DS1817 MAXIM | Alldatasheet
Document overview
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Technical content
FEATURES
/g167 Automatically restarts a microprocessor after power failure /g167 Maintains reset for 150 ms after VCC returns to an in-tolerance condition /g167 Reduces need for discrete components /g167 Precision temperature-compensated voltage reference and voltage sensor /g167 Accurate 5%, 10% or 20% power monitoring /g167 20% tolerance for use with 3.0-volt systems /g167 Low-cost TO-92 or space saving surface mount SOT-23 packages available /g167 Push-pull active high output /g167 Operating temperature -40°C to +85°C PIN ASSIGNMENT PIN DESCRIPTION TO-92
1 RST Active High Reset Output
2 V CC Power Supply
3 GND Ground
DESCRIPTION
The DS1817 EconoReset uses a precisi on temperature reference and comparator circuit to monitor the status of the power supply (V CC). When an out-of-tolerance condition is detected, an internal power-fail signal is generated which forces reset to the active state. When V CC 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. DS1817 Active High 3.3V EconoReset www.maxim-ic.com TOP VIEW SOT-23 PACKAGE See Mech. Drawings Section On Website1 2 3 1 2 3 BOTTOM VIEW TO-92 PACKAGE See Mech. Drawings Section On Website DALLAS DS1817 Econo Reset
The DS1817 provides the function of detecting out-of- tolerance power supply conditions and warning a processor based system of impending power failure. When V CC is detected as out-of-tolerance, the RST signal is asserted. On power-up, RS T is kept active for approximately 150 ms after the power supply has reached the selected tolerance. This allows the pow er supply and microprocessor to stabilize before RST is released. BLOCK DIAGRAM (CMOS OUTPUT) Figure 1 APPLICATION EXAMPLE Figure 2
TIMING DIAGRAM: POWER-UP Figure 3 TIMING DIAGRAM: POWER-DOWN Figure 4
ABSOLUTE MAXIMUM RATINGS* Voltage on VCC Pin Relative to Ground -0.5V to +7.0V Voltage on RST Relative to Ground -0.5V to 5V CC +0.5V Operating Temperature -40°C to +85°C Storage Temperature -55°C to +125°C Soldering Temperature 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 (-40/g176C to +85/g176C) PARAMETER SYMBOL MIN TYP MAX UNITS NOTES Supply Voltage V CC 0.0 5.5 V 1 DC ELECTRICAL CHARACTERISTICS (-40/g176C to +85/g176C; VCC=1.2V to 5.5V) PARAMETER SYMBOL MIN TYP MAX UNITS NOTES Output Voltage @ 0-500 /g109A VOH VCC -0.5V VCC -0.1V Output Current @ 2.4V I OH 350 /g109A 2 Output Current @ 0.4V I OL +10 mA 2 Operating Current VCC < 5.5 I CC 28 35 /g109A 3 VCC Trip Point (DS1817-5) V CCTP 2.98 3.06 3.15 V 1 VCC Trip Point (DS1817-10) V CCTP 2.80 2.88 2.97 V 1 VCC Trip Point (DS1817-20) V CCTP 2.47 2.55 2.64 V 1 Output Capacitance C OUT 10 pF AC ELECTRICAL CHARACTERISTICS (-40/g176C to +85/g176C; VCC=1.2V to 5.5V) PARAMETER SYMBOL MIN TYP MAX UNITS NOTES RESET Active Time t RST 100 150 250 ms VCC Detect to RST t RPD 25 /g109s VCC Slew Rate (VCCTP (MAX) to VCCTP (MIN)) tF 300 /g109s 6 VCC Slew Rate (VCCTP (MIN) to VCCTP (MAX)) tR 0n s VCC Detect to RST t RPU 100 150 250 ms 4, 5
NOTES: 1. All voltages are referenced to ground. 2. Measured with VCC /g179 2.7V. 3. Measured with RST output open. 4. Measured with 2.7V /g179 VCC /g179 3.3V. 5. tR = 5 /g109s. 6. The tF value is for reference in defining values for T RPD 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% SOT-23 PACKAGE