MIC6315 Micrel MIC6315 Open-Drain µP Reset Circuit General Description Features The MIC6315 is an inexpensive reset generator circuit that monitors power supplies in microprocessor based systems. The function of this device is to assert a reset if either the power supply drops below a designated reset threshold level or /MR is forced low. Several different reset threshold levels are available to accommodate 3V, 3.3V or 5V powered systems. The MIC6315 has an active low, open-drain /RESET output. The reset output is guaranteed to remain asserted for a minimum of either 20ms, 140ms, or 1100ms after VCC has risen above the designed reset threshold level. The MIC6315 comes in a 4-pin SOT-143 package. • Precision voltage monitor for 3V, 3.3V or 5V power supplies • /RESET remains valid with VCC as low as 1V • 5µA supply current • 20ms, 140ms, or 1100ms minimum reset pulse widths available • Manual reset input • 4-pin SOT-143 package Typical Application Applications • • • • • Portable equipment Intelligent instruments Critical microprocessor power monitoring Printers/computers Embedded controllers VCC VCC VCC 10k MIC6315 MR µP RESET RESET Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com September 2008 1 M9999-091608 MIC6315 Micrel Ordering Information(1, 2) Nominal VTH (V) Min. tRST (ms) Operating Temp. Range Package 2.63 20 –40°C to +85°C 4-lead SOT-143 Standard Part Number Marking Pb-Free Part Number Marking MIC6315-26D2U NY MIC6315-26D2UY NY MIC6315-29D2U NM MIC6315-29D2UY NM 2.93 20 –40°C to +85°C 4-lead SOT-143 MIC6315-30D2U N2 MIC6315-30D2UY N2 3.00 20 –40°C to +85°C 4-lead SOT-143 MIC6315-31D2U NF MIC6315-31D2UY NF 3.08 20 –40°C to +85°C 4-lead SOT-143 MIC6315-40D2U NW MIC6315-40D2UY NW 4.00 20 –40°C to +85°C 4-lead SOT-143 MIC6315-41D2U N6 MIC6315-41D2UY N6 4.10 20 –40°C to +85°C 4-lead SOT-143 MIC6315-44D2U NG MIC6315-44D2UY NG 4.38 20 –40°C to +85°C 4-lead SOT-143 MIC6315-46D2U NQ MIC6315-46D2UY NQ 4.63 20 –40°C to +85°C 4-lead SOT-143 MIC6315-26D3U NR MIC6315-26D3UY NR 2.63 140 –40°C to +85°C 4-lead SOT-143 MIC6315-29D3U NP MIC6315-29D3UY NP 2.93 140 –40°C to +85°C 4-lead SOT-143 MIC6315-30D3U N3 MIC6315-30D3UY N3 3.00 140 –40°C to +85°C 4-lead SOT-143 MIC6315-31D3U NU MIC6315-31D3UY NU 3.08 140 –40°C to +85°C 4-lead SOT-143 MIC6315-40D3U N8 MIC6315-40D3UY N8 4.00 140 –40°C to +85°C 4-lead SOT-143 MIC6315-41D3U N5 MIC6315-41D3UY N5 4.10 140 –40°C to +85°C 4-lead SOT-143 MIC6315-42D3U 0N MIC6315-42D3UY 0N 4.20 140 –40°C to +85°C 4-lead SOT-143 MIC6315-44D3U NH MIC6315-44D3UY NH 4.38 140 –40°C to +85°C 4-lead SOT-143 MIC6315-46D3U NX MIC6315-46D3UY NX 4.63 140 –40°C to +85°C 4-lead SOT-143 MIC6315-26D4U NS MIC6315-26D4UY NS 2.63 1100 –40°C to +85°C 4-lead SOT-143 MIC6315-29D4U NN MIC6315-29D4UY NN 2.93 1100 –40°C to +85°C 4-lead SOT-143 MIC6315-30D4U N4 MIC6315-30D4UY N4 3.00 1100 –40°C to +85°C 4-lead SOT-143 MIC6315-31D4U 2N MIC6315-31D4UY 2N 3.08 1100 –40°C to +85°C 4-lead SOT-143 MIC6315-40D4U M9 MIC6315-40D4UY M9 4.00 1100 –40°C to +85°C 4-lead SOT-143 MIC6315-41D4U M7 MIC6315-41D4UY M7 4.10 1100 –40°C to +85°C 4-lead SOT-143 MIC6315-44D4U NJ MIC6315-44D4UY NJ 4.38 1100 –40°C to +85°C 4-lead SOT-143 MIC6315-46D4U NZ MIC6315-46D4UY NZ 4.63 1100 –40°C to +85°C 4-lead SOT-143 Notes: 1. All devices available in tape and reel only. 2. Parts not yet assigned an identification code are shown as “zz”. Contact Micrel for details. Minimum order may apply. Pin Configuration GND 1 4 VCC MIC6315 RESET 2 3 MR MIC6315-xxDyU 4-Lead SOT-143 Pin Description Pin Number Pin Name 1 GND 2 /RESET 3 /MR 4 M9999-091608 VCC Pin Function IC Ground Pin. /RESET goes low if VCC falls below the reset threshold and remains asserted for one reset timeout period after VCC exceeds the reset threshold. Manual Reset Input. A logic low on /MR forces a reset. The reset will remain asserted as long as /MR is held low and for one reset timeout period after /MR goes high. This input can be shorted to ground via a switch or be driven by TTL or CMOS logic. Float if unused. Power Supply Input. 2 September 2008 MIC6315 Micrel Absolute Maximum Ratings(1) Operating Ratings(2) Terminal Voltage (VCC, /RESET).........................................–0.3V to 6.0V (/MR)...........................................–0.3V to (VCC + 0.3V) Rate of Rise (VCC)................................................... 100V/µs Input Current (VCC, /MR)............................................. 20mA Output Current (/RESET)............................................ 