Maxim MAX920 Sot23, 1.8v, nanopower, beyond-the-rails comparators with/without reference Datasheet

19-1512; Rev 0; 7/99
SOT23, 1.8V, Nanopower, Beyond-the-Rails
Comparators With/Without Reference
Features
♦ Ultra-Low Supply Current
380nA per Comparator (MAX919/MAX920)
750nA per Comparator with Reference
(MAX917/MAX918)
♦ Guaranteed to Operate Down to +1.8V
♦ Internal 1.245V ±1.5% Reference
(MAX917/MAX918)
♦ Input Voltage Range Extends 200mV
Beyond-the-Rails
♦ CMOS Push/Pull Output with ±8mA Drive
Capability (MAX917/MAX919)
♦ Open-Drain Output Versions Available
(MAX918/MAX920)
♦ Crowbar-Current-Free Switching
♦ Internal Hysteresis for Clean Switching
♦ No Phase Reversal for Overdriven Inputs
♦ Space-Saving SOT23 Package
Applications
Ordering Information
2-Cell Battery Monitoring/Management
Ultra-Low-Power Systems
Mobile Communications
PART
TEMP.
RANGE
PINSOT
PACKAGE TOP MARK
MAX917EUK-T
-40°C to +85°C
5 SOT23-5
Notebooks and PDAs
MAX917ESA
-40°C to +85°C
8 SO
Threshold Detectors/Discriminators
MAX918EUK-T
-40°C to +85°C
5 SOT23-5
Sensing at Ground or Supply Line
MAX918ESA
-40°C to +85°C
8 SO
Telemetry and Remote Systems
MAX919EUK-T
-40°C to +85°C
5 SOT23-5
Medical Instruments
MAX919ESA
-40°C to +85°C
8 SO
MAX920EUK-T
-40°C to +85°C
5 SOT23-5
MAX920ESA
-40°C to +85°C
8 SO
Selector Guide
OUTPUT
TYPE
SUPPLY
CURRENT
(nA)
Yes
Push/Pull
750
Yes
Open-Drain
750
No
Push/Pull
380
No
Open-Drain
380
PART
INTERNAL
REFERENCE
MAX917
MAX918
MAX919
MAX920
Typical Application Circuit appears at end of data sheet.
—
ADIR
—
ADIS
—
ADIT
—
Pin Configurations
TOP VIEW
OUT 1
VEE 2
( ) ARE FOR MAX917/MAX918.
5
VCC
4
IN- (REF)
MAX917
MAX918
MAX919
MAX920
IN+ 3
Beyond-the-Rails is a trademark of Maxim Integrated Products.
Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd.
ADIQ
SOT23-5
Pin Configurations continue at end of data sheet.
________________________________________________________________ Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
MAX917–MAX920
General Description
The MAX917–MAX920 nanopower comparators in
space-saving SOT23 packages feature Beyond-theRails™ inputs and are guaranteed to operate down to
+1.8V. The MAX917/MAX918 feature an on-board
1.245V ±1.5% reference and draw an ultra-low supply
current of only 750nA, while the MAX919/MAX920 (without reference) require just 380nA of supply current.
These features make the MAX917–MAX920 family of
comparators ideal for all 2-cell battery applications,
including monitoring/management.
The unique design of the output stage limits supply-current surges while switching, virtually eliminating the
supply glitches typical of many other comparators. This
design also minimizes overall power consumption
under dynamic conditions. The MAX917/MAX919 have
a push/pull output stage that sinks and sources current.
Large internal output drivers allow Rail-to-Rail® output
swing with loads up to 8mA. The MAX918/MAX920
have an open-drain output stage that makes them suitable for mixed-voltage system design.
