MIC1832 3.3V Voltage Supervisor with Manual Reset, Watchdog Timer and Dual Reset Outputs General Description Features The MIC1832 is a low-current microprocessor supervisor for monitoring 3.3V and 3V systems. The device features logic-selectable (TOL) reset thresholds of 10% or 20% of 3.3V; a pushbutton reset input; a watchdog timer with three-state selectable (TD) timeout periods of 150ms, 600ms, or 1.2s; a fixed reset timeout period of 250ms (min); and active-low open-drain reset (/RST) and activehigh push-pull reset (RST) outputs. The /RST output maintains a valid reset condition for VCC as low as 1.4V. The MIC1832 asserts a reset condition if the supply voltage drops below the reset threshold, the pushbutton reset is asserted low, or the watchdog timer does not see a high-to-low transition on the watchdog timer input within the watchdog timer period. A reset condition is held for the reset timeout period of 250ms (min) after the pushbutton input is released, after the supply voltage increases above the reset threshold voltage, or after the watchdog has initiated a reset. The MIC1832 is a drop-in replacement for the DS1832. It operates over the –40°C to +85°C temperature range and is available in Pb-Free 8-pin SOIC and PDIP packages. Data sheets and support documentation can be found on Micrel’s web site at: www.micrel.com. • • • • • • • Low-current version of DS1832 Low current: 15µA (typ), 25µA (max) Selectable threshold (TOL): 10% or 20% of 3.3V Selectable watchdog timer (TD): 150ms, 600ms, 1.2s Power OK/Reset time delay: 250ms (min) Debounced pushbutton reset input Dual complementary reset outputs o Active-low, open-drain reset output o Active-high, push-pull reset output • Available in Pb-Free 8-pin SOIC and PDIP packages • –40°C to +85°C temperature range • Pin-for-Pin compatible with MIC1232/DS1232/CAT1232 Applications • • • • • Automotive systems Intelligent systems Critical microprocessor power monitoring Battery powered computers Controllers _________________________________________________________________________________________________________________________ Typical Application Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com February 2013 M9999-020413 Micrel, Inc. MIC1832 Ordering Information Part Number Temperature Range Package Lead Finish MIC1832NY –40° to +85°C 8-Pin PDIP Pb-Free MIC1832MY –40° to +85°C 8-Pin SOIC Pb-Free Pin Configuration 8-Pin PDIP 8-Pin SOIC Pin Description Pin Number Pin Name 1 /PBRST Pushbutton Reset input: This input is debounced and can be driven with external logic signals or by using a mechanical pushbutton to actively force a reset. All pulses less than 1ms in duration on the /PBRST pin are ignored; any pulse with a duration of 20ms or greater is guaranteed to cause a reset. 2 TD Time Delay input: This input selects the timebase used by the watchdog timer. When TD = 0V, the watchdog timeout period is set to a normal value of 150ms. When TD = open, the watchdog timeout period is set to a nominal value of 600ms. When TD = VCC, the watchdog period is 1.2s nominally. 3 TOL 4 GND IC ground pin, 0V reference 5 RST RST is asserted high if either VCC goes below the reset threshold, the watchdog times out, or /PBRST is pulled low for a minimum of 20ms. RST remains asserted for one reset timeout period after VCC exceeds the reset threshold, after the watch times out, or after /PBRST goes high. 6 /RST /RST is asserted low if either VCC goes below the reset threshold, the watchdog times out, or /PBRST is pulled low for a minimum of 20ms. /RST remains asserted for one reset timeout period after VCC exceeds the reset threshold, after the watch times out, or after /PBRST goes high. Opendrain output 7 /ST Input to watchdog timer. If /ST does not see a transition from high to low within the watchdog timeout period, RST and /RST are asserted. 8 VCC Primary supply input. February 2013 Pin Function Tolerance Select input: This input selects whether 10% or 20% of VCC is used as the reset threshold voltage. When TOL = 0V, the 10% tolerance level is selected and when TOL = VCC, a 20% tolerance level is selected. 2 M9999-020413 Micrel, Inc. MIC1832 Absolute Maximum Ratings(1) Operating Ratings(2) Terminal Voltage VCC ............................................................. .–0.3V to 7V All other inputs ............................ .–0.3V to (VCC + 0.3V) Input Current VCC. ..................................................................... 250mA GND, all other inputs ............................................ 25mA Lead Temperature (soldering, 10 sec.) ...................... 300°C Storage Temperature ................................ –65°C to 150°C Operating Temperature Range MIC1832M/N........................................... –40°C to 85°C Power Dissipation ................................................... 700mW Electrical Characteristics VCC = 1.4V to 5.5V; TA = Operating Temperature Range; bold values indicate –40°C≤ TA ≤ +85°C, unless noted. Parameter Condition Supply Voltage Range VCC Min ICC @ VCC = 5V (3) ICC @ VCC = 3.3V /ST and /PBRST Input Levels Units 5.5 V 18 30 µA 15 25 µA (4) VIH 2 VCC + 0.3 V (5) VIH VCC – 0.4 VCC + 0.3 V –0.3 0.5 V ±1 µA VIL (6) Max 1.4 (3) Supply Current Typ Input Leakage, /ST IIL Output Voltage, /RST, RST ISOURCE = 350µA, VCC = 3.3V 2.4 V 0.4 V Output Voltage, /RST, RST ISINK= 10mA, VCC = 3.3V Output Voltage VCC = 1.4V, ISINK = 50µA 0.3 V VCC 10% Trip Point (Reset Threshold Voltage) TOL = Gnd 2.80 2.88 2.97 V VCC 20% Trip Point (Reset Threshold Voltage) TOL = VCC 2.47 2.55 2.64 V Input Capacitance, /ST, TOL (7) CIN 5 pF 7 pF Output Capacitance, /RST, RST COUT (7) Notes: 1. Exceeding the absolute maximum rating may damage the device. 2. The device is not guaranteed to function outside its operating rating. 3. ICC is measured with /PBRST and all outputs open and inputs within 0.5V of supply rails. 4. Measured with VCC ≥ 2.7V. 5. Measured with VCC < 2.7V. 6. /PBRST has an internal pull-up resistor to VCC (typ. 40kΩ). 7. Guaranteed by design at TA = 25°C. February 2013 3 M9999-020413 Micrel, Inc. MIC1832 AC Electrical Characteristics VCC = 1.4V to 5.5V TA = Operating Temperature Range; bold values indicate –40°C≤ TA ≤ +85°C, unless noted. Parameter /PBRST Min. Pulse Width, tPB Condition Min /PBRST = VIL (1) Typ Max 20 Units ms 1 4 20 ms Reset Active Time, tRST 250 610 1000 ms /ST Pulse Width, tST 20 /PBRST Delay, tPBD /ST Timeout Period, tTD ns TD = 0V 62.5 150 250 ms TD = Open 250 600 1000 ms TD = VCC 500 1200 2000 ms VCC Fall Time, tF VCC Rise Time, tR VCC Detect to /RST Low and RST High, tRPD VCC Falling (2) VCC Detect to /RST Low and RST Low, tRPD VCC Falling (1) 40 µs 0 ns 250 5 8 µs 610 1000 µs Notes: 1. /PBRST must be held low for a minimum of 20ms to guarantee a reset. 2. VCC falling at 8.5mV/µs. February 2013 4 M9999-020413 Micrel, Inc. MIC1832 Timing Diagrams Figure 1. Power-Up/Power-Down Sequence Figure 2. Watchdog Input Figure 3. Pushbutton Reset February 2013 5 M9999-020413 Micrel, Inc. MIC1832 Application Information Power Monitor The /RST and RST pins are asserted whenever VCC falls below the reset threshold voltage determined by the TOL pin. A 10% of 3.3V tolerance level (2.97V reset threshold voltage) can be selected by connecting the TOL pin to ground. A 20% of 3.3V tolerance level (2.64V reset threshold voltage) can be selected by connecting the TOL pin to VCC. The reset pins will remain asserted for a period of 250ms after VCC has risen above the reset threshold voltage. The reset function ensures that the microprocessor is properly reset and powers up into a known condition after a power failure. /RST will remain valid with VCC as low as 1.4V. Pushbutton Reset Input The /PBRST input can be driven with a manual pushbutton switch or with external logic signals. The input is internally debounced and requires an active low signal to force the reset outputs into their active states. The /PBRST input recognizes any pulse that is 20ms or longer in duration and ignores all pulses that are less than 1ms in duration. Watchdog Timer The microprocessor can be mounted by connecting the /ST pin (watchdog input) to a bus line or I/O line. If a high-to-low does not occur on the /ST pin within the watchdog timeout period determined by the TD pin (see the Electrical Characteristics Table), the /RST and the RST will remain asserted for 250ms. A minimum pulse of 20ns or any transition high-to-low on the /ST pin resets the watchdog timer. The watchdog timer is reset if /ST sees a valid transition within the watchdog timeout period. Block Diagram February 2013 6 M9999-020413 Micrel, Inc. MIC1832 Package Information(1) 8-Pin DIP (N) 8-Pin SOIC (M) Note: 1. Package information is correct as of the publication date. For updates and most current information, go to www.micrel.com. MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this data sheet. This information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry, specifications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellectual property rights is granted by this document. Except as provided in Micrel’s terms and conditions of sale for such products, Micrel assumes no liability whatsoever, and Micrel disclaims any express or implied warranty relating to the sale and/or use of Micrel products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. © 2000 Micrel, Incorporated. February 2013 7 M9999-020413