ADM708S

3 V, Voltage Monitoring Microprocessor Supervisory Circuits ADM706P/ADM706R/ADM706S/ADM706T, ADM708R/ADM708S/ADM708T FEATURES Precision supply voltage monitor 2.63 V (ADM706P, ADM706R, ADM708R) 2.93 V (ADM706S, ADM708S) 3.08 V (ADM706T, ADM708T) 100 μA quiescent current 200 ms reset pulse width Debounced manual reset input (MR) Independent watchdog timer 1.6 second timeout (ADM706x) Reset output Active high (ADM706P) Active low (ADM706R, ADM706S, ADM706T) Both active high and active low (ADM708R, ADM708S, ADM708T) Voltage monitor for power-fail or low battery warning Guaranteed RESET valid with VCC = 1 V Superior upgrade for MAX706P/R/S/T, MAX708R/S/T WATCHDOG INPUT (WDI) FUNCTIONAL BLOCK DIAGRAMS WATCHDOG TRANSITION DETECTOR VCC 70μA MR VCC VREF* POWER-FAIL INPUT (PFI) 1.25V WATCHDOG TIMER WATCHDOG OUTPUT (WDO) RESET AND WATCHDOG TIMEBASE RESET GENERATOR RESET, (P = RESET) ADM706P/ADM706R/ ADM706S/ADM706T POWER-FAIL OUTPUT (PFO) 06435-001 * VOLTAGE REFERENCE = 2.63V (P/R), 2.93V (S), 3.08V (T) Figure 1. ADM706P/ADM706R/ADM706S/ADM706T VCC 70μA MR RESET GENERATOR VREF * POWER-FAIL INPUT (PFI) 1.25V * VOLTAGE REFERENCE = 2.63V (R), 2.93V (S), 3.08V (T) RESET RESET APPLICATIONS Microprocessor systems Computers Controllers Intelligent instruments Critical microprocessor monitoring Battery-operated systems Portable instruments VCC ADM708R/ADM708S/ ADM708T 06435-002 POWER-FAIL OUTPUT (PFO) Figure 2. ADM708R/ADM708S/ADM708T GENERAL DESCRIPTION The ADM706P/ADM706R/ADM706S/ADM706T and the ADM708R/ADM708S/ADM708T microprocessor supervisory circuits are suitable for monitoring either 3 V or 3.3 V power supplies. The ADM706P/ADM706R/ADM706S/ADM706T provide power-supply monitoring circuitry that generate a reset output during power-up, power-down, and brownout conditions. The reset output remains operational with VCC as low as 1 V. Independent watchdog monitoring circuitry is also provided. This is activated if the watchdog input has not been toggled within 1.6 seconds. In addition, there is a 1.25 V threshold detector for power-fail warning, low battery detection, or to monitor an additional power supply. An active low debounced MR input is also included. The ADM706R, ADM706S, and ADM706T are identical except for the reset threshold monitor levels, which are 2.63 V, 2.93 V, and 3.08 V, respectively. The ADM706P is identical to the ADM706R in that the reset threshold is 2.63 V. It differs only in that it has an active high reset output. The ADM708R/ADM708S/ADM708T provide similar functionality as the ADM706R/ADM706S/ADM706T and only differ in that a watchdog timer function is not available. Instead, an active high reset output (RESET) is provided in addition to the active low (RESET) output. All parts are available in narrow 8-lead PDIP and 8-lead SOIC packages. Rev. C Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 ©1995–2008 Analog Devices, Inc. All rights reserved. ADM706P/ADM706R/ADM706S/ADM706T, ADM708R/ADM708S/ADM708T TABLE OF CONTENTS Features .............................................................................................. 1 Applications ....................................................................................... 1 Functional Block Diagrams ............................................................. 