MAX917–MAX920
SOT23, 1.8V, Nanopower, Beyond-the-Rails
Comparators With/Without Reference
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (VCC to VEE)..................................................+6V
Voltage Inputs (IN+, IN-, REF) .........(VEE - 0.3V) to (VCC + 0.3V)
Output Voltage
MAX917/MAX919 ........................(VEE - 0.3V) to (VCC + 0.3V)
MAX918/MAX920 ......................................(VEE - 0.3V) to +6V
Output Current..................................................................±50mA
Output Short-Circuit Duration .............................................10sec
Continuous Power Dissipation (TA = +70°C)
5-Pin SOT23 (derate 7.31mW/°C above +70°C).........571mW
8-Pin SO (derate 5.88mW/°C above +70°C)...............471mW
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—MAX917/MAX918
(VCC = +5V, VEE = 0, VIN+ = VREF, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
Supply Voltage Range
SYMBOL
VCC
CONDITIONS
Inferred from the PSRR test
MIN
VCC = 1.8V
Supply Current
ICC
VCC = 5V
TA = TMIN to TMAX
Inferred from the output swing test
Input Offset Voltage
VOS
(Note 2)
Input-Referred Hysteresis
VHB
(Note 3)
Power-Supply Rejection Ratio
Output Voltage Swing High
PSRR
Output Short-Circuit Current
TA = +25°C
2
1
5
10
1
0.1
1
400
500
55
TA = TMIN to TMAX
TA = +25°C
mV
200
nA
mV/V
mV
300
190
TA = TMIN to TMAX
TA = +25°C
V
mV
190
TA = TMIN to TMAX
400
500
55
TA = TMIN to TMAX
MAX918 only, VO = 5.5V
Sinking, VO = VCC
µA
2
MAX917 only, VCC =
1.8V, ISOURCE = 1mA
ISC
1.30
VCC + 0.2
0.15
MAX917 only, VCC =
5V, ISOURCE = 8mA
Sourcing, VO = VEE
V
4
TA = +25°C
VOL
ILEAK
VEE - 0.2
TA = TMIN to TMAX
VCC = 1.8V to 5.5V
VCC - VOH
UNITS
5.5
1.60
TA = TMIN to TMAX
VCC = 1.8V,
ISINK = 1mA
Output Leakage Current
TA = +25°C
TA = +25°C
VCC = 5V,
ISINK = 8mA
Output Voltage Swing Low
0.80
TA = +25°C
VIN+
IB
MAX
0.75
IN+ Voltage Range
Input Bias Current
TYP
1.8
200
mV
300
0.001
VCC = 5V
95
VCC = 1.8V
8
VCC = 5V
98
VCC = 1.8V
10
_______________________________________________________________________________________
1
µA
mA
SOT23, 1.8V, Nanopower, Beyond-the-Rails
Comparators With/Without Reference
MAX917–MAX920
ELECTRICAL CHARACTERISTICS—MAX917/MAX918 (continued)
(VCC = +5V, VEE = 0, VIN+ = VREF, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
High-to-Low Propagation Delay
(Note 4)
SYMBOL
tPD-
CONDITIONS
VCC = 5V
22
tPD+
MAX918 only
VCC = 1.8V
30
VCC = 5V
95
VCC = 1.8V,
RPULL-UP = 100kΩ
35
VCC = 5V,
RPULL-UP = 100kΩ
120
Rise Time
tRISE
MAX917 only, CL = 15pF
Fall Time
tFALL
CL = 15pF
Power-Up Time
VREF
Reference Voltage Temperature
Coefficient
Reference Output
Voltage Noise
TA = +25°C
1.227
TA = TMIN to TMAX
1.200
TCREF
en
MAX
UNITS
µs
µs
6
tON
Reference Voltage
TYP
17
MAX917 only
Low-to-High Propagation Delay
(Note 4)
MIN
VCC = 1.8V
µs
4
µs
1.2
ms
1.245
1.263
1.290
95
V
ppm/°C
BW = 10Hz to 100kHz
600
BW = 10Hz to 100kHz, CREF = 1nF
215
0.1
mV/V
±0.2
mV/nA
Reference Line Regulation
∆VREF/
∆VCC
1.8V ≤ VCC ≤ 5.5V
Reference Load Regulation
∆VREF/
∆IOUT
∆IOUT = 10nA
µVRMS
ELECTRICAL CHARACTERISTICS—MAX919/MAX920
(VCC = +5V, VEE = 0, VCM = 0, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
Supply Voltage Range
SYMBOL
VCC
CONDITIONS
Inferred from the PSRR test
MIN
1.8
VCC = 1.8V
Supply Current
ICC
VCC = 5V
TA = +25°C
Inferred from the CMRR test
