Maxim MAX965 Single/dual/quad, micropower, ultra-low-voltage, rail-to-rail i/o comparator Datasheet

19-1226; Rev 0; 4/97
Single/Dual/Quad, Micropower,
Ultra-Low-Voltage, Rail-to-Rail I/O Comparators
____________________________Features
♦ Ultra-Low Single-Supply Operation down to +1.6V
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.
♦ Rail-to-Rail Common-Mode Input Voltage Range
♦ 3µA Quiescent Supply Current per Comparator
♦ Open-Drain Outputs Swing Beyond VCC
♦ 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)
________________________Applications
2-Cell Battery-Powered/Portable Systems
Window Comparators
Threshold Detectors/Discriminators
Mobile Communications
Voltage-Level Translation
Ground/Supply-Sensing Applications
PART
INTERNAL
REFERENCE
COMPARATORS
PER
PACKAGE
PROGRAMMABLE
HYSTERESIS
_____________________Selector Guide
MAX965
Yes
1
Yes
MAX966
No
2
No
MAX967
Yes
2
Yes
MAX968
Yes
2
Yes
MAX969
Yes
4
Yes
MAX970
No
4
No
______________Ordering Information
TEMP. RANGE
PIN-PACKAGE
MAX965ESA
PART
-40°C to +85°C
8 SO
MAX965EUA
MAX966ESA
MAX966EUA
MAX967ESA
MAX967EUA
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
8 µMAX
8 SO
8 µMAX
8 SO
8 µMAX
Ordering Information continued on last page.
Pin Configurations appear at end of data sheet.
__________Typical Operating Circuit
VIN
VCC
7
VCC
3 IN+
RPULL-UP
OUT
8
VOUT
4 IN5 HYST
6 REF
MAX965
1.235V
GND
Rail-to-Rail is a registered trademark of Nippon Motorola Ltd.
1
________________________________________________________________ Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800
MAX965–MAX970
_______________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 VCC
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.
MAX965–MAX970
Single/Dual/Quad, Micropower,
Ultra-Low-Voltage, Rail-to-Rail I/O Comparators
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (VCC) ............................................................+6V
Voltages
IN_-, IN_+, REF, HYST ..........................-0.3V to (VCC + 0.3V)
OUT_ ...............................................................-0.3V to +6.0V
Duration of OUT_ Short Circuit to GND or VCC ..........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
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.
ELECTRICAL CHARACTERISTICS
(VCC = +1.6V to +5.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = 3V and TA = +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
POWER SUPPLIES
Supply Voltage Range
VCC
All packages, TA = 0°C to +85°C
1.6
5.5
SO/QSOP packages, TA = -40°C to +85°C
1.7
5.5
µMAX package, TA = -40°C to +85°C
1.8
5.5
Comparator Minimum
Operating Voltage
Supply Current
1.0
ICC
Power-Up Time
(VCC to output valid)
V
V
MAX965
7.0
12
MAX966
6.0
10
MAX967/MAX968
10
16
MAX969
14
22
MAX970
11
18
VCC stepped 0V to 5V
20
1.7V ≤ VCC ≤ 5.5V
0.1
µA
µs
COMPARATOR
Power-Supply Rejection Ratio
PSRR
Common-Mode Voltage Range
VCMR
Input Offset Voltage
VOS
TA = +25°C
TA = -40°C to +85°C
SO package
Common-mode
QSOP
package
range = -0.25V
to 1.3V,
0°C to +85°C
µMAX
VCC > 1.8V
package -40°C to +85°C
Full commonmode range
Input Hysteresis
Input Bias Current
VHYST
IB
-0.25
-0.25
1.0
VCC
VCC - 0.25
3.0
4.0
6.0
7.0
QSOP package
10.0
0°C to +85°C
mV
10.0
-40°C to +85°C
HYST = REF
V
V
4.0
SO package
µMAX
package
mV/V
15.0
±1
mV
Common-mode range = -0.25V to (VCC - 0.25V)
0.001
±5
Full common-mode range, TA = +25°C
0.001
±50
nA
Input Offset Current
IOS
0.2
pA
Input Capacitance
CIN
7.0
pF
2
_______________________________________________________________________________________
Single/Dual/Quad, Micropower,
Ultra-Low-Voltage, Rail-to-Rail I/O Comparators
MAX965–MAX970
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +1.6V to +5.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = 3V and TA = +25°C.)