1 General Description ......................................................................... 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 Absolute Maximum Ratings............................................................ 5 ESD Caution .................................................................................. 5 Pin Configurations and Function Descriptions ........................... 6 Typical Performance Characteristics ............................................. 8 Circuit Information ........................................................................ 10 Power-Fail Reset ......................................................................... 10 Manual Reset............................................................................... 10 Watchdog Timer (ADM706x) .................................................. 10 Power-Fail Comparator ............................................................. 11 Adding Hysteresis to the Power-Fail Comparator ................. 11 Valid RESET Below 1 V VCC ..................................................... 11 Applications Information .............................................................. 12 Monitoring Additional Supply Levels...................................... 12 Microprocessors with Bidirectional RESET ........................... 12 Outline Dimensions ....................................................................... 13 Ordering Guide .......................................................................... 14 REVISION HISTORY 5/08—Rev. B to Rev. C Changes to Applications Section .................................................... 1 Changes to Table 2 ............................................................................ 5 Changes to Table 3 ............................................................................ 6 Changes to Figure 8 .......................................................................... 7 Changes to Figure 16 ........................................................................ 9 2/07—Rev. A to Rev. B Updated Format .................................................................. Universal Changes to Table 1 ............................................................................ 3 Updated Outline Dimensions ....................................................... 12 Changes to Ordering Guide .......................................................... 13 Rev. C | Page 2 of 16 ADM706P/ADM706R/ADM706S/ADM706T, ADM708R/ADM708S/ADM708T SPECIFICATIONS VCC = 2.70 V to 5.5 V (ADM706P/ADM70xR), VCC = 3.00 V to 5.5 V (ADM70xS), VCC = 3.15 V to 5.5 V (ADM70xT), TA = TMIN to TMAX unless otherwise noted. Table 1. Parameter POWER SUPPLY VCC Operating Voltage Range Supply Current LOGIC OUTPUT Reset Threshold (VRST) Min 1.0 100 150 2.55 2.85 3.00 160 160 2.63 2.93 3.08 20 200 200 200 Typ Max 5.5 200 350 2.70 3.00 3.15 280 280 Unit V μA μA V V V mV ms ms ms Test Conditions/Comments VCC < 3.6 V VCC < 5.5 V ADM706P/ADM70xR ADM70xS ADM70xT ADM706P/ADM70xR, VCC = 3 V ADM70xS/ADM70xT, VCC = 3.3 V VCC = 5.0 V Reset Threshold Hysteresis RESET PULSE WIDTH RESET OUTPUT VOLTAGE (ADM70xR/ADM70xS/ADM70xT) VOH VOL VOH VOL VOL RESET OUTPUT VOLTAGE (ADM706P) VOH VOL VOH VOL RESET