MAXIM MAX44269 Technical data

EVALUATION KIT AVAILABLE

19-5986; Rev 1; 12/11

MAX44269

1.3mm x 1.3mm, Low-Power Dual Comparator

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 structure and a unique output stage that limits supply current surges while switching. This design also minimizes overall 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

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.

Typical Application Circuit

V

CC

V

CC

V

CC

V

REF

V

CC

REMOTE KEY

CONNECTOR

ACCESSORY ID

�� Maxim Integrated Products 1

MAX44269

OUT1

OUT2

GND

V

PULL

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

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

PACKAGE THERMAL CHARACTERISTICS (Note 1)

WLP

Junction-to-Ambient Thermal Resistance (qJA) ..........84°C/W

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 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.

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

ELECTRICAL CHARACTERISTICS

(VCC = 5V, V otherwise noted.) (Note 2)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

DC CHARACTERISTICS

Input-Referred Hysteresis V

Input Offset Voltage V

Input Bias Current I

Output-Voltage Swing Low V

Input Voltage Range V

Output Short-Circuit Current

Output Leakage Current I

GND

= 0V, V

IN-

= V

IN+

HYS

I

SC

LEAK

= 1.2V, R

OS

B

OL

CM

= 100kI to VCC, TA = -40NC to +85NC. Typical values are at TA = +25NC, unless

PULLUP

(V

- 0.2V) P VCM P (VCC + 0.2V) (Note 3) 4 6 mV

GND

V

- 0.2V P VCM P

GND

VCC + 0.2V (Note 4)

TA = +25NC 0.15 TA = -40NC to +85NC 0.2

VCC = 1.8V, I

= 1mA

SINK

VCC = 5V, I

Inferred from VOS test

Sinking, V

VCC = 5.5V, V

SINK

OUT

= 6mA

= V

CC

= 5.5V 0.2 nA

OUT

TA = +25NC 0.15 5

-40NC P TA P +85NC 10

TA = +25NC 105 200

-40NC P TA P +85NC 300 TA = +25NC 285 350

-40NC P TA P +85NC 450

V

GND

- 0.2V

VCC = 1.8V 3 VCC = 5V 30

V

CC

+ 0.2V

mV

nA

mV

V

mA

�� Maxim Integrated Products 2

MAX44269

1.3mm x 1.3mm, Low-Power Dual Comparator

ELECTRICAL CHARACTERISTICS (continued)

(VCC = 5V, V otherwise noted.) (Note 2)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

AC CHARACTERISTICS

Propagation Delay High to Low (Note 5)

Propagation Delay Low to High (Note 5)

Fall Time t

POWER SUPPLY

Supply Voltage Range V

Power-Supply Rejection Ratio

Supply Current per Comparator

Power-Up Time t

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 V Note 5: Overdrive is defined as the voltage above or below the switching points.

GND

= 0V, V

IN-

= V

= 1.2V, R

IN+

Input overdrive = Q100mV, VCC = 5V 5

t

PHL

t

PLH

F

CC

PSRR VCC = 1.8V to 5.5V 60 80 dB

I

CC

ON

Input overdrive = Q100mV, VCC = 1.8V 7 Input overdrive = Q20mV, VCC = 5V 8 Input overdrive = Q20mV, VCC = 1.8V 12 Input overdrive = Q100mV, VCC = 5V 34 Input overdrive = Q100mV, VCC = 1.8V 12 Input overdrive = Q20mV, VCC = 5V 35 Input overdrive = Q20mV, VCC = 1.8V 12 C

Guaranteed from PSRR tests 1.8 5.5 V

VCC = 1.8V, TA = +25NC 0.4 0.75

VCC = 5V, -40NC P TA P +85NC 1

= 100kI to VCC, TA = -40NC to +85NC. Typical values are at TA = +25NC, unless

PULLUP

= 15pF 0.2 Fs

LOAD

1 ms

.

REF

Fs

FAVCC = 5V, TA = +25NC 0.5 0.85

�� Maxim Integrated Products 3

MAX44269

06

1.3mm x 1.3mm, Low-Power Dual Comparator

Typical Operating Characteristics

(VCC = 5V, V

GND

= 0V, V

IN-

= V

= 1.2V, R

IN+

= 100kΩ to VCC, TA = -40NC to +85NC. Typical values are at TA = +25NC, unless

PULLUP

otherwise noted. All devices are 100% production tested at TA = +25NC. Temperature limits are guaranteed by design.)

