Rainbow Electronics MAX970 User Manual

_______________General Description

The MAX965–MAX970 single/dual/quad micropower
comparators feature Rail-to-Rail®inputs and outputs, and
fully specified single-supply operation down to +1.6V.
These devices draw less than 5µA per comparator and
have open-drain outputs that can be pulled beyond V

CC

to 6V (max) above ground. In addition, their rail-to-rail
input common-mode voltage range makes these com­parators suitable for ultra-low-voltage operation.

A +1.6V to +5.5V single-supply operating voltage range
makes the MAX965 family of comparators ideal for 2-cell
battery-powered applications. The MAX965/MAX967/
MAX968/MAX969 offer programmable hysteresis and
an internal 1.235V ±1.5% reference. All devices are
available in either space-saving 8-pin µMAX or 16-pin
QSOP packages.

________________________Applications

2-Cell Battery-Powered/Portable Systems
Window Comparators
Threshold Detectors/Discriminators
Mobile Communications
Voltage-Level Translation
Ground/Supply-Sensing Applications

____________________________Features

♦ Ultra-Low Single-Supply Operation down to +1.6V
♦ Rail-to-Rail Common-Mode Input Voltage Range
♦ 3µA Quiescent Supply Current per Comparator
♦ Open-Drain Outputs Swing Beyond V

CC

♦ 1.235V ±1.5% Precision Internal Reference

(MAX965/967/968/969)

♦ 10µs Propagation Delay (50mV overdrive)
♦ Available in Space-Saving Packages:

8-Pin µMAX (MAX965–MAX968)
16-Pin QSOP (MAX969/MAX970)

MAX965–MAX970

Single/Dual/Quad, Micropower,

Ultra-Low-V oltage, Rail-to-Rail I/O Comparators

________________________________________________________________

Maxim Integrated Products

1

V

CC

V

OUT

7

OUT

GND

1.235V

REF6

HYST

1

5

IN-4

IN+3

8

V

CC

V

IN

R

PULL-UP

MAX965

__________Typical Operating Circuit

19-1226; Rev 0; 4/97

PART

MAX965ESA

MAX965EUA
MAX966ESA

-40°C to +85°C

-40°C to +85°C

-40°C to +85°C

TEMP. RANGE PIN-PACKAGE

8 SO
8 µMAX
8 SO

______________Ordering Information

Rail-to-Rail is a registered trademark of Nippon Motorola Ltd.

For free samples & the latest literature: http://www.maxim-ic.com, or phone [phone]

MAX966EUA -40°C to +85°C 8 µMAX
MAX967ESA

-40°C to +85°C 8 SO

MAX967EUA -40°C to +85°C 8 µMAX

PART

INTERNAL

REFERENCE

PROGRAMMABLE

HYSTERESIS

MAX965

Yes Yes

MAX966

No No

MAX967

Yes Yes

MAX968

Yes Yes

MAX969

Yes Yes

MAX970

No No

COMPARATORS

PER

PACKAGE

1

2

2

2

4

4

_____________________Selector Guide

Ordering Information continued on last page.

Pin Configurations appear at end of data sheet.

MAX965–MAX970

Single/Dual/Quad, Micropower,
Ultra-Low-V oltage, Rail-to-Rail I/O Comparators

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VCC= +1.6V to +5.5V, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at VCC= 3V and TA= +25°C.)

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.

Supply Voltage (VCC) ............................................................+6V

Voltages

IN_-, IN_+, REF, HYST ..........................-0.3V to (V

CC

+ 0.3V)

OUT_ ...............................................................-0.3V to +6.0V

Duration of OUT_ Short Circuit to GND or V

CC

..........Continuous

Continuous Power Dissipation

8-Pin SO (derate 5.88mW/°C above +70°C)...............471mW

8-Pin µMAX (derate 4.10mW/°C above +70°C)..........330mW

14-Pin SO (derate 8.33mW/°C above +70°C).............667mW

16-Pin SO (derate 8.70mW/°C above +70°C).............696mW

16-Pin QSOP (derate 5.70mW/°C above +70°C)........457mW

Operating Temperature Range ...........................-40°C to +85°C

Storage Temperature Range.............................-65°C to +150°C

Lead Temperature (soldering, 10sec).............................+300°C

6.0

10.00°C to +85°C

µMAX
package

QSOP package

-40°C to +85°C

Input Offset Voltage V

OS

-40°C to +85°C

0°C to +85°C

QSOP package

SO package 3.0

Common-mode
range = -0.25V
to 1.3V,
VCC> 1.8V

mV

V

-0.25 V

CC

- 0.25

TA= -40°C to +85°C

SO/QSOP packages, TA= -40°C to +85°C

Full common-mode range, TA= +25°C

Common-mode range = -0.25V to (VCC- 0.25V)

