June 1999
1
MIC7211/7221
MIC7211/7221
Micrel
Pin Description
Pin Number
Pin Name
Pin Function
1
OUT
Amplifier Output
2
V+
Positive Supply
3
IN+
Noninverting Input
4
IN
Inverting Input
5
V
Negative Suppy
MIC7211/7221
IttyBittyTM Rail-to-Rail Input Comparator
Preliminary Information
Functional Configuration
OUT
V+
IN
IN+
1
3
4
5
2
V
SOT-23-5 (M5)
General Description
The MIC7211 and MIC7221 are micropower comparators
featuring rail-to-rail input performance in Micrel's IttyBitty
TM
SOT-23-5 package. The MIC7211/21 is ideal for systems
where small size is a critical consideration.
The MIC7211/21 is optimized for single supply operation
from 2.2V to 10V power supplies.
The MIC7211 features a conventional push-pull output while
the MIC7221 has an open-drain output for mixed-voltage
applications with an external pull-up resistor.
The MIC7211/21 benefits small battery-operated portable
electronic devices where small size and the ability to place
the comparator close to the signal source are primary design
concerns.
Pin Configuration
OUT
V+
IN
IN+
1
3
4
5
2
V
Axx
Part
Identification
Features
Small footprint SOT-23-5 package
Guaranteed performance at 2.2V, 2.7V, 5V, and 10V
7
A typical supply current at 5V
<5
s response time at 5V
Push-pull output (MIC7211)
Open-drain output (MIC7221)
Input voltage range may exceed supply voltage by 0.3V
>100mA typical sink or source
Applications
Battery-powered products
Notebook computers and PDAs
PCMCIA cards
Cellular and other wireless communication devices
Alarm and security circuits
Direct sensor interface
Ordering Information
Part Number
Temp. Range
Package
Mark
MIC7211BM5
40
C to +85
C
SOT-23-5
A14
MIC7221BM5
40
C to +85
C
SOT-23-5
A15
Micrel, Inc. 1849 Fortune Drive San Jose, CA 95131 USA tel + 1 (408) 944-0800 fax + 1 (408) 944-0970 http://www.micrel.com
MIC7211/7221
Micrel
MIC7211/7221
2
June 1999
Absolute Maximum Ratings
(Note 1)
Supply Voltage (V
V+
V
V
) ........................................... 12V
Differential Input Voltage (V
IN+
, V
IN
) .............
(V
V+
V
V
)
I/O Pin Voltage (V
IN+
, V
OUT
), Note 3 ..................................
............................................ V
V+
+ 0.3V to V
V
0.3V
Junction Temperature (T
J
) ...................................... +150
C
Storage Temperature (T
S
) ....................... 65
C to +150
C
ESD, Note 6
Operating Ratings
(Note 2)
Supply Voltage (V
V+
V
V
) .............................. 2.2V to 10V
Junction Temperature (T
J
) ......................... 40
C to +85
C
Maximum Junction Temperature (T
J(max)
) Note 4 . +125
C
Package Thermal Resistance
(
JA
) Note 5 .......... 325
C/W
Maximum Power Dissipation .................................... Note 4
DC Electrical Characteristics (2.2V)
V
V
+ = +2.2V, V
V
= 0V, V
CM
= V
OUT
= V
V+
/2; T
J
= 25
C, bold values indicate 40
C
T
J
+85
C; Note 7; unless noted
Symbol
Parameter
Condition
Min
Typ
Max
Units
V
OS
Input Offset Voltage
2
10
mV
TCV
OS
