DS1815 DALLAS | Alldatasheet

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Technical content

FEATURES

/elevenoclock Automatically restarts a microprocessor after power failure /elevenoclock Maintains reset for 150 ms after VCC returns to an in-tolerance condition /elevenoclock Reduces need for discrete components /elevenoclock Precision temperature-compensated voltage reference and voltage sensor /elevenoclock Accurate 5%, 10% or 20% power monitoring /elevenoclock Low-cost TO-92 or space saving surface- mount SOT-23 packages available /elevenoclock Push-pull output for low current operation /elevenoclock Operating temperature -40°C to +85°C PIN ASSIGNMENT PIN DESCRIPTION TO-92

1 RST Active Low Reset Output

2 V CC Power Supply

3 GND Ground

DESCRIPTION

The DS1815 EconoReset uses a precision 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. DS1815 3.3V EconoReset with Push-Pull Output www.dalsemi.com SOT-23 PACKAGE 1 2 3 1 2 3 TO-92 PACKAGE See Mech. Drawings Section

The DS1815 provides the functions 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, 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 APPLICATION DIAGRAM: RST VALID TO 0 VOLTS VCC ON THE DS1815 Figure 3

TIMING DIAGRAM: POWER-UP Figure 4 TIMING DIAGRAM: POWER-DOWN Figure 5

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°C to +85°C) PARAMETER SYMBOL MIN TYP MAX UNITS NOTES Supply Voltage V CC 0.0 5.5 V 1 DC ELECTRICAL CHARACTERISTICS (-40°C to +85°C; VCC=1.2V to 5.5V) PARAMETER SYMBOL MIN TYP MAX UNITS NOTES Output Voltage @ -500 µA VOH VCC -0.5V VCC -0.1V Output Current @ 2.4 V I OH 350 µA 2 Output Current @ 0.4 V I OL +10 mA 2 Operating Current VCC < 5.5 I CC 28 35 µA 3 VCC Trip Point (DS1815-5) V CCTP 2.98 3.06 3.15 V 1 VCC Trip Point (DS1815-10) V CCTP 2.80 2.88 2.97 V 1 VCC Trip Point (DS1815-15) V CCTP 2.47 2.55 2.64 V 1 Output Capacitance C OUT 10 pF AC ELECTRICAL CHARACTERISTICS (-40°C to +85°C; VCC=1.2V to 5.5V) PARAMETER SYMBOL MIN TYP MAX UNITS NOTES RESET Active Time t RST 100 150 250 ms 4 VCC Detect to RST tRPD 25 µs VCC Slew Rate (VCCTP (MAX) to VCCTP (MIN)) tF 300 µs 6 VCC Slew Rate (VCCTP (MIN) to VCCTP (MAX)) tR 0n s VCC Detect to RST tRPU 100 150 250 ms 4, 5

NOTES: 1. All voltages are referenced to ground. 2. Measured with VCC ≥ 2.7V. 3. Measured with RST output open. 4. Measured with 2.7V ≤ VCC ≤ 3.3V. 5. tR = 5 µs. 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.