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MIC809/810
Micrel
MIC809/810
Microprocessor Reset Circuits Final Information
General Description
The MIC809 and MIC810 are inexpensive microprocessor supervisory 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. Several different reset threshold levels are available to accommodate 3V, 3.3V or 5V powered systems. The MIC809 has an active low /RESET output, while the MIC810 offers an active high RESET output. The reset output is guaranteed to remain asserted for a minimum of 140ms after VCC has risen above the designated reset threshold level. The MIC809/810 comes in a 3-pin SOT-23 package. The MIC809 is also available with a shorter reset timeout (30ms min.). See the MIC809-5.
Features
* Precision voltage monitor for 3V, 3.3V or 5V power supplies * /RESET remains valid with VCC as low as 1.4V * <15A supply current * 20ms, 40ms, or 1100ms minimum reset pulse widths available * Manual reset input * Available in 3-pin SOT-23 package
Applications
* * * * * Portable equipment Intelligent instruments Critical microprocessor power monitoring Printers/computers Controllers
Ordering Information
Part Number MIC809LU MIC809MU MIC809JU MIC809TU MIC809SU MIC809RU MIC810LU MIC810MU MIC810JU MIC810TU MIC810SU MIC810RU Marking IL IM IJ IT IS IR JL JM JJ JT JS JR Threshold Voltage 4.63 4.38 4.00 3.08 2.93 2.63 4.63 4.38 4.00 3.08 2.93 2.63 Operating Temp. Range -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C Package 3-lead SOT-23 3-lead SOT-23 3-lead SOT-23 3-lead SOT-23 3-lead SOT-23 3-lead SOT-23 3-lead SOT-23 3-lead SOT-23 3-lead SOT-23 3-lead SOT-23 3-lead SOT-23 3-lead SOT-23
Typical Application
8++ 8++
MIC809
8++
P
4-5-6
4-5-6
Micrel, Inc. * 1849 Fortune Drive * San Jose, CA 95131 * USA * tel + 1 (408) 944-0800 * fax + 1 (408) 944-0970 * http://www.micrel.com
May 2003
1
MIC809/810
MIC809/810
Micrel
Pin Configuration
GND 1
MIC809
RESET 2
3 VCC
GND 1
MIC810
RESET 2
3 VCC
MIC809 3-Lead SOT23 MIC810 3-Lead SOT23
Pin Description
Pin Number MIC809 1 2 Pin Number MIC810 1 N/A Pin Name GND /RESET Pin Function IC Ground Pin /RESET goes low if VCC falls below the reset threshold and remains asserted for one reset timeout period (140ms min.) after VCC exceeds the reset threshold RESET goes high if VCC falls below the reset threshold and remains asserted for one reset timeout period (140ms min.) after VCC exceeds the reset threshold Power Supply Input.
N/A
2
RESET
3
3
VCC
MIC809/810
2
May 2003
MIC809/810
Micrel
Absolute Maximum Ratings(Note 1)
Terminal Voltage (VCC) ................................. -0.3V to 6.0V Input Current (VCC) .................................................... 20mA Output Current (RESET, /RESET) ............................. 20mA Lead Temperature (soldering, 10 sec.) ..................... 300C Storage Temperature (TS) ......................... -65C to 150C Rate of Rise (VCC) ................................................. 100V/s ESD Rating, Note 3
Operating Ratings(Note 2)
Operating Temperature Range MIC809 ..................................................... -40C to 85C MIC810 ..................................................... -40C to 85C Power Dissipation (TA = +70C) .............................. 320mW
Electrical Characteristics
For typical values, VCC = 5V for MIC8_L/M/J, VCC = 3.3V for MIC8_S/T, VCC = 3V for MIC8_R; TA = 25C, bold values indicate -40C TA +85C; unless noted Symbol VCC ICC VTH Parameter Operating Voltage Range Condition TA = 0C to 70C TA = -40C to 85C Supply Current MIC809L/M/J, MIC810L/M/J VCC < 3.6V, MIC809R/S/T, MIC810R/S/T Reset Voltage Threshold MIC809L, MIC810L MIC809M, MIC810M MIC809J, MIC810J MIC809T, MIC810T MIC809S, MIC810S MIC809R, MIC810R tRST VOH VOL Reset Timeout Period /RESET Output Voltage ISOURCE = 800A, MIC809L/M/J ISOURCE = 500A, MIC809R/S/T /RESET Output Voltage VCC = VTH min., ISINK = 3.2mA, MIC809L/M/J VCC = VTH min., ISINK = 1.2mA, MIC809R/S/T VCC > 1.4V, ISINK = 50A, TA = 0C to +70C VCC > 1.6V, ISINK = 50A, TA = -40 to +85C VOH VOL RESET Output Voltage RESET Output Voltage 1.8V < VCC < VTH min., ISOURCE = 150A ISINK = 3.2mA, MIC810L/M/J ISINK = 1.2mA, MIC810R/S/T
Note 1. Note 2. Note 3. Exceeding the absolute maximum rating may damage the device. The device is not guaranteed to function outside its operating rating. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
Min 1.4 1.6
Typ
Max 5.5 5.5
Units V V A A V V V V V V ms V V
9 6 4.50 4.25 3.89 3.00 2.85 2.55 140 VCC-1.5V 0.8xVCC x 4.63 4.38 4.00 3.08 2.93 2.63 240
15 10 4.75 4.50 4.10 3.15 3.00 2.70 560
0.4 0.3 0.3 0.3 0.8xVCC x 0.4 0.3
V V V V V V V
Timing Diagram
VCC VTH VTH
tRST
tRST
/RESET
Reset Timing Diagram
May 2003
3
MIC809/810
MIC809/810
Micrel
Functional Diagram
VCC (3) Reset Threshold (V)
+ -
RESET GENERATOR
RESET (2) RESET (MIC810)
GND (1)
MIC809/810
4
May 2003
MIC809/810
Micrel
Interfacing to Bidirectional Reset Pins The MIC809/810 can interface with Ps with bidirectional reset pins by connecting a 4.7k resistor in series with the MIC809/810 output and the P reset pin. /RESET Valid at Low Voltage A resistor can be added from the /RESET pin to ground to ensure the /RESET output remains low with VCC down to 0V. A 100k resistor connected from the /RESET to ground is recommended. The resistor should be small enough to pulldown any stray leakage currents and large enough not to load the reset output . See Figure below.
Applications Information
Microprocessor Reset The /RESET (or RESET) pin is asserted whenever VCC falls below the reset threshold voltage. The /RESET pin remains asserted for a period of 140ms after VCC has risen above the reset threshold voltage. The reset function ensures 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 1.4V. VCC Transients The MIC809/810 are relatively immune to negative-going VCC glitches below the reset threshold. Typically, a negativegoing transient 125mV below the reset threshold with a duration of 50s (25s for MIC8_R/S/T) or less will not cause a reset.
VCC VCC VCC P RESET
100K
MIC809
RESET
Reset Valid to VCC = 0V
May 2003
5
MIC809/810
MIC809/810
Micrel
Package Information
0.021 0.015
0.055 0.047
0.098 0.083
0.120 0.105 0.0059 0.040 0.031 0.0035 0-81/4
0.079 0.071
0.004 0.001
0.010 0.005
3-lead SOT-23 (M3)
MICREL, INC.
TEL
1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA
FAX
+ 1 (408) 944-0800
+ 1 (408) 944-0970
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. (c) 2003 Micrel, Incorporated.
MIC809/810
6
May 2003

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