MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
����������������������������������������������������������������� Maxim Integrated Products 1
Typical Application Circuit
19-5986; Rev 1; 12/11
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/MAX44269.related.
EVALUATION KIT AVAILABLE
General Description
The MAX44269 is an ultra-small and low-power dual
comparator ideal for battery-powered applications such
as cell phones, notebooks, and portable medical devices
that have extremely aggressive board space and power
constraints. The comparator is available in a miniature
1.3mm x 1.3mm, 9-bump WLP package, making it the
industry’s smallest dual comparator.
The IC can be powered from supply rails as low as 1.8V
and up to 5.5V. It requires just 0.5µA of typical supply
current per comparator. It has a rail-to-rail input struc-
ture and a unique output stage that limits supply current
surges while switching. This design also minimizes over-
all power consumption under dynamic conditions. The
IC has open-drain outputs, making it suitable for mixed
voltage systems. The IC also features internal filtering to
provide high RF immunity. It operates over a -40°C to
+85°C temperature.
Applications
Smartphones
Notebooks
Two-Cell Battery-Powered Devices
Battery-Operated Sensors
Ultra-Low-Power Systems
Portable Medical Mobile Accessories
Features
S Ultra-Low Power Consumption
0.5µA per Comparator
S Ultra-Small 1.3mm x 1.3mm WLP Package
S Guaranteed Operation Down to VCC = 1.8V
S Input Common-Mode Voltage Range Extends
200mV Beyond-the-Rails
S 6V Tolerant Inputs Independent of Supply
S Open-Drain Outputs
S Internal Filters Enhance RF Immunity
S Crowbar-Current-Free Switching
S Internal Hysteresis for Clean Switching
S No Output Phase Reversal for Overdriven Inputs
VCC
VCC
VREF
VCC
VCC
GND
OUT1
OUT2
CONNECTOR
ACCESSORY ID
REMOTE KEY
MAX44269
VPULL
VPULL
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
����������������������������������������������������������������� Maxim Integrated Products 2
MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
VCC to GND .............................................................-0.3V to +6V
INA+, INA-, INB+, INB- to GND .............................. -0.3V to +6V
Continuous Input Current into Any Pin ............................ Q20mA
Maximum Power Dissipation
(derate 11.9mW/NC at TA = +70NC) ............................952mW
Output Voltage to GND (OUT_) ..............................-0.3V to +6V
Output Current (OUT_) .................................................... Q50mA
Output Short-Circuit Duration (OUT_) .......................Continuous
Operating Temperature Range .......................... -40NC to +85NC
Storage Temperature Range ............................ -65NC to +150NC
Junction Temperature .....................................................+150NC
Lead Temperature (soldering, 10s) ................................+300NC
Soldering Temperature (reflow) ......................................+260NC
WLP
Junction-to-Ambient Thermal Resistance (qJA) ..........84°C/W
ABSOLUTE MAXIMUM RATINGS
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-
layer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional opera-
tion 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.
PACKAGE THERMAL CHARACTERISTICS (Note 1)
ELECTRICAL CHARACTERISTICS
(VCC = 5V, VGND = 0V, VIN- = VIN+ = 1.2V, RPULLUP = 100kI to VCC, TA = -40NC to +85NC. Typical values are at TA = +25NC, unless
otherwise noted.) (Note 2)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
DC CHARACTERISTICS
Input-Referred Hysteresis VHYS (VGND - 0.2V) P VCM P (VCC + 0.2V) (Note 3) 4 6 mV
Input Offset Voltage VOS VGND - 0.2V P VCM P
VCC + 0.2V (Note 4)
TA = +25NC 0.15 5 mV
-40NC P TA P +85NC 10
Input Bias Current IB
TA = +25NC 0.15 nA
TA = -40NC to +85NC 0.2
Output-Voltage Swing Low VOL
VCC = 1.8V,
ISINK = 1mA
TA = +25NC 105 200
mV
-40NC P TA P +85NC 300
VCC = 5V, ISINK = 6mA TA = +25NC 285 350
-40NC P TA P +85NC 450
Input Voltage Range VCM Inferred from VOS test VGND
- 0.2V
VCC
+ 0.2V V
Output Short-Circuit
Current ISC Sinking, VOUT = VCC
VCC = 1.8V 3 mA
VCC = 5V 30
Output Leakage Current ILEAK VCC = 5.5V, VOUT = 5.5V 0.2 nA
����������������������������������������������������������������� Maxim Integrated Products 3
MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
Note 2: All devices are 100% production tested at TA = +25NC. Temperature limits are guaranteed by design.
