Micrel MIC842LBC5 Comparator with 1.25% reference and adjustable hysteresi Datasheet

MIC841/842
Comparator with 1.25% Reference
and Adjustable Hysteresis
General Description
Features
The MIC841 and MIC842 are micropower, precision
voltage comparators with an on-chip voltage reference.
Both devices are intended for voltage monitoring
applications. External resistors are used to set the voltage
monitor threshold. When the threshold is crossed,
the outputs switch polarity.
The MIC842 incorporates a voltage reference and
comparator with fixed internal hysteresis; two external
resistors are used to set the switching threshold voltage.
The MIC841 provides a similar function with user
adjustable hysteresis; this part requires three external
resistors to set the upper and lower thresholds
(the difference between the threshold voltages being the
hysteresis voltage).
Both the MIC841 and MIC842 are available with push-pull
or open-drain output stage. The push-pull output stage is
configured either active high or active low; the open-drain
output stage is only configured active low.
Supply current is extremely low (1.5μA, typical), making it
ideal for portable applications.
The MIC841/2 is supplied in Micrel’s Teeny™ 5-pin
SC-70 package.
Data sheets and support documentation are found on the
Micrel web site: www.micrel.com.
•
•
•
•
•
•
•
•
1.5V to 5.5V operating range
1.5μA typical supply current
±1.25% voltage threshold accuracy
10nA max input leakage current over temperature
10µs propagation delay
Externally adjustable hysteresis (MIC841)
Internal 20mV hysteresis (MIC842)
Output options
- Push-pull, active high
- Push-pull, active low
- Open drain, active low
• Open drain output can be pulled to 6V regardless of VDD
• Immune to brief input transients
• Teeny™ 5-pin SC-70 package
Applications
•
•
•
•
Smart phones
PDAs
Precision battery monitoring
Battery chargers
______________________________________________________________________________________________________________________
Typical Application
Threshold Detection with
Adjustable Hysteresis
Threshold Detector with
Internal Fixed Hysteresis
Teeny™ 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
March 2011
M9999-030811-B
Micrel, Inc.
MIC841/2
Ordering Information
Part Number
Marking
Hysteresis
Adjustment
Output
Stage
Output
Function
Temperature
Range
MIC841HBC5
B13
External
Push Pull
Active High
–40° to +85°C
SC-70-5
MIC841LBC5
B14
External
Push Pull
Active Low
–40° to +85°C
SC-70-5
MIC841NBC5
B15
External
Open Drain
Active High
–40° to +85°C
SC-70-5
MIC842HBC5
B16
Internal
Push Pull
Active High
–40° to +85°C
SC-70-5
MIC842LBC5
B17
Internal
Push Pull
Active Low
–40° to +85°C
SC-70-5
MIC842NBC5
B18
Internal
Open Drain
Active High
–40° to +85°C
SC-70-5
MIC841HYC5
B13
External
Push Pull
Active High
–40° to +85°C
9
SC-70-5
MIC841LYC5
B14
External
Push Pull
Active Low
–40° to +85°C
9
SC-70-5
MIC841NYC5
B15
External
Open Drain
Active High
–40° to +85°C
9
SC-70-5
MIC842HYC5
B16
Internal
Push Pull
Active High
–40° to +85°C
9
SC-70-5
MIC842LYC5
B17
Internal
Push Pull
Active Low
–40° to +85°C
9
SC-70-5
MIC842NYC5
B18
Internal
Open Drain
Active High
–40° to +85°C
9
SC-70-5
March 2011
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Pb-Free
Package
M9999-030811-B
Micrel, Inc.
MIC841/2
Pin Configuration
MIC841
SC-70-5 (C5)
MIC842
SC-70-5 (C5)
Pin Description MIC841
Pin Number
1
2
3
Pin Name
HTH
GND
LTH
OUT
4
OUT
OUT
5
VDD
Pin Function
High Threshold Input. HTH and LTH monitor external voltages.
