DS1816 MAXIM | Alldatasheet

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Technical content

FEATURES

/g167 Automatically restarts a microprocessor after power failure /g167 Maintains reset for 150ms 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 3V systems /g167 Low-cost TO-92 or space saving SOT-23 packages available /g167 Efficient open-drain output with internal 5k/g87/g32pull-up resistor /g167 Operating temperature -40/g176C to +85/g176C PIN ASSIGNMENT PIN DESCRIPTION TO-92

1 RST Active Low Reset Output

2 V CC Power Supply

3 GND Ground

DESCRIPTION

The DS1816 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 fo r approximately 150ms to allow the power supply and processor to stabilize. DS1816 3.3V EconoReset with Open Drain Output 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 DS1816 Econo Reset

OPERATION — POWER MONITOR The DS1816 provides the function of detecting out-of- tolerance power supply conditions and warning a processor-based system of imp ending 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 150ms after the power supply has reached the selected tolerance. This allows the power supply and microprocessor to stabilize before RST is released. BLOCK DIAGRAM (OPEN-DRAIN 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 V CC + 0.5V Operating Temperature Range -40°C to +85°C Storage Temperature Range -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 Current @ 0.4V I OL +10 mA 2, 3 Operating Current VCC < 5.5V I CC 28 35 /g109A 4 VCC Trip Point (DS1816-5) V CCTP 2.98 3.06 3.15 V 1 VCC Trip Point (DS1816-10) V CCTP 2.80 2.88 2.97 V 1 VCC Trip Point (DS1816-20) V CCTP 2.47 2.55 2.64 V 1 Internal Pull-Up Resistor R P 3.5 5.5 7.5 k/g87 7 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 5 VCC Detect to RST tRPD 25 /g109s VCC Slew Rate (VCCTP (MAX) to VCCTP (MIN)) tF 300 /g109s 8 VCC Slew Rate (VCCTP (MIN) to VCCTP (MAX)) tR 0n s VCC Detect to RST tRPU 100 150 250 ms 5, 6

NOTES: 1. All voltages are referenced to ground. 2. Measured with VCC /g179 2.7V. 3. A 1k/g87/g32external pull-up resistor may be required in some applications for proper operation of the microprocessor reset control circuit. 4. Measured with RST output open. 5. Measured with 2.7V /g163 VCC /g163 3.3V. 6. tR = 5/g109s 7. VOH and IOH are a function of the value of RP and the associated output load conditions. 8. The tF 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”, &“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.