MAX44269EWL+T [MAXIM]
Comparator, 2 Func, 10000uV Offset-Max, 39000ns Response Time, BICMOS, PBGA9, 1.30 X 1.30 MM, 0.40 MM PITCH, ROHS COMPLIANT, WLP-9;
| 型号： | MAX44269EWL+T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Comparator, 2 Func, 10000uV Offset-Max, 39000ns Response Time, BICMOS, PBGA9, 1.30 X 1.30 MM, 0.40 MM PITCH, ROHS COMPLIANT, WLP-9 放大器 信息通信管理 |
| 文件： | 总14页 (文件大小：2289K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-5986; Rev 1; 12/11
E V A L U A T I O N K I T A V A I L A B L E
General Description
Features
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.
S Ultra-Low Power Consumption
0.5µA per Comparator
S Ultra-Small 1.3mm x 1.3mm WLP Package
S Guaranteed Operation Down to V = 1.8V
CC
S Input Common-Mode Voltage Range Extends
200mV Beyond-the-Rails
S 6V Tolerant Inputs Independent of Supply
S Open-Drain Outputs
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.
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
Ordering Information appears at end of data sheet.
Applications
Smartphones
Notebooks
For related parts and recommended products to use with this part,
refer to www.maxim-ic.com/MAX44269.related.
Two-Cell Battery-Powered Devices
Battery-Operated Sensors
Ultra-Low-Power Systems
Portable Medical Mobile Accessories
Typical Application Circuit
V
CC
V
CC
V
PULL
MAX44269
V
CC
OUT1
OUT2
V
REF
V
PULL
V
CC
REMOTE KEY
CONNECTOR
GND
ACCESSORY ID
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1
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.
MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
ABSOLUTE MAXIMUM RATINGS
CC
INA+, INA-, INB+, INB- to GND..............................-0.3V to +6V
Continuous Input Current into Any Pin............................ Q20mA
Maximum Power Dissipation
V
to GND.............................................................-0.3V to +6V
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
(derate 11.9mW/NC at T = +70NC) ............................952mW
A
Output Voltage to GND (OUT_) ..............................-0.3V to +6V
Output Current (OUT_).................................................... Q50mA
PACKAGE THERMAL CHARACTERISTICS (Note 1)
WLP
Junction-to-Ambient Thermal Resistance (q ) ..........84°C/W
JA
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.
ELECTRICAL CHARACTERISTICS
(V
= 5V, V
= 0V, V = V
= 1.2V, R
= 100kIto V , T = -40NC to +85NC. Typical values are at T = +25NC, unless
CC
GND
IN-
IN+
PULLUP CC A A
otherwise noted.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
P(V + 0.2V) (Note 3)
MIN
TYP
MAX
UNITS
DC CHARACTERISTICS
Input-Referred Hysteresis
V
(V
- 0.2V) PV
4
6
5
mV
mV
HYS
GND
CM
CC
T
= +25NC
0.15
V
V
- 0.2V PV
P
A
GND
CM
Input Offset Voltage
Input Bias Current
V
OS
+ 0.2V (Note 4)
-40NC PT P+85NC
10
CC
A
T
T
= +25NC
0.15
0.2
A
I
nA
mV
V
B
= -40NC to +85NC
= 1.8V,
A
T
= +25NC
105
200
300
350
450
V
I
A
CC
= 1mA
-40NC PT P+85NC
SINK
A
Output-Voltage Swing Low
Input Voltage Range
V
OL
T
= +25NC
285
A
V
= 5V, I
= 6mA
CC
SINK
-40NC PT P+85NC
A
V
V
CC
+ 0.2V
GND
V
Inferred from V
test
CM
OS
- 0.2V
V
V
= 1.8V
= 5V
3
Output Short-Circuit
Current
CC
I
Sinking, V
= V
mA
nA
SC
OUT
CC
30
0.2
CC
Output Leakage Current
I
V
= 5.5V, V
= 5.5V
LEAK
CC
OUT
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2
MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
ELECTRICAL CHARACTERISTICS (continued)
(V
= 5V, V
= 0V, V = V
= 1.2V, R
= 100kIto V , T = -40NC to +85NC. Typical values are at T = +25NC, unless