Input Offset Voltage
VOS
-0.2V ≤ VCM ≤
(VCC + 0.2V) (Note 2)
Input-Referred Hysteresis
VHB
-0.2V ≤ VCM ≤ (VCC + 0.2V) (Note 3)
IB
TA = TMIN to TMAX
0.45
TA = TMIN to TMAX
VCM
Input Bias Current
MAX
UNITS
5.5
V
0.80
µA
0.38
Input Common-Mode
Voltage Range
TA = +25°C
TYP
TA = +25°C
1.2
VEE - 0.2
VCC + 0.2
1
TA = TMIN to TMAX
5
10
4
0.15
V
mV
mV
1
2
nA
_______________________________________________________________________________________
3
MAX917–MAX920
SOT23, 1.8V, Nanopower, Beyond-the-Rails
Comparators With/Without Reference
ELECTRICAL CHARACTERISTICS—MAX919/MAX920 (continued)
(VCC = +5V, VEE = 0, VCM = 0, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
Input Offset Current
SYMBOL
CONDITIONS
IOS
PSRR
VCC = 1.8V to 5.5V
Common-Mode Rejection Ratio
CMRR
(VEE - 0.2V) ≤ VCM ≤ (VCC + 0.2V)
Output Voltage Swing Low
Output Leakage Current
VCC - VOH
VOL
ILEAK
TA = +25°C
MAX919 only, VCC =
1.8V, ISOURCE = 1mA
TA = +25°C
1
mV/V
0.5
3
mV/V
190
400
VCC = 1.8V,
ISINK = 1mA
TA = +25°C
ISC
tPD-
tPD+
MAX920 only
200
mV
300
190
TA = TMIN to TMAX
400
500
55
TA = TMIN to TMAX
MAX920 only, VO = 5.5V
pA
500
55
TA = TMIN to TMAX
TA = +25°C
MAX919 only
Low-to-High Propagation Delay
(Note 4)
UNITS
TA = TMIN to TMAX
VCC = 5V,
ISINK = 8mA
Sinking, VO = VCC
High-to-Low Propagation Delay
(Note 4)
MAX
0.1
MAX919 only, VCC =
5V, ISOURCE = 8mA
Sourcing, VO = VEE
Output Short-Circuit Current
TYP
10
Power-Supply Rejection Ratio
Output Voltage Swing High,
MIN
200
mV
300
0.001
VCC = 5V
95
VCC = 1.8V
8
VCC = 5V
98
VCC = 1.8V
10
VCC = 1.8V
17
VCC = 5V
22
VCC = 1.8V
30
VCC = 5V
95
VCC = 1.8V
RPULL-UP = 100kΩ
35
VCC = 5V
RPULL-UP = 100kΩ
120
1
µA
mA
µs
µs
Rise Time
tRISE
MAX919 only, CL = 15pF
6
Fall Time
tFALL
CL = 15pF
4
µs
1.2
ms
Power-Up Time
tON
µs
Note 1: All specifications are 100% tested at TA = +25°C. Specification limits over temperature (TA = TMIN to TMAX) are guaranteed
by design, not production tested.
Note 2: VOS is defined as the center of the hysteresis band at the input.
Note 3: The hysteresis-related trip points are defined as the edges of the hysteresis band, measured with respect to the center of
the band (i.e., VOS) (Figure 2).
Note 4: Specified with an input overdrive (VOVERDRIVE) of 100mV, and load capacitance of CL = 15pF. VOVERDRIVE is defined
above and beyond the offset voltage and hysteresis of the comparator input. For the MAX917/MAX918, reference voltage
error should also be added.
4
_______________________________________________________________________________________
SOT23, 1.8V, Nanopower, Beyond-the-Rails
Comparators With/Without Reference
TA = +25°C
700
TA = -40°C
600
MAX917-920 toc02
800
600
MAX917/MAX918
SUPPLY CURRENT vs. TEMPERATURE
TA = +85°C
500
TA = +25°C
400
900
850
SUPPLY CURRENT (nA)
SUPPLY CURRENT (nA)
TA = +85°C
SUPPLY CURRENT (nA)
MAX917-920 toc01
900
MAX919/MAX920
SUPPLY CURRENT vs.
SUPPLY VOLTAGE AND TEMPERATURE
MAX917-920 toc03
MAX917/MAX918
SUPPLY CURRENT vs.
SUPPLY VOLTAGE AND TEMPERATURE
VCC = 5V
800
750
VCC = 3V
700
650
VCC = 1.8V
600
TA = -40°C
550
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
1.5
5.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
-40
5.5
10
35
60
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
MAX919/MAX920
SUPPLY CURRENT vs. TEMPERATURE
MAX917/MAX918
SUPPLY CURRENT vs.