Note 3: Hysteresis is the input voltage difference between the two switching points.
Note 4: VOS is the average of the positive and negative trip points minus VREF.
Note 5: Overdrive is defined as the voltage above or below the switching points.
ELECTRICAL CHARACTERISTICS (continued)
(VCC = 5V, VGND = 0V, VIN- = VIN+ = 1.2V, RPULLUP = 100kI to VCC, TA = -40NC to +85NC. Typical values are at TA = +25NC, unless
otherwise noted.) (Note 2)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
AC CHARACTERISTICS
Propagation Delay High to
Low (Note 5) tPHL
Input overdrive = Q100mV, VCC = 5V 5
Fs
Input overdrive = Q100mV, VCC = 1.8V 7
Input overdrive = Q20mV, VCC = 5V 8
Input overdrive = Q20mV, VCC = 1.8V 12
Propagation Delay Low to
High (Note 5) tPLH
Input overdrive = Q100mV, VCC = 5V 34
Fs
Input overdrive = Q100mV, VCC = 1.8V 12
Input overdrive = Q20mV, VCC = 5V 35
Input overdrive = Q20mV, VCC = 1.8V 12
Fall Time tFCLOAD = 15pF 0.2 Fs
POWER SUPPLY
Supply Voltage Range VCC Guaranteed from PSRR tests 1.8 5.5 V
Power-Supply Rejection
Ratio PSRR VCC = 1.8V to 5.5V 60 80 dB
Supply Current per
Comparator ICC
VCC = 1.8V, TA = +25NC 0.4 0.75
FAVCC = 5V, TA = +25NC 0.5 0.85
VCC = 5V, -40NC P TA P +85NC 1
Power-Up Time tON 1 ms
����������������������������������������������������������������� Maxim Integrated Products 4
MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
Typical Operating Characteristics
(VCC = 5V, VGND = 0V, VIN- = VIN+ = 1.2V, RPULLUP = 100kΩ to VCC, TA = -40NC to +85NC. Typical values are at TA = +25NC, unless
otherwise noted. All devices are 100% production tested at TA = +25NC. Temperature limits are guaranteed by design.)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX44269 toc01
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (µA)
5.55.04.54.03.53.02.52.0
0.2
0.4
0.6
0.8
1.0
1.2
0
1.5 6.0
VOUT = HIGH
TA = -40°C
TA = +85°C
TA = +25°C
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX44269 toc02
0.2
0.4
0.6
0.8
1.0
1.2
1.4
0
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (µA)
5.55.04.54.03.53.02.52.01.5 6.0
TA = -40°C
TA = +85°C
TA = +25°C
VOUT = LOW
SUPPLY CURRENT vs. TRANSITION
FREQUENCY (VOVERDRIVE = 20mV)
MAX44269 toc03
INPUT FREQUENCY (Hz)
SUPPLY CURRENT (µA)
1k10010
2
4
6
8
10
12
14
0
1 10k
VCC = 5V
VCC = 2.7V
VCC = 1.8V
INPUT OFFSET VOLTAGE
vs. TEMPERATURE
MAX44269 toc04
TEMPERATURE (°C)
INPUT OFFSET VOLTAGE (mV)
806020 400-20
-0.45
-0.40
-0.35
-0.30
-0.25
-0.20
-0.15
-0.10
-0.05
0
-0.50
-40 100
VDD = 2.7V
VDD = 5V
VDD = 1.8V
INPUT BIAS CURRENT
vs. TEMPERATURE
MAX44269 toc05
TEMPERATURE (°C)
INPUT BIAS CURRENT (nA)
806020 400-20
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
0.20
0
-40 100
VDD = 2.7V
VDD = 5V
VDD = 1.8V
INPUT BIAS CURRENT
vs. COMMON-MODE VOLTAGE
MAX44269 toc06
INPUT COMMON-MODE VOLTAGE (V)
INPUT BIAS CURRENT (nA)
542 310
50
100
150
200
250