All packages, TA= 0°C to +85°C

VCCstepped 0V to 5V

MAX970

MAX966
MAX967/MAX968

TA= +25°C

MAX969

1.7V ≤ VCC≤ 5.5V

CONDITIONS

7.0C

IN

Input Capacitance pF

0.2I

OS

Input Offset Current

0.001 ±50

nA

0.001 ±5

I

B

Input Bias Current

4.0

-0.25 V

CC

V

CMR

Common-Mode Voltage Range

V

0.1 1.0

PSRRPower-Supply Rejection Ratio

1.7 5.5V

CC

Supply Voltage Range V

1.6 5.5

mV/V

20

Power-Up Time
(VCCto output valid)

11 18

µA

7.0 12

I

CC

Supply Current

6.0 10
10 16
14 22

UNITSMIN TYP MAXSYMBOLPARAMETER

4.0

15.0

10.0

Full common­mode range

7.0

µMAX package, TA= -40°C to +85°C 1.8 5.5

MAX965

Comparator Minimum
Operating Voltage

V1.0

µs

pA

HYST = REF mV±1V

HYST

Input Hysteresis

2 _______________________________________________________________________________________

COMPARATOR

POWER SUPPLIES

SO package

µMAX
package

V

MAX965–MAX970

Single/Dual/Quad, Micropower,

Ultra-Low-V oltage, Rail-to-Rail I/O Comparators

_______________________________________________________________________________________

3

3

4

-60

MAX965 SUPPLY CURRENT

vs. TEMPERATURE

MAX965-TOC1b

TEMPERATURE (°C)

SUPPLY CURRENT (µA)

5

7
6

8

9

10

11

12

13

-40 -20 0 20 40 60 80 100

V

IN+

> V

IN-

VCC = 5.0V

VCC = 2.0V

VCC = 3.0V

4.0

-60

MAX966 SUPPLY CURRENT

vs. TEMPERATURE

MAX965-TOC2b

TEMPERATURE (°C)

SUPPLY CURRENT (µA)

4.5

5.5

5.0

6.0

6.5

7.0

7.5

8.0

8.5

9.0

-40 -20 0 20 40 60 80 100

V

IN+

> V

IN-

VCC = 5.0V

VCC = 2.0V

VCC = 3.0V

5

-60

MAX967/MAX968 SUPPLY CURRENT

vs. TEMPERATURE

MAX965-TOC3b

TEMPERATURE (°C)

SUPPLY CURRENT (µA)

6

8
7

9

10

11

12

13

14

15

-40 -20 0 20 40 60 80 100

V

IN+

> V

IN-

VCC = 5.0V

VCC = 2.0V

VCC = 3.0V

ELECTRICAL CHARACTERISTICS (continued)

(VCC= +1.6V to +5.5V, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at VCC= 3V and TA= +25°C.)

f = 100Hz to 100kHz, C

REF

= 0.1µF

HYST = REF

SO package

CONDITIONS

µV

RMS

10Output Voltage Noise

nA200 400I

REF-

Sink Current

µA15 50I

REF+

Source Current

V

1.125 1.235 1.255

V

REF

Reference Voltage

UNITSMIN TYP MAXSYMBOLPARAMETER

1.205 1.235 1.265

__________________________________________Typical Operating Characteristics

(VCC= +3.0V, R

PULL-UP

= 100kΩ, VCM= 0V, TA= +25°C, unless otherwise noted.)

