Final Electrical Specifications LTC1726 Triple Supply Monitor and µP Supervisor with Adjustable Reset and Watchdog Timer January 2000 U 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 U DESCRIPTIO ■ ■ ■ ■ 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 , LTC and LT are registered trademarks of Linear Technology Corporation. U ■ 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. TYPICAL APPLICATIO S 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 2 CRT 47nF 1 3 VCC5 VCC3 VCCA 8 RST RT CWT 47nF 6 1.8V (VTRIP = 1.665V) R1 66.5k 1% 3.3V R2 100k 1% 2.5V 0.1µF µP 5 WT WDI 2 CRT 47nF CWT 47nF GND tRT = 155ms tWT= 1s 4 R2 100k 1% 3 RT RST 6 RESET µP LTC1726-2.5 7 I/O 1 VCC25 VCC3 VCCA 8 RESET LTC1726-5 7 R1 66.5k 1% 0.1µF 5 WT WDI I/O GND 1726 TA01 tRT = 155ms tWT= 1s 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. 4 1726 TA02 1 LTC1726 W W W AXI U U ABSOLUTE RATI GS Terminal Voltage VCC3, VCC5/VCC25, VCCA ......................... RST ....................................................... WDI ....................................................... RT, WT .................................................. (Notes 1, 2) – 0.3V to 7V – 0.3V to 7V – 0.3V to 7V – 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 U U W 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 TJMAX = 125°C, θJA = 200°C/W LTKZ LTLA ORDER PART NUMBER LTC1726ES8-2.5 LTC1726ES8-5 LTC1726IS8-2.5 LTC1726IS8-5 TOP VIEW VCC3 1 VCC25/ 2 VCC5 VCCA 3 8 RT 7 WT 6 RST GND 4 5 WDI S8 PART MARKING S8 PACKAGE 8-LEAD PLASTIC SO 172625 726I25 17265 1726I5 TJMAX = 125°C, θJA = 150°C/W Consult factory for Military grade parts. ELECTRICAL CHARACTERISTICS 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 PARAMETER CONDITIONS MIN TYP MAX UNITS VRT3 Reset Threshold VCC3 VCC3 Input Threshold ● 3.036 3.085 3.135 V VRT5 Reset Threshold VCC5 VCC5 Input Threshold (5V Version) ● 4.600 4.675 4.750 V VRT25 Reset Threshold VCC25 VCC25 Input Threshold (2.5V Version) ● 2.300 2.337 2.375 V VRTA Reset Threshold VCCA VCCA Input Threshold ● 0.985 1.000 1.015 V VCC VCC3 or VCC5 Operating Voltage RST in Correct Logic State ● 1 7 V IVCC3 VCC3 Supply Current VCC5/VCC25 > VCC3 VCC5/VCC25 < VCC3, VCC3 = 3.3V ● ● 1 16 2 30 µA µA IVCC5 VCC5 Supply Current VCC5 = 5V ● 16 30 µA IVCC25 VCC25 Supply Current VCC25 < VCC3, VCC25 = 2.5V (Note 4) ● 1 2 µA IVCCA VCCA Input Current VCCA = 1V ● – 15 0 15 nA RT Charge Current Out VRT = 0V ● 1.4 2 2.6 µA WT Charge Current Out VWT = 0V ● 1.4 2 2.6 µA RT Discharge Current Out VRT = 1.3V ● 14 20 26 µA WT Discharge Current Out VWT = 1.3V ● 14 20 26 µA 2 LTC1726 ELECTRICAL CHARACTERISTICS 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 PARAMETER CONDITIONS tRT Reset Time-Out Period CRT = 1500pF 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 5) ISOURCE = 1µA ● 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 ● ● ● ● VIH WDI Input Threshold High ● VIL WDI Input Threshold Low ● 0.3 • VCC3 V tWP WDI Pulse Width ● 40 ns tWT Watchdog Time-Out Period ● 23 ● MIN TYP MAX 3.5 5 6.5 WDI Leakage Current ms µs 130 CWT = 1500pF UNITS 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 33 ● 43 ms ±1 µA LTC1726-5 Only VOVR VCC5 Reset Override Voltage (Note 6) VCC3 ±0.025 Override VCC5 Ability to Assert RST Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. 