SUPPLY CURRENT vs. TRANSITION

SUPPLY CURRENT vs. SUPPLY VOLTAGE

1.2

1.0

0.8

0.6

0.4

SUPPLY CURRENT (µA)

0.2

0

1.5 6.0

V

= HIGH

OUT

TA = +85°C

TA = +25°C

SUPPLY VOLTAGE (V)

TA = -40°C

MAX44269 toc01

5.55.04.54.03.53.02.52.0

INPUT OFFSET VOLTAGE

vs. TEMPERATURE

0

-0.05

-0.10

-0.15

-0.20

-0.25

-0.30

VDD = 2.7V

-0.35

INPUT OFFSET VOLTAGE (mV)

-0.40

-0.45

-0.50

-40 100

VDD = 5V

VDD = 1.8V

TEMPERATURE (°C)

MAX44269 toc04

806020 400-20

OUTPUT-VOLTAGE LOW

vs. PULLUP RESISTANCE

10,000

)

EE

- V

1000

OL

100

10

OUTPUT VOLTAGE LOW (V

1

100 100k 54321

PULLUP RESISTANCE (I)

10k1k

MAX44269 toc07

SUPPLY CURRENT vs. SUPPLY VOLTAGE

1.4

V

= LOW

OUT

TA = +85°C

TA = +25°C

SUPPLY VOLTAGE (V)

TA = -40°C

1.2

1.0

0.8

0.6

SUPPLY CURRENT (µA)

0.4

0.2

0

INPUT BIAS CURRENT

vs. TEMPERATURE

0.20

0.18

0.16

0.14

0.12

0.10

VDD = 2.7V

0.08

0.06

INPUT BIAS CURRENT (nA)

0.04

0.02

0

-40 100

VDD = 5V

VDD = 1.8V

TEMPERATURE (°C)

SHORT-CIRCUIT CURRENT

vs. SUPPLY VOLTAGE

40

V

35

30

25

20

15

10

SHORT-CIRCUIT CURRENT (mA)

= LOW

OUT

5

0

TA = -40°C

TA = +25°C

TA = +85°C

SUPPLY VOLTAGE (V)

5.55.04.54.03.53.02.52.01.5 6.0

806020 400-20

14

12

MAX44269 toc02

10

8

6

SUPPLY CURRENT (µA)

4

2

0

1 10k

500

450

MAX44269 toc05

400

350

300

250

200

150

INPUT BIAS CURRENT (nA)

100

50

0

-1 6

45

40

MAX44269 toc08

35

30

25

20

OCCURRENCE (%)

15

10

5

0

FREQUENCY (V

OVERDRIVE

VCC = 1.8V

INPUT FREQUENCY (Hz)

INPUT BIAS CURRENT

vs. COMMON-MODE VOLTAGE

VDD = 2.7V

VDD = 5V

VDD = 0V

INPUT COMMON-MODE VOLTAGE (V)

INPUT OFFSET VOLTAGE HISTOGRAM

-2 INPUT OFFSET VOLTAGE (mV)

= 20mV)

VCC = 5V

VCC = 2.7V

1k10010

VDD = 1.8V

MAX44269 toc03

MAX44269 toc06

542 310

MAX44269 toc09

2.52.01.0 1.5-1.0 -0.5 0 0.5-1.5

�� Maxim Integrated Products 4

MAX44269

1.3mm x 1.3mm, Low-Power Dual Comparator

Typical Operating Characteristics (continued)

(VCC = 5V, V

GND

= 0V, V

IN-

= V

= 1.2V, R

IN+

= 100kΩ to VCC, TA = -40NC to +85NC. Typical values are at TA = +25NC, unless

PULLUP

otherwise noted. All devices are 100% production tested at TA = +25NC. Temperature limits are guaranteed by design.)