10

CMRRCommon-Mode Rejection Ratio mV/V1.5 4.0

f = 100Hz to 100kHz, C

REF

= 1000pFInput Voltage Noise e

n

µV

RMS

0.2I

OUT

= 100µA, 1.6V < VCC< 2.7V

OUT Output Voltage Low V

OL

V

20

Propagation Delay t

PD-

µs

10

R

PULL-UP

= 1MΩ,

C

LOAD

= 15pF, high to low

10mV overdrive
50mV overdrive

QSOP package

HYST Input Voltage Range V

V

REF -

0.05

V

REF

I

HYST

HYST Input Leakage nA±5
Hysteresis Gain V/V1.0

µMAX package, TA= -40°C to +85°C 1.185 1.235 1.285

µMAX package, TA= 0°C to +85°C 1.205 1.235 1.265

0.4I

OUT

= 500µA, 2.7V < VCC< 5.5V

REFERENCE

MAX965–MAX970

Single/Dual/Quad, Micropower,
Ultra-Low-V oltage, Rail-to-Rail I/O Comparators

4 _______________________________________________________________________________________

0

0

MAX965 SUPPLY CURRENT

vs. SUPPLY VOLTAGE

(INCLUDES REFERENCE CURRENT)

MAX965/70-TOC7a

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (µA)

2

4

6

8

10

12

14

1 2 3 4 5 6

V

IN+

> V

IN-

-60 -20 0-40 20 40 60 80 100

COMPARATOR OUTPUT SHORT-CIRCUIT

SINK CURRENT vs. TEMPERATURE

MAX965/70 -TOC8a

TEMPERATURE (°C)

OUTPUT SHORT-CIRCUIT SINK CURRENT (mA)

VCC = 2V

VCC = 3V

V

IN+

< V

IN-

VCC = 5V

0

2

4

6

8

10

12

14

0

1.5

1.0

0.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 42 6 8 10 12

COMPARATOR OUTPUT

LOW VOLTAGE vs. SINK CURRENT

MAX965/70-09a

SINK CURRENT (mA)

OUTPUT LOW VOLTAGE (V)

V

IN+

= < V

IN-

V

CC

= 5V

V

CC

= 3V

V

CC

= 2V

6

-60

PROPAGATION DELAY (t

PD-

)

vs. TEMPERATURE

MAX965-TOC10a

TEMPERATURE (°C)

DELAY (µs)

7

4

5

9
8

10

11

12

13

14

-40 -20 0 20 40 60 80 100

VOD = 50mV

VCC = 2.0V

VCC = 5.0V

VCC = 3.0V

70

0

0.001 0.01 0.1

PROPAGATION DELAY (t

PD-

)

vs. CAPACITIVE LOAD

10

MAX4108/9-11a

CAPACITIVE LOAD (µF)

DELAY (µs)

30

20

40

50

60

VOD = 50mV

VCC = 5.0V

VCC = 3.0V

VCC = 2.0V

0

0

PROPAGATION DELAY (t

PD-

)

vs. INPUT OVERDRIVE

MAX965-TOC12a

INPUT OVERDRIVE (mV)

DELAY (µs)

10

5

15

20

25

30

20 40 60 80 100 120 140 160

VCC = 5.0V

VCC = 2.0V

VCC = 3.0V

_____________________________Typical Operating Characteristics (continued)

(VCC= +3.0V, R

PULL-UP

= 100kΩ, VCM= 0V, TA= +25°C, unless otherwise noted.)

8

-60

MAX969 SUPPLY CURRENT

vs. TEMPERATURE

MAX965-TOC4b

TEMPERATURE (°C)

SUPPLY CURRENT (µA)

12

10

14

16

18

20

-40 -20 0 20 40 60 80 100

V

IN+

> V

IN-

VCC = 5.0V

VCC = 2.0V

VCC = 3.0V

7

-60

MAX970 SUPPLY CURRENT

vs. TEMPERATURE

MAX965-TOC5b

TEMPERATURE (°C)

SUPPLY CURRENT (µA)

8

10

9

11

12

13

14

15

16

-40 -20 0 20 40 60 80 100

V

IN+

> V

IN-

VCC = 2.0V

VCC = 3.0V

VCC = 5.0V

0

0

SUPPLY CURRENT PER COMPARATOR

vs. SUPPLY VOLTAGE

(EXCLUDES REFERENCE CURRENT)

MAX965-TOC6b

SUPPLY VOLTAGE (V)