PARAMETER
SYMBOL
Common-Mode Rejection Ratio
CMRR
CONDITIONS
MIN
TYP
MAX
UNITS
1.5
4.0
mV/V
VREF
V
±5
nA
VREF 0.05
HYST Input Voltage Range
HYST Input Leakage
IHYST
Hysteresis Gain
Input Voltage Noise
en
f = 100Hz to 100kHz, CREF = 1000pF
1.0
V/V
10
µVRMS
IOUT = 100µA, 1.6V < VCC < 2.7V
0.2
IOUT = 500µA, 2.7V < VCC < 5.5V
0.4
OUT Output Voltage Low
VOL
Propagation Delay
tPD-
RPULL-UP = 1MΩ,
CLOAD = 15pF, high to low
Reference Voltage
VREF
SO package
QSOP package
µMAX package, TA = 0°C to +85°C
µMAX package, TA = -40°C to +85°C
Source Current
IREF+
HYST = REF
Sink Current
IREF-
10mV overdrive
20
50mV overdrive
10
V
µs
REFERENCE
Output Voltage Noise
1.125
1.205
1.205
1.185
1.235
1.235
1.235
1.235
15
50
200
400
nA
10
µVRMS
f = 100Hz to 100kHz, CREF = 0.1µF
1.255
1.265
1.265
1.285
V
V
µA
__________________________________________Typical Operating Characteristics
(VCC = +3.0V, RPULL-UP = 100kΩ, VCM = 0V, TA = +25°C, unless otherwise noted.)
MAX966 SUPPLY CURRENT
vs. TEMPERATURE
10
9
8
VCC = 3.0V
7
6
5
-40
-20
0
7.0
VCC = 5.0V
6.5
6.0
VCC = 3.0V
5.5
20
40
TEMPERATURE (°C)
60
80
13
12
VCC = 5.0V
11
10
VCC = 3.0V
9
8
VCC = 2.0V
6
VIN+ > VIN-
4.0
100
14
7
VCC = 2.0V
4.5
VIN+ > VIN-
3
-60
7.5
5.0
VCC = 2.0V
4
8.0
SUPPLY CURRENT (µA)
VCC = 5.0V
8.5
SUPPLY CURRENT (µA)
11
15
MAX965-TOC2b
12
SUPPLY CURRENT (µA)
9.0
MAX965-TOC1b
13
MAX967/MAX968 SUPPLY CURRENT
vs. TEMPERATURE
MAX965-TOC3b
MAX965 SUPPLY CURRENT
vs. TEMPERATURE
VIN+ > VIN-
5
-60
-40
-20
0
20
40
TEMPERATURE (°C)
60
80
100
-60
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
_______________________________________________________________________________________
3
_____________________________Typical Operating Characteristics (continued)
(VCC = +3.0V, RPULL-UP = 100kΩ, VCM = 0V, TA = +25°C, unless otherwise noted.)