LEAKAGE CURRENT vs. TEMPERATURE

0.50

0.45

0.40

0.35

0.30

0.25

VCC = 5V

0.20

0.15

0.10

OUTPUT LEAKAGE CURRENT (nA)

0.05

0

-50 110

VCC = 2.7V

TEMPERATURE (°C)

PROPAGATION DELAY vs. TEMPERATURE

(V

OVERDRIVE

45

40

35

30

25

20

15

PROPAGATION DELAY (µs)

10

5

0

-40 100

= 100mV, VDD = 5V)

t

PLH

t

PHL

TEMPERATURE (°C)

INPUT REFERRED HYSTERESIS

vs. TEMPERATURE

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

INPUT REFERRED HYSTERESIS (mV)

0.5

0

-40 100 TEMPERATURE (°C)

VCC = 1.8V

907030 50-10 10-30

806020 400-20

120

100

MAX44269 toc10

80

60

40

PROPAGATION DELAY (µs)

20

0

60

50

MAX44269 toc13

40

30

20

PROPAGATION DELAY (µs)

10

0

0 1000

MAX44269 toc16

V

IN+

20mV/div

V

OUT

1V/div

PROPAGATION DELAY

vs. PULLUP RESISTANCE

t

PLH

t

PHL

100k

PULLUP RESISTANCE (I)

1M10k1k

PROPAGATION DELAY

vs. INPUT OVERDRIVE (t

TA = -40°C

INPUT OVERDRIVE VOLTAGE (mV)

PLH

TA = +25°C

TA = +85°C

800600400200

)

SMALL-SIGNAL TRANSIENT RESPONSE

= 1.8V)

(V

CC

20µs/div

MAX44269 toc17

MAX44269 toc11

PROPAGATION DELAY (µs)

10M

MAX44269 toc14

PROPAGATION DELAY (µs)

20mV/div

100

90

80

70

60

50

40

30

20

10

12

10

V

OUT

2V/div

0

8

6

4

2

0

IN+

PROPAGATION DELAY vs. CAPACITIVE LOAD

t

PLH

CAPACITIVE LOAD (pF)

PROPAGATION DELAY

vs. INPUT OVERDRIVE (t

TA = -40°C

TA = +85°C

0 1000

INPUT OVERDRIVE VOLTAGE (mV)

SMALL-SIGNAL TRANSIENT RESPONSE

= 5V)

(V

CC

20µs/div

t

PHL

8006004002000 1000

PHL

TA = +25°C

800600400200

MAX44269 toc12

)

MAX44269 toc15

MAX44269 toc18

�� Maxim Integrated Products 5

MAX44269

1.3mm x 1.3mm, Low-Power Dual Comparator

Typical Operating Characteristics (continued)

(VCC = 5V, V

GND

= 0V, V

IN-

= V

= 1.2V, R

IN+

= 100kΩ to VCC, TA = -40NC to +85NC. Typical values are at TA = +25NC, unless

PULLUP

otherwise noted. All devices are 100% production tested at TA = +25NC. Temperature limits are guaranteed by design.)

LARGE-SIGNAL TRANSIENT RESPONSE

= 5V)

(V

CC

V

IN+

V

OUT

2V/div

20µs/div

NO OUTPUT PHASE REVERSAL

V

IN

MAX44269 toc20

MAX44269 toc22

V

100mV/div

V

1V/div

V

200mV/div

V

2V/div

LARGE-SIGNAL TRANSIENT RESPONSE

= 1.8V)

(V

CC

IN+

OUT

20µs/div

POWER-UP RESPONSE

IN

CC

MAX44269 toc19

200mV/div

MAX44269 toc21

-0.3V TO +6V

V

OUT

2V/div

800µs/div

OUT

20µs/div

�� Maxim Integrated Products 6

TOP VIEW

MAX44269

1.3mm x 1.3mm, Low-Power Dual Comparator

Bump Configuration

MAX44269

1

+

INA- INA+ OUTA

A

B

GND N.C. V

C

INB- INB+ OUTB

23

CC

WLP

PIN NAME FUNCTION

A1 INA- Comparator A Inverting Input A2 INA+ Comparator A Noninverting Input A3 OUTA Comparator A Output B1 GND B2 N.C. Not Connected

B3 V C1 INB- Comparator B Inverting Input C2 INB+ Comparator B Noninverting Input C3 OUTB Comparator B Output

CC

Negative Supply Voltage. Bypass to GND with a 1.0FF capacitor.

Positive Supply Voltage. Bypass to GND with a 1.0FF capacitor.