CC
GND
IN-
IN+
PULLUP CC A A
otherwise noted.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
AC CHARACTERISTICS
Input overdrive = Q100mV, V
Input overdrive = Q100mV, V
= 5V
5
7
CC
= 1.8V
Propagation Delay High to
Low (Note 5)
CC
t
t
Fs
PHL
PLH
Input overdrive = Q20mV, V
Input overdrive = Q20mV, V
= 5V
8
CC
= 1.8V
12
34
12
35
12
0.2
CC
Input overdrive = Q100mV, V
Input overdrive = Q100mV, V
= 5V
CC
= 1.8V
Propagation Delay Low to
High (Note 5)
CC
Fs
Fs
Input overdrive = Q20mV, V
Input overdrive = Q20mV, V
= 5V
CC
= 1.8V
CC
Fall Time
t
C
= 15pF
F
LOAD
POWER SUPPLY
Supply Voltage Range
V
Guaranteed from PSRR tests
1.8
60
5.5
V
CC
Power-Supply Rejection
Ratio
PSRR
V
= 1.8V to 5.5V
80
dB
CC
V
V
V
= 1.8V, T = +25NC
0.4
0.5
0.75
0.85
1
CC
CC
CC
A
Supply Current per
Comparator
I
= 5V, T = +25NC
FA
CC
A
= 5V, -40NC PT P+85NC
A
Power-Up Time
t
1
ms
ON
Note 2: All devices are 100% production tested at T = +25NC. Temperature limits are guaranteed by design.
A
Note 3: Hysteresis is the input voltage difference between the two switching points.
Note 4: V
is the average of the positive and negative trip points minus V
.
OS
REF
Note 5: Overdrive is defined as the voltage above or below the switching points.
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3
MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
Typical Operating Characteristics
(V
= 5V, V
= 0V, V = V
= 1.2V, R
= 100kΩ to V , T = -40NC to +85NC. Typical values are at T = +25NC, unless
PULLUP CC A A
CC
GND
IN-
IN+
otherwise noted. All devices are 100% production tested at T = +25NC. Temperature limits are guaranteed by design.)
A
SUPPLY CURRENT vs. TRANSITION
SUPPLY CURRENT vs. SUPPLY VOLTAGE
SUPPLY CURRENT vs. SUPPLY VOLTAGE
FREQUENCY (V
= 20mV)
OVERDRIVE
1.2
1.0
0.8
0.6
0.4
0.2
0
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
14
12
10
8
T = +85°C
A
T = +85°C
A
V
= 5V
CC
6
T = +25°C
A
T = -40°C
A
T = +25°C
A
T = -40°C
A
V
= 2.7V
CC
4
V
= 1.8V
CC
2
V
= HIGH
V
= LOW
OUT
OUT
0
1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
SUPPLY VOLTAGE (V)
1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
SUPPLY VOLTAGE (V)
1
10
100
1k
10k
INPUT FREQUENCY (Hz)
INPUT OFFSET VOLTAGE
vs. TEMPERATURE
INPUT BIAS CURRENT
vs. TEMPERATURE
INPUT BIAS CURRENT
vs. COMMON-MODE VOLTAGE
0
-0.05
-0.10
-0.15
-0.20
-0.25
-0.30
-0.35
-0.40
-0.45
-0.50
0.20
0.18
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0
500
450
400
350
300
250
200
150
100
50
V
= 5V
DD
V
= 5V
DD
V
= 1.8V
DD
V
= 2.7V
DD
V
= 2.7V
DD
V
= 5V
DD
V
= 2.7V
DD
V
= 1.8V
DD
V
= 0V
1
DD
V
= 1.8V
60
DD
0
-40 -20
0
20
40
80 100
-40 -20
0
20
40
60
80 100
-1
0
2
3
4
5
6
TEMPERATURE (°C)
TEMPERATURE (°C)
INPUT COMMON-MODE VOLTAGE (V)
OUTPUT-VOLTAGE LOW
vs. PULLUP RESISTANCE
SHORT-CIRCUIT CURRENT
vs. SUPPLY VOLTAGE
INPUT OFFSET VOLTAGE HISTOGRAM
10,000
1000
100
10
40
35
30
25
20
15
10
5
45
40
35
30
25
20
15
10
5
V
= LOW
OUT
T
A
= -40°C
T
A
= +25°C
T
= +85°C
A
1
0
0
100
1k
10k
100k
0
1
2
3
4
5
6
-2 -1.5 -1.0 -0.5
0
0.5 1.0 1.5 2.0 2.5
PULLUP RESISTANCE (I)
SUPPLY VOLTAGE (V)
INPUT OFFSET VOLTAGE (mV)
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4
MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
Typical Operating Characteristics (continued)
(V
= 5V, V
= 0V, V = V
= 1.2V, R
= 100kΩ to V , T = -40NC to +85NC. Typical values are at T = +25NC, unless
PULLUP CC A A
CC
GND
IN-
IN+
otherwise noted. All devices are 100% production tested at T = +25NC. Temperature limits are guaranteed by design.)
