Micrel MIC842 Comparator with reference Datasheet

MIC841/2
Micrel
MIC841/842
Comparator with Reference
General Description
The MIC841 and MIC842 are micropower, precision voltage
comparators with an on-chip voltage reference.
Teeny™
Features
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.
• Optimized for PDAs, cellular telephones, pagers,
and other battery-powered devices
• Output can be pulled up to 6V regardless of supply
voltage (841NBC5 only)
• High ±1.25% voltage threshold accuracy
• Built in hysteresis for noise suppression
(MIC842)
• Extremely low 1.5µA typical supply current
• Immune to brief input transients
• Teeny™ 5-lead SC-70 package
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 high.
Supply current is extremely low (1.5µA, typical), making it ideal
for portable applications.
Applications
•
•
•
•
•
•
The MIC841/2 is supplied in Micrel’s Teeny™ 5-lead SC-70
package.
Data sheets and support documentation can be found on
Micrel’s web site at www.micrel.com.
PDAs
Pagers
Cordless phones
Consumer electronics
Embedded controllers
Personal electronics
Typical Application
VIN VDD
MIC841
R1
5
3
R2
1
VDD
OUT
VIN VDD
4
LTH
HTH
GND
2
VOUT
MIC842
VLTH > V HTH
VREF = 1.24V
1.5V ≤ V DD ≤ 5.5V
R1
5
1
R3
VDD
OUT
INP
GND
4
2
VOUT
VREF = 1.24V
1.5V ≤ VDD ≤ 5.5V
R2
Threshold Detection with Hysteresis Set by a Third
External Resistor
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
January 2005
1
MIC841/2
MIC841/2
Micrel
Ordering Information
Part Number
Marking
Hysteresis
Adjustment
Output
Stage
Output
Function
Temp. Range
Pb-Free
Package
MIC841HBC5
B13
External
Push Pull
Active High
–40°C to +85°C
SC-70-5
MIC841LBC5
B14
External
Push Pull
Active Low
–40°C to +85°C
SC-70-5
MIC841NBC5
B15
External
Open Drain
Active High
–40°C to +85°C
SC-70-5
MIC842HBC5
B16
Internal
Push Pull
Active High
–40°C to +85°C
SC-70-5
MIC842LBC5
B17
Internal
Push Pull
Active Low
–40°C to +85°C
SC-70-5
MIC842NBC5
B18
Internal
Open Drain
Active High
–40°C to +85°C
MIC841HYC5
B13
External
Push Pull
Active High
–40°C to +85°C
SC-70-5
MIC841LYC5
B14
External
Push Pull
Active Low
–40°C to +85°C
SC-70-5
MIC841NYC5
B15
External
Open Drain
Active High
–40°C to +85°C
SC-70-5
MIC842HYC5
B16
Internal
Push Pull
Active High
–40°C to +85°C
SC-70-5
MIC842LYC5
B17
Internal
Push Pull
Active Low
–40°C to +85°C
SC-70-5
MIC842NYC5
B18
Internal
Open Drain
Active High
–40°C to +85°C
SC-70-5
MIC841/2
2
SC-70-5
January 2005
MIC841/2
Micrel
Pin Configuration
NC GND INP
LTH GND HTH
3
2
3
1
2
1
Bxx
Bxx
4
5
4
5
OUT
VDD
OUT
VDD
MIC842
SC-70-5 (C5)
MIC841
SC-70-5 (C5)
Pin Description MIC841
Pin Number
Pin Name
1
HTH
High-Voltage Threshold (Input): Analog input to a comparator. This is the
voltage input assigned to detect a high-voltage condition. When the level on
this pin exceeds VREF, OUT is asserted and the condition is latched until
VLTH < VREF.
2
GND
Ground.
3
LTH
Low-Voltage Threshold (Input): Analog input to a comparator. This is the
voltage input assigned to detect a low voltage condition. When the level on
this pin falls below VREF, OUT is de-asserted and the condition is latched
until VHTH > VREF.
4
OUT (“N” Version)
Output: Active-high, open-drain output. This output is de-asserted and
latched when VLTH <VREF, indicating a low voltage condition. This state
remains latched until VHTH > VREF.
OUT (“H” Version)
Output: Push-pull output. This output is de-asserted and latched when VLTH
< VREF, indicating a low voltage condition. This state remains latched until
VHTH > VREF.
OUT (“L” Version)
Output: Push-pull output. This output is asserted and latched when
VLTH < VREF, indicating a low voltage condition. This state remains latched
until VHTH > VREF.
5
VDD
Pin Function
Power Supply (Input): Independent supply input for internal circuitry.
Pin Description MIC842
Pin Number
Pin Name
1
INP
Input: Analog input to the comparator. When VINP > VREF + VHYST, VOUT is
asserted, and the condition is held until VINP < VREF.
2
GND
Ground.
3
NC
4
OUT (“N” Version)
Output: Active-high, open-drain output. This output is de-asserted when
VINP < VREF, indicating a low voltage input. The output is asserted when
VINP > VREF + VHYST.
OUT (“H” Version)
Output: Push-pull output. This output is de-asserted and latched when
VINP < VREF, indicating a low voltage condition. This state remains latched
until VINP > VREF + VHYST.
OUT (“L” Version)
Output: Push-pull output. This output is asserted and latched when
VINP < VREF, indicating a low voltage condition. This state remains latched
until VINP > VREF + VHYST.
5
January 2005
VDD
Pin Function
No Connect.
Power Supply (Input): Independent supply input for internal circuitry.
3
MIC841/2
MIC841/2
Micrel
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Voltage (VDD) ..................................... –0.3V to +7V
Input Voltage (VINP) ...................................................... +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) ......................................... –0.3V to 6V
Ambient Temperature Range (TA) ............. –40°C to +85°C
Junction Temperature (TJ) ....................... Internally Limited
Package Thermal Resistance (θJA) ...................... 450°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
Min
IDD
Supply Current
output not asserted
IINP
Input Leakage Current
VREF
Reference Voltage
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
VHYST
Hysteresis Voltage, (Note 5)
MIC842 only
tD
Propagation Delay
VINP = 1.352V to 1.128V
12
µs
VINP = 1.143V to 1.367V
8
µs
VOUT
Output Voltage-Low
(Note 6)
Output Voltage-High
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.
MIC841/2
4
January 2005
MIC841/2
Micrel
Block Diagrams
VDD
5
VIN
VDD
VDD
VIN
5
Low-Voltage
Detect
High-Voltage
Detect
INP
LTH
VLTH
VTH
3
1
OUT
OUT
R Q
4
4
High-Voltage
Detect
HTH
VHTH
VDD
S Q
1
1.24V
Bandgap
Reference
MIC842H
1.24V
Bandgap
Reference
2
GND
MIC841H
2
GND
VDD
5
VIN
VDD
VIN
VDD
Low-Voltage
Detect
5
LTH
VLTH
VTH
OUT
R Q
1
OUT
4
High-Voltage
Detect
HTH
VHTH
High-Voltage
Detect
INP
3
VDD
4
S Q
1
1.24V
Bandgap
Reference
1.24V
Bandgap
Reference
MIC842L
2
GND
MIC841L
2
GND
VDD
5
VIN
VDD
Low-Voltage
Detect
VDD
VIN
5
LTH
VLTH
INP
3
R Q
High-Voltage
Detect
HTH
VHTH
VTH
OUT
VDD
High-Voltage
Detect
OUT
1
4
4
S Q
1
1.24V
Bandgap
Reference
1.24V
Bandgap
Reference
MIC842N
2
GND
MIC841N
2
January 2005
GND
5
MIC841/2
MIC841/2
Micrel
Once the desired trip points are determined, set the VIN(HI)
threshold first.
Applications 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.”
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) = 3.6V = 1.24 