300
350
400
450
500
0
-1 6
VDD = 2.7V
VDD = 0V
VDD = 1.8V
VDD = 5V
OUTPUT-VOLTAGE LOW
vs. PULLUP RESISTANCE
MAX44269 toc07
PULLUP RESISTANCE (I)
OUTPUT VOLTAGE LOW (VOL - VEE)
10k1k
10
100
1000
10,000
1
100 100k 54321
SHORT-CIRCUIT CURRENT
vs. SUPPLY VOLTAGE
MAX44269 toc08
SHORT-CIRCUIT CURRENT (mA)
5
10
15
20
25
30
35
40
0
SUPPLY VOLTAGE (V)
06
VOUT = LOW
TA = -40°C
TA = +85°C
TA = +25°C
INPUT OFFSET VOLTAGE HISTOGRAM
MAX44269 toc09
INPUT OFFSET VOLTAGE (mV)
OCCURRENCE (%)
2.52.01.0 1.5-1.0 -0.5 0 0.5-1.5
5
10
15
20
25
30
35
40
45
0
-2
����������������������������������������������������������������� Maxim Integrated Products 5
MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
Typical Operating Characteristics (continued)
(VCC = 5V, VGND = 0V, VIN- = VIN+ = 1.2V, RPULLUP = 100kΩ to VCC, TA = -40NC to +85NC. Typical values are at TA = +25NC, unless
otherwise noted. All devices are 100% production tested at TA = +25NC. Temperature limits are guaranteed by design.)
LEAKAGE CURRENT vs. TEMPERATURE
MAX44269 toc10
TEMPERATURE (°C)
OUTPUT LEAKAGE CURRENT (nA)
907030 50-10 10-30
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
0
-50 110
VCC = 5V VCC = 2.7V
VCC = 1.8V
PULLUP RESISTANCE (I)
100k 10M
PROPAGATION DELAY (µs)
1M10k1k
PROPAGATION DELAY
vs. PULLUP RESISTANCE
MAX44269 toc11
20
40
60
80
100
120
0
tPHL
tPLH
PROPAGATION DELAY
vs. CAPACITIVE LOAD
MAX44269 toc12
CAPACITIVE LOAD (pF)
8006004002000 1000
PROPAGATION DELAY (µs)
10
20
30
40
50
60
70
80
90
100
0
tPHL
tPLH
PROPAGATION DELAY vs. TEMPERATURE
(VOVERDRIVE = 100mV, VDD = 5V)
MAX44269 toc13
TEMPERATURE (°C)
PROPAGATION DELAY (µs)
806020 400-20
5
10
15
20
25
30
35
40
45
0
-40 100
tPHL
tPLH
INPUT OVERDRIVE VOLTAGE (mV)
PROPAGATION DELAY (µs)
800600400200
10
20
30
40
50
60
0
0 1000
PROPAGATION DELAY
vs. INPUT OVERDRIVE (tPLH)
MAX44269 toc14
TA = +25°C
TA = -40°C
TA = +85°C
INPUT OVERDRIVE VOLTAGE (mV)
PROPAGATION DELAY (µs)
800600400200
2
4
6
8
10
12
0
0 1000
PROPAGATION DELAY
vs. INPUT OVERDRIVE (tPHL)
MAX44269 toc15
TA = +25°C
TA = -40°C
TA = +85°C
INPUT REFERRED HYSTERESIS
vs. TEMPERATURE
MAX44269 toc16
TEMPERATURE (°C)
INPUT REFERRED HYSTERESIS (mV)
806020 400-20
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
0
-40 100
SMALL-SIGNAL TRANSIENT RESPONSE
(VCC = 1.8V)
MAX44269 toc17
VIN+
20mV/div
VOUT
1V/div
20µs/div
SMALL-SIGNAL TRANSIENT RESPONSE
(VCC = 5V)
MAX44269 toc18
VIN+
20mV/div
VOUT
2V/div
20µs/div
����������������������������������������������������������������� Maxim Integrated Products 6
MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
Typical Operating Characteristics (continued)
(VCC = 5V, VGND = 0V, VIN- = VIN+ = 1.2V, RPULLUP = 100kΩ to VCC, TA = -40NC to +85NC. Typical values are at TA = +25NC, unless
otherwise noted. All devices are 100% production tested at TA = +25NC. Temperature limits are guaranteed by design.)