A
PROPAGATION DELAY
vs. CAPACITIVE LOAD
PROPAGATION DELAY
vs. PULLUP RESISTANCE
LEAKAGE CURRENT vs. TEMPERATURE
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0
100
90
80
70
60
50
40
30
20
10
0
120
100
80
60
40
20
0
t
PLH
t
PLH
V
= 5V
CC
V
CC
= 2.7V
t
PHL
t
PHL
1M
V
= 1.8V
CC
-50 -30 -10 10 30 50 70 90 110
TEMPERATURE (°C)
1k
10k
100k
10M
0
200
400
600
800
1000
PULLUP RESISTANCE (I)
CAPACITIVE LOAD (pF)
PROPAGATION DELAY
PROPAGATION DELAY
PROPAGATION DELAY vs. TEMPERATURE
vs. INPUT OVERDRIVE (t
)
vs. INPUT OVERDRIVE (t
)
(V
= 100mV, V = 5V)
PLH
PHL
OVERDRIVE
DD
60
50
40
30
20
10
0
12
10
8
45
40
35
30
25
20
15
10
5
T
= +25°C
A
T
= -40°C
A
T
A
= -40°C
t
PLH
6
T
A
= +25°C
T
= +85°C
A
4
t
PHL
2
T
A
= +85°C
0
0
0
200
400
600
800
1000
0
200
400
600
800
1000
-40 -20
0
20
40
60
80 100
INPUT OVERDRIVE VOLTAGE (mV)
INPUT OVERDRIVE VOLTAGE (mV)
TEMPERATURE (°C)
INPUT REFERRED HYSTERESIS
vs. TEMPERATURE
SMALL-SIGNAL TRANSIENT RESPONSE
SMALL-SIGNAL TRANSIENT RESPONSE
(V = 1.8V)
(V = 5V)
CC
CC
MAX44269 toc17
MAX44269 toc18
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
V
IN+
20mV/div
V
IN+
20mV/div
V
OUT
1V/div
V
OUT
2V/div
-40 -20
0
20
40
60
80 100
20µs/div
20µs/div
TEMPERATURE (°C)
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5
MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
Typical Operating Characteristics (continued)
(V
= 5V, V
= 0V, V = V
= 1.2V, R
= 100kΩ to V , T = -40NC to +85NC. Typical values are at T = +25NC, unless
PULLUP CC A A
CC
GND
IN-
IN+
otherwise noted. All devices are 100% production tested at T = +25NC. Temperature limits are guaranteed by design.)
A
LARGE-SIGNAL TRANSIENT RESPONSE
LARGE-SIGNAL TRANSIENT RESPONSE
(V = 5V)
(V = 1.8V)
CC
CC
MAX44269 toc20
MAX44269 toc19
V
V
IN+
IN+
100mV/div
200mV/div
V
V
OUT
OUT
2V/div
1V/div
20µs/div
20µs/div
NO OUTPUT PHASE REVERSAL
POWER-UP RESPONSE
MAX44269 toc22
MAX44269 toc21
V
IN
200mV/div
V
IN
-0.3V TO +6V
V
CC
2V/div
V
OUT
V
OUT
2V/div
20µs/div
800µs/div
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6
MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
Bump Configuration
TOP VIEW
MAX44269
1
2
3
+
INA-
INA+
OUTA
A
B
C
GND
INB-
N.C.
V
CC
INB+
OUTB
WLP
Bump Description
PIN
A1
A2
A3
B1
B2
B3
C1
C2
C3
NAME
INA-
FUNCTION
Comparator A Inverting Input
INA+
OUTA
GND
N.C.