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. V Note 4: Both VCC3 and VCC25/VCC5 can act as the supply depending on which pin has the greatest potential. Note 5: The output pin RST has weak internal pull-ups 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 6: 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. U W TYPICAL PERFOR A CE CHARACTERISTICS VCC5 Threshold Voltage vs Temperature VCC3 Threshold Voltage vs Temperature 3.135 4.725 4.700 4.675 4.650 4.625 80 100 1726 G01 1.015 3.125 VCCA THRESHOLD VOLTAGE, VRTA (V) VCC3 THRESHOLD VOLTAGE, VRT3 (V) VCC5 THRESHOLD VOLTAGE, VRT5 (V) 4.750 4.600 –60 –40 –20 0 20 40 60 TEMPERATURE (°C) VCCA Threshold Voltage vs Temperature 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 1726 G02 1.010 1.005 1.000 0.995 0.990 0.985 20 40 60 –60 –40 –20 0 TEMPERATURE (°C) 80 100 1726 G03 3 LTC1726 U W TYPICAL PERFOR A CE CHARACTERISTICS VCC25 Threshold Voltage vs Temperature IVCC5 vs Temperature 1.5 VCC5 = 5V 1.4 VCC3 = 3.3V 2.360 18 1.3 17 1.2 2.345 16 1.1 2.330 2.315 2.300 20 40 60 –60 –40 –20 0 TEMPERATURE (°C) IVCC3 (µA) VCC5 = 5V 19 VCC3 = 3.3V IVCC5 (µA) VCC25 THRESHOLD VOLTAGE, VRT25 (V) IVCC3 vs Temperature (LTC1726-5) 20 2.375 15 14 13 0.8 0.7 11 0.6 80 IVCC25 vs Temperature (LTC1726-2.5) 16 1.0 0.9 15 14 0.8 13 0.7 12 0.6 11 80 10 –60 –40 –20 0 20 40 60 TEMPERATURE (°C) 100 80 100 TA = 25°C 600 500 400 VCCA Input Current vs Input Voltage 300 200 100 0 1 10 100 0.1 RESET COMPARATOR OVERDRIVE VOLTAGE (% OF VCC) 1726 G09 Watchdog Time-Out Period vs Temperature 40 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 Reset Pulse Width vs Temperature 6.0 CWT = 1500pF 5.8 38 RESET PULSE WIDTH, tRT (ms) WATCHDOG TIME PERIOD, tWT (ms) TA = 25°C 1.5 RESET OCCURS ABOVE CURVE 1726 G08 1726 G07 INPUT CURRENT (nA) TYPICAL TRANSIENT DURATION (µs) 1.1 IVCC3 (µA) IVCC25 (µA) 18 17 4 700 VCC3 = 3.3V 19 VCC25 = 2.5V 1.2 36 34 32 30 28 26 20 40 60 –60 –40 –20 0 TEMPERATURE (°C) 100 Typical Transient Duration vs Comparator Overdrive 20 1.3 80 1726 G06 IVCC3 vs Temperature (LTC1726-2.5) 1.5 VCC3 = 3.3V 1.4 VCC25 = 2.5V 2.0 0.5 –60 –40 –20 0 20 40 60 TEMPERATURE (°C) 100 1726 G05 1726 G04 0.5 –60 –40 –20 0 20 40 60 TEMPERATURE (°C) 0.9 12 10 –60 –40 –20 0 20 40 60 TEMPERATURE (°C) 80 100 1.0 CRT = 1500pF 5.6 5.4 5.2 5.0 4.8 4.6 4.4 4.2 80 100 1726 G10 4.0 –60 –40 –20 0 20 40 60 TEMPERATURE (°C) 80 100 1726 G11 LTC1726 U W TYPICAL PERFOR A CE CHARACTERISTICS RST Output Voltage vs Supply Voltage (LTC1726-2.5) Time-Out Period vs Capacitance 106 TA = 25°C RST OUTPUT VOLTAGE (V) 105 tRT OR tWT (µs) VCC3 = VCC25 = VCCA 10k PULL-UP FROM VCC3 TO RST TA = 25°C 3 tWT 104 tRT 103 102 10 0.1 1 10 102 CRT OR CWT (pF) 103 104 2 1 0 0 1 2 3 VCC3 (V) 1726 G12 1726 F13 U U U 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. 