LARGE-SIGNAL TRANSIENT RESPONSE
(VCC = 1.8V)
MAX44269 toc19
VIN+
100mV/div
VOUT
1V/div
20µs/div
LARGE-SIGNAL TRANSIENT RESPONSE
(VCC = 5V)
MAX44269 toc20
VIN+
200mV/div
VOUT
2V/div
20µs/div
POWER-UP RESPONSE
MAX44269 toc21
VIN
200mV/div
VCC
2V/div
VOUT
2V/div
800µs/div
NO OUTPUT PHASE REVERSAL
MAX44269 toc22
VIN
-0.3V TO +6V
VOUT
20µs/div
����������������������������������������������������������������� Maxim Integrated Products 7
MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
Bump Description
Bump Configuration
PIN NAME FUNCTION
A1 INA- Comparator A Inverting Input
A2 INA+ Comparator A Noninverting Input
A3 OUTA Comparator A Output
B1 GND Negative Supply Voltage. Bypass to GND with a 1.0FF capacitor.
B2 N.C. Not Connected
B3 VCC Positive Supply Voltage. Bypass to GND with a 1.0FF capacitor.
C1 INB- Comparator B Inverting Input
C2 INB+ Comparator B Noninverting Input
C3 OUTB Comparator B Output
WLP
TOP VIEW
MAX44269
1
INA- INA+ OUTA
GND N.C. VCC
+
23
B
C
A
INB- INB+ OUTB
����������������������������������������������������������������� Maxim Integrated Products 8
MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
Detailed Description
The MAX44269 is a general-purpose dual comparator for
battery-powered devices where area, power, and cost
constraints are crucial. The IC can operate with a low
1.8V supply rail typically consuming 0.5µA quiescent cur-
rent per comparator. This makes it ideal for mobile and
very low-power applications. The IC’s common-mode
input voltage range extends 200mV beyond-the-rails. An
internal 4mV hysteresis ensures clean output switching,
even with slow-moving input signals.
Input Stage Structure
The input common-mode voltage range extends from
(VGND - 0.2V) to (VCC + 0.2V). The comparator operates
at any different input voltage within these limits with low
input bias current. Input bias current is typically 0.15nA if
the input voltage is between the supply rails.
The IC features a unique input ESD structure that can
handle voltages from -0.3V to 6V independent of supply
voltage. This allows for the device to be powered down
with a signal still present on the input without damag-
ing the part. This feature is useful in applications where
one of the inputs has transient spikes that exceed the
supply rails.
No Output Phase Reversal
for Overdriven Inputs
The IC’s design is optimized to prevent output phase
reversal if both the inputs are within the input common
mode voltage range. If one of the inputs is outside the
input common-mode voltage range, then output phase
reversal does not occur as long as the other input is
kept within the valid input common-mode voltage range.
This behavior is shown in the No Output Phase Reversal
graph in the Typical Operating Characteristics section.
