Dual Processor Supervisors with Watchdog ADM335 FEATURES Dual supervisory circuits Supply voltage range of 2.7 V to 5.5 V Pretrimmed threshold options:.8 V, 2.5 V, 3.3 V, and 5 V Adjustable.6 V voltage reference Maximum supply current of 4 μa 4 ms (minimum) reset timeout Watchdog timer with.6 sec (typical) timeout valid from VDD. V Push-pull and outputs 8-lead, narrow body SOIC package Temperature range: 4 C to +85 C APPLICATIONS Supervising DSPs/microcontrollers Industrial and portable equipment Wireless systems Notebook/desktop computers GENERAL DESCRIPTION The ADM335 is a dual voltage supervisor designed to monitor two supplies and provide a reset signal to DSP and microprocessor-based systems. There are five models available, all of which feature a combination of internally pretrimmed undervoltage threshold options for monitoring.8 V, 2.5 V, 3.3 V, and 5 V supplies. There is also an adjustable input option with an undervoltage threshold voltage of.6 V. The ADM335-8, ADM335-25, and ADM335-33 models have two internally fixed thresholds. The ADM335-4 and ADM335-5 offer one internally fixed threshold and one externally programmable threshold via a resistor string. See the Ordering Guide for a list of all available options. During power-up, is asserted when the supply voltage exceeds. V. The device then monitors the SENSEv input pins and holds the output low as long as either of the SENSEv inputs remains below the rising threshold voltage, VIT+. Once the supplies monitored at the SENSEv inputs rise above their associated thresholds, the reset signal remains low for the reset timeout period before deasserting. Subsequently, if a voltage monitored by the SENSEv pins falls below its associated falling threshold, VIT, the output asserts. The ADM335 features both an active high and an active low output. V DD MR SENSE SENSE2 GND WDI V DD MR SENSE GND SENSE2 WDI FUNCTIONAL BLOCK DIAGRAMS R R3 4kΩ R2 R4 TRANSITION DETECTION R 4kΩ R2 TRANSITION DETECTION.25V.6V WATCHDOG LOGIC + TIMER Figure. WATCHDOG LOGIC + TIMER Figure 2.. ADM335-8 ADM335-25 ADM335-33 LOGIC + TIMER OSCILLATOR ADM335-4 ADM335-5 LOGIC + TIMER OSCILLATOR 6922-2 As well as providing power-on reset signals, an on-chip watchdog timer can reset the microprocessor if it fails to strobe within the preset timeout period. A reset signal can also be asserted by an external push button through the manual reset input pin. The ADM335 is available in an 8-lead, narrow body SOIC package. The device operates over the extended industrial temperature range of 4 C to +85 C. 6922- Rev. 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 96, Norwood, MA 262-96, U.S.A. Tel: 78.329.47 www.analog.com Fax: 78.46.33 27 Analog Devices, Inc. All rights reserved.
ADM335 TABLE OF CONTENTS Features... Applications... General Description... Functional Block Diagrams... Revision History... 2 Specifications... 3 Timing Requirements... 5 Switching Characteristics... 5 Functional Truth Table... 5 Absolute Maximum Ratings... 6 Thermal Resistance... 6 ESD Caution...6 Pin Configuration and Function Descriptions...7 Typical Performance Characteristics...8 Theory of Operation... Input Configuration... Reset Output... Watchdog Timer... Manual Reset (MR)... Outline Dimensions... 2 Ordering Guide... 2 REVISION HISTORY 8/7 Revision : Initial Version Rev. Page 2 of 2
