, Watchdog Timer and Battery Backup 5V Supply Monitor and Watchdog Timer 5V Supply Monitor, Watchdog Timer and Push-Button Reset Micropower Precision Triple Supply Monitor for 5V, 3.3V and ADJ Micropower Precision Triple Supply Monitor for 2.5V, 3.3V and ADJ Precision Triple Supply Monitor for PCI Applications Micropower Triple Supply Monitor with Individual Outputs Micropower Triple Supply Monitor with Individual Outputs Micropower Triple Supply Monitor in 5-Pin SOT-23 Package Micropower Triple Supply Monitor in 5-Pin SOT-23 Package Micropower Triple Supply Monitor in 5-Pin SOT-23 Package Micropower Triple Supply Monitor for 3V, 1.8V and ADJ Quad Supply Monitor Quad Supply Monitor with Watchdog Timer Quad Supply Monitor with Selectable Supply Tolerance Precision Quad Supply Monitor in SOT-23 Precision Six Supply Monitor Octal Positive/Negative Voltage Monitor COMMENTS 4.65V Threshold 2.9V Threshold 4.65V Threshold 4.37V/4.62V Threshold 4.725V, 3.118V, 1V Thresholds (± 0.75%) 5V, 3.3V, ADJ 2.363V, 3.118V, 1V Thresholds (± 0.75%) 2.5V, 3.3V, ADJ Meets PCI tFAIL Timing Specifications 4.675V, 3.086V, 1V Thresholds (± 1.5%) 5V, 3.3V, ADJ 2.338V, 3.086V, 1V Thresholds (± 1.5%) 2.5V, 3.3V, ADJ 4.675V, 3.086V, 1V Thresholds (± 1.5%) 5V, 3.3V, ADJ 2.338V, 3.086V, 1V Thresholds (± 1.5%) 2.5V, 3.3V, ADJ 2.805V, 1.683V, 1V Thresholds (± 1.5%) 3V, 1.8V, ADJ Push-Pull RESET Output, SOT-23 Adjustable Reset Timer Adjustable Watchdog and Reset Timers Reset Disable for Margining Applications Fixed and Adjustable Threshold Combinations 8-Lead ThinSOT and 3mm × 2mm DFN Packages 8 Low Voltage Adjustable Inputs (0.5V) 12 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● U 12V (± 5%) VTRIP = 11.2V (± 0.17V) 5V 3.3V 47nF VCC3 100nF R3* 10k 5% R1 1.07M 0.1% R2 105k 0.1% RT 47nF LTC1726-5 VCC5 100nF VCCA RST RESET µP GND WDI I/O 1726 TA09 WT V VTRIP = CCA (R1 + R2) R2 V R1 = R2 TRIP – 1 VCCA ( ) tRT = 155ms tWT = 1s 1726fb LT/LWI 1106 REV B • PRINTED IN USA www.linear.com © LINEAR TECHNOLOGY CORPORATION 2000