Open-Drain Output
The IC features an open-drain output, enabling greater
control of speed and power consumption in the circuit
design. The output logic level is also independent from
the input, allowing for simple level translation.
RF Immunity
The IC has very high RF immunity due to on-chip filtering
of RF sensitive nodes. This allows the IC to hold its output
state even in the presence of high amounts of RF noise.
This improved RF immunity makes the IC ideal for mobile
wireless devices.
Applications Information
Hysteresis
Many comparators oscillate in the linear region of opera-
tion 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 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 and the output trips, the hysteresis effectively
causes one comparator input to move quickly past the
other. This takes the input out of the region where oscil-
lation occurs. This provides clean output transitions for
noisy, slow-moving input signals. The IC has an internal
hysteresis of 4mV. Additional hysteresis can be generat-
ed with three resistors using positive feedback (Figure 2).
Figure 1. Threshold Hysteresis Band (Not to Scale)
Figure 2. Adding Hysteresis with External Resistors
THERSHOLDS
IN+
IN-
OUT
VHYST
VTH
VTL
HYSTERESIS BAND
VCC
R2
R3
R1
R4
VIN
VREF
GND
OUT
MAX44269
����������������������������������������������������������������� Maxim Integrated Products 9
MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
Use the following procedure to calculate resistor values.
1) Select R3. Input bias current at IN_+ is less than15nA.
To minimize errors caused by the input bias current,
the current through R3 should be at least 1.5µA.
Current through R3 at the trip point is (VREF - VOUT)/
R3. Considering the two possible output states in solv-
ing for R3 yields two formulas:
R3 = VREF/IR3 and R3 = [(VCC - VREF)/IR3] - R1
Use the smaller of the two resulting resistor values.
For example, for VCC = 5V, IR3 = -1.5µA, R1 = 200kI,
and a VREF = 1.24V, the two resistor values are 827kI
and 1.5MI. Therefore, for R3 choose the standard
value of 825kI.
2) Choose the hysteresis band required (VHB). In this
example, the VHB = 50mV.
3) Calculate R2 according to the following equation:
= +
+
HB
CC REF
V
R2 (R1 R3) x R1) / R 3
(V
V
For this example, insert the value:
50mV
R2 (200k 0.825M ) 9.67k
5.3
= Ω+ Ω = Ω
For this example, choose standard value R2 = 9.76kI.
4) Choose the trip point for VIN rising (VTHR) in such a
way that:
HB
THR REF CC
V
V V1
V
>+
VTHR is the threshold voltage at which the com-
parator switches its output from low to high, as VIN
rises above the trip point. For this example, choose
VTHR = 3V.
5) Calculate R4 as follows:
THR
REF
1
R4 11
V
x R2 R2 R3
V
1
R4 6.93k
3 11
1.24 x 9.76 9.76 825
=
−−
= = Ω
−−
For this example, choose a standard value of 6.98kI.
6) Verify the trip voltages and hysteresis as follows:
THR REF
THF REF
CC
111
xR2
VV R2 R3 R4
111
x R2
VV R2 R1 R3 R4
R2 xV
R1 R3
= ++
= ++
+
−+
The hysteresis network in Figure 2 can be simplified if the
reference voltage is chosen to be at midrail and the trip
points of the comparator are chosen to be symmetrical
about the reference voltage. Use the circuit in Figure 3
if the reference voltage can be designed to be at the
center of the hysteresis band. For the symmetrical case,
follow the same steps outlined in the paragraph above
to calculate the resistor values except that in this case,
resistor R4 approaches infinity (open). So in the previous
example with VREF = 2.5V, if VTHR = 2.525V and VTHF
= 2.475V then using the above formulas, we get R1 =
200kI, R2 = 9.09kI and R3 = 825kI, R4 = not installed.