ADM335 SPECIFICATIONS VDD = 2.7 V to 5.5 V, 4 C TA +85 C, unless otherwise noted. Table. ADM335-8, ADM335-25, and ADM335-33 Parameter Min Typ Max Unit Test Conditions/Comments OPERATING VOLTAGE RANGE, VDD 2.7 5.5 V SUPPLY CURRENT, IDD 4 μa INPUT CAPACITANCE, CI pf VI = V to VDD, OUTPUT High Level Output Voltage, VOH VDD.2 V IOH = 2 μa VDD.4 V IOH = 2 ma, VDD = 3.3 V VDD.4 V IOH = 3 ma, VDD = 5.5 V Low Level Output Voltage, VOL.2 V IOL = 2 μa.4 V IOL = 2 ma, VDD = 3.3 V.4 V IOL = 3 ma, VDD = 5.5 V Power-Up Reset Voltage.4 V IOL = 2 μa, VDD. V SENSE INPUTS Falling Threshold Voltage, VIT.64.68.72 V TA = C to 85 C 2.2 2.25 2.3 V TA = C to 85 C 2.86 2.93 3. V TA = C to 85 C 4.46 4.55 4.64 V TA = C to 85 C.64.68.73 V TA = 4 C to +85 C 2.2 2.25 2.32 V TA = 4 C to +85 C 2.86 2.93 3.2 V TA = 4 C to +85 C 4.46 4.55 4.67 V TA = 4 C to +85 C Hysteresis at SENSEv Inputs, VHYS 5 mv VIT =.68 V 2 mv VIT = 2.25 V 3 mv VIT = 2.93 V 4 mv VIT = 4.55 V WDI Average High Level Input Current, IH(AV) 5 μa WDI = VDD = 5.5 V Average Low Level Input Current, IL(AV) 5 2 μa WDI = V, VDD = 5.5 V INPUT VOLTAGE AT MR AND WDI High Level, VIH.7 VDD V Low Level, VIL.3 VDD V INPUT TRANSITION RISE AND FALL RATE AT MR 5 ns/v HIGH LEVEL INPUT CURRENT, IH WDI 2 7 μa WDI = VDD = 5.5 V MR 3 8 μa MR =.7 VDD, VDD = 5.5 V SENSE 5 8 μa SENSE = VDD = 5.5 V SENSE2 6 9 μa SENSE2 = VDD = 5.5 V LOW LEVEL INPUT CURRENT, IL WDI 2 7 μa WDI = V, VDD = 5.5 V MR 43 6 μa MR = V, VDD = 5.5 V SENSEv + μa SENSE, SENSE2 = V The lowest supply voltage at which becomes active. tr, VDD 5 μs/v. Rev. Page 3 of 2
ADM335 VDD = 2.7 V to 5.5 V, 4 C TA +85 C, unless otherwise noted. Table 2. ADM335-4 and ADM335-5 Parameter Min Typ Max Unit Test Conditions/Comments OPERATING VOLTAGE RANGE, VDD 2.7 5.5 V SUPPLY CURRENT, IDD 4 μa INPUT CAPACITANCE, CI pf VI = V to VDD, OUTPUT High-Level Output Voltage, VOH VDD.2 V IOH = 2 μa VDD.4 V IOH = 2 ma, VDD = 3.3 V VDD.4 V IOH = 3 ma, VDD = 5.5 V Low-Level Output Voltage, VOL.2 V IOH = 2 μa.4 V IOH = 2 ma, VDD = 3.3 V.4 V IOH = 3 ma, VDD = 5.5 V Power-Up Reset Voltage.4 V IOH = 2 μa, VDD. V SENSEv INPUTS Falling Input Threshold Voltage, VIT.5952.6.648 V TA = 4 C to +85 C 2.23 2.25 2.29 V TA = 4 C to +85 C 2.9 2.93 2.98 V TA = 4 C to +85 C Hysteresis at SENSEv Inputs, VHYS mv VIT =.6 V 2 mv VIT = 2.25 V 3 mv VIT = 2.93 V WDI Average High Level Input Current, IH(AV) 5 μa WDI = VDD = 5.5 V Average Low Level Input Current, IL(AV) 5 2 μa WDI = V, VDD = 5.5 V INPUT VOLTAGE AT MR AND WDI High Level, VIH.7 VDD V Low Level, VIL.3 VDD V INPUT TRANSITION RISE AND FALL RATE AT MR 5 ns/v HIGH LEVEL INPUT CURRENT, IH WDI 2 7 μa WDI = VDD = 5.5 V MR 3 8 μa MR =.7 VDD, VDD = 5.5 V SENSE 5 8 μa SENSE = VDD = 5.5 V SENSE2 5 +5 na SENSE2 = VDD = 5.5 V LOW LEVEL INPUT CURRENT, IL WDI 2 7 μa WDI = V, VDD = 5.5 V MR 43 6 μa MR = V, VDD = 5.5 V SENSEv + μa SENSE, SENSE2 = V The lowest supply voltage at which becomes active. tr, VDD 5 μs/v. Rev. Page 4 of 2