OUTPUT VOLTAGE (ADM708x) VOH VOL VOH VOL WATCHDOG INPUT (ADM706x) Watchdog Timeout Period 0.8 × VCC 0.3 VCC − 1.5 V 0.4 0.3 VCC − 0.6 V 0.3 VCC − 1.5 V 0.4 0.8 × VCC 0.3 VCC − 1.5 V 0.4 1.00 1.60 2.25 V V V V V V V V V V V V V sec VRST (max) < VCC < 3.6 V, ISOURCE = 500 μA VRST (max) < VCC < 3.6 V, ISINK = 1.2 mA 4.5 V < VCC < 5.5 V, ISOURCE = 800 μA 4.5 V < VCC < 5.5 V, ISINK = 3.2 mA VCC = 1 V, ISINK = 100 μA VRST (max) < VCC < 3.6 V, ISOURCE = 215 μA VRST (max) < VCC < 3.6 V, ISINK = 1.2 mA 4.5 V < VCC < 5.5 V, ISOURCE = 800 μA 4.5 V < VCC < 5.5 V, ISINK = 3.2 mA VRST (max) < VCC < 3.6 V, ISOURCE = 500 μA VRST (max) < VCC < 3.6 V, ISINK = 500 μA 4.5 V < VCC < 5.5 V, ISOURCE = 800 μA 4.5 V < VCC < 5.5 V, ISINK = 1.2 mA ADM706P/ADM706R: VCC = 3 V; ADM706S/ADM706T: VCC = 3.3 V; VIL = 0.4 V, VIH = VCC × 0.8 V VRST (max) < VCC < 3.6 V 4.5 V < VCC < 5.5 V VRST (max) < VCC < 3.6 V VRST (max) < VCC < 3.6 V VCC = 5.0 V VCC = 5.0 V WDI = 0 V or VCC VRST (max) < VCC < 3.6 V, ISOURCE = 500 μA 4.5 V < VCC < 5.5 V, ISOURCE = 800 μA VRST (max) < VCC < 3.6 V, ISINK = 500 μA 4.5 V < VCC < 5.5 V, ISINK = 1.2 mA WDI Pulse Width WDI Input Threshold VIL VIH VIL VIH WDI Input Current WDO OUTPUT VOLTAGE VOH VOL 100 50 0.6 0.7 × VCC 0.8 3.5 −1.0 0.8 × VCC VCC − 1.5 V 0.3 0.4 +0.02 +1.0 ns ns V V V V μA V V V V Rev. C | Page 3 of 16 ADM706P/ADM706R/ADM706S/ADM706T, ADM708R/ADM708S/ADM708T Parameter MANUAL RESET INPUT MR Pull-Up Current (MR = 0 V ) MR Pulse Width MR INPUT THRESHOLD VIL VIH VIL VIH MR TO RESET OUTPUT DELAY POWER-FAIL INPUT PFI Input Threshold PFI Input Current PFO OUTPUT VOLTAGE VOH VOL VOH VOL Min 25 100 500 150 Typ 70 250 Max 250 600 Unit μA μA ns ns V V V V ns ns V nA V V V V VRST (max) < VCC < 3.6 V, ISOURCE = 500 μA VRST (max) < VCC < 3.6 V, ISINK = 1.2 mA 4.5 V < VCC < 5.5 V, ISOURCE = 800 μA 4.5 V < VCC < 5.5 V, ISINK = 3.2 mA Test Conditions/Comments VRST (max) < VCC < 3.6 V 4.5 V < VCC < 5.5 V VRST (max) < VCC < 3.6 V 4.5 V < VCC < 5.5 V VRST (max) < VCC < 3.6 V VRST (max) < VCC < 3.6 V 4.5 V < VCC < 5.5 V 4.5 V < VCC < 5.5 V VRST (max) < VCC < 3.6 V 4.5 V < VCC < 5.5 V ADM70xP/ADM70xR, VCC = 3 V ADM70xS/ADM70xT, VCC = 3.3 V, PFI falling 0.6 0.7 × VCC 0.8 2.0 750 250 1.2 −25 0.8 × VCC 0.3 VCC − 1.5 V 0.4 1.25 +0.01 1.3 +25 Rev. C | Page 4 of 16 ADM706P/ADM706R/ADM706S/ADM706T, ADM708R/ADM708S/ADM708T ABSOLUTE MAXIMUM RATINGS TA = 25°C unless otherwise noted. Table 2. Parameter VCC All Other Inputs Input Current VCC GND Digital Output Current Power Dissipation, N-8 (PDIP) θJA Thermal Impedance Power Dissipation, R-8 (SOIC) θJA Thermal Impedance Operating Temperature Range Industrial (Version A) Lead Temperature (Soldering, 10 sec) Vapor Phase (60 sec) Infrared (15 sec) Storage Temperature Range ESD Rating Rating −0.3 V to +6 V −0.3 V to VCC + 0.3 V 20 mA 20 mA 20 mA 727 mW 135°C/W 470 mW 110°C/W −40°C to +85°C 300°C 215°C 220°C −65°C to +150°C >4.5 kV Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ESD CAUTION Rev. C | Page 5 of 16 ADM706P/ADM706R/ADM706S/ADM706T, ADM708R/ADM708S/ADM708T PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS MR 1 VCC 2 GND 3 8 WDO RESET MR 1 VCC 2 GND 3 06435-003 ADM706P 7 Figure 3. ADM706P Figure 4. ADM706R/ADM706S/ADM706T Table 3. Pin Function Descriptions