Input Offset Voltage
1
V/
C
Temperature Drift
TCV
OS
Input Offset Voltage
3.3
V
/
month
Drift Over Time
I
B
Input Bias Current
0.5
pA
I
OS
Input Offset Current
0.25
pA
CMRR
Common-Mode Rejection Ratio
0V
V
CM
2.2V
60
dB
PSRR
Positive Power Supply
V
V+
= 2.2V to 5V
90
dB
Rejection Ratio
A
VOL
Gain
125
dB
V
OH
Output Voltage (High)
MIC7211, I
LOAD
= 2.5mA
2.1
2.18
V
V
OL
Output Voltage (Low)
I
LOAD
= 2.5mA
0.02
0.1
V
I
S
Supply Current
V
OUT
= low
5
12
A
DC Electrical Characteristics (2.7V)
V
V
+ = +2.7V, V
V
= 0V, V
CM
= V
OUT
=
V
V+
/2; T
J
= 25
C, bold values indicate 40
C
T
J
+85
C; Note 7; unless noted
Symbol
Parameter
Condition
Min
Typ
Max
Units
V
OS
Input Offset Voltage
2
10
mV
TCV
OS
Input Offset Voltage
1
V/
C
Temperature Drift
TCV
OS
Input Offset Voltage
3.3
V
/
month
Drift Over Time
I
B
Input Bias Current
0.5
pA
I
OS
Input Offset Current
0.25
pA
CMRR
Common-Mode Rejection Ratio
0V
V
CM
2.7V
65
dB
PSRR
Positive Power Supply
V
V+
= 2.7V to 5V
90
dB
Rejection Ratio
A
VOL
Gain
125
dB
V
OH
Output Voltage (High)
MIC7211, I
LOAD
= 2.5mA
2.6
2.68
V
V
OL
Output Voltage (Low)
I
LOAD
= 2.5mA
0.02
0.1
V
I
S
Supply Current
V
OUT
= low
5
12
A
June 1999
3
MIC7211/7221
MIC7211/7221
Micrel
DC Electrical Characteristics (5V)
V
V
+ = +5.0V, V
V
= 0V, V
CM
= V
OUT
= V
V+
/2; T
J
= 25
C, bold values indicate 40
C
T
J
+85
C; Note 7; unless noted
Symbol
Parameter
Condition
Min
Typ
Max
Units
V
OS
Input Offset Voltage
2
10
mV
TCV
OS
Input Offset Voltage
1
V/
C
Temperature Drift
TCV
OS
Input Offset Voltage
3.3
V
/
month
Drift Over Time
I
B
Input Bias Current
0.5
pA
I
OS
Input Offset Current
0.25
pA
CMRR
Common-Mode Rejection Ratio
0V
V
CM
5.0V
70
dB
PSRR
Positive Power Supply
V
V+
= 5.0V to 10V
90
dB
Rejection Ratio
A
VOL
Gain
125
dB
V
OH
Output Voltage (High)
MIC7211, I
LOAD
= 5mA
4.9
4.95
V
V
OL
Output Voltage (Low)
I
LOAD
= 5mA
0.05
0.1
V
I
S
Supply Current
V
OUT
= low
7
14
A
I
SC
Short Circuit Current
MIC7211, sourcing
150
mA
sinking
110
mA
DC Electrical Characteristics (10V)
V
V
+ = +10V, V
V
= 0V, V
CM
= V
OUT
= V
V+
/2; T
J
= 25
C, bold values indicate 40
C
T
J
+85
C; Note 7; unless noted
Symbol
Parameter
Condition
Min
Typ
Max
Units
V
OS
Input Offset Voltage
2
10
mV
TCV
OS
Input Offset Voltage
1
V/
C
Temperature Drift
TCV
OS
Input Offset Voltage
3.3
V
/
month
Drift Over Time
I
B
Input Bias Current
0.5
pA
I
OS
Input Offset Current
0.25
pA
CMRR
Common-Mode Rejection Ratio
0V
V
CM
10V
75
dB
PSRR
Positive Power Supply
V
V+
= 5.0V to 10V
90
dB
Rejection Ratio
A
VOL
Gain
125
dB
V
OH
Output Voltage (High)
MIC7211, I
LOAD
= 5mA
9.9
9.95
V
V
OL
Output Voltage (Low)
I
LOAD
= 5mA
0.05
0.1
V
I
S
Supply Current
V
OUT
= low
12
25
A
I
SC
Short Circuit Current
MIC7211, sourcing
165
mA
sinking
125
mA
MIC7211/7221
Micrel
MIC7211/7221
4
June 1999
AC Electrical Characteristics
V
V
= 0V, V
CM
= V
OUT
= V
V+
/2; T
J
= 25
C, bold values indicate 40
C
T
J
+85
C; Note 7; unless noted
Symbol
Parameter
Condition
Min
Typ
Max
Units