Ground.
Low Threshold Input. LTH and HTH monitor external voltages.
(“H” Version) Active-Low Push-Pull Output. OUT asserts low when VLTH <
VREF. OUT remains low until VHTH > VREF.
(“L” Version) Active-High Push-Pull output. OUT asserts high when VLTL <
VREF. OUT remains high until VHTH > VREF.
(“N” Version) Active-Low, Open-Drain Output. OUT asserts low when VLTH <
VREF. OUT remains low until VHTH > VREF.
Power Supply Input
Pin Description MIC842
Pin Number
1
2
3
Pin Name
INP
GND
NC
OUT
4
OUT
OUT
5
March 2011
VDD
Pin Function
Threshold Input. INP monitors an external voltage.
Ground
No Connect. Not internally connected.
(“H” Version) Active-Low, Push-Pull Output. OUT asserts low when VINP <
VREF. OUT remains low until VINP > (VREF+ VHYST).
(“L” Version) Active-High, Push-Pull Output. OUT asserts high when VINP <
VREF. OUT remains high until VINP > (VREF+ VHYST).
(“N” Version) Active-Low, Open-Drain Output. OUT asserts low when VINP <
VREF. OUT remains low until VINP > (VREF+ VHYST).
Power Supply Input
3
M9999-030811-B
Micrel, Inc.
MIC841/2
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Voltage (VDD)....................................... –0.3V to +7V
Input Voltage (VINP, VLTH, VLTL) .......................................+7V
Output Current (IOUT) .................................................±20mA
Storage Temperature (TS)........................ –65°C to +150°C
ESD Rating, Note 3 ....................................................... 1kV
Supply Voltage (VDD)................................... +1.5V to +5.5V
Input Voltage (VINP VLTH, VLTL)........................... –0.3V to 6V
VOUT (‘H’ and ‘L’ versions)............................................... VDD
VOUT (‘N’ version) ............................................................. 6V
Ambient Temperature Range (TA) ............. –40°C to +85°C
Junction Temperature (TJ) ........................................ 150°C
Package Thermal Resistance (θJA).................... 256.5°C/W
Electrical Characteristics(4)
1.5V ≤ VDD ≤ 5.5V; TA = +25°C, bold values indicate –40°C≤ TA ≤ +85°C, unless noted.
Symbol
Parameter
Condition
IDD
Supply Current
Output not asserted
IINP
Input Leakage Current
VREF
Reference Voltage
VHYST
Hysteresis Voltage, (Note 5)
tD
Propagation Delay
Output Voltage-Low
VOUT
(Note 6)
Output Voltage-High
Min
Typ
Max
Units
1.5
3
μA
0.005
10
nA
0°C to 85°C
1.225
1.240
1.256
V
–40°C to 85°C
1.219
1.240
1.261
V
8
20
35
mV
MIC842 only
VINP = 1.352V to 1.128V
12
μs
VINP = 1.143V to 1.367V
8
μs
ISINK = 1.6mA, VDD ≥ 1.6V
0.05
0.3
V
ISINK = 100μA, VDD ≥ 1.2V
0.005
0.4
V
ISOURCE = 500μA, VDD ≥ 1.6V
0.99VDD
V
ISOURCE = 50μA, VDD ≥ 1.2V
0.99VDD
V
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.
Specification for packaged product only.
5.
VHTH = VREF + VHYST.
6.
VDD operating range is 1.5V to 5.5V. Output is guaranteed to be de-asserted down to VDD = 1.2V.
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Micrel, Inc.
MIC841/2
Block Diagrams
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Micrel, Inc.
MIC841/2
Application Information
Output
The MIC841N and MIC842N outputs are an open-drain
MOSFET, so most applications will require a pull-up
resistor. The value of the resistor should not be too large
or leakage effects may dominate. 470kΩ is the
maximum recommended value. Note that the output of
“N” version may be pulled up as high as 6V regardless of
the ICs supply voltage. The “H” and “L” versions of the
MIC841 and MIC842 have a push-pull output stage, with
a diode clamped to VDD. Thus, the maximum output
voltage of the “H” and “L” versions is VDD. See “Electrical
Characteristics.”