ADM706P/ADM706R/ADM706S/ADM706T Pin No. 1 Mnemonic MR Description Manual Reset Input. When taken below 0.6 V, a RESET/RESET is generated. MR can be driven from TTL, CMOS logic, or from a manual reset switch because it is internally debounced. An internal 70 μA pull-up current holds the input high when floating. Power Supply Input. Ground. Ground reference for all signals (0 V). Power-Fail Input. PFI is the noninverting input to the power-fail comparator. When PFI is less than 1.25 V, PFO goes low. If unused, PFI should be connected to GND. Power-Fail Output. PFO is the output from the power-fail comparator. It goes low when PFI is less than 1.25 V. Watchdog Input. If WDI remains either high or low for longer than the watchdog timeout period, the watchdog output, WDO, goes low. The timer resets with each transition at the WDI input. Either a high-to-low or a low-to-high transition clears the counter. The internal timer is also cleared whenever reset is asserted. Logic Output. RESET goes low for 200 ms when triggered. It is triggered either by VCC being below the reset threshold or by a low signal on the MR input. RESET remains low whenever VCC is below the reset threshold. It remains low for 200 ms after VCC goes above the reset threshold or MR goes from low to high. A watchdog timeout does not trigger RESET unless WDO is connected to MR. Logic Output. RESET is an active high output suitable for systems that use active high reset logic. It is the inverse of RESET. Watchdog Output. WDO goes low if the internal watchdog timer times out as a result of inactivity on the WDI input. It remains low until the watchdog timer is cleared. WDO also goes low during low line conditions. Whenever VCC is below the reset threshold, WDO remains low. As soon as VCC goes above the reset threshold, WDO goes high immediately. 2 3 4 5 6 VCC GND PFI PFO WDI 7 (ADM706R/ADM706S/ ADM706T Only) RESET 7 (ADM706P Only) 8 RESET WDO Rev. C | Page 6 of 16 06435-004 6 WDI TOP VIEW PFI 4 (Not to Scale) 5 PFO PFI 4 WDI TOP VIEW 5 PFO (Not to Scale) 6 ADM706R/ ADM706S/ ADM706T 8 7 WDO RESET ADM706P/ADM706R/ADM706S/ADM706T, ADM708R/ADM708S/ADM708T MR 1 VCC 2 GND 3 PFI 4 NC TOP VIEW 5 PFO (Not to Scale) 6 ADM708R/ ADM708S/ ADM708T 8 7 RESET RESET NC = NO CONNECT Figure 5. ADM708R/ADM708S/ADM708T Table 4. Pin Function Descriptions ADM708R/ADM708S/ADM708T Pin No. 1 Mnemonic MR Description Manual Reset Input. When taken below 0.6 V, a RESET/RESET is generated. MR can be driven from TTL, CMOS logic, or from a manual reset switch because it is internally debounced. An internal 70 μA pull-up current holds the input high when floating. Power Supply Input. Ground. Ground reference for all signals (0 V). Power-Fail Input. PFI is the noninverting input to the power-fail comparator. When PFI is less than 1.25 V, PFO goes low. If unused, PFI should be connected to GND. Power-Fail Output. PFO is the output from the power-fail comparator. It goes low when PFI is less than 1.25 V. No Connect. Logic Output. RESET goes low for 200 ms when triggered. It is triggered either by VCC being below the reset threshold or by a low signal on the MR input. RESET remains low whenever VCC is below the reset threshold. It remains low for 200 ms after VCC goes above the reset threshold or MR goes from low to high. A watchdog timeout does not trigger RESET unless WDO is connected to MR. Logic Output. RESET is an active high output suitable for systems that use active high reset logic. It is the inverse of RESET. 