Jack Detect
The IC can be used to detect peripheral devices
connected to a circuit. This includes a simple jack-
detect scheme for cell phone applications. The Typical
Application Circuit shows how the device can be used in
conjunction with an external reference to detect a remote
key connection and an accessory ID input. The open-
drain output of the devices allows the output logic level
to be controlled independent of the peripheral device’s
load, making interfacing and controlling external devices
as simple as monitoring a few digital inputs on a micro-
controller or codec.
Figure 3. Simplified External Hysteresis Network if VREF is at
the Center of the Hysteresis Band
VCC
R2
R3
R1
VIN
VREF
GND
OUT
MAX44269
���������������������������������������������������������������� Maxim Integrated Products 10
MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
Logic-Level Translator
Due to the open-drain output of the IC, the device can
translate between two different logic levels (Figure 4). If
the internal 4 mV hysteresis is not sufficient, then exter-
nal resistors can be added to increase the hysteresis as
shown in Figure 2 and Figure 3.
Power-On Reset Circuit
The IC can be used to make a power-on reset circuit as
displayed in Figure 5. The positive input provides the
ratiometric reference with respect to the power supply
and is created by a simple resistive divider. Choose
reasonably large values to minimize the power consump-
tion in the resistive divider. The negative input provides
the power-on delay time set by the time constant of the
RC circuit formed by R2 and C1. This simple circuit can
be used to power up the system in a known state after
ensuring that the power supply is stable. Diode D1 pro-
vides a rapid reset in the event of unexpected power loss.
Relaxation Oscillator
The IC can also be used to make a simple relaxation
oscillator (Figure 6). By adding the RC circuit R5 and
C1, a standard Schmidt Trigger circuit referenced to
a set voltage is converted into an astable multivibra-
tor. As shown in Figure 7, IN- is a sawtooth waveform
with capacitor C1 alternately charging and discharging
through resistor R5. The external hysteresis network
formed by R1 to R4 defines the trip voltages as:
T_RISE CC
T_FALL CC
R3 x R4
V
VR2R3 R2R4 R3R4
R4R5(R1 R2 R3)
R1R 3 R 4
V
VR4R5 (R1 R2 R3) R1R3R4
R2(R1R3 R3R5 R1R5)
=
++
++
+
=
++ +
+ ++
Using the basic time domain equations for the charging
and discharging of an RC circuit, the logic-high time,
logic-low time, and frequency can be calculated as:
=
T_FALL
LOW T_RISE
V
R5C1 ln
tV
Figure 6. Relaxation Oscillator
Figure 5. Power-On Reset Circuit
Figure 4. Logic-Level Translator
VCC
R3
R2
R4
R5
R1
GND
OUT
MAX44269
VCC
C1
VCC
VCC
R1
R4
R3 D1 R2
C1
GND
RESET
MAX44269
VCC
VPULL
VIN
VREF
GND
OUT
R1
MAX44269
���������������������������������������������������������������� Maxim Integrated Products 11
MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
Since the comparator’s output is open drain, it goes to
high impedance corresponding to logic-high. So, when
the output is at logic-high, the C1 capacitor charges
through the resistor network formed by R1 to R5 as shown
in Figure 8. An accurate calculation of tHIGH would have
involved applying thevenin’s theorem to compute the
equivalent thevenin voltage (VTHEVENIN) and thevenin
resistance (RTHEVENIN) in series with the capacitor
C1. tHIGH can then be computed using the basic time
domain equations for the charging RC circuit as:
−
=
−
T_RISE
THEVENIN
HIGH THEVENIN T_FALL
THEVENIN
VV
R C1 ln
tVV
[ ]
[ ]
THEVENIN
CC CC
THEVENIN
R (R2 R4) R3 R1 R5
V (R2 R4) R3 V x R4
V(R2 R4) R3 R1 R2 R4
R1
x(R2 R4) R3 R1
= ++
+
= +
++ +
++
The tHIGH calculation can be simplified by selecting the
component values in such a way that R3 >> R1 and R5
>> R1. This ensures that the output of the comparator
goes close to VCC when at logic-high (that is, VTHEVENIN
~ VCC and RTHEVENIN ~ R5). With this selection, tHIGH
can be approximated as:
−
=
−
T_RISE
CC
HIGH T_FALL
CC
VV
R5C1 ln
tVV
The frequency of the relaxation oscillator is:
( )
( )
HIGH LOW CC T_RISE
T_FALL
T_RISE T_FALL
CC
11
fVV
tt V
R 5 C1 1n V
VV
= =
+
−
−
Simple PWM Generation Circuit
A pulse-width modulated (PWM) signal generator can be
made utilizing both comparators in the IC (Figure 9). The
capacitor/feedback resistor combination on INA- deter-
mines the switching frequency and the analog control
voltage determines the pulse width.