t
RISE
Rise Time
V
V+
= 5.0V, f = 10kHz, C
LOAD
= 50pF
75
ns
overdrive = 10mV, Note 9
t
FALL
Fall Time
V
V+
= 5.0V, f = 10kHz, C
LOAD
= 50pF
70
ns
overdrive = 10mV, Note 9
t
PHL
Propagation Delay-High to Low
V
V+
= 2.2V, f = 10kHz, C
LOAD
= 50pF
10
s
overdrive = 10mV, Note 9
V
V+
= 2.2V, f = 10kHz, C
LOAD
= 50pF
6.0
s
overdrive = 100mV, Note 9
V
V+
= 5.0V, f = 10kHz, C
LOAD
= 50pF
13
s
overdrive = 10mV, Note 9
V
V+
= 5.0V, f = 10kHz, C
LOAD
= 50pF
5
s
overdrive = 100mV, Note 9
t
PLH
Propagation Delay-Low to High
V
V+
= 2.2V, f = 10kHz, C
LOAD
= 50pF
13.5
s
overdrive = 10mV, Note 9
V
V+
= 2.2V, f = 10kHz, C
LOAD
= 50pF
4.0
s
overdrive = 100mV, Note 9
V
V+
= 5.0V, f = 10kHz, C
LOAD
= 50pF
11.5
s
overdrive = 10mV, Note 9
V
V+
= 5.0V, f = 10kHz, C
LOAD
= 50pF
3.0
s
overdrive = 100mV, Note 9
Note 1.
Exceeding the absolute maximum rating may damage the device.
Note 2.
The device is not guaranteed to function outside its operating rating.
Note 3.
I/O pin voltage is any external voltage to which an input or output is referenced.
Note 4.
The maximum allowable power dissipation is a function of the maximum junction temperature, T
J(max)
; the junction-to-ambient thermal
resistance,
JA
; and the ambient temperature, T
A
. The maximum allowable power dissipation at any ambient temperature is calculated using
P
D(max)
= (T
J(max)
T
A
)
JA
. Exceeding the maximum allowable power dissipation will result in excessive die temperature.
Note 5.
Thermal resistance,
JA
, applies to a part soldered on a printed circuit board.
Note 6.
Devices are ESD sensitive. Handling precautions recommended.
Note 7.
All limits guaranteed by testing on statistical analysis.
Note 8.
Continuous short circuit may exceed absolute maximum T
J
under some conditions.
Note 9.
The MIC7221 requires 5k
pull-up resistor.
V+
V
OUT
MIC7211 Push-Pull Output
V+
V
OUT
MIC7221 Open-Drain Output
Partial Functional Diagrams
June 1999
5
MIC7211/7221
MIC7211/7221
Micrel
Application Information
The small outline and low supply current (typically 7
A at 5V)
of the MIC7211/21 are the primary advantages of these
comparators. They have been characterized for 2.2V, 2.7V,
5V, and 10V operation.
Their 2.2V capability is especially useful in low-battery volt-
age situations. Low-voltage operation allows longer battery
life or deeper discharge capability. Even at 2.2V, the output
can drive several logic-gate inputs. At 2.5mA, the output
stage voltage drop is guaranteed to not exceed 0.1V.
Outputs
The MIC7211 has a push-pull output while the MIC7221 has
an open-drain output, otherwise both comparators share a
common design.
The open-drain MIC7221 output can be pulled up to 10V,
even when the supply voltage is as low as 2.2V. Conversely,
the output also can be pulled up to voltages that are lower
than the positive supply. Logic-level translation is readily
facilitated by the ability to pull the open-drain output to
voltages above or below the power supply.