OUTPUT TRANSITION FREQUENCY
MAX919/MAX920
SUPPLY CURRENT vs.
OUTPUT TRANSITION FREQUENCY
VCC = 3V
400
VCC = 1.8V
10
VCC = 3V
8
6
VCC = 1.8V
-15
10
35
60
85
8
6
VCC = 3V
4
1
10
100
1k
10k
VCC = 1.8V
0
0
-40
10
2
2
300
VCC = 5V
12
4
350
MAX917-920 toc06
12
85
14
SUPPLY CURRENT (µA)
450
VCC = 5V
14
SUPPLY CURRENT (µA)
VCC = 5V
MAX917-920 toc05
16
MAX917-920 toc04
500
1
100k
10
100
1k
10k
100k
OUTPUT TRANSITION FREQUENCY (Hz)
OUTPUT TRANSITION FREQUENCY (Hz)
OUTPUT VOLTAGE LOW vs. SINK CURRENT
OUTPUT VOLTAGE LOW vs. SINK CURRENT
AND TEMPERATURE
MAX917/MAX919
OUTPUT VOLTAGE HIGH vs. SOURCE CURRENT
350
500
VCC = 5V
400
VOL (mV)
300
250
200
150
0.6
TA = +25°C
300
TA = +85°C
200
VCC = 1.8V
0.5
VCC = 3V
VCC - VOH (V)
VCC = 3V
MAX917-920 toc08
600
MAX917-920 toc07
VCC = 1.8V
400
VCC = 5V
MAX917-920 toc09
TEMPERATURE (°C)
450
VOL (mV)
-15
SUPPLY VOLTAGE (V)
550
SUPPLY CURRENT (nA)
500
300
500
0.4
0.3
0.2
TA = -40°C
100
100
50
0
0.1
0
0
2
4
6
8
10
SINK CURRENT (mA)
12
14
16
0
0
2
4
6
8
10
SINK CURRENT (mA)
12
14
16
0
2
4
6
8
10 12 14 16 18 20
SOURCE CURRENT (mA)
_______________________________________________________________________________________
5
MAX917–MAX920
Typical Operating Characteristics
(VCC = +5V, VEE = 0, CL = 15pF, VOVERDRIVE = 100mV, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(VCC = +5V, VEE = 0, CL = 15pF, VOVERDRIVE = 100mV, TA = +25°C, unless otherwise noted.)
TA = +25°C
TA = +85°C
0.3
0.2
TA = -40°C
0.1
80
60
VCC = 3V
40
4
6
8
-40
10 12 14 16 18 20
60
VCC = 3V
40
0
-15
10
35
60
85
VCC = 1.8V
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
OFFSET VOLTAGE vs. TEMPERATURE
HYSTERESIS VOLTAGE vs. TEMPERATURE
MAX917/MAX918
REFERENCE VOLTAGE vs. TEMPERATURE
VHB (mV)
0.07
VCC = 3V
0.06
4.0
3.5
0.05
VCC = 5V
3.0
0.04
MAX917-920 toc15
4.5
0.08
1.246
REFERENCE VOLTAGE (V)
MAX917-920 toc14
5.0
MAX917-920 toc13
VCC = 1.8V
0.09
1.245
VCC = 3V
1.244
VCC = 1.8V
1.243
1.242
VCC = 5V
-15
10
35
60
2.5
-40
85
-15
10
35
60
1.241
-40
85
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
MAX917/MAX918
REFERENCE VOLTAGE vs.
SUPPLY VOLTAGE
MAX917/MAX918
REFERENCE OUTPUT VOLTAGE vs.
REFERENCE SOURCE CURRENT
MAX917/MAX918
REFERENCE OUTPUT VOLTAGE vs.
REFERENCE SINK CURRENT
VCC = 3V
1.2435
VREF (V)
1.2455
1.2450
VCC = 1.8V
1.2430
VCC = 5V
1.2425
1.2460
MAX917-920 toc17
1.2440
MAX917-920 toc16
1.2460
VCC = 1.8V
1.2455
VREF (V)
0.03
-40
MAX917-920 toc18
VOS (mV)
80
SOURCE CURRENT (mA)
0.10
1.2450
VCC = 3V
1.2445
VCC = 5V
1.2445
1.2440
1.5
1.2420
1.2440
1.2415
2.0
2.5
3.0
3.5
4.0
4.5
SUPPLY VOLTAGE (V)
6
VCC = 5V
100
20
VCC = 1.8V
0
2
120
20
0
0
MAX917-920 toc11
100
140
SOURCE CURRENT (mA)
0.4
VCC = 5V
SINK CURRENT (mA)
0.5
VCC - VOH (V)
120
MAX917-920 toc10
0.6
MAX917/MAX919
SHORT-CIRCUIT SOURCE CURRENT
vs. TEMPERATURE
SHORT-CIRCUIT SINK CURRENT
vs. TEMPERATURE
MAX917-920 toc12
MAX917/MAX919
OUTPUT VOLTAGE HIGH vs.