SUPPLY CURRENT PER COMPARATOR (µA)

0.5

1.0

1.5

2.0

2.5

3.0

3.5

1 2 3 4 5 6

V

IN+

> V

IN-

MAX965–MAX970

Single/Dual/Quad, Micropower,

Ultra-Low-V oltage, Rail-to-Rail I/O Comparators

_______________________________________________________________________________________ 5

4.0

3.8

2.0

0.01 0.1 1 10 100

SUPPLY CURRENT PER COMPARATOR

vs. OUTPUT TRANSITION FREQUENCY

2.4

2.2

MAX965/70 TOC13A

OUTPUT TRANSITION FREQUENCY (kHz)

SUPPLY CURRENT PER COMPARATOR (µA)

2.8

2.6

3.2

3.0

3.6

3.4

VCC = 5.5V

VCC = 1.6V

100

120
110

140
130

160
150

170

190
180

200

-60 -20 0-40 20 40 60 80 100

INPUT OFFSET VOLTAGE

vs. TEMPERATURE

MAX965/70-TOC14a

TEMPERATURE (°C)

INPUT OFFSET VOLTAGE (µV)

0

1.0

0.5

2.0

1.5

3.5

3.0

2.5

4.0

-40 -20 0 20 40 60 80 100

INPUT BIAS CURRENT

vs. TEMPERATURE

MAX965/70-TOC15a

TEMPERATURE (°C)

INPUT BIAS CURRENT (pA)

VCC = 5.0V

VCC = 3.0V

0

10

5

15

30

35

25
20

40

0 1.0 1.5 2.0 2.50.5 3.0 3.5 4.0 4.5 5.0

PROGRAMMED HYSTERESIS

vs. COMMON-MODE VOLTAGE

MAX965/70 TOC16

COMMON-MODE VOLTAGE (V)

PROGRAMMED HYSTERESIS (mV)

V

CC

= 5.0V

V

HYST

= 22mV (PROGRAMMED)

1.2320

1.2325

1.2335

1.2330

1.2340

1.2345

-60 -20 0-40 20 40 60 80 100

REFERENCE VOLTAGE

vs. TEMPERATURE

MAX965/70 TOC6a

TEMPERATURE (°C)

REFERENCE VOLTAGE (V)

VCC = 5V

VCC = 3V

VCC = 2V

1.223

1.229

1.227

1.225

1.231

1.233

1.237

1.235

1.239

1.0 1.8 2.6 3.4 4.2 5.0 5.8

REFERENCE VOLTAGE
vs. SUPPLY VOLTAGE

MAX965/70-TOC13

V

CC

(V)

REFERENCE VOLTAGE (V)

0.6

0.8

0.7

1.0

0.9

1.3

1.2

1.1

1.4

0 200100 300 400 500 600 700

REFERENCE VOLTAGE

vs. SOURCE CURRENT

MAX965/70-TOC18a

SOURCE CURRENT (µA)

REFERENCE VOLTAGE (V)

_____________________________Typical Operating Characteristics (continued)

(VCC= +3.0V, R

PULL-UP

= 100kΩ, VCM= 0V, TA= +25°C, unless otherwise noted.)

IN+

OUT

PROPAGATION DELAY (t

PD+

)

MAX965/70-TOC15

2µs/div

VCC = 3V

50mV/div

2V/div

50mV/div

2V/div

IN+

OUT

PROPAGATION DELAY (t

PD-

)

MAX965/70-TOC16b

2µs/div

VCC = 3V

MAX965–MAX970

Single/Dual/Quad, Micropower,
Ultra-Low-V oltage, Rail-to-Rail I/O Comparators

6 _______________________________________________________________________________________

_____________________________________________________________Pin Descriptions

FUNCTION

PIN

MAX965

MAX966

— 1 Comparator A Open-Drain Output

1 2 Ground
2 — No Connection. Not internally connected.

— 4 Comparator A Inverting Input

4 — Comparator Inverting Input

— 3 Comparator A Noninverting Input

3 — Comparator Noninverting Input

7 7 Positive Supply Voltage, +1.6V to +5.5V

6 — Internal Reference Output. Typically 1.235V with respect to GND.