ADM335 TIMING REQUIREMENTS VDD = 2.7 V to 5.5 V, RL = MΩ, CL = 5 pf, TA = 25 C. Table 3. ADM335-8, ADM335-25 and ADM335-33 Parameter Min Typ Max Unit Test Conditions/Comments PULSE WIDTH (tw) SENSEv 6 μs VSENSEvL = VIT.3 V, VSENSEvH = VIT+ +.3 V MR ns VIH =.7 VDD, VIL =.3 VDD WDI ns VIH =.7 VDD, VIL =.3 VDD Table 4. ADM335-4 and ADM335-5 Parameter Min Typ Max Unit Test Conditions/Comments PULSE WIDTH (tw) SENSEv 3 μs VSENSEvL = VIT.3 V, VSENSEvH = VIT+ +.3 V MR ns VIH =.7 VDD, VIL =.3 VDD WDI ns VIH =.7 VDD, VIL =.3 VDD SWITCHING CHARACTERISTICS VDD = 2.7 V to 5.5 V, RL = MΩ, CL = 5 pf, TA = 25 C. Table 5. ADM335-8, ADM335-25 and ADM335-33 Parameter Min Typ Max Unit Test Conditions/Comments Watchdog Timeout (tt(out))..6 2.3 sec VI(SENSEv) VIT+ +.2 V, MR.7 VDD Delay Time (td) 4 2 28 ms VI(SENSEv) VIT+ +.2 V, MR.7 VDD Propagation Delay, High-to-Low, MR to / (tphl) 2 5 ns VI(SENSEv) VIT+ +.2 V, VIH.7 VDD, VIL.3 VDD Propagation Delay, Low-to-High, MR to / (tplh) 2 5 ns VI(SENSEv) VIT+ +.2 V, VIH.7 VDD, VIL.3 VDD Propagation Delay, High-to-Low, SENSEv to / (tphl) 5 μs VIH = VIT+ +.3 V, VIL = VIT.3 V, MR.7 VDD Propagation Delay, Low-to-High, SENSEv to / (tplh) 5 μs VIH = VIT+ +.3 V, VIL = VIT.3 V, MR.7 VDD The reset timeout delay of 2 ms masks the propagation delay. Table 6. ADM335-4 and ADM335-5 Parameter Min Typ Max Unit Test Conditions/Comments Watchdog Timeout (tt(out))..6 2.3 sec VI(SENSEv) VIT+ +.2 V, MR.7 VDD Delay Time (td) 4 2 28 ms VI(SENSEv) VIT+ +.2 V, MR.7 VDD Propagation Delay, High-to-Low, MR to / (tphl) 2 5 ns VI(SENSEv) VIT+ +.2 V, VIH.7 VDD, VIL.3 VDD Propagation Delay, Low-to-High, MR to / (tplh) 2 5 ns VI(SENSEv) VIT+ +.2 V, VIH.7 VDD, VIL.3 VDD Propagation Delay, High-to-Low, SENSEv to / (tphl) 3 μs VIH = VIT+ +.3 V, VIL = VIT.3 V, MR.7 VDD Propagation Delay, Low-to-High, SENSEv to / (tplh) 3 μs VIH = VIT+ +.3 V, VIL = VIT.3 V, MR.7 VDD The reset timeout delay of 2 ms masks the propagation delay. FUNCTIONAL TRUTH TABLE Table 7. MR SENSE > VIT SENSE2 > VIT2 L X X L H H L H H L H H L H H H L X = don t care. Rev. Page 5 of 2
ADM335 ABSOLUTE MAXIMUM RATINGS Table 8. Parameter Supply Voltage Range, VDD MR, WDI Rating.3 V to +6 V.3 V to VDD +.3 V SENSE, SENSE2 (VDD +.3 V)VIT/VREF,.3 V to +6 V Maximum Low Output Current 5 ma Maximum High Output Current 5 ma Input Clamp Current (VI < V, VI > VDD) ±2 ma Output Clamp Current (VO < V, VO > VDD) ±2 ma Operating Temperature Range 4 C to +85 C Storage Temperature Range 65 C to +5 C Lead Temperature Soldering ( sec) 3 C Vapor Phase (6 sec) 25 C Infrared (5 sec) 22 C 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. THERMAL RESISTANCE Table 9. Package Type θja Unit 8-Lead SOIC_N (R-8) 26 C/W ESD CAUTION Rev. Page 6 of 2
ADM335 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS SENSE SENSE2 2 WDI 3 GND 4 ADM335 TOP VIEW (Not to Scale) 8 7 6 5 V DD MR Figure 3. Pin Configuration 6922-3 Table. Pin Function Descriptions Pin No. Mnemonic Description SENSE Sense Input Voltage. 2 SENSE2 Sense Input Voltage 2. 3 WDI Watchdog Timer Input. 4 GND Ground. 5 Active-Low Reset Output. 6 Active-High Reset Output. 7 MR Manual Reset Input. 8 VDD Supply Voltage. Rev. Page 7 of 2
