MIC1232_06 MICREL | Alldatasheet

Document overview

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Technical content

Features

  • Power OK/Reset time delay, 250ms min.
  • Watchdog timer, 150ms, 600ms, or 1.2s typical
  • Precision supply voltage monitor, select between 5% or 10% of supply voltage
  • Available in 8-pin surface mount (SO)
  • Debounced External reset input
  • Low supply current, <18µA typical

Applications

  • Automotive systems
  • Intelligent systems
  • Critical microprocessor power monitoring
  • Battery powered computers
  • Controllers Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com

Ordering Information

MIC1232N MIC1232NY –40ºC to +85ºC 8-Pin PDIP MIC1232M MIC1232MY –40ºC to +85ºC 8-Pin SOIC

MIC1232 Micrel, Inc. Pin Configuration TD TOL GND VCC RST RST MIC1232 PBRST ST 8-Pin PDIP Package 8-Pin SOIC Package Pin Description Pin Number Pin Name Pin Function 1 /PBRST Pushbutton Reset Input: This input is debounced and can be driven with ex- ternal logic signals or by means of a mechanical pushbutton to actively force a reset. All pulses less than 1ms in duration on the /PBRST pin are ignored, whereas, 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 et to a nominal value of 600ms and when TD = V CC, the watchdog period is 1.2s nominally.

3 TOL Tolerance Select Input: Selects whether 5% or 10% of VCC is used as the

reset threshold voltage. When TOL = 0V, the 5% tolerance level is selected and when TOL = VCC, a 10% tolerance level is selected.

4 GND IC ground pin, 0V reference

5 RST RST is asserted high if either VCC goes below the reset threshold, the watch-

dog 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 or 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 watch- dog 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 or after the watch times out or after /PBRST goes high. Open-drain 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 will be asserted.

8 VCC Primary supply input, +5V

MIC2755 Micrel, Inc.

Electrical Characteristics

VCC = 4.5V to 5.5V; TA = Operating Temperature Range, bold values indicate –40°C ≤ TA ≤ +85°C; unless noted Parameter Condition Min Typ Max Units Supply Voltage Range VCC 4.5 5.5 V Supply Current ICC, (Note 4) 18 40 µA /ST and /PBRST Input Levels V IH, (Note 5) 2.0 V CC+0.3 V VIL –0.3 0.8 V Input Leakage IIL ±1 µA Output Souce Current, RST V OH = 2.4V 1.0 10 mA Output Sink Current, /RST. RST V OL = 0.4V 2.0 10 mA VCC 5% Trip Point (Reset TOL = GND 4.5 4.62 4.74 V Threshold Voltage) VCC 10% Trip Point (Reset TOL = V CC 4.25 4.37 4.49 V Threshold Voltage) Input Capacitance, /ST, TOL C IN, (Note 6) 5 pF Output Capacitance, /RST, RST C OUT, (Note 6) 7 pF VCC = 4.5V to 5.5V; TA = Operating Temperature Range, bold values indicate –40°C ≤ TA ≤ +85°C; unless noted /PBRST Min. Pulse Width, tPB /PBRST = V IL (Note 7) 20 ms /PBRST Delay, tPBD 1 4 20 ms Reset Active Time, tRST 250 610 1000 ms /ST Pulse Width, tST 20 ms /ST Timeout Period, tTD TD = 0V 62.5 150 250 ms TD = Open 250 600 1000 ms TD = VCC 500 1200 2000 ms VCC Fall Time, tF 10 µs VCC Rise Time, tR 0 ns VCC Detect to /RST Low V CC Falling (Note 8) 50 150 µs and RST High, tRPD VCC Detect to /RST Low V CC Falling (Note 9) 250 610 1000 µs and RST Low, tRPD Note 1. Exceeding the absolute maximum rating may damage the device. Note 2. The device is not guaranteed to function outside its operating rating. Note 4. I CC is measured with outputs open and inputs within 0.5V of supply rails Note 5. /PBRST has an internal pull-up resistor to VCC (typ. 40kΩ) Note 6. Guaranteed by design Note 7. /PBRST must be held low for a minimum of 20ms to guarantee a reset Note 8. VCC falling at 1.66mV/µs Note 9. /RST has an open drain output Absolute Maximum Ratings (Note 1) Terminal Voltage Input Current ESD Rating, Note 3 Operating Ratings (Note 2) Operating Temperature Range

MIC2755 Micrel, Inc. Applications Information Power Monitor The /RST and RST pins are asserted whenever V CC falls below the reset threshold voltage as determined by the TOL pin. A 5% tolerance level (4.62V reset threshold voltage) can be selected by connecting the TOL pin to ground and a 10% tolerance can be selected by connecting the TOL pin to V CC. The reset pins will remain asserted for a period of 250ms after V CC has risen above the reset threshold voltage. The reset function ensures the microprocessor is properly reset and powers up into a known condition after a power failure. /RST will remain valid with V CC as low as 1.4V. 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 Block Diagram REF WATCHDOG TIMER VCC (8) GND (4) RST (5) TD (2) RST (6)RESET GENERATOR ST (7) TIMEOUT SELECT PBRST (1) MANUAL RESET DEBOUNCE TRIP POINT SELECT TOL (3) period (determined by the TD pin, see Table 1.), the /RST and the RST will remain asserted for 250ms when this occurs. A minimum pulse of 75ns or any transition high-to-low on the /ST pin will reset the watchdog timer. The watchdog timer will be reset if /ST sees a valid transition within the watchdog timeout period. 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 will recognize any pulse that is 20ms in duration or greater and will ignore all pulses that are less than 1ms in duration.

MIC1232 Micrel, Inc.

Package Information

0.260 0.240 0.400 0.370 0.023 0.015 0.110 0.090 0.150 0.120 0.150 0.125 0.035 0.015 0.370 0.300 0.310 0.290 8-Pin PDIP (N) 8-Pin SOIC (M) 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 This information furnished by Micrel in this data sheet is believed to be accurate and reliable. However no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. 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, Inc.