2 3 4 5 6 7 VCC GND PFI PFO NC RESET 8 RESET Rev. C | Page 7 of 16 06435-005 ADM706P/ADM706R/ADM706S/ADM706T, ADM708R/ADM708S/ADM708T TYPICAL PERFORMANCE CHARACTERISTICS VCC = 3.3V TA = 25°C 1.3V PFI VCC 1.2V 3V PFO RESET 06435-013 0V 06435-016 400ms/DIV 500ns/DIV Figure 6. ADM70xR/ADM70xS/ADM70xT RESET Output Voltage vs. Supply Voltage Figure 9. PFI Deassertion Response Time VCC = VRT TA = 25°C 3V VCC RESET RESET 3V 06435-014 RESET 0V 0V 06435-017 400ms/DIV 100ns/DIV Figure 7. RESET Output Voltage vs. Supply Voltage Figure 10. RESET, RESET Assertion VCC = 3.3V TA = 25°C 1.3V PFI 1.2V 3V 3V RESET VCC = VRT TA = 25°C 3V RESET PFO 0V 0V 06435-018 06435-015 0V 500ns/DIV 100ns/DIV Figure 8. PFI Assertion Response Time Figure 11. RESET, RESET Deassertion Rev. C | Page 8 of 16 ADM706P/ADM706R/ADM706S/ADM706T, ADM708R/ADM708S/ADM708T TA = 25°C 3V VCC 2V 3V RESET 0V 06435-019 2µs/DIV Figure 12. ADM70xR/ADM70xS/ADM70xT RESET Response Time Rev. C | Page 9 of 16 ADM706P/ADM706R/ADM706S/ADM706T, ADM708R/ADM708S/ADM708T CIRCUIT INFORMATION MANUAL RESET WATCHDOG INPUT (WDI) WATCHDOG TRANSITION DETECTOR VCC 70μA MR VCC VREF* POWER-FAIL INPUT (PFI) 1.25V WATCHDOG TIMER WATCHDOG OUTPUT (WDO) RESET AND WATCHDOG TIMEBASE RESET GENERATOR RESET, (P = RESET) The MR input allows other reset sources, such as a manual reset switch, to generate a processor reset. The input is effectively debounced by the timeout period (200 ms typical). The MR input is TTL-/CMOS-compatible; it can also be driven by any logic reset output. If unused, the MR input can be tied high or left floating. VCC VRT VRT ADM706P/ADM706R/ ADM706S/ADM706T POWER-FAIL OUTPUT (PFO) 06435-006 tRS RESET tRS * VOLTAGE REFERENCE = 2.63V (P/R), 2.93V (S), 3.08V (T) Figure 13. ADM706 Functional Block Diagram VCC 70μA MR VCC VREF * POWER-FAIL INPUT (PFI) 1.25V * VOLTAGE REFERENCE = 2.63V (R), 2.93V (S), 3.08V (T) RESET GENERATOR RESET RESET MR MR EXTERNALLY DRIVEN LOW WDO NOTES RESET = COMPLEMENT OF RESET 06435-008 Figure 15. RESET, MR, and WDO Timing ADM708R/ADM708S/ ADM708T 06435-007 POWER-FAIL OUTPUT (PFO) WATCHDOG TIMER (ADM706x) The watchdog timer circuit is used to monitor the activity of the microprocessor to check that it is not stalled in an indefinite loop. An output line on the processor is used to toggle the watchdog input (WDI) line. If this line is not toggled within the timeout period (1.6 seconds), the watchdog output (WDO) is driven low. The WDO output is connected to a nonmaskable interrupt (NMI) on the processor. Therefore, if the watchdog timer times out, an interrupt is generated. The interrupt service routine is used to rectify the problem. The watchdog timer is cleared either by a high-to-low or by a low-to-high transition on WDI. Pulses as narrow as 50 ns are detected. The timer is also cleared by RESET/RESET going active. Therefore, the watchdog timeout period begins after reset goes inactive. When VCC falls below the reset threshold, WDO is forced low whether or not the watchdog timer has timed out. Normally, this generates an