20mA Lead Temperature (soldering, 10 sec.)....................... 300°C Storage Temperature (TS).......................... –65°C to 150°C ESD Rating(3)................................................................ 3kV Operating Temperature Range.................... –40°C to +85°C Input Voltage (/RESET)..................................... GND – 5.5V Power Dissipation (TA = +70°C)............................... 320mW Electrical Characteristics For typical values, VCC = 2.5V to 5.5V, TA = 25°C; bold values indicate –40°C ≤ TA ≤ +85°C; unless noted Symbol VCC Parameter Condition Supply Current VTH Reset Voltage Threshold Note 4 Reset Timeout Period D2U Typ 1 Operating Voltage Range ICC tRST Min VCC = 5.5V, no load VCC = 3.6V, no load Max Units 5.5 V 5 15 µA 5 10 µA VTH–2.5% VTH VTH+2.5% V 20 28 44 ms D3U 140 200 320 ms D4U 1100 1500 2500 ms VOL VCC ≥ 4.0V, ISINK = 3.2mA 0.4 V 0.3 V VCC ≥ 1.0V, ISINK = 50µA 0.3 V /RESET Output Voltage VCC > 2.5V, ISINK = 1.2mA 1 µA 10 µs 0.5 /RESET Output Leakage /RESET deasserted /MR Minimum Pulse Width /MR to Reset Delay VIH /MR Input Threshold VTH > 4.0V VIL /MR Input Threshold /MR Pull-Up Resistance /MR Glitch Immunity VTH < 4.0V µs 2.3 V 0.7×VCC V VTH > 4.0V VTH < 4.0V 10 20 0.8 0.25×VCC 30 100 V V kΩ ns Notes: 1. Exceeding the absolute maximum rating may damage the device. 2. The device is not guaranteed to function outside its operating rating. 3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF. 4. Various reset thresholds available. See ordering information or contact factory. September 2008 3 M9999-091608 MIC6315 Micrel Timing Diagram VCC VTH /MR tRST tRST /RESET Reset Timing Diagram Functional Diagram + VCC (4) Reset Threshold (V) RESET (2) - RESET GENERATOR MR (3) GND (1) M9999-091608 4 September 2008 MIC6315 Micrel Applications Information Wire OR'ing The /RESET Output Because the RESET output is open-drain, several reset sources can be wire-ORed, in parallel, to allow resets from multiple sources. VCC Transients The MIC6315 is relatively immune to negative-going VCC glitches below the reset threshold. Typically, a negative-going transient 125mV below the reset threshold with a duration of 20µs or less will not cause an unwanted reset. If additional transient immunity is needed, a bypass capacitor can be placed a close as possible to the MIC6315. Microprocessor Reset The /RESET pin is asserted whenever VCC falls below the reset threshold voltage or if /MR (manual reset) is forced low. The /RESET pin remains asserted for the duration of the reset timeout period after VCC has risen above the reset threshold or /MR has returned high. The reset function ensure the microprocessor is properly reset and powers up in a known condition after a power failure. /RESET will remain valid with VCC as low as 1V. The /RESET output is a simple open-drain N-channel MOSFET structure. A pull-up resistor must be used to pull this output up to some voltage. For most applications, this voltage will be the same power supply that supplies VCC to the MIC6315. It is possible, however, to tie this resistor to some other voltage. This will allow the MIC6315 to monitor one voltage while level-shifting the /RESET output to some other voltage. The pull-up voltage must be limited to 6.0V or less (absolute maximum) to avoid damage to the MIC6315. The resistor must be small enough to supply current to the inputs and leakage paths that are driven by the /RESET output. /RESET Valid at Low Voltage As VCC drops to 0V, the MIC6315 will no longer be able to pull the /RESET output low. At this point, the pull-up resistor will pull the output high. The value of the pull-up resistor and the voltage it is connected to will affect the point at which this happens. September 2008 +5.0V +3.3V VCC VCC MIC6315 MR RESET 10k 5V SYSTEM RESET MIC6315 Used in a Multiple Supply System 5 M9999-091608 MIC6315 Micrel Package Information 0.950 (0.0374) TYP 1.40 (0.055) 2.50 (0.098) 1.20 (0.047) 2.10 (0.083) CL CL DIMENSIONS: MM (INCH) 1.12 (0.044) 0.81 (0.032) 3.05 (0.120) 2.67 (0.105) 0.800 (0.031) TYP 0.400 (0.016) TYP 3 PLACES 8 0 0.10 (0.004) 0.013 (0.0005) 0.150 (0.0059) 0.089 (0.0035) 0.41 (0.016) 0.13 (0.005) 4-Pin SOT-143 (U) 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 The information furnished by Micrel in this datasheet 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 at Purchaser’s own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. © 2005 Micrel, Incorporated. M9999-091608 6 September 2008