 R3 
R3 = 344kΩ
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.
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.”
 1MΩ 
VIN(LO) = 3.1V = 1.24 

 R2 + 344k 
R2 = 56kΩ
1MΩ − (R2 − R3) = R1
R1 = 600kΩ
The accuracy of the resistors can be chosen based upon the
accuracy required by the system.
Programming the MIC841 Thresholds
The low-voltage threshold is calculated using:
VIN(LO)
Programming the MIC842 Thresholds
The voltage threshold is calculated using:
 R1 + R2 + R3 
= VREF 

 R2 + R3 
 R1 + R2 
VIN(LO) = VREF 

 R2 
The high-voltage threshold is calculated using:
 R1 + R2 + R3 
VIN(HI) = VREF 

R3


where:
VREF = 1.240V
where, for both equations:
VIN
VREF = 1.240V
MIC842N
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.
VIN
R1
5
1
VDD
OUT
INP
GND
470k
4
VOUT
2
R2
VDD
Figure 2. MIC842 Example Circuit
MIC841N
R1
604k
1%
5
1
R2
56k
1%
R3
340k
1%
3
VDD
OUT
4
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.
470k
VOUT
LTH
HTH
GND
2
Figure 1. MIC841 Example Circuit
MIC841/2
6
January 2005
MIC841/2
Micrel
Input Transients
The MIC841/2 is inherently immune to very short negativegoing “glitches.” Very brief transients may exceed the VIN(LO)
threshold without tripping the output.
MAX. TRANSIENT DURATION (µs)
As shown in Figure 3, 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.
Input Transient
Response
140
120
100
80
60
40
20
0
1
10
100
1000
RESET COMP. OVERDRIVE, VREF–VLTH (mV)
Figure 3. Input Transient Response
January 2005
7
MIC841/2
MIC841/2
Micrel
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)
DIMENSIONS:
MM (INCH)
1.00 (0.039) 1.10 (0.043)
0.80 (0.032) 0.80 (0.032)
0.10 (0.004)
0.00 (0.000)
0.30 (0.012)
0.15 (0.006)
0.18 (0.007)
0.10 (0.004)
0.30 (0.012)
0.10 (0.004)
SC-70 (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
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.
MIC841/2
8
January 2005