Bump Description

�� Maxim Integrated Products 7

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 current 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 (V

- 0.2V) to (VCC + 0.2V). The comparator operates

GND

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 damaging 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 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 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 oscillation occurs. This provides clean output transitions for noisy, slow-moving input signals. The IC has an internal hysteresis of 4mV. Additional hysteresis can be generated with three resistors using positive feedback (Figure 2).

IN+

IN-

V

HYST

OUT

Figure 1. Threshold Hysteresis Band (Not to Scale)

R2

V

IN

R4

THERSHOLDS

HYSTERESIS BAND

R3

V

REF

V

CC

MAX44269

GND

OUT

V

TH

V

TL

R1

Figure 2. Adding Hysteresis with External Resistors

�� Maxim Integrated Products 8

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 (V

REF

- V

OUT

)/ R3. Considering the two possible output states in solving for R3 yields two formulas:

R3 = V

/IR3 and R3 = [(VCC - V

REF

)/IR3] - R1

REF

Use the smaller of the two resulting resistor values.

For example, for VCC = 5V, IR3 = -1.5µA, R1 = 200kI, 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 (VHB). In this example, the VHB = 50mV.

3) Calculate R2 according to the following equation:

V

= +

R2 (R1 R3)

V

CC

HB

(V

REF

x R 1) / R 3

+

For this example, insert the value:

50mV

R2 (200k 0.825M ) 9.67k

= Ω+ Ω = Ω

 

5.3



For this example, choose standard value R2 = 9.76kI.

4) Choose the trip point for VIN rising (V

) in such a

THR

way that:



V

V V1

>+

THR REF

V

is the threshold voltage at which the com-

THR

parator switches its output from low to high, as V

HB



V

CC



IN

rises above the trip point. For this example, choose V

= 3V.

THR

5) Calculate R4 as follows:

=

R4



V

THR



V

REF



= = Ω

R4 6.93k



3 11



1.24 x 9.76 9.76 825



1

11



−−

x R2 R2 R3

 

1

  

−−

     

For this example, choose a standard value of 6.98kI.

6) Verify the trip voltages and hysteresis as follows:

THR REF

= ++

VV

THF REF

x R2

   

R2 R3 R4

   

111

       

R2 R1 R3 R4

   

R2

−

R1 R3

+

x

V

CC

111

   

xR2

= ++

VV

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 V

= 2.5V, if V

REF

= 2.525V and V

THR

THF

= 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 jackdetect 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 opendrain 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 microcontroller or codec.

V

CC

R3

R2

V

IN

V

REF

MAX44269

OUT

GND

R1

�� Maxim Integrated Products 9

Figure 3. Simplified External Hysteresis Network if V the Center of the Hysteresis Band

REF

is at

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 external 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 consumption 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 provides a rapid reset in the event of unexpected power loss.

V

CC

V

MAX44269

V

IN

V

REF

PULL

R1

OUT

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 multivibrator. 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:

R3 x R4

R2R3 R2R4 R3R4

++

R4R5(R1 R2 R3)

R1R 3 R 4

+

++

++ +

R2(R1R3 R3R5 R1R5)

V

T_FALL

V

T_RISE

V

=

CC

V

=

CC

R4R5 (R1 R2 R3) R1R3R4

+ ++

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

t

LOW

R5C1 ln

=

T_FALL

 

V

T_RISE



GND

Figure 4. Logic-Level Translator

V

CC

D1 R2

R3

R4

C1

Figure 5. Power-On Reset Circuit

�� Maxim Integrated Products 10

V

CC

MAX44269

GND

RESET

V

CC

R3

V

CC

R2

R4

R1

C1

Figure 6. Relaxation Oscillator

MAX44269

OUT

GND

R5

R1

MAX44269

 

 

 

 

11

+ 

  

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 t

would have

HIGH

involved applying thevenin’s theorem to compute the equivalent thevenin voltage (V resistance (R C1. t

can then be computed using the basic time

HIGH

THEVENIN

) in series with the capacitor

THEVENIN

) and thevenin

domain equations for the charging RC circuit as:

−

V

T_RISE

−

V

T_FALL

V x R4

CC

The t

V

HIGH

V

HIGH

THEVENIN

R (R2 R4) R3 R1 R5

THEVENIN

= ++

[ ]