5 —

Hysteresis Input. Connect HYST to REF if not used. Input voltage range
is from V

REF

to (V

REF

- 50mV).

— 6 Comparator B Noninverting Input

— 5 Comparator B Inverting Input

MAX967

1
2

—

—

—

3

—

7

6

5

4

—

MAX968

1
2

—

—

—

3

—

7

6

5

—

4

NAME

OUTA

GND

N.C.

INA-

IN-

INA+

IN+

V

CC

REF

HYST

INB+

INB-

8 — — — OUT Comparator Open-Drain Output

— 8 8 8 OUTB Comparator B Open-Drain Output

MAX965–MAX968

50mV/div

1V/div

IN+

OUT

10kHz RESPONSE

MAX965/70-TOC18

20µs/div

2V/div

2V/div

V

CC

OUT

POWER-UP/DOWN RESPONSE

MAX965/70-TOC17

5µs/div

_____________________________Typical Operating Characteristics (continued)

(VCC= +3.0V, R

PULL-UP

= 100kΩ, V

CM

= 0V, TA= +25°C, unless otherwise noted.)

MAX965–MAX970

Single/Dual/Quad, Micropower,

Ultra-Low-V oltage, Rail-to-Rail I/O Comparators

_______________________________________________________________________________________ 7

________________________________________________Pin Descriptions (continued)

_______________Detailed Description

The MAX965–MAX970 single/dual/quad, micropower,
ultra-low-voltage comparators feature Rail-to-Rail

®

inputs and outputs and an internal 1.235V ±1.5%
bandgap reference. These devices operate from a sin­gle +1.6V to +5.5V supply voltage range, and consume
less than 5µA supply current per comparator over the
extended temperature range. Internal hysteresis is pro­grammable up to ±50mV using two external resistors
and the device’s internal reference. The rail-to-rail input
common-mode voltage range and the open-drain out­puts allow easy voltage-level conversion for multivolt­age systems. All inputs and outputs can tolerate a
continuous short-circuit fault condition to either rail.

The MAX965 is a single comparator with adjustable
hysteresis and a reference output pin. The MAX966 is a
dual comparator without the reference and without
adjustable hysteresis. The MAX967 is a dual compara-

tor configured as a dual voltage monitor with common
hysteresis adjustment and a reference output. The dual
MAX968 is similar to the MAX967, but is configured as
a window comparator. The MAX969 is a quad com­parator with a common hysteresis adjustment and a ref­erence output pin. The MAX970 is a quad comparator
without a reference and without hysteresis adjustment.
(See Functional Diagrams and Selector Guide.)

Comparator Input

The MAX965–MAX970 have a -0.25V to VCCinput com­mon-mode range. Both comparator inputs may operate
at any differential voltage within the common-mode
voltage range, and the comparator displays the correct
output logic state.

Low-Voltage Operation: VCCDown to 1V

The minimum operating voltage is 1.6V. As the supply
voltage falls below 1.6V, performance degrades
and supply current falls. The reference does not

MAX969/MAX970

FUNCTION

MAX969

SO

4 4 Comparator A Inverting Input

3 3 Positive Supply Voltage, +1.6V to +5.5V

2 2 Comparator A Open-Drain Output

1 1 Comparator B Open-Drain Output

8 — Internal Reference Output. Typically 1.235V with respect to GND.

— — No Connection. Not internally connected.

7 7 Comparator B Noninverting Input

6 6 Comparator B Inverting Input

5 5 Comparator A Noninverting Input

MAX970

QSOP

4

3

2

1

—

8, 9

7

6

5

NAME

INA-

VCC

OUTA

OUTB

REF

N.C.

