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MIC845
Micro-Power Comparator / Battery Monitor
General Description
The MIC845 is a precision micro-power voltage comparator with an on-chip 2.55V reference voltage source. Intended for voltage monitoring applications, the MIC845 can be used with an external resistor divider to detect a wide range of voltages, or without external resistors to directly monitor voltages with its high input impedance CMOS input. The MIC845 incorporates a voltage reference and comparator with fixed internal hysteresis. When the 2.55V internal threshold is crossed, the output switches polarity. MIC845 is available with a push-pull or open-drain output stage. The push-pull output stage is configured for both active high or active low output; the open-drain output stage is only configured active high. Supply current is extremely low (typically 1A), making it ideal for portable applications. MIC845 is supplied in Micrel's TeenyTM 5-lead SC70 package. Data sheets and support documentation can be found on Micrel's web site at www.micrel.com.
TeenyTM
Features
* * * * Extremely low 1A supply current (typical) 2.55V on chip reference 2% voltage threshold accuracy Optimized for PDAs, cellular telephones, pagers, and other battery-powered devices * Open-drain output can be pulled up to 6V regardless of supply voltage * 5-lead SC-70 package
Applications
* * * * * * PDAs Pagers Cordless phones Portable electronics Motherboards Bladed servers
____________________________________________________________________________________________________
Typical Applications
VIN VDD MIC845
3.3V MIC845
VDD
R1
OUT GND
VOUT
Memory power
VDD INP OUT GND
to Host
INP
R2
VREF = 2.55V 2.75V < VDD < 5.5V
Lithium Coin Cell
Threshold Detector with Internal Fixed Hysteresis
Nano-Power Battery Monitor
TeenyTM is a trademark of Micrel, Inc. Micrel Inc. * 2180 Fortune Drive * San Jose, CA 95131 * USA * tel +1 (408) 944-0800 * fax + 1 (408) 474-1000 * http://www.micrel.com
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M9999-070505 (408) 955-1690
Micrel, Inc.
MIC845
Ordering Information
Part Number Standard MIC845HBC5 MIC845LBC5 MIC845NBC5 Marking B19 B20 B21 Pb-Free MIC845HYC5 MIC845LYC5 MIC845NYC5 Marking* B19 B20 B21 -40 to +85C -40 to +85C -40 to +85C SC-70 SC-70 SC-70
Temperature Range
Package
* Note: Underscore on device marking indicates Pb-Free packaging.
Pin Configuration
INP GND NIC 1 3 2
4 OUT
5 VDD
SC-70-5 (C5)
(TOP VIEW)
Pin Description
Pin Number 1 2 3 4 Pin Name NIC GND INP OUT ("N" Version) OUT ("H" Version) OUT ("L" Version) 5 VDD Pin Function No Internal Connection. A signal applied to this pin will have no effect on device operation. Ground Input: Analog input to the comparator. When VINP > VREF+ VHYST, VOUT is asserted, and the condition is held until VINP < VREF. Output: Active-high, open-drain output. This output is low when VINP < VREF, indicating a low voltage input. The output is high when VINP > VREF + VHYST. Output: Active-high, Push-pull output. This output is low when VINP < VREF, indicating a low voltage condition. The output is high when VINP > VREF+ VHYST. Output: Active-low, Push-pull output. This output is high when VINP < VREF, indicating a low voltage condition. The output is low when VINP > VREF+ VHYST. Power Supply (Input): Independent supply input for internal circuitry.
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MIC845
Absolute Maximum Ratings(1)
Supply Voltage (VDD) ..............................-0.3V to +6V Input Voltage (VINP).................................-0.3V to +6V Output Current (IOUT)......................................... 20mA Junction Temperature (TJ) .............. -40C to +125C Storage Temperature (Ts)............... -65C to +150C Lead Temperature (soldering, 5 sec.) ..............260C ESD Rating(3) ........................................................3kV
Operating Ratings(2)
Supply voltage (VDD) ........................ +2.75V to +5.5V Input Voltage............................................... -0.3 to 6V Ambient Temperature (TA)................ -40C to +85C Junction to Ambient Thermal Resistance: SC-70 (JA) ............................................ 450C/W
Electrical Characteristics
2.75V < VDD < 5.5V; TA = 25C, Bold values indicate -40C< TA < +85C, unless noted.