5 LTC1726 U U U 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: with tRT in µs and CRT in pF. As an example, a 47nF capacitor will generate a 155ms watchdog time-out period. tRT = 3.30 • CRT W BLOCK DIAGRA 2µA WDI 5 TRANSITION DETECT WATCHDOG TIMER 7 WT + CWT – VCC3 1 22µA VCC3 + POWER DETECT VCC INTERNAL – VCC5/VCC25 2 VCC5 /VCC25 VCC3 + 6µA – VCCA 3 1V GND 4 6 RST ADJUSTABLE RESET PULSE GENERATOR + 2µA 22µA BANDGAP REFERENCE 8 + 1726 BD RT CRT W UW TI I G DIAGRA S VCC Monitor Timing VCCX Watchdog Timing Diagram VRTX WDI tRT tWT tRT tWT tRT RST RST 1726 TD01 6 tWP 1726 TD02 LTC1726 U W U U 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. 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 0 VRT3 ≤ VCC ≤ 4.15V 1 4.15V ≤ VCC ≤ VRT5 0 VRT5 ≤ VCC 1 VCC 3.3V OR 5V 2 3 4 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 R1 10k VCC3 VCC5 VCCA RST 6 TO SYSTEM RESET GND 1726 F01 PINS 5, 7 AND 8 NOT SHOWN FOR CLARITY Figure 1. Single Supply Monitor with Others Disabled 5 RST OUTPUT VOLTAGE (V) 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. LTC1726-5 1 Override Functions (5V Versions Only) 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. RST 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 7 LTC1726 U W U 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 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 4 0.1µF R1 10k VCC3 VCC5 VCCA RST 6 TO SYSTEM RESET GND 1726 F03 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). 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. RST OUTPUT VOLTAGE (V) 5 VCC5 = VCCA = 0V TO 5V 10k PULL-UP FROM RST TO VCC5 TA = 25°C 4 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: 3 2 1 CRT = tRT/3.30 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 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. 8 with CRT in pF and tRT in µs (i.e., 1500pF ⇒ 4.95ms). 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). LTC1726 U TYPICAL APPLICATIO S Disabling the Watchdog Timer LTC1726-5/2.5 3.3V ADJUSTABLE SUPPLY R1* 5V/2.5V R2* 1 VCC3 2 V / CC5 VCC25 3 VCCA 4 GND RT WT RST WDI CRT 8 7 6 5 SYSTEM RESET 1726 TA03 *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 RT VCC5 WT VCCA RST GND WDI CRT 8 CWT 7 6 5 SYSTEM RESET WDI 1726 TA04 *TO PRESERVE THRESHOLD ACCURACY, SET PARALLEL COMBINATION OF R1 AND R2 ≤ 66.5k Dual Supply Monitor (3.3V and 5V, Defeat VCCA Input) LTC1726-5 3.3V 5V 1 2 3 4 VCC3 RT VCC5 WT VCCA RST GND WDI CRT 8 CWT 7 6 5 SYSTEM RESET WDI 1726 TA05 9 LTC1726 U TYPICAL APPLICATIO S Dual Supply Monitor (3.3V or 5V Plus Adjustable) 3.3V OR 5V LTC1726-5 1 2 ADJUSTABLE SUPPLY R1* 3 R2* 4 VCC3 RT VCC5 WT VCCA RST GND WDI 4.7k CRT 8 REFER TO LTC1726-X OVERRIDE FUNCTIONS IN THE APPLICATIONS INFORMATION SECTION CWT 7 6 SYSTEM RESET 5 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 