INB+

INB-

INA+

PIN

9 — — HYST

Hysteresis Input. Connect to REF if not used. Input voltage range is
from (V

REF

- 50mV) to V

REF

.
10 8 10 INC- Comparator C Inverting Input
11 9 11 INC+ Comparator C Noninverting Input
12 10 12 IND- Comparator D Inverting Input
13 11 13 IND+ Comparator D Noninverting Input
14 12 14 GND Ground
15 13 15 OUTD Comparator D Open-Drain Output
16 14 16 OUTC Comparator C Open-Drain Output

MAX965–MAX970

Single/Dual/Quad, Micropower,
Ultra-Low-V oltage, Rail-to-Rail I/O Comparators

8 _______________________________________________________________________________________

OUTB

OUTA

INA­INA+

INB­INB+

REF

OUTC

V

CC

V

CC

OUTD

IND+

IND-

INC+

INC-

+

1.235V
GND HYST

OUTB

OUTA

INA­INA+

INB­INB+

OUTC

OUTD

IND+

IND-

INC+

INC-

GND

MAX969 MAX970

V

CC

V

CC

OUT

IN+ OUTA

INA+

GND

GND

GND

INA-

INB+

INB-

OUTB

OUTA

INA+

REF

REF

REF

REF

REF

V

CC

V

CC

1.235V

1.235V

INB-

HYST

OUTB

OUTA

INA+

REF

INB+

HYST

OUTB

IN-

HYST

REF

+

GND

1.235V

MAX965

MAX968MAX967

MAX966

________________________________________________________Functional Diagrams

MAX965–MAX970

Single/Dual/Quad, Micropower,

Ultra-Low-V oltage, Rail-to-Rail I/O Comparators

function below about 1.5V, although the comparators
typically continue to operate with a supply voltage as
low as 1V. At low supply voltages (<1.6V), the input
common-mode range remains rail-to-rail, but the com­parator’s output sink capability is reduced and propa­gation delay increases (see Typical Operating
Characteristics).

Figure 1 shows a typical comparator application that
monitors VCCat 1.6V. Resistor divider R1/R2 sets the
voltage trip point (V

TRIP

) at 1.6V. As VCCdrops below

1.6V and approaches 1V, the reference voltage typical­ly falls below the divider voltage (V+). This causes the
comparator output to change state. If OUT’s state must
be maintained under these conditions, a latching circuit
is required.

Comparator Output

The MAX965–MAX970 contain a unique slew-rate­controlled output stage capable of rail-to-rail operation
with an external pull-up resistor. Typical comparators
consume orders of magnitude more current during
switching than during steady-state operation. With the
MAX965 family of comparators, during an output transi­tion from high to low, the output slew rate is limited to
minimize switching current.

Voltage Reference

With VCCgreater than 1.6V but less than 5.5V, the inter­nal 1.235V bandgap reference is ±1.5% accurate over
the commercial temperature range and ±2.5% accu­rate over the extended temperature range. The REF
output is typically capable of sourcing 50µA. To reduce
reference noise or to provide noise immunity, bypass
REF with a capacitor (0.1nF to 0.1µF).

Noise Considerations

The comparator has an effective wideband peak-to­peak noise of around 10µV. The voltage reference has
peak-to-peak noise approaching 1.0mV with a 0.1µF
bypass capacitor. Thus, when a comparator is used
with the reference, the combined peak-to-peak noise is
about 1.0mV. This, of course, is much higher than the
individual components’ RMS noise. Avoid capacitive
coupling from any output to the reference pin. Crosstalk
can significantly increase the references’ actual noise.

__________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 MAX965–MAX970 have internal hysteresis to
counter parasitic effects and noise. In addition, with the
use of external resistor, the MAX965/MAX967/
MAX968/MAX969’s hysteresis can be programmed to
as much as ±50mV (see the section Adding Hysteresis
to the MAX965/MAX967/MAX968/MAX969).

The hysteresis in a comparator creates two trip points:
one for the rising input voltage and one for the falling
input voltage (Figure 2). The difference between the trip
points is the hysteresis. When the comparator’s input
voltages are equal, the hysteresis effectively causes
one comparator input voltage to move quickly past the
other, thus taking the input out of the region where
oscillation occurs.

