DS1815R-20-U+

DS1815 3.3V EconoReset with Push-Pull Output www.maxim-ic.com FEATURES § § § § § § § § PIN ASSIGNMENT Automatically restarts a microprocessor after power failure Maintains reset for 150ms 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 Low-cost TO-92 or space saving surfacemount SOT-23 packages available Push-pull output for low current operation Operating temperature -40°C to +85°C 3 DALLAS DS1815 Econo Reset 1 1 2 3 2 TOP VIEW SOT-23 PACKAGE See Mech. Drawings Section On Website 1 2 3 BOTTOM VIEW TO-92 PACKAGE See Mech. Drawings Section On Website PIN DESCRIPTION TO-92 1 2 3 RST VCC GND Active Low Reset Output Power Supply Ground SOT-23 1 2 3 RST VCC GND Active Low Reset Output Power Supply Ground DESCRIPTION The DS1815 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 150ms to allow the power supply and processor to stabilize. 1 of 5 041002 DS1815 OPERATION — POWER MONITOR The DS1815 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, the RST signal is asserted. On power-up, RST is kept active for approximately 150ms 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 APPLICATION DIAGRAM: RST VALID TO 0 VOLTS VCC ON THE DS1815 Figure 3 2 of 5 DS1815 TIMING DIAGRAM: POWER-UP Figure 4 TIMING DIAGRAM: POWER-DOWN Figure 5 3 of 5 DS1815 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 Output Voltage @ -500mA SYMBOL VOH Output Current @ 2.4V IOH Output Current @ 0.4V IOL Operating Current VCC < 5.5 ICC VCC Trip Point (DS1815-5) VCCTP VCC Trip Point (DS1815-10) (-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 mA 2 mA 2 28 35 mA 3 2.98 3.06 3.15 V 1 VCCTP 2.80 2.88 2.97 V 1 VCC Trip Point (DS1815-20) 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 ms VCC Slew Rate (VCCTP (MAX) to VCCTP (MIN)) tF 300 ms VCC Slew Rate (VCCTP (MIN) to VCCTP (MAX)) tR 0 ns tRPU 100 VCC Detect to RST 4 of 5 150 250 ms NOTES 4 6 4, 5 DS1815 NOTES: 1. All voltages are referenced to ground. 2. Measured with VCC ³ 2.7V. 3. Measured with RST output open. 4. Measured with 2.7V £ VCC £ 3.3V. 5. tR = 5ms. 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. PART MARKING CODES “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