MAX969 SUPPLY CURRENT
vs. TEMPERATURE
14
VCC = 3.0V
VCC = 5.0V
12
11
VCC = 3.0V
10
VCC = 2.0V
9
10
VCC = 2.0V
8
VIN+ > VIN-
8
VIN+ > VIN-
2.0
1.5
1.0
0.5
VIN+ > VIN0
0
20
40
60
80
100
-60
-40
-20
MAX965/70-TOC7a
14
12
10
8
6
4
2
VIN+ > VIN-
OUTPUT SHORT-CIRCUIT SINK CURRENT (mA)
MAX965 SUPPLY CURRENT
vs. SUPPLY VOLTAGE
(INCLUDES REFERENCE CURRENT)
0
20
40
60
80
0
100
1
2
3
4
5
4
5
COMPARATOR OUTPUT
LOW VOLTAGE vs. SINK CURRENT
14
VIN+ < VIN-
12
VCC = 5V
10
8
6
VCC = 3V
4
5.0
VIN+ = < VIN-
4.5
4.0
3.5
3.0
2.5
VCC = 2V VCC = 3V
2.0
1.5
VCC = 5V
0.5
0
-60
-40
-20
0
20
40
60
80
0
100
2
4
6
8
10
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
SINK CURRENT (mA)
PROPAGATION DELAY (tPD-)
vs. TEMPERATURE
PROPAGATION DELAY (tPD-)
vs. CAPACITIVE LOAD
PROPAGATION DELAY (tPD-)
vs. INPUT OVERDRIVE
VCC = 2.0V
VOD = 50mV
30
60
25
50
VCC = 3.0V
VCC = 5.0V
8
7
20
DELAY (µs)
10
DELAY (µs)
11
12
MAX965-TOC12a
12
70
MAX965-TOC10a
13
6
1.0
VCC = 2V
2
6
14
9
3
COMPARATOR OUTPUT SHORT-CIRCUIT
SINK CURRENT vs. TEMPERATURE
MAX4108/9-11a
0
2
SUPPLY VOLTAGE (V)
0
0
1
TEMPERATURE (°C)
OUTPUT LOW VOLTAGE (V)
-20
MAX965/70 -TOC8a
-40
TEMPERATURE (°C)
SUPPLY CURRENT (µA)
2.5
7
-60
VCC = 2.0V
40
30
VCC = 3.0V
15
VCC = 2.0V
VCC = 3.0V
10
20
6
VOD = 50mV
4
VCC = 5.0V
0
0
-60
-40
-20
0
20
40
TEMPERATURE (°C)
60
80
100
VCC = 5.0V
5
10
5
4
3.0
MAX965/70-09a
VCC = 5.0V
14
13
MAX965-TOC6b
15
3.5
SUPPLY CURRENT PER COMPARATOR (µA)
16
MAX965-TOC5b
MAX965-TOC4b
16
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
18
12
SUPPLY CURRENT PER COMPARATOR
vs. SUPPLY VOLTAGE
(EXCLUDES REFERENCE CURRENT)
MAX970 SUPPLY CURRENT
vs. TEMPERATURE
20
DELAY (µs)
MAX965–MAX970
Single/Dual/Quad, Micropower,
Ultra-Low-Voltage, Rail-to-Rail I/O Comparators
0.001
0.01
CAPACITIVE LOAD (µF)
0.1
0
20
40
60
80 100
120 140 160
INPUT OVERDRIVE (mV)
_______________________________________________________________________________________
Single/Dual/Quad, Micropower,
Ultra-Low-Voltage, Rail-to-Rail I/O Comparators
MAX965–MAX970
_____________________________Typical Operating Characteristics (continued)
(VCC = +3.0V, RPULL-UP = 100kΩ, VCM = 0V, TA = +25°C, unless otherwise noted.)