THRESHOLDS

OUT

IN-

IN+

V

HB

HYSTERESIS

BAND

V

REF

- V

HYST

Figure 2. Threshold Hysteresis Band

REF

GND

V

CC

V

TRIP

= 1.22 + 1

V

CC

V

REF

OUT

R1 47k

R2 150k

V+

V

CC

V+

t

1.6V

1.0V

100k

MAX965

R1
R2

R1 = x R2

- 1

V

TRIP

1.22

Figure 1. Operation below 1.6V

_______________________________________________________________________________________ 9

MAX965–MAX970

Single/Dual/Quad, Micropower,
Ultra-Low-V oltage, Rail-to-Rail I/O Comparators

10 ______________________________________________________________________________________

HYST

REF

GND

V

CC

R1

R2

MAX965
MAX967
MAX968
MAX969

+1.6V TO +5.5V

I

REF

Figure 3. Programming the HYST Pin

GND

V

CC

V

CC

OUT

R3

R1

R2

R4

V

REF

V

IN

MAX966
MAX970

Figure 4. External Hysteresis

Figure 2 illustrates the case in which IN- has a fixed
voltage applied, and IN+ is varied. If the inputs were
reversed, the figure would be the same, except with an
inverted output.

Adding Hysteresis to the

MAX965/MAX967/MAX968/MAX969

To add hysteresis to the MAX965/MAX967/MAX968/
MAX969, connect resistor R1 between REF and HYST,
and connect resistor R2 between HYST and GND
(Figure 3). If additional hysteresis is not required,
connect HYST to REF. When hysteresis is added, the
upper and lower trip points change by the same
amount in opposite directions. The hysteresis band (the
difference between the upper and lower trip points,
VHB) is approximately twice the voltage between HYST
and REF. The HYST input voltage range is from REF
down to (REF - 50mV). This yields a hysteresis band
from ±1mV to a maximum of ±50mV. Calculate the val­ues of R1 and R2 for the desired hysteresis band with
the following formulas:

R1 = VHB/ I

REF

R2 = (V

REF

- VHB) / I

REF

where I

REF

(the current sourced by the reference) does
not exceed the REF source capability (12µA typical),
and is significantly larger than the HYST leakage cur­rent (5nA typical). I

REF

values between 0.1µA and 4µA

are good choices. If 2.4MΩ is chosen for R2 (I

REF

=

0.5µA), the equation for R1 and VHBcan be approxi­mated as:

R1(kΩ) = 2 x VHB(mV)

In the MAX967/MAX968/MAX969, the HYST pin pro­grams the same hysteresis for all comparators in the
package.

Due to the internal structure of the input developed for
ultra-low-voltage operation, the hysteresis band varies
with common-mode voltage. The graph Programmed
Hysteresis vs. Common-Mode Voltage in the Typical
Operating Characteristics shows this variation. Notice
that the hysteresis band increases to almost twice the
calculated value toward the ends of the common-mode
range. This is apparent only when programming addi­tional hysteresis using the HYST pin. The hysteresis
band is constant when HYST is connected to REF.

Adding Hysteresis to the MAX966/MAX970

The MAX966/MAX970 do not have a HYST pin for pro­gramming hysteresis. Hysteresis can be generated with
three resistors using positive feedback (Figure 4). This
method generally draws more current than the method
using the HYST pin on the MAX965/MAX967/MAX968/
MAX969. Also, the positive feedback method slows
hysteresis response time. Use the following procedure
to calculate the resistor values:

1) Select R3. The leakage current of IN+ is under 5nA,
so the current through R3 should be at least 500nA
to minimize errors caused by leakage current. The
current through R3 at the trip point is (V

REF

- V

OUT

) /
R3. Taking into consideration the two possible out­put states and solving for R3 yields two formulas:

R3 = V

REF

/ 500nA

and

R3 = (V

REF

- VCC) / 500nA

Use the smaller of the two resulting resistor values.
For example, if V

REF

= 1.2V and VCC= 5.0V, then
the two resistor values are 2.4MΩ and 7.6mΩ. For
R3, choose the 2.2MΩ standard value.

2) Choose the hysteresis band required (VHB). For this
example, choose 50mV.

MAX965–MAX970

Single/Dual/Quad, Micropower,

Ultra-Low-V oltage, Rail-to-Rail I/O Comparators

______________________________________________________________________________________ 11

3) Calculate R1: R1 = (R3 + R4) x (VHB/ VCC). Putting
in the values for this example, R1 = (2.2MΩ + 10k) x
(50mV / 5.0V) = 22.1kΩ.

4) Choose the trip point for VINrising. This is the
threshold voltage where the comparator output tran­sitions from low to high as VINrises above the trip
point. For this example, choose 3.0V.