ADM335 TYPICAL PERFORMANCE CHARACTERISTICS INPUT THRESHOLD VOLTAGE, V IT (V).63.6.5999.5997.5995.5993.599.5989 T A = 25 C.5987 V DD = 2V.5985 4 2 2 4 6 8 FREE AIR TEMPERATURE, T A ( C) Figure 4. Sense Threshold Voltage vs. Free Air Temperature at VDD 6922-4 MINIMUM PULSE DURATION AT SENSE, t W (µs) 9 8 7 6 5 4 3 2 V DD = 5.5V 2 3 4 5 6 7 8 9 SENSE THRESHOLD OVERDRIVE (mv) Figure 7. ADM335-8, ADM335-25 and ADM335-33 Minimum Pulse Duration at SENSE vs. Sense Threshold Overdrive 6922-7 SUPPLY CURRENT, I DD (µa) 4 35 3 25 2 5 5 SENSEv = 5.5V 5 T A = 25 C..5.5..5 2. 2.5 3. 3.5 4. 4.5 5. 5.5 6. 6.5 SUPPLY VOLTAGE, V DD (V) Figure 5. Supply Current vs. Supply Voltage 6922-5 MINIMUM PULSE DURATION AT SENSE, t W (µs) 4 39 38 37 36 35 34 33 32 3 V DD = 5.5V 3 2 3 4 5 6 7 8 9 SENSE THRESHOLD OVERDRIVE (mv) Figure 8. ADM335-4 and ADM335-5 Minimum Pulse Duration at SENSE vs. Sense Threshold Overdrive 6922-7 2 2.5 INPUT CURRENT, I I (µa) 2 3 4 5 6 7 V DD = 5.5V 8 T A = 25 C 9. 7..5.5..5 2. 2.5 3. 3.5 4. 4.5 5. 5.5 6. 6.5 INPUT VOLTAGE AT MR, V I (V) Figure 6. Input Current vs. Input Voltage at MR 6922-6 HIGH LEVEL OUTPUT VOLTAGE, V OH (V) 2..5..5 4 C V DD = 2V C +25 C +85 C 2 3 4 5 6 HIGH LEVEL OUTPUT CURRENT, I OH (ma) Figure 9. High Level Output Voltage vs. High Level Output Current 6922-8 Rev. Page 8 of 2
ADM335 HIGH LEVEL OUTPUT VOLTAGE, V OH (V) 6. 5.5 5. 4.5 4. 3.5 3. 2.5 2..5 4 C C +25 C +85 C. V.5 DD = 5.5V 2 3 4 5 6 6922-9 LOW LEVEL OUTPUT VOLTAGE, V OL (V)..9.8.7.6.5.4.3.2 4 C C +25 C +85 C V. DD = 5.5V 5 5 2 25 3 35 4 45 5 55 6 6922-6 HIGH LEVEL OUTPUT CURRENT, I OH (ma) LOW LEVEL OUTPUT CURRENT, I OL (ma) Figure. High Level Output Voltage vs. High Level Output Current Figure 2. Low Level Output Voltage vs. Low Level Output Current LOW LEVEL OUTPUT VOLTAGE, V OL (V).25.2.5..5 4 C C +25 C +85 C V DD = 2V 2 3 4 5 6 LOW LEVEL OUTPUT CURRENT, I OL (ma) 6922- Figure. Low Level Output Voltage vs. Low Level Output Current Rev. Page 9 of 2
ADM335 THEORY OF OPERATION The ADM335 is a dual voltage supervisor designed to monitor two supplies and provide a reset signal to DSP and microprocessor-based systems. There are five models available, all of which feature a combination of internally pretrimmed undervoltage threshold options for monitoring.8 V, 2.5 V, 3.3 V, and 5 V supplies. There is also an adjustable input option with an undervoltage threshold of.6 V. The ADM335-8, ADM335-25, and ADM335-33 have two internally fixed thresholds, while the ADM335-4 and ADM335-5 offer one internally fixed threshold and one externally programmable threshold via a resistor string. See the Ordering Guide for a list of all available options. INPUT CONFIGURATION The ADM335 is powered through VDD. To increase noise immunity in noisy applications, place a. μf capacitor between the VDD input and ground. The SENSEv inputs are resistant to short power supply glitches. Do not allow an unused SENSEv input to float or to be grounded, instead connect it to a supply voltage greater than its specified threshold voltage. Typically, the threshold voltage at each adjustable SENSEv input is.6 V. To monitor a voltage greater than.6 V, connect a resistor divider network to the device as depicted in Figure 3, where, V MONITERED OUTPUT R+ R2 =.6 V R2 MONITORED VOLTAGE R R2 V REF =.6V Figure 3. Setting the Adjustable Monitor The reset outputs are guaranteed to be in the correct state for VDD