interrupt, but it is overridden by RESET/RESET going active. tWP WDI Figure 14. ADM708 Functional Block Diagram POWER-FAIL RESET The reset output provides a reset (RESET or RESET) output signal to the microprocessor whenever the VCC input is below the reset threshold. The actual reset threshold voltage is dependent on whether a P, R, S, or T suffix device is used. An internal timer holds the reset output active for 200 ms after the voltage on VCC rises above the threshold. This is intended as a power-on reset signal for the microprocessor. It allows time for both the power supply and the microprocessor to stabilize after power-up. If a power supply brownout or interruption occurs, the reset line is similarly activated and remains active for 200 ms after the supply recovers. If another interruption occurs during an active reset period, the reset timeout period continues for an additional 200 ms. The reset output is guaranteed to remain valid with VCC as low as 1 V. This ensures that the microprocessor is held in a stable shutdown condition as the power supply starts up. The ADM706P provides an active high RESET signal; the ADM706R/ADM706S/ADM706T provide an active low RESET signal; and the ADM708R/ADM706S/ADM706T provide both RESET and RESET. tWD tWD tWD WDO tRS Figure 16. Watchdog Timing Rev. C | Page 10 of 16 06435-009 RESET RESET EXTERNALLY TRIGGERED BY MR ADM706P/ADM706R/ADM706S/ADM706T, ADM708R/ADM708S/ADM708T POWER-FAIL COMPARATOR The power-fail comparator is an independent comparator that can be used to monitor the input power supply. The inverting input of the comparator is internally connected to a 1.25 V reference voltage. The noninverting input is available at the PFI input. This input is used to monitor the input power supply via a resistive divider network. When the voltage on the PFI input drops below 1.25 V, the comparator output (PFO) goes low, indicating a power failure. For early warning of power failure, the comparator is used to monitor the preregulator input simply by choosing an appropriate resistive divider network. The PFO output is used to interrupt the processor so that a shutdown procedure is implemented before the power is lost. INPUT POWER R1 1.25V POWER-FAIL PFI INPUT PFO POWER-FAIL OUTPUT INPUT POWER R1 1.25V PFI R2 ADM663A 3.3V VCC – + PFO TO MICROPROCESSOR NMI ADM706P/ADM706R/ ADM706S/ADM706T/ ADM708R/ADM708S/ ADM708T R3 3.3V PFO 0V VL VIN VH Figure 18. Adding Hysteresis to the Power-Fail Comparator R2 06435-010 ADM706P/ADM706R/ ADM706S/ADM706T/ ADM708R/ADM708S/ ADM708T ⎡ ⎛ R2 + R3 ⎞ ⎤ ⎟ R1⎥ VH = 1.25 ⎢1 + ⎜ ⎢ ⎜ R2 × R3 ⎟ ⎥ ⎠⎦ ⎣⎝ ⎛ 1.25 VCC − 1.25 ⎞ VL = 1.25 + R1 ⎜ − ⎟ R3 ⎝ R2 ⎠ ⎛ R1 + R2 ⎞ VMID = 1.25 ⎜ ⎟ ⎝ R2 ⎠ Figure 17. Power-Fail Comparator ADDING HYSTERESIS TO THE POWER-FAIL COMPARATOR For increased noise immunity, hysteresis can be added to the power-fail comparator. Because the comparator circuit is noninverting, hysteresis is added simply by connecting a resistor between the PFO output and the PFI input as shown in Figure 18. When PFO is low, Resistor R3 sinks current from the summing junction at the PFI pin. When PFO is high, Resistor R3 sources current into the PFI summing junction. This results in differing trip levels for the comparator. Further noise immunity