When working with large resistors on the input to the
devices, a small amount of leakage current can cause
voltage offsets that degrade system accuracy. The
maximum recommended total resistance from VIN to
ground is 3MΩ. The accuracy of the resistors can be
chosen based upon the accuracy required by the
system. The inputs may be subjected to voltages as high
as 6V steady-state without adverse effects of any kind
regardless of the ICs supply voltage. This applies even if
the supply voltage is zero. This permits the situation in
which the IC’s supply is turned off, but voltage is still
present on the inputs. See “Electrical Characteristics.”
Figure 1. MIC841 Example Circuit
Once the desired trip points are determined, set the
VIN(HI) threshold first.
For example, use a total of 1MΩ = R1 + R2 + R3. For a
typical single-cell lithium ion battery, 3.6V is a good “high
threshold” because at 3.6V the battery is moderately
charged. Solving for R3:
⎛ 1MΩ ⎞
VIN(HI) − 3.6 V − 1.24⎜
⎟
⎝ R3 ⎠
R3 = 344kΩ
Programming the MIC841 Thresholds
The low-voltage threshold is calculated using:
Once R3 is determined, the equation for VIN(LO) can be
used to determine R2. A single lithium-ion cell, for
example, should not be discharged below 2.5V. Many
applications limit the drain to 3.1V. Using 3.1V for the
VIN(LO) threshold allows calculation of the two remaining
resistor values.
⎛ R1 + R2 + R3 ⎞
VIN(LO ) − VREF ⎜
⎟
⎝ R 2 + R3 ⎠
The high-voltage threshold is calculated using:
⎛ 1MΩ ⎞
VIN(LO ) − 3.1V − 1.24⎜
⎟
⎝ R2 + 344k ⎠
⎛ R1 + R2 + R3 ⎞
VIN(HI) − VREF ⎜
⎟
R3
⎝
⎠
R2 = 56kΩ
1MΩ - (R2 - R3) = R1
where, for both equations:
R1 = 600kΩ
The accuracy of the resistors can be chosen based upon
the accuracy required by the system.
In order to provide the additional criteria needed to solve
for the resistor values, the resistors can be selected
such that they have a given total value, that is, R1 + R2
+ R3 = RTOTAL. A value such as 1MΩ for RTOTAL is a
reasonable value because it draws minimum current but
has no significant effect on accuracy.
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Micrel, Inc.
MIC841/2
VIN(HI)
VIN(LO)
VIN
Input Transients
The MIC841/2 is inherently immune to very short
negative-going “glitches.” Very brief transients may
exceed the VIN(LO) threshold without tripping the output.
As shown in Figure 4, the narrower the transient, the
deeper the threshold overdrive that will be ignored by the
MIC841/2. The graph represents the typical allowable
transient duration for a given amount of threshold
overdrive that will not generate an output.
VHYSTERISIS
0V
OUT
H AND N VERSIONS
0V
OUT
L VERSION
0V
Figure 2. Output Response and Hysteresis
Programming the MIC842 Thresholds
The voltage threshold is calculated using:
⎛ R1 + R2 ⎞
VIN(LO ) − VREF ⎜
⎟
⎝ R2 ⎠
where:
VREF = 1.240V
Figure 4. Input Transient Response
Figure 3. MIC842 Example Circuit
In order to provide the additional criteria needed to solve
for the resistor values, the resistors can be selected
such that they have a given total value, that is, R1 + R2
= RTOTAL. A value such as 1MΩ for RTOTAL is a
reasonable value because it draws minimum current but
has no significant effect on accuracy.
March 2011
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Micrel, Inc.
MIC841/2
Package Information
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
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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.
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© 2005 Micrel, Incorporated.
March 2011
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