DS1813 DS1813 5V EconoReset with Pushbutton FEATURES PIN ASSIGNMENT * Automatically restarts a microprocessor after power 3 failure * Monitors pushbutton for external override * Maintains reset for typically 150 ms after VCC returns to an in-tolerance condition 1 * Reduces need for discrete components * Precision temperature-compensated reference and voltage sensor 2 SOT-23 PACKAGE voltage * Low-cost 1 2 3 * Efficient 1 2 3 TO-92 or space saving surface-mount SOT-23 packages available open-drain output with internal 5.5K pull-up resistor * Operating temperature -40C to +85C TO-92 PACKAGE See Mech. Drawings Section PIN DESCRIPTIONS 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 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 sig- Copyright 1995 by Dallas Semiconductor Corporation. All Rights Reserved. For important information regarding patents and other intellectual property rights, please refer to Dallas Semiconductor data books. nal is kept in the active state for approximately 150 ms to allow the power supply and processor to stabilize. 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 150 ms. 082196 1/5 DS1813 OPERATION - POWER MONITOR OPERATION - PUSHBUTTON RESET 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 150 ms after the power supply has reached the selected tolerance. This allows the power supply and microprocessor to stabilize before RST is released. 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 1 s. When the pushbutton is held low, the RESET is forced active low and will remain active low for about 150 ms after the pushbutton is released. See Figure 2 for an application example and Figure 3 for the timing diagram. BLOCK DIAGRAM (OPEN-DRAIN OUTPUT) Figure 1 VCC 5.5K RESET MONITOR RST Vcc TOLERANCE AND BIAS + - 150 ms DELAY GROUND T.C. REFERENCE APPLICATION EXAMPLE Figure 2 VCC DS1813 082196 2/5 RST MICROPROCESSOR RESET DS1813 TIMING DIAGRAM: PUSHBUTTON RESET Figure 3 tPB tRST RST VIH VIL TIMING DIAGRAM: POWER UP Figure 4 tR VCCTP(MAX) VCCTP VCCTP(MIN) VCC tRPU VOH RST TIMING DIAGRAM: POWER DOWN Figure 5 tF VCC VCCTP(MAX) VCCTP VCCTP(MIN) RST tRPD VOL 082196 3/5 DS1813 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 UNITS NOTES 5.5 V 1 (-40C to +85C; VCC = 1.2V to 5.5V) SYMBOL MIN IOL +10 Output Current @ 0.4 volts MAX TYP MAX UNITS NOTES mA 2, 3 30 40 A 4 VCC Trip Point (DS1813-5) VCCTP 4.50 4.62 4.75 V 1 VCC Trip Point (DS1813-10) VCCTP 4.25 4.35 4.49 V 1 VCC Trip Point (DS1813-15) VCCTP 4.00 4.13 4.24 V 1 RP 3.50 5.5 7.5 K 10 pF Operating Current VCC < 5.5 ICC Internal Pull-Up Resistor Output Capacitance COUT AC ELECTRICAL CHARACTERISTICS PARAMETER (-40C to +85C; VCC = 1.2V to 5.5V) SYMBOL MIN TYP MAX UNITS RESET Active Time tRST 100 150 300 ms VCC Detect to RST tRPD 2 5 s VCC Slew Rate (VCCTP (MAX) - VCCTP (MIN)) tF 300 s VCC Slew Rate (VCCTP (MIN) - VCCTP (MAX)) tR 0 ns tRPU 100 tPB 1 VCC Detect to RST Push-button Detect to RST Push-button Reset tPBRST 100 150 300 ms NOTES 5 s 150 300 ms NOTES: 1. All voltages are referenced to ground. 2. Measured with VCC > 2.7 volts. 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 = 5 s. 082196 4/5 DS1813 PART MARKING CODES 3 ABCD 1 "A", "B", &"C" represent the device type. 810 811 812 813 815 816 817 818 .... .... .... .... .... .... .... .... DS1810 DS1811 DS1812 DS1813 DS1815 DS1816 DS1817 DS1818 2 "D" represents the device tolerance. A ...... B ...... C...... D...... 5% 10% 15% 20% 082196 5/5