ASM1834U

November 2006 rev 1.5 ASM1834/A/D All devices operate over the extended industrial temperature range. Devices are available in 8-pin DIP, surface mount 8-pin SO and 8-Pin MicroSO packages. Die are also available. Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset General Description The ASM1834 supervisors simultaneously monitor both 3.3V and 5V power sources and generate reset signals when either supply is out of tolerance. When an out-of-tolerance condition is detected, the output-reset signal of the affected supply becomes active and resets the system microprocessor/ microcontroller. On power-up and after the supply voltage returns to an in-tolerance condition, the reset signal remains active for approximately 350ms. This allows the power supply and system microprocessor to stabilize. Tolerance levels are independently selectable for both supplies. Tolerance options are 5% and 10% percent for the 5V supply and 10% and 20% percent for the 3.3V supply. The ASM1834 and ASM1834D have push-pull reset output stages. The ASM1834A reset outputs are open drain devices that can both be connected to either 5V or 3.3V supply. The ASM1834 and ASM1834A have active LOW reset outputs. The ASM1834D has active HIGH reset outputs. All devices can generate reset signals through an internally debounced pushbutton reset input that affects both reset outputs. • • • • • • Key Features • • • • • Monitors 5V and 3.3V supplies simultaneously 5V and 3.3V power-on reset 350ms reset time Debounced pushbutton reset input Push-pull CMOS output • ASM1834, ASM1834D • Eliminates external pull-up resistors • Active LOW (ASM1834), HIGH (ASM1834D) Open Drain Output • ASM1834A • Active LOW Selectable 5V and 3.3V trip point tolerance Internal power drawn from highest input voltage, 5V or 3.3V Precision temperature-compensated voltage reference and comparator Low cost surface mount SO, compact MicroSO and DIP packages. Wide operating temperature, -40°C to +85°C Applications • • • • • • • Microprocessors PDAs, Hand-held PCs Embedded Controllers Telecommunication Systems Power Supplies Wireless / Cellular Systems Networking Hardware Typical Operating Circuit 3.3V +5V ASM1834 5VIN 3.3VIN RESET PBRST 5VTOL GND 3.3VTOL 3.3V 5V µP RESET GND P ulseCore Semiconductor Corporation 1715 S. Bascom Ave Suite 200 Campbell, CA 95008 • T el: 408-879-9077 • F ax: 408-879-9018 www.pulsecoresemi.com Notice: The information in this document is subject to change without notice November 2006 rev 1.5 ASM1834/A/D ASM1834 5V Tolerance Bias Low TC Reference 40kΩ + For ASM1834D Block Diagram 1 5 VIN ASM1834A 2 5V RESET 5 VTOL 3 350ms Delay 2 5V RESET 5V RESET (ASM1834D) 7 Pushbutton Level Sense and Debounce 3.3V RESET PBRST 3.3 VIN 5 8 3.3 VTOL 6 4 3.3V Tolerance Bias + For ASM1834D 350ms Delay 7 3.3V RESET 3.3V RESET (ASM1834D) GND - Pin Configuration 5VIN 5V RESET * 5V TOL GND 1 2 3 4 8 3.3VIN 3.3V RESET * 3.3V TOL PBRST ASM1834 ASM1834A ASM1834D 7 6 5 Pin Description * AS1834D reset outputs are active HIGH (5V RESET and 3.3V RESET) Outputs are open-drain for AS1834A. Pin # 1 2 3 4 5 6 7 8 Pin Name 5VIN 5V RESET 5V RESET 5V TOL GND PBRST 3.3V TOL 3.3V RESET 3.3V RESET 3.3VIN 5V power supply input. Function 5V reset output (Active LOW, ASM1834, ASM1834A. Open drain outputs for ASM1834A). 5V reset output (Active HIGH, AS1834D). 5V input tolerance select: 10% tolerance for 5VTOL= 5VIN and 5% tolerance for 5VTOL = GND Ground. Debounced manual pushbutton reset input (40kΩ internal pull-up). 