Although specified short-circuit output current specified for
these parts typically exceeds 100mA, their output is not
intended to sink or source anywhere near 100mA. The short-
circuit rating is only presented as additional information
regarding output impedance and may be useful for determin-
ing the voltage drop one may experience when driving a given
load.
Input Bias Current
The low input-bias current (typically 0.5pA) requirement of
the MIC7211/21 provides flexibility in the kinds of circuitry and
devices that can be directly interfaced.
Designs using an amplifier for transducer-to-comparator
impedance transformation may be simplified by using the
MIC7211/21's low-input-current requirement to eliminate the
amplifier.
Input Signal Levels
Input signals may exceed either supply rail by up to 0.2V
without phase inversion or other adverse effects. The inputs
have internal clamp diodes to the supply pins.
R
IN
V
IN
(
100V)
V
REF
R1
R
F
V
OUT
100k
0.1F
Note: R
F
and R1 control hysteresis (typically, R
F
>> R1).
V
+
Figure 1. Driving the Input Beyond the Supply Rails
Larger input swings can be accommodated if the input current
is limited to 1mA or less. Using a 100k input resistor will allow
an input to swing up to 100V beyond either supply rail.
Because of the low input bias current of the device, even
larger input resistors are practical. See Figure 1. The ability
to swing the input beyond either rail facilitates some other-
wise difficult circuits, such as a single-supply zero-crossing
detector or a circuit that senses its own supply voltage.
The comparator must be powered if an input is pulled above
the rail, even with current limiting in effect. Figure 2 shows a
hypothetical situation where an input is pulled higher than the
rail when the power supply is off or not present. Figure 2 also
shows external clamp diodes for additional input circuit
protection. Discrete clamp diodes can be arbitrarily more
robust than the internal clamp diodes.
The power supply has been simplified (real power supplies do
not have a series output diode); however, this illustrates a
common characteristic of most positive-voltage power sup-
plies: they are designed to source, but not sink, current. If the
supply is off, or disconnected, there is no limiting voltage for
the clamp diode to reference. The input signal can charge the
the bypass capacitor, and possibly the filter capacitor, up to
the applied input (V
IN
). This may be high enough to cause a
thin-oxide rupture in a CMOS integrated circuit.
V
+
R
IN
V
IN
(>>V+)
V
REF
R1
R
F
V
OUT
0.1F
Note: 1V
V
++
10V
V
++
R
PU
POSSIBLE
DISCONNECT
0V WHEN
SUPPLY
IS OFF
Power
Supply
Output
Figure 2. Avoid This Condition
Ideally, the supply for the comparator and the input-produc-
ing circuitry should the same or be switched simultaneously.
Bypass Capacitors
CMOS circuits, especially logic gates with their totem-pole
(push-pull) output stages, generate power supply current
spikes (noise) on the supply and/or ground lines. These
spikes occur because, for a finite time during switching, both
output transistors are partially on allowing "shoot-through
current." Bypass capacitors reduce this noise.
Adequate bypassing for the MIC7211 comparator is 0.01
F;
in low-noise systems, where this noise may interfere with the
functioning or accuracy of nearby circuitry, 0.1
F is recom-
mended. Because the MIC7221 does not have a totem-pole
output stage, this spiking is not evident; however, switching
a capacitive load can present a similar situation.
Thermal Behavior
The thermal impedance of a SOT-23-5 package is 325C/W.
The 5V Electrical Characteristics table shows a maximum
voltage drop of 0.1V for a 5mA output current, making the
output resistance about 20
(R = 0.1/0.005 = 20
). Attempt-
ing to draw the typical specified output short-circuit current of
150mA (sourcing) can be expected to cause a die tempera-
ture
rise of 146C. (Operating die temperature for ICs should
generally not exceed 125C.) Using a series resistance is the
simplest form of protecting against damage by excessive
output current.
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