Figure 7. Relaxation Oscillator Waveforms Figure 9. PWM Generator
Figure 8. Charging Network Corresponding to Logic-High Output
VCC
VCC
VCC
INA-
C1
GND
R2
OUT
MAX44269
R3
ANALOG
CONTROL
VOLTAGE
R6
R1
R5
R4
VT_RISE
C1 WAVEFORM
OUT
WAVEFORM
VT_FALL
R2
R3 R5
C1
R4
VCC
R1
VCC
RTHEVENIN
VTHEVENIN C1
���������������������������������������������������������������� Maxim Integrated Products 12
MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
Ordering Information
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
Window Detector Circuit
The IC is ideal for window detectors (undervoltage/over-
voltage detectors). Figure 10 shows a window detector
circuit for a single-cell Li+ battery with a 2.9V end-of-life
charge, a peak charge of 4.2V, and a nominal value of
3.6V. Choose different thresholds by changing the values
of R1, R2, and R3. OUTA provides an active-low under-
voltage indication, and OUTB provides an active-low
overvoltage indication. The open-drain outputs of both
the comparators are wired OR to give an active-high
power-good signal.
The design procedure is as follows:
1) Select R1. The input bias current into INB- is less than
15nA, so the current through R1 should exceed 1.5µA
for the thresholds to be accurate. In this example,
choose R1 = 825kI (1.24V/1.5µA).
2) Calculate R2 + R3. The overvoltage threshold should
be 4.2V when VIN is rising. The design equation is as
follows:
OTH
REF
V
R2 R3 R1 x 1
V
4.2
825 x 1
1.24
=1969k
+= −
= −
Ω
3) Calculate R2. The undervoltage threshold should be
2.9V when VIN is falling. The design equation is as
follows:
( ) ( )
( )
REF
UTH
V
R2 (R1 R2 R3)x R1
V
825 1969 x 1.24 / 2.9 825
370k
=++ −
=+−
= Ω
For this example, choose a 374kI standard value 1%
resistor.
4) Calculate R3:
R3 (R2 R3) R2
1969k 374k
=1.595M
=+−
= Ω− Ω
Ω
For this example, choose a 1.58MI standard value 1%
resistor.
Board Layout and Bypassing
Use 1.0FF bypass capacitors from VCC to GND. To maxi-
mize performance, minimize stray inductance by putting
this capacitor close to the VCC pin and reducing trace
lengths.
Figure 10. Window Detector Circuit
Chip Information
PROCESS: BiCMOS
PART TEMP RANGE PIN-
PACKAGE
TOP
MARK
MAX44269EWL+T -40NC to +85NC9 WLP +AJL
VCC
5V
VIN
INB+
INA+
VOTH = 4.2V
VUTH = 2.9V
INA-
INB-
GND
R1
R2
R3
GND
OUTB
OUTA POWER
GOOD
MAX44269
REF
1.24V
���������������������������������������������������������������� Maxim Integrated Products 13
MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
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.
PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO.
9 WLP W91B1-6 21-0430 Refer to Application Note 1891
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 14
© 2011 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 9/11 Initial release —
1 12/11 Revised Electrical Characteristics, Typical Operating Characteristics, and Figure 5. 3, 5, 6, 9, 10