3.3V input tolerance select: 20% tolerance for 3.3VTOL = 3.3VIN and 10% tolerance for 3.3VTOL=GND. 3.3V reset output (Active LOW, ASM1834, ASM1834A. Open drain outputs for ASM1834A). 3.3V reset output (Active HIGH, AS1834D). 3.3V power supply input. Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset Notice: The information in this document is subject to change without notice 2 of 10 November 2006 rev 1.5 ASM1834/A/D Detailed Description Operation Power Monitor The ASM1834 supervisors simultaneously detect out-oftolerance power supply conditions on both 3.3V and 5V power supplies. If the voltages at 5VIN or 3.3VIN are outside the tolerance band, the reset for the falling supply voltage becomes active. When the monitored supply returns to an intolerance state, the reset remains active for approximately 350ms before returning to the inactive state. On power-up, the reset signals are kept active for approximately 350ms after the power supply voltages have reached the selected tolerance. This allows the power supply and microprocessor to stabilize before the reset is removed. All supply current for the ASM1834 devices is drawn from the input (5VIN or 3.3VIN) with the highest voltage level. The outputs draw current from their input supplies 5VIN and 3.3VIN. RESET VOH RESET VIN VINTP (MAX) VINTP VINTP (MIN) tF tRPD RESET Slews with VCC Figure 2: Timing Diagram: Power Down (ASM1834D only) Reset Signal Polarity and Output Stage Structure The ASM1834 and the ASM1834A supervisors have active LOW reset signals. The ASM1834D reset outputs are active HIGH. The ASM1834 and the ASM1834D have CMOS push-pull output stages. The ASM1834A has open drain reset outputs. ~~ ~ RESET Polarity LOW LOW LOW LOW LOW LOW HIGH HIGH HIGH VOL ~~ tR VINTP(MAX) VINTP tRPU RESET VOH Part # ASM1834 ASM1834U ASM1834S ASM1834A VOL RESET Output Stage Configuration Push-Pull Push-Pull Push-Pull Open Drain Open Drain Open Drain Push-Pull Push-Pull Push-Pull VINTP(MIN) ~ ~ VIN ASM1834AU ASM1834AS ASM1834D ASM1834DU ASM1834DS Figure 1: Timing Diagram: Power Up (ASM1834D only) ~~ ~~ Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset Notice: The information in this document is subject to change without notice 3 of 10 November 2006 rev 1.5 Manual Reset Operation Push-button switch input, PBRST, allows the user to override the internal trip point detection circuits and issue reset signals. The pushbutton input is debounced and is pulled HIGH through an internal 40kΩ resistor. When at least one of the reset outputs is not asserted, a push button initiated reset signal can be issued by holding PBRST LOW for at least 2ms. When PBRST is held LOW, both resets become active and remain active for approximately 350ms after PBRST returns HIGH. (See figures 3 and 4). Reset Output Signal ASM1834/A/D Reset output signals are valid as long as either voltage at 5VIN or 3.3VIN is above 1.2V. In addition, the ASM1834 has push-pull outputs that can remain valid below a 1.2V input level. To sink current below 1.2V, a resistor should be connected from the RESET output to ground. This resistor guarantees a valid reset signal down to 0V. A 100kΩ value is suggested. The AS1834A open drain reset outputs require pull-up resistors and must be low enough in value to pull the output into a HIGH state. Resistor value is not critical in most applications and a value of 10kΩ is suggested. (See Figures 3.3V 5 and 6). The ASM1834A open drain reset outputs can be connected to the same potential through a single pull-up resistor. In this configuration a failure on either supply will generate an active LOW reset. If the inputs are pulled-up to different voltages, the reset outputs (pin 2 and pin 7) cannot be connected to form a wired “AND” (see figure 7). 