DS1810 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 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 DS1810 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. DS1810 5V 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 DS1810 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, 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 (PUSH-PULL OUTPUT) Figure 1 APPLICATION EXAMPLE Figure 2 OUTPUT VALID CONDITIONS All versions of the DS1810 can maintain a valid output as long as V CC remains above 1.2 volt. However, the RST outputs on the DS1810 use a push-pull structure which can maintain a valid output below 1.2 volts on an input. To sink current below 1.2 volts, a resistor can be connected from RST to Ground (see Figure 3). This arrangement will maintain a valid value on the RST outputs even it V CC approaches 0 volts. During both power-up and -down this arrangement will draw current when RST is in the high state. A value of about 100 k/c4762 should be adequate to maintain a valid condition.

APPLICATION DIAGRAM: RST VALID TO 0 VOLTS VCC ON THE DS1810 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 V 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 1.2 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 @ 0-500 µA VOH VCC-0.5V V CC-0.1V V 1 Output Current @ 2.4V I OH 350 µA 2 Output Current @ 0.4V I OL +10 mA 2 Operating Current VCC < 5.5 I CC 30 40 µA 3 VCC Trip Point (DS1810-5) V CCTP 4.50 4.62 4.75 V 1 VCC Trip Point (DS1810-10) V CCTP 4.25 4.37 4.49 V 1 VCC Trip Point (DS1810-15) V CCTP 4.00 4.12 4.24 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 100 150 300 ms VCC Detect to RST tRPD 25 µs VCC Slew Rate (VCCTP (MAX) to VCCTP (MIN)) tF 300 µs VCC Slew Rate (VCCTP (MIN) to VCCTP (MAX)) tR 0n s VCC Detect to RST tRPU 100 150 300 ms 4

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