V (R2 R4) R3

CC

= +

(R2 R4) R3 R1 R2 R4

x

(R2 R4) R3 R1



calculation can be simplified by selecting the

R C1 ln

=

t

THEVENIN

V

THEVENIN



+



[ ]

++ +



R1

++

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, V ~ VCC and R

THEVENIN

~ R5). With this selection, t

THEVENIN

HIGH

can be approximated as:

−

V

T_RISE

t

HIGH

R5C1 ln

=

CC

V

−

V

T_FALL

CC

The frequency of the relaxation oscillator is:

f

= =

tt

HIGH LOW

R 5 C1 1n

V

T_FALL

V

T_RISE

−

VV

( )

CC T_RISE

−

V

( )

CC

V

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- determines the switching frequency and the analog control voltage determines the pulse width.

V

CC

R2

R4

Figure 8. Charging Network Corresponding to Logic-High Output

V

CC

R1

R3 R5

R

THEVENIN

C1

V

THEVENIN

R4

V

CC

R2

V

CC

T_FALL

C1

R1

R3

V

T_FALL

C1 WAVEFORM

V

T_RISE

OUT

WAVEFORM

Figure 7. Relaxation Oscillator Waveforms Figure 9. PWM Generator

�� Maxim Integrated Products 11

C1

ANALOG

CONTROL

VOLTAGE

INA-

MAX44269

GND

OUT

R5

V

CC

R6

MAX44269

=+−

1.3mm x 1.3mm, Low-Power Dual Comparator

Window Detector Circuit

The IC is ideal for window detectors (undervoltage/overvoltage 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 undervoltage 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:





V

+= −

R2 R3 R1 x 1

= −

825 x 1

=1969k

OTH





V



REF







4.2







1.24





Ω

Board Layout and Bypassing

Use 1.0FF bypass capacitors from VCC to GND. To maximize performance, minimize stray inductance by putting this capacitor close to the VCC pin and reducing trace lengths.

= 4.2V

V

OTH

= 2.9V

V

UTH

V

IN

R3

INA+

R2

REF

1.24V

GND

R1

Figure 10. Window Detector Circuit

INA-

INB+

INB-

5V

MAX44269

GND

V

CC

OUTA

OUTB

POWER GOOD

3) Calculate R2. The undervoltage threshold should be

2.9V when VIN is falling. The design equation is as follows:



V

R2 (R1 R2 R3)x R1

=++ −

825 1969 x 1.24 / 2.9 825

( ) ( )

( )

= Ω

370k

REF



V

UTH



For this example, choose a 374kI standard value 1%

resistor.

4) Calculate R3:

R3 (R2 R3) R2

=+−

1969k 374k

= Ω− Ω

=1.595M

Ω

For this example, choose a 1.58MI standard value 1% resistor.

�� Maxim Integrated Products 12

Chip Information

PROCESS: BiCMOS

Ordering Information

PART TEMP RANGE

MAX44269EWL+T

+Denotes a lead(Pb)-free/RoHS-compliant package.

T = Tape and reel.

-40NC to +85NC

PIN-

PACKAGE

9 WLP +AJL

TOP

MARK

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 Integrated Products 13

MAX44269

1.3mm x 1.3mm, Low-Power Dual Comparator

Revision History

REVISION

NUMBER

0 9/11 Initial release — 1 12/11 Revised Electrical Characteristics, Typical Operating Characteristics, and Figure 5. 3, 5, 6, 9, 10

REVISION

DATE

DESCRIPTION

CHANGED

PAGES

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.

MAXIM MAX44269 Technical data

Specifications and Main Features

Frequently Asked Questions

User Manual

General Description

Applications

Features

Typical Application Circuit

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

Typical Operating Characteristics

Bump Configuration

Bump Description

Detailed Description

Input Stage Structure

Open-Drain Output

RF Immunity

Applications Information

Hysteresis

Jack Detect

Logic-Level Translator

Power-On Reset Circuit

Relaxation Oscillator

Figure 4. Logic-Level Translator

Figure 5. Power-On Reset Circuit

Figure 6. Relaxation Oscillator

Simple PWM Generation Circuit

Figure 7. Relaxation Oscillator Waveforms Figure 9. PWM Generator

Window Detector Circuit

Board Layout and Bypassing

Figure 10. Window Detector Circuit

Chip Information

Ordering Information

Package Information

Revision History