The MAX9647/MAX9648 comparators are drop-in, pin-forpin compatible replacements for the LMX331/LMX331H.
The MAX9648 has the added benefit of internal hysteresis to provide noise immunity, preventing output oscillations even with slow moving input signals.
Advantages of the ICs include low supply voltage, small
package, and low cost. They also offer a wide supply
voltage range, wide operating temperature range, competitive CMRR and PSRR, response time characteristics,
input offset, low noise, output saturation voltage, input
bias current, and RF immunity.
The ICs are available in both 5-pin SC70 and SOT23
packages.
Applications
Mobile Communications
Notebooks and PDAs
Automotive Applications
Battery-Powered Electronics
General-Purpose Portable Devices
General-Purpose Low-Voltage Applications
Features
SGuaranteed +1.8V to +5.5V Performance
S-40NC to +125NC Automotive Temperature Range
SLow Supply Current (60µA/Channel at
V
= +5.0V)
DD
SInput Common-Mode Voltage Range Includes
Ground
SNo Phase Reversal for Overdriven Inputs
SLow Output Saturation Voltage (120mV)
SInternal 2mV Hysteresis (MAX9648)
S5-Pin SC70 Space-Saving Package
(2.0mm x 2.1mm x 1.0mm)
Ordering Information appears at end of data sheet.
For related parts and recommended products to use with this part,
refer to www.maxim-ic.com/MAX9647.related.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
DC ELECTRICAL CHARACTERISTICS—2.7V OPERATION
(VDD = 2.7V, VSS = 0V, VCM = 0V, RL = 5.1kI connected to VDD, typical values are at TA = +25NC, unless otherwise noted. Boldface
limits apply at the defined temperature extremes.) (Note 1)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
Input Offset VoltageV
Input Voltage HysteresisV
Input Offset Voltage Average
Temperature Drift
Input Bias CurrentI
Input Offset CurrentI
Input Voltage RangeV
Voltage GainA
Output Saturation VoltageV
Output Sink CurrentI
Supply Current I
Output Leakage Current
HYST
TCV
OS
B
OS
CM
V
SAT
O
S
MAX9648 only2mV
OS
TA = +25NCQ0.0003Q250
TA = -40NC to +85NC
TA = -40NC to +125NC
TA = +25NCQ0.0003Q50
TA = -40NC to +85NC
TA = -40NC to +125NC
MAX9647 only500V/mV
I
P 1mA
SINK
VO P 1.5V
(Note 2)52100
TA = +25NC
TA = -40NC to +125NC
Operating Temperature Range ........................ -40NC to +125NC
Junction Temperature .....................................................+150NC
Storage Temperature Range ............................ -65NC to +150NC
Lead Temperature (soldering, 10s) ................................+300NC
Soldering Temperature (reflow) ......................................+260NC
0.47mV
1.5
±400
±400
±150
±150
-0.1
2.0
25mV
516mA
0.005
FV/NC
nA
nA
V
FA
1
2
FATA = -40NC to +85NC
AC ELECTRICAL CHARACTERISTICS—2.7V OPERATION
(VDD = 2.7V, VSS = 0V, VCM = 0V, RL = 5.1kI connected to VDD, typical values are at TA = +25NC, unless otherwise noted. Boldface
limits apply at the defined temperature extremes.) (Note 1)
(VDD = 5V, VSS = 0V, VCM = 0V, RL = 5.1kI connected to VDD, typical values are at TA = +25NC, unless otherwise noted. Boldface
limits apply at the defined temperature extremes.) (Note 1)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
TA = +25NC
Input Offset VoltageV
Input Voltage HysteresisMAX9648 only2mV
Input Offset Voltage Average
