DS1810 5V EconoReset with Push-Pull Output www.dalsemi.com FEATURES PIN ASSIGNMENT Automatically restarts a microprocessor after power failure Maintains reset for 150 ms after VCC returns to an in-tolerance condition Reduces need for discrete components Precision temperature-compensated voltage reference and voltage sensor Low-cost TO-92 or space saving surface mount SOT-23 packages available Push-Pull output for low current operation Operating temperature -40°C to +85°C 3 1 2 SOT-23 PACKAGE 1 2 3 1 2 3 TO-92 PACKAGE See Mech. Drawings Section PIN DESCRIPTION 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 DS1810 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 signal is kept in the active state for approximately 150 ms to allow the power supply and processor to stabilize. 1 of 5 111999 DS1810 OPERATION - POWER MONITOR The DS1810 provides the function 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. 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 VCC 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 VCC 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 kኚ should be adequate to maintain a valid condition. 2 of 5 DS1810 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 3 of 5 DS1810 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 VCC +0.5V -40°C to +85°C -55°C to +125°C 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 PARAMETER Supply Voltage SYMBOL VCC MIN 1.2 DC ELECTRICAL CHARACTERISTICS PARAMETER SYMBOL Output Voltage @ 0-500 µA VOH Output Current @ 2.4V IOH Output Current @ 0.4V IOL Operating Current VCC < 5.5 ICC VCC Trip Point (DS1810-5) VCCTP VCC Trip Point (DS1810-10) (-40°C to +85°C) TYP MAX 5.5 UNITS V NOTES 1 (-40°C to +85°C; VCC=1.2V to 5.5V) MIN TYP MAX VCC-0.5V VCC-0.1V 350 +10 UNITS NOTES V 1 µA 2 mA 2 30 40 µA 3 4.50 4.62 4.75 V 1 VCCTP 4.25 4.37 4.49 V 1 VCC Trip Point (DS1810-15) VCCTP 4.00 4.12 4.24 V 1 Output Capacitance COUT 10 pF AC ELECTRICAL CHARACTERISTICS PARAMETER (-40°C to +85°C; 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 µs VCC Slew Rate (VCCTP (MAX) to VCCTP (MIN)) tF 300 µs VCC Slew Rate (VCCTP (MIN) to VCCTP (MAX)) tR 0 ns tRPU 100 VCC Detect to RST 4 of 5 150 300 ms NOTES 4 DS1810 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 SOT-23 PACKAGE “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% 5 of 5