SOURCE CURRENT AND TEMPERATURE
REFERENCE VOLTAGE (V)
MAX917–MAX920
SOT23, 1.8V, Nanopower, Beyond-the-Rails
Comparators With/Without Reference
5.0
5.5
1.2435
0
1
2
3
4
5
6
7
SOURCE CURRENT (nA)
8
9
10
0
1
2
3
4
5
6
7
SINK CURRENT (nA)
_______________________________________________________________________________________
8
9
10
SOT23, 1.8V, Nanopower, Beyond-the-Rails
Comparators With/Without Reference
MAX917/MAX919
PROPAGATION DELAY (tPD+)
vs. TEMPERATURE
tPD+ (µs)
VCC = 3V
10
VCC = 3V
60
VCC = 1.8V
20
-15
10
35
60
85
-40
60
85
0.1
1
10
100
CAPACITIVE LOAD (nF)
MAX917/MAX919
PROPAGATION DELAY (tPD+)
vs. CAPACITIVE LOAD
PROPAGATION DELAY (tPD-)
vs. INPUT OVERDRIVE
MAX917/MAX919
PROPAGATION DELAY (tPD+)
vs. INPUT OVERDRIVE
VCC = 3V
100
MAX917-920 toc23
70
MAX917-920 toc22
120
VCC = 1.8V
60
90
1000
VCC = 5V
80
70
VCC = 5V
VCC = 3V
tPD+ (µs)
tPD- (µs)
50
80
40
VCC = 1.8V
60
VCC = 3V
50
40
30
30
VCC = 5V
40
20
35
TEMPERATURE (°C)
140
60
10
TEMPERATURE (°C)
160
100
-15
VCC = 5V
0
0.01
0
-40
VCC = 3V
60
40
20
0
tPD+ (µs)
80
80
40
5
VCC = 1.8V
20
20
10
0
10
0.1
1
10
100
1000
0
10
20
30
40
50
0
10
20
30
40
CAPACITIVE LOAD (nF)
INPUT OVERDRIVE (mV)
INPUT OVERDRIVE (mV)
MAX918/MAX920
PROPAGATION DELAY (tPD-) vs.
PULL-UP RESISTANCE
MAX918/MAX920
PROPAGATION DELAY (tPD+) vs.
PULL-UP RESISTANCE
PROPAGATION DELAY (tPD-)
(VCC = 5V)
VCC = 1.8V
19
18
250
MAX917-920 toc25
20
tPD- (µs)
VCC = 3V
200
17
150
100
VCC = 5V
15
IN+
(50mV/
div)
VCC = 5V
OUT
(2V/div)
VCC = 3V
16
50
MAX917-920 toc27
MAX917-920 toc26
0
0.01
tPD- (µs)
VCC = 1.8V
100
MAX917-920 toc24
15
VCC = 5V
100
VCC = 5V
20
tPD- (µs)
120
MAX917-920 toc21
VCC = 1.8V
120
tPD- (µs)
25
140
MAX917-920 toc19
30
PROPAGATION DELAY (tPD-)
vs. CAPACITIVE LOAD
MAX917-920 toc20
PROPAGATION DELAY (tPD-)
vs. TEMPERATURE
MAX917–MAX920
Typical Operating Characteristics (continued)
(VCC = +5V, VEE = 0, CL = 15pF, VOVERDRIVE = 100mV, TA = +25°C, unless otherwise noted.)
50
VCC = 1.8V
14
0
10
100
1k
RPULL-UP (kΩ)
10k
10
100
1k
10k
20µs/div
RPULL-UP (kΩ)
_______________________________________________________________________________________
7
MAX917–MAX920
SOT23, 1.8V, Nanopower, Beyond-the-Rails
Comparators With/Without Reference
Typical Operating Characteristics (continued)
(VCC = +5V, VEE = 0, CL = 15pF, VOVERDRIVE = 100mV, TA = +25°C, unless otherwise noted.)
