ADM709TARZ-REEL

a Power Supply Monitor with Reset ADM709 FEATURES Precision Supply Voltage Monitor +5 V, +3.3 V, +3 V Power Supply Monitor 35 mA Quiescent Current 140 ms (min) Power-On Reset Pulse Low Cost 8-Pin DIP/SO Packages Upgrade for MAX709 FUNCTIONAL BLOCK DIAGRAM ADM709 VCC RESET GENERATOR VTH RESET GND APPLICATIONS Microprocessor Systems Computers Controllers Intelligent Instruments Critical mP Monitoring Automotive Systems Critical mP Power Monitoring VCC VCC ADM709 RESET µP RESET GND GENERAL DESCRIPTION The ADM709 contains a power supply monitor which generates a system reset during power-up, power-down and brownout conditions. When VCC falls below the reset threshold, RESET goes low and holds the µP in reset. On power-up the RESET output is held low for 140 ms after VCC rises above the threshold. The RESET output remains operational with VCC as low as 1 V. Three supply-voltage threshold levels are available suitable for +5 V, +3.3 V and for +3 V supply monitoring. The actual reset voltage threshold is given below. The ADM709 is available in 8-pin DIP and SOIC packages. Table I. Reset Threshold Suffix Voltage (V) L M T S R 4.65 4.40 3.08 2.93 2.63 GND Typical Operating Circuit ORDERING GUIDE Model Reset Threshold Temperature Range Package Option* ADM709LAN ADM709LAR ADM709MAN ADM709MAR ADM709TAN ADM709TAR ADM709SAN ADM709SAR ADM709RAN ADM709RAR 4.65 V 4.65 V 4.40 V 4.40 V 3.08 V 3.08 V 2.93 V 2.93 V 2.63 V 2.63 V –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 N-8 SO-8 N-8 SO-8 N-8 SO-8 N-8 SO-8 N-8 SO-8 *N = Plastic DIP; SO = SOIC. REV. 0 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 which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. © Analog Devices, Inc., 1995 One Technology Way, P.O. Box 9106, Norwood. MA 02062-9106, U.S.A. Tel: 617/329-4700 Fax: 617/326-8703 ADM709–SPECIFICATIONS (V CC Parameter Min VCC Operating Voltage Range 1.0 1.2 Supply Current Reset Threshold 4.5 4.25 3.00 2.85 2.55 VCC to RESET Delay RESET Active Time-Out Period = Full Operating Range, TA = TMIN to TMAX unless otherwise noted) Typ Max Units Test Conditions/Comments 35 35 65 65 5.5 5.5 85 110 150 200 V V µA µA µA µA TA = 0°C to +70°C TA = –40°C to +85°C VCC < 3.6 V, TA = 0°C to +70°C VCC < 3.6 V, TA = –40°C to +85°C VCC < 5.5 V, TA = 0°C to +70°C VCC < 5.5 V, TA = –40°C to +85°C 4.65 4.40 3.08 2.93 2.63 4.75 4.50 3.15 3.00 2.70 V V V V V ADM709L ADM709M ADM709T ADM709S ADM709R µs VCC = Reset Threshold max–min 380 ms VCC = Reset Threshold max, VCC Rising 0.3 V 0.4 V 0.3 0.4 V V V ADM709R/S/T, ISINK = 1.2 mA. VCC = Reset Threshold min ADM709L/M, ISINK = 3.2 mA. VCC = Reset Threshold min ISINK = 50 µA. VCC ≥ 1.0 V ISINK = 100 µA. VCC ≥ 1.2 V ADM709R/S/T, ISOURCE = 500 µA, VCC ≥ Reset Threshold max ADM709L/M, ISOURCE = 800 µA, VCC ≥ Reset Threshold max 20 140 RESET Output Voltage 0.8 × VCC 280 VCC–1.5 V V Specifications subject to change without notice. PIN FUNCTION DESCRIPTION ABSOLUTE MAXIMUM RATINGS* (TA = +25°C unless otherwise noted) VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +6 V RESET Output . . . . . . . . . . . . . . . . . . . –0.3 V to VCC + 0.3 V VCC Input Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 mA RESET Output Current . . . . . . . . . . . . . . . . . . . . . . . . 20 mA Power Dissipation, N-8 DIP . . . . . . . . . . . . . . . . . . . . 727 mW θJA Thermal Impedance . . . . . . . . . . . . . . . . . . . . . 135°C/W Power Dissipation, SO-8 SOIC . . . . . . . . . . . . . . . . . . 470 mW θJA Thermal Impedance . . . . . . . . . . . . . . . . . . . . . 