Comparator A Noninverting Input
Comparator A Output
Negative Supply Voltage. Bypass to GND with a 1.0FF capacitor.
Not Connected
V
Positive Supply Voltage. Bypass to GND with a 1.0FF capacitor.
Comparator B Inverting Input
CC
INB-
INB+
OUTB
Comparator B Noninverting Input
Comparator B Output
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7
MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
Detailed Description
Applications Information
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.
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).
Input Stage Structure
The input common-mode voltage range extends from
(V
GND
- 0.2V) to (V
+ 0.2V). The comparator operates
CC
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.
THERSHOLDS
IN+
V
TH
HYSTERESIS BAND
IN-
V
V
HYST
TL
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.
OUT
Figure 1. Threshold Hysteresis Band (Not to Scale)
V
CC
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.
R3
R1
MAX44269
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.
R2
V
IN
OUT
R4
V
REF
GND
Figure 2. Adding Hysteresis with External Resistors
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8
MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
Use the following procedure to calculate resistor values.
6) Verify the trip voltages and hysteresis as follows:
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.
1
R2
1
R3
1
R4
=
xR2
+
+
V
V
REF
THR
1
R2
1
1
Current through R3 at the trip point is (V
- V
)/
OUT
REF
=
x R2
+
+
V
V
REF
THF
R3. Considering the two possible output states in solv-
ing for R3 yields two formulas:
R1+ R3 R4
R2
R1+ R3
−
x
V
CC
R3 = V
/IR3 and R3 = [(V
- V )/IR3] - R1
REF
REF
CC
Use the smaller of the two resulting resistor values.
For example, for V = 5V, IR3 = -1.5µA, R1 = 200kI,
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
CC
and a V
= 1.24V, the two resistor values are 827kI
REF
and 1.5MI. Therefore, for R3 choose the standard
value of 825kI.
2) Choose the hysteresis band required (V ). In this
HB
example, the V
= 50mV.
HB
3) Calculate R2 according to the following equation:
example with V
= 2.475V then using the above formulas, we get R1 =
200kI, R2 = 9.09kIand R3 = 825kI, R4 = not installed.
= 2.5V, if V
= 2.525V and V
REF
THR THF
V
HB
x R1) / R3
R2 = (R1+ R3)
+
(V
V
CC
REF
For this example, insert the value:
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.
50mV
R2 = (200kΩ + 0.825MΩ)
= 9.67kΩ
5.3
For this example, choose standard value R2 = 9.76kI.
4) Choose the trip point for V rising (V
IN
) in such a
THR
way that:
V
HB
V
> V
1+
THR
REF
V
CC
V
is the threshold voltage at which the com-
THR
parator switches its output from low to high, as V
IN
rises above the trip point. For this example, choose
= 3V.
V
CC
V
THR
R3
5) Calculate R4 as follows:
1
R4 =
R1
1
R2
1
R3
MAX44269
V
THR
x R2
−
−
R2
V
REF
V
IN
1
OUT
R4 =
= 6.93kΩ
3
1
9.76
1
825
V
REF
−
−
1.24x 9.76
GND
For this example, choose a standard value of 6.98kI.
Figure 3. Simplified External Hysteresis Network if V
the Center of the Hysteresis Band
is at
REF
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9
MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
Logic-Level Translator
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:
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.
R3x R4
R2R3 + R2R4 + R3R4
= V
V
T_RISE
CC
R4R5(R1+ R2 + R3)
+R1R 3R 4
R4R5(R1+ R2 + R3) + R1R3R4
+R2(R1R3 + R3R5 + R1R5)
= V
V
T_FALL
CC
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:
V
CC
V
PULL
MAX44269
V
IN
V
T_FALL
R1
= R5C1 ln
t
LOW
V
T_RISE
OUT
V
REF
V
CC
GND
R3
V
CC
Figure 4. Logic-Level Translator
R1
R2
R4
MAX44269
V
CC
V
CC
OUT
D1
R2
R3
MAX44269
R1
GND
R5
RESET
C1
C1
R4
GND
Figure 6. Relaxation Oscillator
Figure 5. Power-On Reset Circuit
���������������������������������������������������������������� Maxim Integrated Products 10
MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
Since the comparator’s output is open drain, it goes to
The frequency of the relaxation oscillator is:
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
1
1
f =
=
+
t
t
V
− V
(
)
)
HIGH LOW
V
CC
T_RISE
T_FALL
R5C11n
in Figure 8. An accurate calculation of t
would have
HIGH
V
−
V
(
V
T_RISE
CC
T_FALL
involved applying thevenin’s theorem to compute the
equivalent thevenin voltage (V ) and thevenin
THEVENIN
Simple PWM Generation Circuit
resistance (R
) in series with the capacitor
THEVENIN
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.