MAX917/MAX919
PROPAGATION DELAY (tPD+)
(VCC = 5V)
MAX917-920 toc29
MAX917-920 toc28
MAX917-920 toc30
IN+
(50mV/
div)
IN+
(50mV/
div)
OUT
(2V/div)
IN+
(50mV/
div)
OUT
(2V/div)
OUT
(2V/div)
20µs/div
20µs/div
20µs/div
PROPAGATION DELAY (tPD-)
(VCC = 1.8V)
MAX917/MAX919
PROPAGATION DELAY (tPD+)
(VCC = 1.8V)
MAX917/MAX919
10kHz RESPONSE (VCC = 1.8V)
MAX917-920 toc31
MAX917-920 toc32
MAX917-920 toc33
IN+
(50mV/
div)
IN+
(50mV/
div)
IN+
(50mV/
div)
OUT
(1V/div)
OUT
(1V/div)
OUT
(1V/div)
20µs/div
20µs/div
20µs/div
MAX917/MAX919
1kHz RESPONSE (VCC = 5V)
POWER-UP/DOWN RESPONSE
MAX917-920 toc34
200µs/div
8
MAX917/MAX919
PROPAGATION DELAY (tPD+)
(VCC = 3V)
PROPAGATION DELAY (tPD-)
(VCC = 3V)
MAX917-920 toc35
IN+
(50mV/div)
VCC
(2V/div)
OUT
(2V/div)
OUT
(2V/div)
40µs/div
_______________________________________________________________________________________
SOT23, 1.8V, Nanopower, Beyond-the-Rails
Comparators With/Without Reference
VCC
VCC
IN+
IN+
OUT
OUT
REF
IN-
MAX919
MAX920
MAX917
MAX918
REF
1.245V
VEE
VEE
Pin Description
PIN
MAX917/MAX918
MAX919/MAX920
NAME
FUNCTION
SOT23-5
SO
SOT23-5
SO
1
6
1
6
OUT
Comparator Output
2
4
2
4
VEE
Negative Supply Voltage
3
3
3
3
IN+
Comparator Noninverting Input
—
—
4
2
IN-
Comparator Inverting Input
4
2
—
—
REF
1.245V Reference Output and Comparator Inverting Input
5
7
5
7
VCC
Positive Supply Voltage
—
1, 5, 8
—
1, 5, 8
N.C.
No Connection. Not internally connected.
Detailed Description
The MAX917/MAX918 feature an on-board 1.245V
±1.5% reference, yet draw an ultra-low supply current
of 750nA. The MAX919/MAX920 (without reference)
consume just 380nA of supply current. All four devices
are guaranteed to operate down to +1.8V. Their common-mode input voltage range extends 200mV
beyond-the-rails. Internal hysteresis ensures clean output switching, even with slow-moving input signals.
Large internal output drivers allow rail-to-rail output
swing with up to ±8mA loads.
The output stage employs a unique design that minimizes supply-current surges while switching, virtually
eliminating the supply glitches typical of many other
comparators. The MAX917/MAX919 have a push/pull
output stage that sinks as well as sources current. The
MAX918/MAX920 have an open-drain output stage that
can be pulled beyond VCC to an absolute maximum of
6V above VEE. These open-drain versions are ideal for
implementing wire-Or output logic functions.
Input Stage Circuitry
The input common-mode voltage range extends from
VEE - 0.2V to VCC + 0.2V. These comparators operate
at any differential input voltage within these limits. Input
bias current is typically ±0.15nA if the input voltage is
between the supply rails. Comparator inputs are protected from overvoltage by internal ESD protection
diodes connected to the supply rails. As the input voltage exceeds the supply rails, these ESD protection
diodes become forward biased and begin to conduct.
_______________________________________________________________________________________
9
MAX917–MAX920
Functional Diagrams
MAX917–MAX920
SOT23, 1.8V, Nanopower, Beyond-the-Rails
Comparators With/Without Reference
Output Stage Circuitry
The MAX917–MAX920 contain a unique break-beforemake output stage capable of rail-to-rail operation with
up to ±8mA loads. Many comparators consume orders
of magnitude more current during switching than during steady-state operation. However, with this family of
comparators, the supply-current change during an output transition is extremely small. In the Typical Operating Characteristics, the Supply Current vs. Output
Transition Frequency graphs show the minimal supplycurrent increase as the output switching frequency
approaches 1kHz. This characteristic reduces the need
for power-supply filter capacitors to reduce glitches
created by comparator switching currents. In batterypowered applications, this characteristic results in a
substantial increase in battery life.