is achieved by connecting a capacitor between PFI and GND. VALID RESET BELOW 1 V VCC The ADM706R/ADM706S/ADM706T, ADM708R/ADM708S/ ADM708T are guaranteed to provide a valid reset level with VCC as low as 1 V. Refer to the Typical Performance Characteristics section. As VCC drops below 1 V, the internal transistor does not have sufficient drive to hold it on so the voltage on RESET is no longer held at 0 V. A pull-down resistor, as shown in Figure 19, can be connected externally to hold the line low if it is required. ADM706R/ADM706S/ ADM706T/ADM708R/ ADM708S/ADM708T RESET 06435-012 GND R1 Figure 19. RESET Valid Below 1 V Rev. C | Page 11 of 16 06435-011 0V ADM706P/ADM706R/ADM706S/ADM706T, ADM708R/ADM708S/ADM708T APPLICATIONS INFORMATION A typical operating circuit is shown in Figure 20. The unregulated dc input supply is monitored using the PFI input via the resistive divider network. Resistor R1 and Resistor R2 are to be selected so that when the supply voltage drops below the desired level (for example, 5 V), the voltage on PFI drops below the 1.25 V threshold, thereby generating an interrupt to the microprocessor. Monitoring the preregulator input gives additional time to execute an orderly shutdown procedure before power is lost. UNREGULATED DC MONITORING ADDITIONAL SUPPLY LEVELS It is possible to use the power-fail comparator to monitor a second supply as shown in Figure 22. The two sensing resistors, R1 and R2, are selected such that the voltage on PFI drops below 1.25 V at the minimum acceptable input supply. The PFO output can be connected to the MR input so that a reset is generated when the supply drops out of tolerance. In this case, if either supply drops out of tolerance, a reset is generated. VX +3V/+3.3V VCC ADM666A IN GND OUT 3.3V R1 RESET RESET MICROPROCESSOR VCC RESET VCC RESET I/O LINE MICROPROCESSOR WDO PFO NMI INTERRUPT GND PFI MR GND MANUAL RESET Figure 22. Monitoring 3 V/3.3 V and an Additional Supply, VX 06435-020 MICROPROCESSORS WITH BIDIRECTIONAL RESET To prevent contention for microprocessors with a bidirectional reset line, a current limiting resistor is to be inserted between the ADM706R/ADM706S/ADM706T, ADM708R/ADM708S/ ADM708T RESET output pin and the microprocessor reset pin. This limits the current to a safe level if there are conflicting output reset levels. A suitable resistor value is 4.7 kΩ. If the reset output is required for other uses, it should be buffered as shown in Figure 23. +3V/+3.3V BUFFERED RESET Figure 20. Typical Application Circuit Microprocessor activity is monitored using the WDI input. This is driven using an output line from the processor. The software routines toggle this line at least once every 1.6 seconds. If a problem occurs and this line is not toggled, WDO goes low and a nonmaskable interrupt is generated. This interrupt routine is to be used to clear the problem. If, in the event of inactivity on the WDI line, a system reset is required, the WDO output is to be connected to the input as shown in Figure 21. RESET RESET VCC ADM706R/ADM706S/ ADM706T/ADM708R/ ADM708S/ADM708T RESET GND MICROPROCESSOR RESET GND 06435-023 ADM706R/ ADM706S/ WDI PFI ADM706T MR WDO GND I/O LINE MICROPROCESSOR 06435-021 Figure 23. Bidirectional Input/Output RESET Figure 