down to. V. During power-up, is asserted when the supply voltage becomes greater than. V. 6922-2 SENSEv V (NOM) V IT t d t d t Figure 4. Reset Timing Diagram Once the supplies monitored at the SENSEv pins rise above their associated threshold level, the signal remains low for the reset timeout period before deasserting. Subsequently, if either of the supplies monitored by the SENSEv pins falls below its associated threshold the output reasserts. The ADM335 features both an active-low, push-pull output and an active-high, push-pull output. WATCHDOG TIMER The ADM335 features a watchdog timer that monitors microprocessor activity. A timer circuit is cleared with every low-to-high or high-to-low logic transition on the watchdog input pin (WDI). If the timer counts through the preset watchdog timeout period of.6 sec, is asserted, as shown in Figure 5. The microprocessor is required to toggle the WDI pin to avoid being reset. Therefore, failure of the microprocessor to toggle WDI within the timeout period indicates a code execution error and the reset pulse generated restarts the microprocessor in a known state. The watchdog timer can be disabled by leaving WDI floating. WDI t WD t t 6922-3 t d t 6922-4 Figure 5. Watchdog Timing Diagram Rev. Page of 2
ADM335 MANUAL (MR) The ADM335 features a manual reset input, which when driven low, asserts the reset output, as shown in Figure 6. When MR transitions from low to high, reset remains asserted for the duration of the reset active timeout period before deasserting. An external push-button switch can be connected between MR and ground to allow the user to generate a reset. MR t d t t 6922-5 Figure 6. Manual Reset Timing Diagram Rev. Page of 2
ADM335 OUTLINE DIMENSIONS 5. (.968) 4.8 (.89) 4. (.574) 3.8 (.497) 8 5 4 6.2 (.244) 5.8 (.2284).25 (.98). (.4) COPLANARITY. SEATING PLANE.27 (.5) BSC.75 (.688).35 (.532).5 (.2).3 (.22) 8.25 (.98).7 (.67).5 (.96).25 (.99).27 (.5).4 (.57) 45 ORDERING GUIDE Model COMPLIANT TO JEDEC STANDARDS MS-2-AA 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 7. 8-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-8) Dimensions shown in millimeters and (inches) Nominal Supervised Voltage Threshold Voltage (Typical) SENSE SENSE2 SENSE SENSE2 Temperature Range 247 -A Package Description ADM335-8ARZ 3.3 V.8 V 2.93 V.68 V 4 C to +85 C 8-Lead SOIC_N R-8 ADM335-8ARZ-RL7 3.3 V.8 V 2.93 V.68 V 4 C to +85 C 8-Lead SOIC_N R-8 ADM335-25ARZ 3.3 V 2.5 V 2.93 V 2.25 V 4 C to +85 C 8-Lead SOIC_N R-8 ADM335-25ARZ-RL7 3.3 V 2.5 V 2.93 V 2.25 V 4 C to +85 C 8-Lead SOIC_N R-8 ADM335-33ARZ 5 V 3.3 V 4.55 V 2.93 V 4 C to +85 C 8-Lead SOIC_N R-8 ADM335-33ARZ-RL7 5 V 3.3 V 4.55 V 2.93 V 4 C to +85 C 8-Lead SOIC_N R-8 ADM335-4ARZ 3.3 V Adjustable 2 2.93 V.6 V 4 C to +85 C 8-Lead SOIC_N R-8 ADM335-4ARZ-RL7 3.3 V Adjustable 2 2.93 V.6 V 4 C to +85 C 8-Lead SOIC_N R-8 ADM335-5ARZ 2.5 V Adjustable 2 2.25 V.6 V 4 C to +85 C 8-Lead SOIC_N R-8 ADM335-5ARZ-RL7 2.5 V Adjustable 2 2.25 V.6 V 4 C to +85 C 8-Lead SOIC_N R-8 Z = RoHS Compliant Part. 2.6 V adjustable. External resistor divider determines the actual sense voltage. Package Option 27 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D6922--8/7() Rev. Page 2 of 2