DS1813 5V EconoReset with Pushbutton www.maxim-ic.com GENERAL DESCRIPTION PIN CONFIGURATIONS The DS1813 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. 3 DALLAS DS1813 Econo Reset 1 1 2 3 The DS1813 also monitors a pushbutton on the reset output. If the reset line is pulled low, a reset is generated upon release and will be held in reset output low for typically 150ms. 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 FEATURES Automatically Restarts a Microprocessor After Power Failure Monitors Pushbutton for External Override Maintains Reset for Typically 150ms After VCC Returns to an In-Tolerance Condition Reduces Need for Discrete Components Precision Temperature-Compensated Voltage Reference and Voltage Sensor Low-Cost TO-92 or Space-Saving SurfaceMount SOT-23 Packages Available Efficient Open-Drain Output with Internal 5.5k Pullup Resistor -40C to +85C Operating Temperature PIN DESCRIPTION PIN TO-92 SOT-23 1 of 5 NAME FUNCTION 1 1 RST Active-Low Reset Output 2 2 VCC Power Supply 3 3 GND Ground REV: 022306 DS1813 OPERATION--POWER MONITOR The DS1813 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. OPERATION--PUSHBUTTON RESET The DS1813 provides for a pushbutton switch for manual reset control. When the DS1813 is not in a reset cycle, a pushbutton reset can be generated by pulling the RST pin low for at least 1s. When the pushbutton is held low, the RST is forced active low and will remain active low for about 150ms after the pushbutton is released. See Figure 2 for an application example and Figure 3 for the timing diagram. Figure 1. Block Diagram (Open-Drain Output) Figure 2. Application Example 2 of 5 DS1813 Figure 3. Timing Diagram: Pushbutton Reset Figure 4. Timing Diagram: Power-Up Figure 5. Timing Diagram: Power-Down 3 of 5 DS1813 ABSOLUTE MAXIMUM RATINGS Voltage Range on VCC Pin Relative to Ground......................................................-0.5V to +7.0V Voltage Range on RST Relative to Ground..................................................-0.5V to (VCC +0.5V) Operating Temperature Range........................................................................-40C to +85C Storage Temperature Range.........................................................................-55C to +125C Soldering Temperature.................................................See IPC/JEDEC J-STD-020 Specification 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 (TA = -40C to +85C) PARAMETER Supply Voltage SYMBOL MIN VCC 0 TYP MAX UNITS NOTES 5.5 V 1 MAX UNITS NOTES mA 2, 3 V 1 V 1 A 4 V 1 6 DC ELECTRICAL CHARACTERISTICS (VCC = 1.2V to 5.5V, TA = -40C to +85C.) PARAMETER SYMBOL Output Current at 0.4V IOL Voltage Input Low VIL Voltage Input High VIH Operating Current VCC < 5.5 ICC DS1813-5 VCC Trip Point DS1813-10 VCCTP DS1813-15 Internal Pullup Resistor Output Capacitance RP MIN TYP 10 0.4 0.7 x VCC 30 40 4.50 4.62 4.75 4.25 4.35 4.49 4.00 4.13 4.24 3.50 5.5 7.5 k 10 pF COUT AC ELECTRICAL CHARACTERISTICS (VCC = 1.2V to 5.5V, TA = -40C to +85C.) PARAMETER SYMBOL Reset Active Time tRST VCC Detect to RST tRPD MIN TYP MAX UNITS 100 150 300 ms 2 5 s VCC Slew Rate (VCCTP(MAX) - VCCTP(MIN)) tF 300 s VCC Slew Rate (VCCTP(MIN) - VCCTP(MAX)) tR 0 ns VCC Detect to RST tRPU 100 Pushbutton Detect to RST tPB 1 tPBRST 100 Pushbutton Reset 4 of 5 150 300 ms s 150 300 ms NOTES 7 5 DS1813 NOTES: 1) All voltages are referenced to ground. 2) Measured with VCC 2.7V. 3) A 1k external resistor may be required in some applications for proper operation of the microprocessor reset control circuit. 4) Measured with RST output open. 5) tR = 5s. 6) VOH and IOH are a function of the value of RP and the associated output load conditions. 7) This 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," and "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 Maxim/Dallas Semiconductor cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim/Dallas Semiconductor product. No circuit patent licenses are implied. Maxim/Dallas Semiconductor reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2006 Maxim Integrated Products * Printed USA The Maxim logo is a registered trademark of Maxim Integrated Products, Inc. The Dallas logo is a registered trademark of Dallas Semiconductor Corporation.