ADJUSTABLE SUPPLY R1* 3 R2* 4 VCC3 RT VCC25 WT VCCA RST GND WDI 4.7k CRT 8 CWT 7 6 SYSTEM RESET 5 WDI 1726 TA07 *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 ADJUSTABLE RESET TRIP THRESHOLD 2.74V 10 6 35.7k 1% 3.3V 2.8k 5V 1% 22.1k 1% LTC1726-5 1 2 3 4 VCC3 RT VCC5 WT VCCA RST GND WDI 1726 TA08 CRT 8 CWT 7 6 5 SYSTEM RESET WDI LTC1726 U PACKAGE DESCRIPTIO Dimensions in (inches) unless otherwise noted. MS8 Package 8-Lead Plastic MSOP (LTC DWG # 05-08-1660) 0.118 ± 0.004* (3.00 ± 0.102) 8 7 6 5 0.118 ± 0.004** (3.00 ± 0.102) 0.193 ± 0.006 (4.90 ± 0.15) 1 4 2 3 0.040 ± 0.006 (1.02 ± 0.15) 0.007 (0.18) 0.034 ± 0.004 (0.86 ± 0.102) 0° – 6° TYP SEATING PLANE 0.012 (0.30) 0.0256 REF (0.65) BSC 0.021 ± 0.006 (0.53 ± 0.015) 0.006 ± 0.004 (0.15 ± 0.102) MSOP (MS8) 1098 * DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE S8 Package 8-Lead Plastic Small Outline (Narrow 0.150) (LTC DWG # 05-08-1610) 0.189 – 0.197* (4.801 – 5.004) 8 7 6 5 0.150 – 0.157** (3.810 – 3.988) 0.228 – 0.244 (5.791 – 6.197) 1 0.010 – 0.020 × 45° (0.254 – 0.508) 0.008 – 0.010 (0.203 – 0.254) 0.053 – 0.069 (1.346 – 1.752) 0°– 8° TYP 0.016 – 0.050 (0.406 – 1.270) 0.014 – 0.019 (0.355 – 0.483) TYP *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE 2 3 4 0.004 – 0.010 (0.101 – 0.254) 0.050 (1.270) BSC SO8 1298 11 LTC1726 U TYPICAL APPLICATIO Triple Supply Monitor with Watchdog Timer and Manual Reset Button 12V (± 5%) VTRIP = 11.2V (± 0.17V) 5V 3.3V 1500pF 1 100nF R3* 10k 5% MANUAL RESET BUTTON (NORMALLY OPEN) R1 1.07M 0.1% VCC3 RT 8 1500pF LTC1726-5 2 VCC5 WT VCCA RST GND WDI 7 100nF 3 R2 105k 0.1% 4 6 RESET µP 5 I/O 1726 TA09 *OPTIONAL RESISTOR RECOMMENDED TO EXTEND ESD TOLERANCE 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 4.65V Threshold LTC694-3.3 3.3V Supply Monitor, Watchdog Timer and Battery Backup 2.9V Threshold LTC699 5V Supply Monitor and Watchdog Timer 4.65V Threshold LTC1232 5V Supply Monitor, Watchdog Timer and Push-Button Reset 4.37V/4.62V Threshold LTC1326 Micropower Precision Triple Supply Monitor for 5V, 3.3V and ADJ 4.725V, 3.118V, 1V Thresholds (±0.75%) 5V, 3.3V, ADJ LTC1326-2.5 Micropower Precision Triple Supply Monitor for 2.5V, 3.3V and ADJ 2.363V, 3.118V, 1V Thresholds (±0.75%) 2.5V, 3.3V, ADJ LTC1536 Precision Triple Supply Monitor for PCI Applications Meets PCI tFAIL Timing Specifications LTC1727-5 Micropower Triple Supply Monitor with Individual Outputs 4.675V, 3.086V, 1V Thresholds (±1.5%) 5V, 3.3V, ADJ LTC1727-2.5 Micropower Triple Supply Monitor with Individual Outputs 2.338V, 3.086V, 1V Thresholds (±1.5%) 2.5V, 3.3V, ADJ LTC1728-5 Micropower Triple Supply Monitor in 5-Pin SOT-23 Package 4.675V, 3.086V, 1V Thresholds (±1.5%) 5V, 3.3V, ADJ LTC1728-2.5 Micropower Triple Supply Monitor in 5-Pin SOT-23 Package 2.338V, 3.086V, 1V Thresholds (±1.5%) 2.5V, 3.3V, ADJ 12 Linear Technology Corporation 1726i LT/TP 0100 4K • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com LINEAR TECHNOLOGY CORPORATION 2000