Temperature Drift
Input Bias CurrentI
Input Offset CurrentI
Input Voltage RangeV
Voltage GainA
Output Saturation VoltageV
Output Sink CurrentI
Supply Current (Note 2)I
Output Leakage Current
OS
TCV
B
OS
CM
SAT
O
S
TA = -40NC to +85NC
TA = -40NC to +125NC
OS
TA = +25NCQ0.007Q250
TA = -40NC to +85NC
TA = -40NC to +125NC
TA = +25NCQ0.007Q50
TA = -40NC to +85NC
TA = -40NC to +125NC
MAX9647 only20500V/mV
V
TA = +25NC
I
P 4mA
SINK
VO P 1.5V
TA = +25NC
TA = -40NC to +125NC
TA = +25NC
TA = -40NC to +125NC
TA = -40NC to +85NC
TA = -40NC to +125NC
1035mA
0.47
1.5
±400
±400
±150
±150
-0.1
4.2
120400
60120
0.005
9
9
700
700
150
170
1
2
mV
FV/NC
nA
nA
V
mV
FATA = -40NC to +85NC
FATA = -40NC to +85NC
AC ELECTRICAL CHARACTERISTICS–5.0V OPERATION
(VDD = 5V, VSS = 0V, VCM = 0V, RL = 5.1kI connected to VDD, typical values are at TA = +25NC, unless otherwise noted. Boldface
limits apply at the defined temperature extremes.) (Note 1)
(VDD = 1.8V, VSS = 0V, VCM = 0V, RL = 5.1kI connected to VDD, typical values are at TA = +25NC, unless otherwise noted. Boldface
limits apply at the defined temperature extremes.) (Note 1)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
Input Offset VoltageV
Input Voltage HysteresisMAX9648 only2mV
Input Offset Voltage Average
Temperature Drift
Input Bias CurrentI
Input Offset CurrentI
Input Voltage RangeV
Output Saturation VoltageV
Power-Supply Rejection RatioPSRRVDD = 1.8V to 5.5V6090dB
Output Sink CurrentI
Supply Current I
Output Leakage Current0.001
TCV
OS
B
OS
CM
SAT
O
S
OS
I
P 1mA
SINK
VO P 1.5V
(Note 2)50100
0.45mV
1.5
0.0003nA
0.0003nA
-0.1
1
56mV
6.4mA
FV/NC
FA
FA
V
AC ELECTRICAL CHARACTERISTICS—1.8V OPERATION
(VDD = 1.8V, VSS = 0V, VCM = 0V, RL = 5.1kI connected to VDD, typical values are at TA = +25NC, unless otherwise noted. Boldface
limits apply at the defined temperature extremes.) (Note 1)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
Propagation Delay Output
High to Low (Note 3)
Propagation Delay Output
Low to High (Note 3)
Note 1: All devices are production tested at TA = +25NC. All temperature limits are guaranteed by design.
Note 2: Supply current when output is high.
Note 3: Input overdrive is the overdrive voltage beyond the offset and hysteresis-determined trip points.
The MAX9647/MAX9648 are low-cost, general-purpose
comparators that have a single-supply +1.8V to +5V
operating voltage range. The common-mode input range
extends from -0.1V below the negative supply to within
+0.7V of the positive supply. They require approximately
60FA per comparator with a 5V supply and 52FA with a
2.7V supply.
The MAX9648 has 2mV of hysteresis for noise immunity.
This significantly reduces the chance of output oscillations even with slow moving input signals. The ICs are
ideal for automotive applications because they operate from -40NC to +125NC. See the Typical Operating
Characteristics.
4
SC70/SOT23
Pin Description
Applications Information
Hysteresis
Many comparators oscillate in the linear region of operation because of noise or undesired parasitic feedback.
This tends to occur when the voltage on one input is
equal or very close to the voltage on the other input. The
MAX9648 has internal hysteresis to counter parasitic
effects and noise.