3.4
3.2
VCC = 5.5V
2.8
2.6
VCC = 1.6V
180
170
160
150
140
130
2.0
1.5
1.0
100
-60
-40
-20
60
80
-40
100
25
20
VCC = 5V
1.2340
1.2330
15
10
VCC = 2V
1.2325
VCC = 5.0V
VHYST = 22mV (PROGRAMMED)
1.2320
-40
-20
MAX965/70-TOC18a
1.2
100
1.235
1.233
1.231
1.229
1.227
0
20
40
60
80
100
1.0
1.8
2.6
3.4
4.2
5.0
5.8
VCC (V)
PROPAGATION DELAY (tPD-)
MAX965/70-TOC15
1.3
80
1.237
PROPAGATION DELAY (tPD+)
1.4
60
1.239
TEMPERATURE (°C)
COMMON-MODE VOLTAGE (V)
REFERENCE VOLTAGE
vs. SOURCE CURRENT
40
1.223
-60
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
20
1.225
VCC = 3V
0
0
0
REFERENCE VOLTAGE
vs. SUPPLY VOLTAGE
1.2335
5
-20
TEMPERATURE (°C)
1.2345
REFERENCE VOLTAGE (V)
30
40
REFERENCE VOLTAGE
vs. TEMPERATURE
MAX965/70 TOC16
35
20
TEMPERATURE (°C)
PROGRAMMED HYSTERESIS
vs. COMMON-MODE VOLTAGE
40
0
REFERENCE VOLTAGE (V)
10
MAX965/70 TOC6a
1
VCC = 3.0V
0
100
0.1
OUTPUT TRANSITION FREQUENCY (kHz)
PROGRAMMED HYSTERESIS (mV)
2.5
0.5
110
2.0
REFERENCE VOLTAGE (V)
3.0
120
2.2
0.01
VCC = 5.0V
3.5
MAX965/70-TOC13
2.4
190
INPUT BIAS CURRENT (pA)
3.6
4.0
MAX965/70-TOC14a
MAX965/70 TOC13A
3.8
200
INPUT OFFSET VOLTAGE (µV)
SUPPLY CURRENT PER COMPARATOR (µA)
4.0
3.0
INPUT BIAS CURRENT
vs. TEMPERATURE
INPUT OFFSET VOLTAGE
vs. TEMPERATURE
MAX965/70-TOC15a
SUPPLY CURRENT PER COMPARATOR
vs. OUTPUT TRANSITION FREQUENCY
MAX965/70-TOC16b
VCC = 3V
VCC = 3V
IN+
50mV/div
IN+
50mV/div
1.1
1.0
0.9
0.8
OUT
2V/div
OUT
2V/div
0.7
0.6
0
100
200
300
400
500
600
700
2µs/div
2µs/div
SOURCE CURRENT (µA)
_______________________________________________________________________________________
5
MAX965–MAX970
Single/Dual/Quad, Micropower,
Ultra-Low-Voltage, Rail-to-Rail I/O Comparators
_____________________________Typical Operating Characteristics (continued)
(VCC = +3.0V, RPULL-UP = 100kΩ, VCM = 0V, TA = +25°C, unless otherwise noted.)
10kHz RESPONSE
POWER-UP/DOWN RESPONSE
MAX965/70-TOC18
MAX965/70-TOC17
IN+
50mV/div
VCC
2V/div
OUT
1V/div
OUT
2V/div
20µs/div
5µs/div
_____________________________________________________________Pin Descriptions
MAX965–MAX968
PIN
NAME
FUNCTION
MAX965
MAX966
MAX967
MAX968
—
1
1
1
OUTA
Comparator A Open-Drain Output
1
2
2
2
GND
Ground
2
—
—
—
N.C.
No Connection. Not internally connected.
3
—
—
—
IN+
Comparator Noninverting Input
—
3
3
3
INA+
4
—
—
—
IN-
—
4
—
—
INA-
Comparator A Inverting Input
—
5
—
4
INB-
Comparator B Inverting Input
—
6
4
—
INB+
Comparator B Noninverting Input
5
—
5
5
HYST
Hysteresis Input. Connect HYST to REF if not used. Input voltage range
is from VREF to (VREF - 50mV).
6
—
6
6
REF
Internal Reference Output. Typically 1.235V with respect to GND.