C1. t
can then be computed using the basic time
domain equations for the charging RC circuit as:
HIGH
V
V
−
−
V
THEVENIN
T_RISE
= R
C1 ln
THEVENIN
t
HIGH
V
THEVENIN
T_FALL
R
= (R2 R4) + R3 R1+ R5
[
]
THEVENIN
V
V
CC
CC
R2
R4
R1
V
(R2 R4) + R3
]
+
[
V
xR4
CC
CC
R
R3
R5
THEVENIN
V
=
THEVENIN
(R2 R4) + R3 + R1
R1
(R2 R4) + R3 + R1
R2 + R4
V
C1
C1
THEVENIN
x
The t
calculation can be simplified by selecting the
HIGH
component values in such a way that R3 >> R1 and R5
>> R1. This ensures that the output of the comparator
Figure 8. Charging Network Corresponding to Logic-High Output
goes close to V
when at logic-high (that is, V
CC
THEVENIN
~ V
and R
~ R5). With this selection, t
CC
THEVENIN HIGH
R4
can be approximated as:
V
CC
V
CC
V
V
−
−
V
CC
T_RISE
= R5C1 ln
t
HIGH
R2
R3
V
CC
T_FALL
R1
INA-
R5
V
T_FALL
C1 WAVEFORM
C1
V
T_RISE
V
CC
MAX44269
ANALOG
CONTROL
VOLTAGE
R6
OUT
OUT
WAVEFORM
GND
Figure 7. Relaxation Oscillator Waveforms
Figure 9. PWM Generator
���������������������������������������������������������������� Maxim Integrated Products 11
MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
Window Detector Circuit
Board Layout and Bypassing
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.
Use 1.0FF bypass capacitors from V to GND. To maxi-
CC
mize performance, minimize stray inductance by putting
this capacitor close to the V
lengths.
pin and reducing trace
CC
5V
V
V
= 4.2V
= 2.9V
OTH
UTH
V
IN
V
CC
R3
R2
MAX44269
INA+
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).
OUTA
OUTB
POWER
GOOD
INA-
INB+
2) Calculate R2 + R3. The overvoltage threshold should
be 4.2V when V is rising. The design equation is as
IN
REF
1.24V
follows:
INB-
GND
V
OTH
R2 + R3 = R1 x
−1
R1
V
GND
REF
4.2
1.24
= 825 x
−1
Figure 10. Window Detector Circuit
=1969kΩ
3) Calculate R2. The undervoltage threshold should be
Chip Information
2.9V when V is falling. The design equation is as
IN
follows:
PROCESS: BiCMOS
V
REF
R2 = (R1+ R2 + R3)x
− R1
V
UTH
Ordering Information
= 825 + 1969 x 1.24 / 2.9 − 825
(
)
(
)
)
(
PIN-
TOP
= 370kΩ
PART
TEMP RANGE
PACKAGE
MARK
For this example, choose a 374kIstandard value 1%
MAX44269EWL+T -40NC to +85NC
9 WLP
+AJL
resistor.
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
4) Calculate R3:
R3 = (R2 + R3) − R2
= 1969kΩ − 374kΩ
=1.595MΩ
For this example, choose a 1.58MI standard value 1%
resistor.
���������������������������������������������������������������� Maxim Integrated Products 12
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.
21-0430
LAND PATTERN NO.
9 WLP
W91B1-6
Refer to Application Note 1891
���������������������������������������������������������������� Maxim Integrated Products 13
MAX44269
1.3mm x 1.3mm, Low-Power
Dual Comparator
Revision History
REVISION REVISION
PAGES
DESCRIPTION
CHANGED
NUMBER
DATE
0
1
9/11
Initial release
Revised Electrical Characteristics, Typical Operating Characteristics, and Figure 5.
—
12/11
3, 5, 6, 9, 10
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.
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