VCC
120nA
REF
VEE
Figure 1. MAX917/MAX918 Voltage Reference Output
Equivalent Circuit
Reference (MAX917/MAX918)
The internal reference in the MAX917/MAX918 has an
output voltage of +1.245V with respect to VEE. Its typical temperature coefficient is 95ppm/°C over the full
-40°C to +85°C temperature range. The reference is a
PNP emitter-follower driven by a 120nA current source
(Figure 1). The output impedance of the voltage reference is typically 200kΩ, preventing the reference from
driving large loads. The reference can be bypassed
with a low-leakage capacitor. The reference is stable
for any capacitive load. For applications requiring a
lower output impedance, buffer the reference with a
low-input-leakage op amp, such as the MAX406.
Applications Information
Low-Voltage, Low-Power Operation
The MAX917–MAX920 are ideally suited for use with most
battery-powered systems. Table 1 lists a variety of battery
types, capacities, and approximate operating times for
the MAX917–MAX920, assuming nominal conditions.
Internal 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 MAX917–MAX920 have internal hysteresis to
counter parasitic effects and noise.
The hysteresis in a comparator creates two trip points:
one for the rising input voltage (VTHR) and one for the
falling input voltage (VTHF) (Figure 2). The difference
between the trip points is the hysteresis (VHB). When
the comparator’s input voltages are equal, the hysteresis effectively causes one comparator input to move
quickly past the other, thus taking the input out of the
region where oscillation occurs. 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.
Table 1. Battery Applications Using MAX917–MAX920
BATTERY
TYPE
RECHARGEABLE
VFRESH
(V)
VEND-OF-LIFE
(V)
CAPACITY,
AA SIZE
(mA-h)
MAX917/MAX918
OPERATING TIME
(hr)
MAX919/MAX920
OPERATING TIME
(hr)
Alkaline
(2 Cells)
No
3.0
1.8
2000
2.5 x 106
5 x 106
Nickel-Cadmium
(2 Cells)
Yes
2.4
1.8
750
937,500
1.875 x 106
Lithium-Ion
(1 Cell)
Yes
3.5
2.7
1000
1.25 x 106
2.5 x 106
Nickel-MetalHydride
(2 Cells)
Yes
2.4
1.8
1000
1.25 x 106
2.5 x 106
10
______________________________________________________________________________________
SOT23, 1.8V, Nanopower, Beyond-the-Rails
Comparators With/Without Reference
MAX917–MAX920
VCC
THRESHOLDS
IN+
R3
VTHR
R1
HYSTERESIS
INVHB
VIN
VCC
BAND
R2
OUT
VEE
VTHF
MAX917
MAX919
VREF
OUT
Figure 2. Threshold Hysteresis Band
Additional Hysteresis (MAX917/MAX919)
The MAX917/MAX919 have a 4mV internal hysteresis
band (VHB). Additional hysteresis can be generated
with three resistors using positive feedback (Figure 3).
Unfortunately, this method also slows hysteresis response time. Use the following procedure to calculate
resistor values.
1) Select R3. Leakage current at IN is under 2nA, so
the current through R3 should be at least 0.2µA to
minimize errors caused by leakage current. The current through R3 at the trip point is (VREF - VOUT)/R3.
Considering the two possible output states in solving
for R3 yields two formulas: R3 = VREF/IR3 or R3 =
(VCC - VREF)/IR3. Use the smaller of the two resulting
resistor values. For example, when using the
MAX917 (VREF = 1.245V) and VCC = 5V, and if we
choose IR3 = 1µA, then the two resistor values are
1.2MΩ and 3.8MΩ. Choose a 1.2MΩ standard value
for R3.
2) Choose the hysteresis band required (VHB). For this
example, choose 50mV.
3) Calculate R1 according to the following equation:
R1 = R3 (VHB / VCC)
For this example, insert the values
R1 = 1.2MΩ (50mV/5V) = 12kΩ
4) Choose the trip point for VIN rising (VTHR) such that
VTHR > VREF · (R1 + R3)/R3 (VTHF is the trip point for
VIN falling). This is the threshold voltage at which the
comparator switches its output from low to high as
V IN rises above the trip point. For this example,
choose 3V.
