DS1817 DS1817 Active High 3.3V EconoReset FEATURES PIN ASSIGNMENT * Automatically restarts a microprocessor after power 3 failure * Maintains reset for 150 ms after VCC returns to an in- tolerance condition * Reduces need for discrete components * Precision temperature-compensated reference and voltage sensor 1 2 SOT-23 PACKAGE See Mech. Drawing voltage * Accurate 5%, 10% or 20% power monitoring * 20% tolerance for use with 3.0 volt systems 1 2 3 1 2 3 * Low-cost TO-92 or space saving surface mount SOT-23 packages available * Push-Pull active high output TO-92 PACKAGE See Mech. Drawings * Operating temperature -40C to +85C PIN DESCRIPTIONS TO-92 1 2 3 RST VCC GND Active High Reset Output Power Supply Ground SOT-23 1 2 3 RST VCC GND Active High Reset Output Power Supply Ground DESCRIPTION The DS1817 EconoReset uses a precision temperature 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 state. When VCC returns to an in-tolerance condition, the reset signal is kept in the active state for approximately 150 ms to allow the power supply and processor to stabilize. 032598 1/5 DS1817 OPERATION - POWER MONITOR The DS1817 provides the function 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, the RST signal is asserted. On power-up, RST is kept active for approximately 150 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 (CMOS OUTPUT) Figure 1 VCC VCC TOLERANCE BIAS + 150 ms DELAY GROUND - T.C. REFERENCE APPLICATION EXAMPLE Figure 2 VCC DS1817 032598 2/5 RST MICROPROCESSOR RESET RST DS1817 TIMING DIAGRAM: POWER UP Figure 3 tR VCCTP(MAX) VCCTP(MIN) VCCTP V IN tRPU VOL RST TIMING DIAGRAM: POWER DOWN Figure 4 tF VCC VCCTP(MAX) VCCTP VCCTP(MIN) tRPD VOH RST SLEWS WITH VCC RST 032598 3/5 DS1817 ABSOLUTE MAXIMUM RATINGS* Voltage on VCC Pin Relative to Ground Voltage on RST Relative to Ground Operating Temperature Storage Temperature Soldering Temperature -0.5V to +7.0V -0.5V to 5VCC +0.5V -40C to +85C -55C to +125C 260C 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 0.0 (-40C to +85C) TYP DC ELECTRICAL CHARACTERISTICS PARAMETER MAX UNITS NOTES 5.5 V 1 (-40C to +85C; VCC = 1.2V to 5.5V) SYMBOL MIN TYP Output Voltage @ 0-500 A VOH VCC-0.5V VCC-0.1V MAX Output Current @ 2.4V IOH Output Current @ 0.4V IOL 350 +10 UNITS NOTES V 1 A 2 mA 2 28 35 A 3 VCC Trip Point (DS1817-5) VCCTP 2.98 3.06 3.15 V 1 VCC Trip Point (DS1817-10) VCCTP 2.80 2.88 2.97 V 1 VCC Trip Point (DS1817-20) VCCTP 2.47 2.55 2.64 V 1 Output Capacitance COUT 10 pF Operating Current VCC < 5.5 ICC AC ELECTRICAL CHARACTERISTICS PARAMETER (-40C to +85C; VCC = 1.2V to 5.5V) SYMBOL MIN TYP MAX UNITS RESET Active Time tRST 100 150 250 ms VCC Detect to RST tRPD 2 5 s VCC Slew Rate (VCCTP (MAX) to VCCTP (MIN)) tF 300 s VCC Slew Rate (VCCTP (MIN) to VCCTP (MAX)) tR 0 ns tRPU 100 VCC Detect to RST 150 250 ms NOTES 6 4, 5 NOTES: 1. All voltages are referenced to ground. 2. Measured with VCC > 2.7V. 3. Measured with RST output open. 4. Measured with 2.7V > VCC > 3.3V. 5. tR = 5 s. 6. The tF value is for reference in defining values for TRPD and should not be considered a requirement for proper operation or use of the device. 032598 4/5 DS1817 PART MARKING CODES 3 ABCD 1 2 SOT-23 PACKAGE "A", "B", & "C" represents the Device Type. 810 - DS1810 811 - DS1811 812 - DS1812 813 - DS1813 815 - DS1815 816 - DS1816 817 - DS1817 818 - DS1818 "D" represents the Device Tolerance. A - 5% B - 10% C - 15% D - 20% 032598 5/5