7
7
7
7
VCC
Positive Supply Voltage, +1.6V to +5.5V
8
—
—
—
OUT
Comparator Open-Drain Output
—
8
8
8
OUTB
6
Comparator A Noninverting Input
Comparator Inverting Input
Comparator B Open-Drain Output
_______________________________________________________________________________________
Single/Dual/Quad, Micropower,
Ultra-Low-Voltage, Rail-to-Rail I/O Comparators
PIN
MAX970
NAME
FUNCTION
MAX969
SO
QSOP
1
1
1
OUTB
Comparator B Open-Drain Output
2
2
2
OUTA
Comparator A Open-Drain Output
3
3
3
VCC
Positive Supply Voltage, +1.6V to +5.5V
4
4
4
INA-
Comparator A Inverting Input
5
5
5
INA+
Comparator A Noninverting Input
6
6
6
INB-
Comparator B Inverting Input
7
7
7
INB+
Comparator B Noninverting Input
—
—
8, 9
N.C.
No Connection. Not internally connected.
8
—
—
REF
Internal Reference Output. Typically 1.235V with respect to GND.
9
—
—
HYST
Hysteresis Input. Connect to REF if not used. Input voltage range is
from (VREF - 50mV) to VREF.
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
_______________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 VCC input 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: VCC Down 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
_______________________________________________________________________________________
7
MAX965–MAX970
________________________________________________Pin Descriptions (continued)
MAX969/MAX970
MAX965–MAX970
Single/Dual/Quad, Micropower,
Ultra-Low-Voltage, Rail-to-Rail I/O Comparators
________________________________________________________Functional Diagrams
VCC
VCC
IN+
OUTB
OUTA
OUT
MAX966
INHYST
REF
MAX965
+
1.235V
REF
INA+
INB+
INA-
INBGND
GND
VCC
INA+
VCC
INA+
OUTA
OUTA
REF
REF
HYST
HYST
REF
REF
1.235V
1.235V
OUTB
OUTB
INB+
INBGND
GND
VCC
OUTB
MAX968
VCC
OUTC
OUTB
OUTA
OUTD
OUTA
OUTD
INA-
IND+
INA-
IND+
INA+
IND-
INA+
IND-
INB-
INC+
INB-
INC+
INB+
INC-
INB+
INC-
REF
+
1.235V
MAX969
REF
GND
8
MAX967
HYST
MAX970
GND
_______________________________________________________________________________________
OUTC
Single/Dual/Quad, Micropower,
Ultra-Low-Voltage, Rail-to-Rail I/O Comparators
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 VCC greater 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.
VCC
1.6V
VCC
THRESHOLDS
IN+
V+
1.0V
VREF
R1
t
47k
100k
V+
INVREF - VHYST
HYSTERESIS
VHB
BAND
VCC
R2
150k
OUT
GND
REF
MAX965
Figure 1. Operation below 1.6V
VTRIP = 1.22 R1 + 1
R2
V
R1 = TRIP - 1 x R2
1.22
OUT
Figure 2. Threshold Hysteresis Band
_______________________________________________________________________________________
9
MAX965–MAX970
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 VCC at 1.6V. Resistor divider R1/R2 sets the
voltage trip point (VTRIP) at 1.6V. As VCC drops 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.
MAX965–MAX970
Single/Dual/Quad, Micropower,
Ultra-Low-Voltage, Rail-to-Rail I/O Comparators
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 / IREF
R2 = (VREF - VHB) / IREF
where IREF (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). IREF values between 0.1µA and 4µA
are good choices. If 2.4MΩ is chosen for R2 (IREF =
0.5µA), the equation for R1 and VHB can 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 (VREF - VOUT) /
R3. Taking into consideration the two possible output states and solving for R3 yields two formulas:
R3 = VREF / 500nA
and
R3 = (VREF - VCC) / 500nA
Use the smaller of the two resulting resistor values.
For example, if VREF = 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.