The hysteresis in a comparator creates two trip points:
one for the rising input voltage and one for the falling
input voltage (Figure 1). The difference between the trip
points is the hysteresis. When the comparator’s input
voltages are equal, the hysteresis effectively causes
one comparator input to move quickly past the other,
thus taking the input out of the region where oscillation
occurs. This provides clean output transitions for noisy,
slow-moving input signals.
Additional hysteresis can be generated with two resistors using positive feedback (Figure 2). Use the following
procedure to calculate resistor values:
1) Find output voltage when output is high:
V
OUT(HIGH)
= VDD - I
LOAD
x R
L
2) Find the trip points of the comparator using these
formulas:
VTH = V
VTL = V
+ ((V
REF
REF
OUT(HIGH)
(1 - (R2/(R1 + R2)))
- V
)R2)/(R1 + R2)
REF
where VTH is the threshold voltage at which the comparator switches its output from high to low as V
rises above
IN
the trip point, and VTL is the threshold voltage at which
the comparator switches its output from low to high as
V
drops below the trip point.
IN
3) The hysteresis band is:
V
= V
HYST
In this example, let VDD = 5V, V
- VTL = VDD(R2/(R1 + R2))
TH
= 2.5V, I
REF
LOAD
=
50nA, and RL = 5.1kI.
V
OUT(HIGH)
= 5.0V - (50 x 10-9 x 5.1 x 103I) ≈ 5.0V
V
= 2.5 + 2.5(R2/(R1 + R2))
TH
VTL = 2.5(1 - (R2/(R1 + R2)))
Select R2. In this example, choose 1kI.
Select V
. In this example, choose 50mV.
HYST
Solve for R1.
V
HYST
= V
OUT(HIGH)
(R2/(R1 + R2))V
0.050V = 5(1000/(R1 + 1000))V
where R1 ≈ 100kI, VTH = 2.525V, and VTL = 2.475V
Choose R1 and R2 to be large enough as not to exceed
the amount of current the reference can supply.
The source current required is V
The sink current is (V
OUT(HIGH)
/(R1 + R2).
REF
- V
REF
) x (R1 + R2).
Choose RL to be large enough to avoid drawing excess
current, yet small enough to supply the necessary current to drive the load. RL should be between 1kI and
10kI. Choose R1 to be much larger than RL to avoid
lowering V
OUT(HIGH)
ir raising V
OUT(LOW)
.
Board Layout and Bypassing
Use 0.1FF bypass capacitors from VDD to VSS. To maximize performance, minimize stray inductance by putting
this capacitor close to the VDD pin and reducing trace
lengths. For slow moving input signals (rise time > 1ms),
use a 1nF capacitor between IN+ and IN- to reduce high
frequency noise.
IN+
IN-
V
HYST
OUT
Figure 1. Threshold Hysteresis Band (Not to Scale)
Figure 2. Adding Hysteresis with External Resistors
REF
V
R2
IN
IN+
IN-
DD
V
SS
R
L
MAX9647
OUT
V
OUT
MAX9647/MAX9648
General-Purpose, Low-Voltage,
Tiny Pack Comparators
Chip Information
PROCESS: BiCMOS
Ordering Information
PART
MAX9647AXK+T
MAX9647AUK+T
MAX9648AXK+T
MAX9648AUK+T
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
TEMP
RANGE
-40NC to
+125NC
-40NC to
+125NC
-40NC to
+125NC
-40NC to
+125NC
PINPACKAGE
5 SC70+AUS
5 SOT23+AFLM
5 SC70+AUT
5 SOT23+AFLN
TOP
MARK
Package Information
For the latest package outline information and land patterns
(footprints), go to www.maxim-ic.com/packages. Note that a
“+”, “#”, or “-” in the package code indicates RoHS status only.
Package drawings may show a different suffix character, but
the drawing pertains to the package regardless of RoHS status.
010/11Initial release—
11/12Revised the Typical Operating Characteristics. 6
REVISION
DATE
DESCRIPTION
PAGES
CHANGED
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied.
Maxim reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical
Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 11