5) Calculate R2 as follows:
R2 = 1/[VTHR/(VREF · R1) - (1 / R1) - (1 / R3)]
Figure 3. MAX917/MAX919 Additional Hysteresis
R2 = 1/[3.0V/(1.2V · 12kΩ) - (1 / 12kΩ) (1/1.2MΩ)] = 8.05kΩ
For this example, choose an 8.2kΩ standard value.
6) Verify the trip voltages and hysteresis as follows:
VIN rising: VTHR = VREF · R1 [(1 / R1) + (1 / R2)
+ (1 / R3)]
VIN falling: VTHF = VTHR - (R1 · VCC / R3)
Hysteresis = VTHR - VTHF
Additional Hysteresis (MAX918/MAX920)
The MAX918/MAX920 have a 4mV internal hysteresis
band. They have open-drain outputs and require an
external pull-up resistor (Figure 4). Additional hysteresis can be generated using positive feedback, but the
formulas differ slightly from those of the MAX917/
MAX919. Use the following procedure to calculate
resistor values.
1) Select R3 according to the formulas R3 = VREF / 1µA
or R3 = (VCC - VREF)/1µA - R4. Use the smaller of
the two resulting resistor values.
2) Choose the hysteresis band required (VHB).
3) Calculate R1 according to the following equation:
R1 = (R3 + R4) (VHB/VCC)
4) Choose the trip point for VIN rising (VTHR) (VTHF is
the trip point for VIN falling). This is the threshold
voltage at which the comparator switches its output
from low to high as VIN rises above the trip point.
5) Calculate R2 as follows:

 1 1 

R2 = 1/ VTHR / VREF ⋅ R1 −   −

 R1 R3 

(
)
______________________________________________________________________________________
11
MAX917–MAX920
SOT23, 1.8V, Nanopower, Beyond-the-Rails
Comparators With/Without Reference
Zero-Crossing Detector
6) Verify the trip voltages and hysteresis as follows:
⋅ R1 
VIN rising:VTHR = VREF
Figure 5 shows a zero-crossing detector application.
The MAX919’s inverting input is connected to ground,
and its noninverting input is connected to a 100mVp-p
signal source. As the signal at the noninverting input
crosses 0V, the comparator’s output changes state.
1
1
1
+
+

R1 R2 R3 
VIN falling:VTHF =
VREF
 1
⋅ R1 
+
1
 R1 R2
+

R1
−
R3 + R4  R3 + R4
1
⋅
VCC
Hysteresis = VTHR - VTHF
Board Layout and Bypassing
Power-supply bypass capacitors are not typically
needed, but use 100nF bypass capacitors close to the
device’s supply pins when supply impedance is high,
supply leads are long, or excessive noise is expected
on the supply lines. Minimize signal trace lengths to
reduce stray capacitance. A ground plane and surface-mount components are recommended.
Logic-Level Translator
The Typical Application Circuit shows an application
that converts 5V logic to 3V logic levels. The MAX920 is
powered by the +5V supply voltage, and the pull-up
resistor for the MAX920’s open-drain output is connected to the +3V supply voltage. This configuration allows
the full 5V logic swing without creating overvoltage on
the 3V logic inputs. For 3V to 5V logic-level translations,
simply connect the +3V supply voltage to VCC and the
+5V supply voltage to the pull-up resistor.
VCC
VCC
100mVp-p
VCC
IN+
R3
OUT
R1
R4
VIN
VCC
R2
IN-
OUT
MAX919
VEE
VREF
VEE
MAX918
MAX920
Figure 5. Zero-Crossing Detector
Typical Application Circuit
Figure 4. MAX918/MAX920 Additional Hysteresis
+5V (+3V)
Pin Configurations (continued)
+3V (+5V)
TOP VIEW
100k
VCC
RPULL-UP
IN-
N.C. 1
IN- (REF) 2
IN+ 3
8
MAX917
MAX918
MAX919
MAX920
VEE 4
N.C.
7
VCC
6
OUT
5
N.C.
OUT
100k
3V (5V)
LOGIC OUT
IN+
MAX920
VEE
SO
5V (3V) LOGIC IN
( ) ARE FOR MAX917/MAX918.
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.
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© 1999 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.