21. RESET from WDO Rev. C | Page 12 of 16 06435-022 ADM706R/ ADM706S/ ADM706T WDI ADM706R/ WDI ADM706S/ PFI ADM706T R2 MR GND PFO ADM706P/ADM706R/ADM706S/ADM706T, ADM708R/ADM708S/ADM708T OUTLINE DIMENSIONS 0.400 (10.16) 0.365 (9.27) 0.355 (9.02) 8 1 5 4 0.280 (7.11) 0.250 (6.35) 0.240 (6.10) 0.100 (2.54) BSC 0.210 (5.33) MAX 0.150 (3.81) 0.130 (3.30) 0.115 (2.92) 0.022 (0.56) 0.018 (0.46) 0.014 (0.36) 0.070 (1.78) 0.060 (1.52) 0.045 (1.14) 0.325 (8.26) 0.310 (7.87) 0.300 (7.62) 0.060 (1.52) MAX 0.195 (4.95) 0.130 (3.30) 0.115 (2.92) 0.015 (0.38) MIN SEATING PLANE 0.005 (0.13) MIN 0.015 (0.38) GAUGE PLANE 0.430 (10.92) MAX 0.014 (0.36) 0.010 (0.25) 0.008 (0.20) COMPLIANT TO JEDEC STANDARDS MS-001 CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN. CORNER LEADS MAY BE CONFIGURED AS WHOLE OR HALF LEADS. Figure 24. 8-Lead Plastic Dual In-Line Package [PDIP] Narrow Body (N-8) Dimension shown in inches and (millimeters) 5.00 (0.1968) 4.80 (0.1890) 4.00 (0.1574) 3.80 (0.1497) 8 1 5 4 6.20 (0.2441) 5.80 (0.2284) 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) COPLANARITY 0.10 SEATING PLANE 1.75 (0.0688) 1.35 (0.0532) 0.50 (0.0196) 0.25 (0.0099) 8° 0° 0.25 (0.0098) 0.17 (0.0067) 1.27 (0.0500) 0.40 (0.0157) 45° 0.51 (0.0201) 0.31 (0.0122) COMPLIANT TO JEDEC STANDARDS MS-012-A A CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN. Figure 25. 8-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-8) Dimensions shown in millimeters and (inches) Rev. C | Page 13 of 16 012407-A 070606-A ADM706P/ADM706R/ADM706S/ADM706T, ADM708R/ADM708S/ADM708T ORDERING GUIDE Model ADM706PAN ADM706PANZ 1 ADM706PAR ADM706PAR-REEL ADM706PARZ1 ADM706PARZ-REEL1 ADM706RAN ADM706RANZ1 ADM706RAR ADM706RAR-REEL ADM706RAR-REEL7 ADM706RARZ1 ADM706RARZ-REEL1 ADM706RARZ-REEL71 ADM706SAN ADM706SANZ1 ADM706SAR ADM706SAR-REEL ADM706SARZ1 ADM706SARZ-REEL1 ADM706TAN ADM706TANZ1 ADM706TAR ADM706TAR-REEL ADM706TARZ1 ADM706TARZ-REEL1 ADM708RAN ADM708RANZ1 ADM708RAR ADM708RAR-REEL ADM708RARZ1 ADM708RARZ-REEL1 ADM708SAN ADM708SANZ1 ADM708SAR ADM708SAR-REEL ADM708SARZ1 ADM708SARZ-REEL1 ADM708TAN ADM708TANZ1 ADM708TAR ADM708TAR-REEL ADM708TARZ1 ADM708TARZ-REEL1 1 Temperature Range −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C Package Description 8-Lead PDIP 8-Lead PDIP 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead PDIP 8-Lead PDIP 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead PDIP 8-Lead PDIP 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead PDIP 8-Lead PDIP 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead PDIP 8-Lead PDIP 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead PDIP 8-Lead PDIP 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead PDIP 8-Lead PDIP 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N Package Option N-8 N-8 R-8 R-8 R-8 R-8 N-8 N-8 R-8 R-8 R-8 R-8 R-8 R-8 N-8 N-8 R-8 R-8 R-8 R-8 N-8 N-8 R-8 R-8 R-8 R-8 N-8 N-8 R-8 R-8 R-8 R-8 N-8 N-8 R-8 R-8 R-8 R-8 N-8 N-8 R-8 R-8 R-8 R-8 Z = RoHS Compliant Part. Rev. C | Page 14 of 16 ADM706P/ADM706R/ADM706S/ADM706T, ADM708R/ADM708S/ADM708T NOTES Rev. C | Page 15 of 16 ADM706P/ADM706R/ADM706S/ADM706T, ADM708R/ADM708S/ADM708T NOTES ©1995–2008 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D06435-0-5/08(C) Rev. C | Page 16 of 16