5) Calculate R2 as follows:

where V

THR

is the rising-voltage trip threshold.

Choose a standard value of 15kΩ.

6) Verify trip voltages and hysteresis as follows:

where V

THR

is the rising-voltage trip point, and V

THF

is the falling-voltage trip point.

Circuit Layout and Bypassing

Power-supply bypass capacitors are not needed if sup­ply impedance is low, but 100nF bypass capacitors
should be used when supply impedance is high or
when supply leads are long. Minimize signal lead
lengths to reduce stray capacitance between the input
and output that might cause instability.

IR Receiver

Figure 5 shows an application using the MAX965 as an
infrared receiver. The infrared photodiode creates a
current relative to the amount of infrared light present.
This current creates a voltage across R1. When this
voltage level crosses the reference voltage applied to
the inverting input, the output transitions. Optional R3
provides additional hysteresis for noise immunity.

2-Cell to TTL Logic-Level Shifter

Figure 6 shows an application using the MAX965
to convert a 2-cell voltage-level signal into a TTL­compatible signal. The supply voltage for the compara­tor comes from the 2-cell supply. The output is pulled
up to a 5V supply.

V ri g
V V x R x

R R R R

V falling
V V

R x V

R R

Hysteresis V V

IN

THR REF

IN

THF THR

CC

THR THF

sin :

:

= + +

+











= −

+











= −

1

111

213 4

1

3 4

R

V

V x R R R R

R

V

x k k M k

k

THR

REF

2

1

1

1

1

1

3 4

2

1

3 0

1 2 22

1

22

1

2 2 10

14 76

=











− −
+

=











− −
+

=

.

.

.

.

GND

V

CC

V

CC

V

CC

V

CC

0.1µF

OUT

R3

R

D

R

PULL-UP

REF

MAX965

HYST

Figure 5. IR Receiver

GND

V

CC

+5V

2 CELLS

0.1µF

OUT

INPUT

REF

MAX965

HYST

Figure 6. 2-Cell to TTL Logic-Level Translator

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.

12 __________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 [phone]

© 1997 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

MAX965–MAX970

Single/Dual/Quad, Micropower,
Ultra-Low-V oltage, Rail-to-Rail I/O Comparators

TRANSISTOR COUNTS:
MAX965 = 216
MAX966 = 190
MAX967/MAX968 = 299
MAX969 = 465
MAX970 = 380

___________________Chip Information

PART TEMP. RANGE PIN-PACKAGE

MAX969EEE -40°C to +85°C 16 QSOP

MAX969ESE

-40°C to +85°C 16 Narrow SO

MAX968EUA -40°C to +85°C 8 µMAX

MAX968ESA

-40°C to +85°C 8 SO

MAX970ESD

-40°C to +85°C 14 SO

MAX970EEE -40°C to +85°C 16 QSOP

_Ordering Information (continued)

__________________________________________________________Pin Configurations

14
13
12
11
10

9
8

1

2
3
4
5
6
7

OUTC
OUTD
GND
IND+INA-

V

CC

OUTA

OUTB

MAX970

IND­INC+
INC-

INB+

INB-

INA+

SO

TOP VIEW

16
15
14
13
12
11
10

9

1
2
3
4
5
6
7
8

OUTC
OUTD
GND
IND+INA-

V

CC

OUTA

OUTB

MAX969

IND-

INC+

INC-

HYST

REF

INB+

INB-

INA+

SO/QSOP

16
15
14
13
12
11
10

9

1
2
3
4
5
6
7
8

OUTC
OUTD
GND
IND+INA-

V

CC

OUTA

OUTB

MAX970

IND­INC+
INC-

N.C.

N.C.

INB+

INB-

INA+

QSOP

1

2
3
4

OUT
V

CC

REF
HYSTIN-

IN+

N.C.

GND

MAX965

SO/µMAX

SO/µMAX

SO/µMAX

8
7

6
5

1

2

3

4

OUTB
V

CC

INB+
INB-INA-

INA+

GND

OUTA

MAX966

8
7

6
5

1

2
3
4

OUTB
V

CC

REF
HYSTINB+

(INB-)

INA+

GND

OUTA

MAX967
MAX968

8
7

6
5

( ) ARE FOR MAX968 ONLY.