DS1233M DS1233M EconoReset FEATURES • Automatically PIN ASSIGNMENT restarts microprocessor after power DALLAS DS1233 Econo Reset failure • Maintains reset for 350 ms after VCC returns to an in-tolerance condition • Reduces need for discrete components • Precision temperature-compensated voltage reference and voltage sensor • Internal 5 KΩ pull-up resistor • Compatible with 1 2 3 1 2 3 1 8 NC VCC 2 7 NC NC 3 6 NC GND 4 5 NC DS1233M 8–PIN SOIC (150 MIL) See Mech. Drawings Section • Low-cost TO-92 package or surface mount 8–pin SOIC packages available RST Motorola 68XXX series and HC16 Microprocessors • Pin function compatible with the Motorola MC33064, MC34064, MC33164, and MC34164 DS1233M TO-92 Package See Mech. Drawings Section • Operating temperature of –40°C to +85°C PIN DESCRIPTIONS TO–92 1 2 3 RST VCC GND – Active Low Reset Output – Power Supply – Ground 8–Pin SOIC RST VCC NC GND – – – – Active Low Reset Output Power Supply No Connect Ground DESCRIPTION The DS1233M EconoReset uses a precision temperature compensated reference and comparator circuit to monitor the status of the power supply (VCC). When an out-of-tolerance condition is detected, an internal power fail signal is generated which forces reset to the active (low) state. When VCC returns to an in-tolerance condition, the reset signal is kept in the active state for approximately 350 ms to allow the power supply and processor to stabilize. 022698 1/4 DS1233M OPERATION – POWER MONITOR The DS1233M provides the functions of detecting out-of-tolerance power supply conditions and warning a processor-based system of impending power failure. When VCC is detected as out-of-tolerance, as defined by the tolerance of the part selected, the RST signal is asserted. On power-up, RST is kept active for approximately 350 ms after the power supply has reached the selected tolerance. This allows the power supply and microprocessor to stabilize before RST is released. BLOCK DIAGRAM Figure 1 VCC 5KΩ RST Vcc TOLERANCE AND BIAS 350 ms DELAY T.C. REFERENCE GROUND APPLICATION EXAMPLE Figure 2 VCC DS1233M 022698 2/4 RST MICROPROCESSOR RESET DS1233M TIMING DIAGRAM: POWER UP Figure 3 tR VHTL VCCTP VLTL VCC tRPU VOH RST VOLTAGE TRIP LEVELS PARAMETER SYMBOL MIN TYP MAX UNITS NOTES Voltage High Trip Level VHTL 4.75 V DS1233M–5, DS1233M–55 Voltage Low Trip Level VLTL 4.00 V DS1233M–5, DS1233M–55 Voltage High Trip Level VHTL 3.14 V DS1233M–3 Voltage Low Trip Level VLTL 2.48 V DS1233M–3 TIMING DIAGRAM: POWER DOWN Figure 4 tF VCC VHTL VCCTP RST VLTL tRPD VOL 022698 3/4 DS1233M ABSOLUTE MAXIMUM RATINGS* Voltage on VCC Pin Relative to Ground Voltage on I/O Relative to Ground Operating Temperature Storage Temperature Soldering Temperature -0.5V to +7.0V –0.5V to VCC + 0.5V –40°C to +85°C -55°C to +125°C 260°C for 10 seconds * This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability. RECOMMENDED DC OPERATING CONDITIONS PARAMETER SYMBOL MIN Supply Voltage VCC 1.2 (–40°C to +85°C) TYP DC ELECTRICAL CHARACTERISTICS PARAMETER MAX UNITS NOTES 5.5 V 1 (–40°C to +85°C; VCC = 1.2V to 5.5V) SYMBOL MIN TYP Output Voltage @ –500 µA VOH VCC–0.5V VCC–0.1V Output Current @ 0.4V IOL +8 Operating Current ICC MAX UNITS NOTES V 1 mA 2, 3 50 µA 4 VCC Trip Point (DS1233M–5) VCCTP 4.25 4.375 4.49 V 1 VCC Trip Point (DS1233M–55) VCCTP 4.5 4.625 4.75 V 1 VCC Trip Point (DS1233M–3) VCCTP 2.64 2.72 2.8 V 1 Output Capacitance COUT 10 pF 6.50 KΩ Internal Pull-Up Resistor RP 3.75 5 SYMBOL MIN TYP MAX UNITS Reset Active Time tRST 200 350 500 ms VCC Detect to RST tRPD 2 10 µs AC ELECTRICAL CHARACTERISTICS PARAMETER (–40°C to +85°C; VCC = 1.2V to 5.5V) VCC Slew Rate (VHTL – VLTL) tF 300 µs VCC Slew Rate (VLTL – VHTL) tR 0 ns tRPU 200 VCC detect to RST 350 500 ms NOTES 5 NOTES: 1. All voltages are referenced to ground. 2. Measured with VCC 2.7V. 3. A 1KΩ external resistor may be required in some applications for proper operation of the microprocessor reset control circuit. 4. Measured with outputs open. 5. tR = 5 µs. 022698 4/4