Parameter IDD IINP IINP_PD VREF VHYST VOUT VOUT Parameter Supply Current Input Leakage Current Input Leakage Current in power down VREF Comparator Hysteresis Output Voltage, `N' Output Voltage, `L' and `H' ISINK = 1.6mA, VDD 2.75V ISINK = 1.6mA, VDD 2.75V ISOURCE = 500A, VDD 2.75V tD Propagation Delay VINP = 2.7V to 2.4V VINP = 2.4V to 2.7V
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. VDD is tied to Gnd, not left floating.
Conditions No load on output VDD = 5.5V, VINP = 0V VDD = 0V (note 4), VINP = 5.5V -40C to 85C
Min
Typ. 1 .005 .005
Max 3 10 10 2.60 40 0.3 0.3
Units A nA nA V mV V V V
2.50 8
2.55 25
0.95 x VDD
0.99 x VDD 12 8 39 26
s s
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MIC845
Typical Characteristics
IDD vs. Temperature
800 600 IDD (nA) 400 200 0 VDD = 4.5V VIN = 0V 1500 1000 500 0 -500 -1000 VDD = 0V VIN = 4.5V -1500 80 -2000 -40 -20 0 20 40 60 TEMPERATURE (C) 80 VDD = 4.5V VIN = 0V VDD = 0V VIN = 4.5V
IIN vs. Temperature
-200 -40 -20 0 20 40 60 TEMPERATURE (C)
IDD vs. Temperature
1200 1000 800 IDD (nA) 600 400 200 0 VDD = 0V VIN = 4.2V VDD = 3V VIN = 4.2V
IIN vs. Temperature
800 600 400 200 0 VDD = 3V VIN = 4.2V 80 VDD = 0V VIN = 4.2V
-200 -40 -20 0 20 40 60 TEMPERATURE (C)
80
-200 -40 -20 0 20 40 60 TEMPERATURE (C)
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MIC845
Block Diagrams
VDD VIN
5
VDD VIN
5
VDD
VDD
VTH
INP
3
High-Voltage Detect
VTH
OUT
4
INP
3
High-Voltage Detect OUT
4
2.55V Bandgap Reference
2.55V Bandgap Reference
2
GND MIC845H
2
GND MIC845L
VDD VIN
5
VDD
VTH
INP
3
High-Voltage Detect
OUT
4
2.55V Bandgap Reference
2
GND MIC845N
VOUT
VOUT
VIN
VREF + Hysteresis VREF
VIN
VREF + Hysteresis VREF
Type H and N
Type L
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MIC845 there will be no conduction from INP to VDD or any circuitry internal to MIC845. Input Transients MIC845 is inherently immune to very short negative-going "glitches." Very brief transients may exceed the VINP threshold without tripping the output. As shown in the figure below, the narrower the transient, the deeper the threshold overdrive that will be ignored by the MIC845. The graph represents the typical allowable transient duration for a given amount of threshold overdrive that will not generate an output.
Input Transient Response
Application Information
Output The MIC845N output is an open-drain MOSFET, so most applications will require a pull-up resistor. It is recommended that the value of this resistor not exceed 470k, otherwise PCB leakages may begin to dominate and give a false output indication. The output of "N" type devices may be pulled up as high as 6V regardless of the IC's supply voltage, without damage to the IC. The "H" and "L" versions of MIC845 have push-pull output stages, no pull-up resistors are required. The maximum output voltage of the "H" and "L" versions is VDD. Input MIC845 has been designed to present an almost infinite input resistance at its INP pin making it ideal for monitoring lithium coin cell and back-up batteries. In applications where the `battery low' voltage is 2.55V, MIC845's INP pin may be tied directly to the cell's positive terminal without any additional circuitry. MIC845's input may be subjected to voltages as high as 6V, steady-state, without any adverse effects, regardless of the IC's supply voltage. This applies even if the supply voltage is zero. This permits a situation wherein the IC's supply is turned off, but an input voltage is still present. Under such conditions,
16 14 12 10 8 6 4 2 0 0
200 400 600 800 1000 COMPARATOR OVERDRIVE VREF - VINP (mV)
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M9999-070505 (408) 955-1690
Micrel, Inc.
MIC845
Package Information
0.65 (0.0256) BSC 1.35 (0.053) 2.40 (0.094) 1.15 (0.045) 1.80 (0.071) 2.20 (0.087) 1.80 (0.071) 1.00 (0.039) 1.10 (0.043) 0.80 (0.032) 0.80 (0.032)
DIMENSIONS: MM (INCH) 0.18 (0.007) 0.10 (0.004)
0.30 (0.012) 0.15 (0.006)
0.10 (0.004) 0.00 (0.000)
0.30 (0.012) 0.10 (0.004)
SC-70-5 (C5)
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. (c) 2005 Micrel, Inc.
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