VCC
+1.6V TO +5.5V
R3
IREF
REF
VCC
R1
R1
HYST
R2
MAX965
MAX967
MAX968
MAX969
R4
VIN
VCC
GND
GND
VREF
Figure 3. Programming the HYST Pin
10
OUT
R2
MAX966
MAX970
Figure 4. External Hysteresis
______________________________________________________________________________________
Single/Dual/Quad, Micropower,
Ultra-Low-Voltage, Rail-to-Rail I/O Comparators
4) Choose the trip point for V IN rising. This is the
threshold voltage where the comparator output transitions from low to high as VIN rises above the trip
point. For this example, choose 3.0V.
5) Calculate R2 as follows:
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
R2 =
R2 =
1
 VTHR 
1
1
−
V
−
R3 + R4
 REF x R1 R1
1
= 14.76k
 3.0V 
1
1
−

−
22k
2.2M + 10k
 1.2 x 22k 
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.
VCC
R3
VCC
where V THR is the rising-voltage trip threshold.
Choose a standard value of 15kΩ.
VCC
0.1µF
6) Verify trip voltages and hysteresis as follows:
VIN rising :
RD
 1

1
1
+
VTHR = VREF x R1 x  +

 R1 R2 R3 + R4 
VCC
HYST
GND
REF
OUT
MAX965
VIN falling :
 R1 x VCC 
VTHF = VTHR − 

 R3 + R4 
RPULL-UP
Figure 5. IR Receiver
Hysteresis = VTHR − VTHF
where VTHR is the rising-voltage trip point, and VTHF
is the falling-voltage trip point.
2 CELLS
0.1µF
+5V
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.
INPUT
VCC
HYST
GND
REF
OUT
MAX965
Figure 6. 2-Cell to TTL Logic-Level Translator
______________________________________________________________________________________
11
MAX965–MAX970
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.
MAX965–MAX970
Single/Dual/Quad, Micropower,
Ultra-Low-Voltage, Rail-to-Rail I/O Comparators
__________________________________________________________Pin Configurations
TOP VIEW
GND
1
8
OUT
N.C. 2
7
VCC
IN+ 3
MAX965
IN- 4
OUTA
1
8
OUTB
GND 2
7
VCC
6
REF
INA+ 3
5
HYST
INA- 4
SO/µMAX
MAX966
OUTA
1
8
OUTB
GND 2
7
VCC
6
REF
5
HYST
6
INB+
INA+ 3
5
INB-
INB+ 4
(INB-)
MAX967
MAX968
SO/µMAX
SO/µMAX
OUTB 1
16 OUTC
OUTB 1
14 OUTC
OUTB 1
16 OUTC
OUTA 2
15 OUTD
OUTA 2
13 OUTD
OUTA 2
15 OUTD
14 GND
VCC 3
12 GND
VCC 3
14 GND
VCC 3
MAX969
MAX970
13 IND+
INA- 4
INA+ 5
12 IND-
INA+ 5
INB- 6
11 INC+
INB- 6
9
INB+ 7
10 INC-
INB+ 7
8
INA- 4
REF 8
9
HYST
MAX970
11 IND+
INA- 4
10 IND-
INA+ 5
12 IND-
INC+
INB- 6
11 INC+
INC-
INB+ 7
10 INC-
N.C. 8
9
SO
SO/QSOP
13 IND+
N.C.
QSOP
( ) ARE FOR MAX968 ONLY.
_Ordering Information (continued)
___________________Chip Information
TEMP. RANGE
PIN-PACKAGE
TRANSISTOR COUNTS:
MAX968ESA
-40°C to +85°C
8 SO
MAX965 = 216
MAX968EUA
MAX969ESE
MAX969EEE
MAX970ESD
MAX970EEE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
8 µMAX
16 Narrow SO
16 QSOP
14 SO
16 QSOP
MAX966 = 190
PART
MAX967/MAX968 = 299
MAX969 = 465
MAX970 = 380
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 (408) 737-7600
© 1997 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.