DS1817 Active High 3.3V EconoReset www.dalsemi.com FEATURES PIN ASSIGNMENT Automatically restarts a microprocessor after power failure Maintains reset for 150 ms after VCC returns to an in-tolerance condition Reduces need for discrete components Precision temperature-compensated voltage reference and voltage sensor Accurate 5%, 10% or 20% power monitoring 20% tolerance for use with 3.0-volt systems Low-cost TO-92 or space saving surface mount SOT-23 packages available Push-pull active high output Operating temperature -40°C to +85°C 3 1 2 SOT-23 PACKAGE See Mech. Drawing 1 2 3 1 2 3 TO-92 PACKAGE See Mech. Drawing PIN DESCRIPTION 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. 1 of 5 Powered by ICminer.com Electronic-Library Service CopyRight 2003 111999 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 APPLICATION EXAMPLE Figure 2 2 of 5 Powered by ICminer.com Electronic-Library Service CopyRight 2003 DS1817 TIMING DIAGRAM: POWER-UP Figure 3 TIMING DIAGRAM: POWER-DOWN Figure 4 3 of 5 Powered by ICminer.com Electronic-Library Service CopyRight 2003 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 -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 0.0 DC ELECTRICAL CHARACTERISTICS PARAMETER SYMBOL Output Voltage @ 0-500 µA VOH Output Current @ 2.4V IOH Output Current @ 0.4V IOL Operating Current VCC < 5.5 ICC VCC Trip Point (DS1817-5) VCCTP VCC Trip Point (DS1817-10) (-40°C to +85°C) TYP MAX UNITS NOTES 5.5 V 1 (-40°C to +85°C; VCC=1.2V to 5.5V) MIN VCC -0.5V TYP VCC -0.1V MAX 350 +10 UNITS V NOTES 1 µA 2 mA 2 28 35 µA 3 2.98 3.06 3.15 V 1 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 AC ELECTRICAL CHARACTERISTICS PARAMETER RESET Active Time VCC Detect to RST SYMBOL tRST (-40°C to +85°C; VCC=1.2V to 5.5V) MIN 100 tRPD TYP 150 MAX 250 UNITS ms 2 5 µs VCC Slew Rate (VCCTP (MAX) to VCCTP (MIN)) tF 300 µs VCC Slew Rate (VCCTP (MIN) to VCCTP (MAX)) tR 0 ns tRPU 100 VCC Detect to RST 4 of 5 Powered by ICminer.com Electronic-Library Service CopyRight 2003 150 250 ms NOTES 6 4, 5 DS1817 NOTES: 1. 2. 3. 4. 5. 6. All voltages are referenced to ground. Measured with VCC ≥ 2.7V. Measured with RST output open. Measured with 2.7V ≥ VCC ≥ 3.3V. tR = 5 µs. 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. PART MARKING CODES SOT-23 PACKAGE “A”, “B”, &“C” represent 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% 5 of 5 Powered by ICminer.com Electronic-Library Service CopyRight 2003