110°C/W Operating Temperature Range Industrial ( A Version) . . . . . . . . . . . . . . . . . –40°C to +85°C Lead Temperature (Soldering, 10 secs) . . . . . . . . . . . . +300°C Vapor Phase (60 secs) . . . . . . . . . . . . . . . . . . . . . . . . . +215°C Infrared (15 secs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +220°C Storage Temperature Range . . . . . . . . . . . . . –65°C to +150°C ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . >5 kV * Mnemonic Pin No. Function NC 1, 4, 5, 6, 8 No Connect Pins. VCC 2 +5 V, +3.3 V, +3 V Power Supply Input. RESET 7 Logic Output. It remains low while VCC is below the reset threshold voltage and for 280 ms (typ) after VCC rises above the threshold. GND 3 Ground, 0 V. PIN CONFIGURATION Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above those listed in the operational sections of this specification is not implied. Exposure to absolute maximum ratings for extended periods of time may affect device reliability. 8 NC VCC 2 ADM709 7 RESET GND 3 TOP VIEW (Not to Scale) 6 NC 5 NC NC 1 NC 4 NC = NO CONNECT –2– REV. 0 ADM709 RESET at Voltages < 1 V ADM709 VCC RESET GENERATOR VTH The ADM709 RESET output is guaranteed to operate with supply voltages as low as 1 V. If it is desired that the RESET output remains low below 1 V, then a pull-down resistor should be connected between the RESET output and GND. A resistor of 100 kΩ is suitable. This is illustrated in Figure 5. RESET GND Figure 1. Functional Block Diagram ADM709 RESET VCC VCC ADM709 R1 GND µP RESET RESET GND Figure 5. RESET Valid @ VCC < 1 V GND Glitch Immunity The ADM709 is immune to short transients which may occur on the VCC line. This is important so that spurious resets are not generated as a result of minor glitches on the power supply. Figure 2. Typical Operating Circuit CIRCUIT INFORMATION RESET Output Additional glitch immunity may be obtained by connecting a capacitor (0.1 µF or greater) as close as possible to the VCC pin on the device. RESET is an active low output which provides a reset signal to the microprocessor whenever the VCC supply voltage is below the reset threshold. An internal timer holds RESET low for 140 ms after the voltage on VCC rises above the threshold. This is intended as a power-on reset signal for the processor. It allows time for the power supply and microprocessor to stabilize after power up. Similarly a power supply brownout will initiate a processor reset. On power-down, the RESET output remains low with VCC as low as 1 V. This ensures that the microprocessor is held in a stable shutdown condition as the power supply drops. VCC VRT Microprocessors with Bidirectional I-O Some microprocessors or microcontrollers such as the MC68HC11 have bidirectional reset lines. In order to avoid signal contention, a resistor of 4.7 kΩ should be connected between the ADM709 RESET output and the microcontroller RESET line. This arrangement is shown in Figure 6. +5V VCC VRT ADM709 tRS RESET RESET GND Figure 3. Power Off/On RESET Timing µP RESET GND Figure 6. Interfacing to Microprocessors with Bidirectional RESET VCC RESET 400ms/DIV Figure 4. RESET Output vs. VCC REV. 0 BUFFERED RESET –3– ADM709 OUTLINE DIMENSIONS Dimensions shown in inches and (mm). 8 C2022–18–4/95 8-Lead Plastic DIP (N-8) 5 0.280 (7.11) PIN 1 0.240 (6.10) 1 4 0.325 (8.25) 0.300 (7.62) 0.430 (10.92) 0.348 (8.84) 0.060 (1.52) 0.015 (0.38) 0.210 (5.33) MAX 0.130 (3.30) MIN 0.160 (4.06) 0.115 (2.93) 0.100 (2.54) BSC 0.022 (0.558) 0.014 (0.356) 0.070 (1.77) 0.045 (1.15) 0.195 (4.95) 0.115 (2.93) 0.015 (0.381) 0.008 (0.204) SEATING PLANE 8-Lead SOIC (SO-8) 5 8 0.1574 (4.00) 0.1497 (3.80) PIN 1 0.2440 (6.20) 0.2284 (5.80) 4 1 0.1968 (5.00) 0.1890 (4.80) 0.0196 (0.50) x 45 ° 0.0099 (0.25) 0.0688 (1.75) 0.0532 (1.35) 0.0500 (1.27) BSC 0.0192 (0.49) 0.0138 (0.35) 0.0098 (0.25) 0.0075 (0.19) 8° 0° 0.0500 (1.27) 0.0160 (0.41) PRINTED IN U.S.A. 0.0098 (0.25) 0.0040 (0.10) –4– REV. 0