5V ASM1834 1 5VIN 3.3VIN 8 2 5V RESET 3.3V RESET 7 3 4 5VTOL GND 3.3VTOL PBRST 6 5 Figure 3: Pushbutton Reset RESET 100kΩ µP Input PBRST tPDLY VIL tPB VIH Figure 5: ASM1834 RESET Valid to 0V 5V 3.3V ~ ~ tRST ASM1834 VOH VOL RESET RESET 10kΩ 1 5VIN 3.3VIN 8 10kΩ Figure 4: Timing Diagram: Pushbutton Reset Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset Notice: The information in this document is subject to change without notice ~~ ~~ 2 5V RESET 3.3V RESET 7 3 4 5VTOL GND 3.3VTOL PBRST 6 5 Figure 6: ASM1834A Open Drain Output Pull-Up Resistor 4 of 10 November 2006 rev 1.5 ASM1834/A/D 5V 3.3V 5V or 3.3V ASM1834A 1 2 3 5V TOL 4 GND PBRST 3.3V TOL 5 5VIN 3.3VIN 8 7 6 10kΩ 5VRESET 3.3VRESET Figure 7: ASM1834A Wired “OR” Connection Trip Point Tolerance Selection The 3.3VTOL and 5VTOL inputs allow independent selection of the reset trip points. If 5VTOL is connected to the 5V supply input, a 10% tolerance is selected. If 5VTOL is grounded, a 5% tolerance is selected. If 3.3VTOL is connected to the 3.3V supply input, a 20% tolerance is selected. If 3.3VTOL is grounded, a 10% tolerance is selected. (Refer table below). The 3.3VTOL and 5VTOL tolerance select inputs should be tied to the ground or to the respective input supply voltage pin, 3.3VIN or 5VIN. 3.3V Input Tolerance Select 3.3V Tolerance 20% 10% TRIP Point (V) MIN 2.47 2.80 NOM 2.55 2.88 MAX 2.64 2.97 5V Tolerance 10% 5% - 5V Input TRIP Point (V) MIN 4.25 4.5 NOM 4.38 4.63 MAX 4.49 4.75 - 5VTOL = 5VIN 5VTOL = GND 3.3VTOL = 3.3VIN 3.3VTOL = GND Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset Notice: The information in this document is subject to change without notice 5 of 10 November 2006 rev 1.5 ASM1834/A/D Absolute Maximum Ratings Parameter Voltage on VCC Voltage on 5V RESET Voltage on 3.3V RESET Min -0.5 -0.5 -0.5 Max 7 +5VIN + 0.5V +3.3VIN + 0.5V (+5VIN + 0.5V) or (+3.3VIN + 0.5V) whichever is greater +85 260 +125 2 200 Unit V V V Voltage on PBRST and reset outputs Operating Temperature Range Soldering Temperature (for 10 sec) Storage Temperature ESD rating HBM MM -0.5 -40 -55 V °C °C °C KV V Note: 1. Voltages are measured with respect to ground 2. These are stress ratings only and functional implication is not implied. Exposure to absolute maximum ratings for extended periods may affect device reliability. Recommended DC Operating Conditions Recommended DC operating condition over the operating temperature range of -40°C to +85°C. All voltages are referenced to ground. Parameter 5V Supply Voltage 3.3V Supply Voltage PBRST Input High Level PBRST Input High Level PBRST Input Low Level Symbol 5VIN 3.3VIN VIH VIH VIL Conditions Min 1.2 1.2 Typ Max 5.5 5.5 VINMAX + 0.3 Unit V V V V Both 3.3VIN and 5VIN >=2.7V Both 3.3VIN and 5VIN =2.7V (ASM1834/1834D only) Output = 0.4V. Either 3.3VIN or 5.5VIN Output Current IOL VOH IIL ICC ICC VINTP VINTP VINTP VINTP COUT tPB tPDLY tRST tF tR tRPU tRPD VINTP(MAX) to VINTP(MIN) VINTP(MIN) to VINTP(MAX) trise = 5µs 200 300 0 200 350 500 350 2 2 500 3.3VIN and 5VIN