Intersil ISL28488 Dual and quad micropower single supply rail-to-rail input and output (rrio) op-amp Datasheet

ISL28288, ISL28488
®
Data Sheet
June 28, 2007
Dual and Quad Micropower Single Supply
Rail-to-Rail Input and Output (RRIO)
Op-Amp
The ISL28288 and ISL28488 are dual and quad channel
micropower operational amplifiers optimized for single
supply operation over the 2.4V to 5V range. They can be
operated from one lithium cell or two Ni-Cd batteries. For
equivalent performance in a single channel op-amp
reference EL8188.
These devices feature an Input Range Enhancement Circuit
(IREC) which enables them to maintain CMRR performance
for input voltages 10% above the positive supply rail and to
100mV below the negative supply. The output operation is
rail to rail.
The ISL28288 and ISL28488 draw minimal supply current
while meeting excellent DC-accuracy, AC-performance,
noise and output drive specifications. The ISL28288
contains a power down enable pin that reduces the power
supply current to typically less than 4µA in the disabled
state.
FN6339.1
Features
• Low power 120µA typical supply current
• 1.5mV max offset voltage
• 30pA max input bias current
• 300kHz typical gain-bandwidth product
• 105dB typical PSRR
• 100dB typical CMRR
• Single supply operation down to 2.4V
• Input is capable of swinging above V+ and below V(ground sensing)
• Rail-to-rail input and output (RRIO)
• Enable Pin (ISL28288 only)
• Pb-free plus anneal available (RoHS compliant)
Applications
• Battery- or solar-powered systems
• 4mA to 25mA current loops
Pinouts
• Handheld consumer products
ISL28288
(10 LD MSOP)
TOP VIEW
IN+_A 1
• Photodiode pre-amps
9 OUT_A
• pH probe amplifiers
8 V+
Ordering Information
V- 3
+
-
EN_B 4
• Thermocouple amplifiers
10 IN-_A
+
EN_A 2
• Medical devices
7 OUT_B
IN+_B 5
6 IN-_B
ISL28488
(16 LD QSOP)
TOP VIEW
OUT_A 1
16 OUT_D
15 IN-_D
IN-_A 2
+
+
IN+_A 3
14 IN+_D
V+ 4
13 V-
IN+_B 5
+
-
+
-
IN-_B 6
12 IN+_C
11 IN-_C
PART NUMBER
(Note)
PART
MARKING
PACKAGE
(Pb-Free)
PKG. DWG.
#
ISL28288FUZ
8288Z
10 Ld MSOP
MDP0043
ISL28288FUZ-T7
8288Z
10 Ld MSOP
MDP0043
ISL28488FAZ
28488 FAZ
16 Ld QSOP
MDP0040
ISL28488FAZ-T7
28488 FAZ
16 Ld QSOP
MDP0040
*“-T7” suffix is for tape and reel. Please refer to TB347 for details on
reel specifications.
NOTE: Intersil Pb-free plus anneal products employ special Pb-free
material sets; molding compounds/die attach materials and 100%
matte tin plate termination finish, which are RoHS compliant and
compatible with both SnPb and Pb-free soldering operations.
Intersil Pb-free products are MSL classified at Pb-free peak reflow
temperatures that meet or exceed the Pb-free requirements of
IPC/JEDEC J STD-020.
10 OUT_C
OUT_B 7
NC 8
9 NC
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright Intersil Americas Inc. 2006, 2007. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
ISL28288, ISL28488
Absolute Maximum Ratings (TA = +25°C)
Thermal Information
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.5V
Supply Turn On Voltage Slew Rate . . . . . . . . . . . . . . . . . . . . . 1V/μs
Differential Input Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5mA
Differential Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5V
Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . V- - 0.5V to V+ + 0.5V
ESD Tolerance
Human Body Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3kV
Machine Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .300V
Thermal Resistance
θJA (°C/W)
10 Ld MSOP Package . . . . . . . . . . . . . . . . . . . . . . .
115
16 Ld QSOP Package . . . . . . . . . . . . . . . . . . . . . . .
112
Output Short-Circuit Duration . . . . . . . . . . . . . . . . . . . . . . .Indefinite
Ambient Operating Temperature Range . . . . . . . . .-40°C to +125°C
Storage Temperature Range . . . . . . . . . . . . . . . . . .-65°C to +150°C
Operating Junction Temperature . . . . . . . . . . . . . . . . . . . . . +125°C
Pb-free reflow profile . . . . . . . . . . . . . . . . . . . . . . . . . .see link below
http://www.intersil.com/pbfree/Pb-FreeReflow.asp
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact product reliability and
result in failures not covered by warranty.
IMPORTANT NOTE: All parameters having Min/Max specifications are guaranteed. Typical values are for information purposes only. Unless otherwise noted, all tests
are at the specified temperature and are pulsed tests, therefore: TJ = TC = TA
Operating Junction
Electrical Specifications
PARAMETER
V+ = 5V, V- = 0V, VCM = 2.5V, RL = Open, TA = +25°C unless otherwise specified.
Boldface limits apply over the operating temperature range, -40°C to +125°C. Temperature data
established by characterization
DESCRIPTION
CONDITIONS
MIN
(Note 1)
TYP
MAX
(Note 1)
UNIT
DC SPECIFICATIONS
VOS
Input Offset Voltage
ΔV OS
-----------------ΔTime
Long Term Input Offset Voltage Stability
ΔV OS
---------------ΔT
Input Offset Voltage vs Temperature
IOS
Input Offset Current
IB
-1.5
-2
ISL28288
±0.05
1.5
2
mV
1.2
µV/Mo
0.9
µV/°C
-30
-80
±5
30
80
pA
-40°C to +85°C
-30
-80
±10
30
80
pA
-40°C to +85°C
5
V
Input Bias Current
CMIR
Common-Mode Voltage Range
Guaranteed by CMRR
0
CMRR
Common-Mode Rejection Ratio
VCM = 0V to 5V
80
75
100
dB
PSRR
Power Supply Rejection Ratio
V+ = 2.4V to 5V
85
80
105
dB
AVOL
Large Signal Voltage Gain
VO = 0.5V to 4.5V, RL = 100kΩ
200
190
300
V/mV
VO = 0.5V to 4.5V, RL = 1kΩ
60
V/mV
Output low, RL = 100kΩ
3
6
30
mV
130
175
225
mV
VOUT
Maximum Output Voltage Swing
Output low, RL = 1kΩ
IS,ON
Quiescent Supply Current, Enabled
2
Output high, RL = 100kΩ
4.990
4.97
4.996
V
Output high, RL = 1kΩ
4.800
4.750
4.880
V
ISL28288, All channels enabled.
120
156
175
µA
ISL28488, All channels enabled.
240
315
350
µA
FN6339.1
June 28, 2007
ISL28288, ISL28488
Electrical Specifications
PARAMETER
V+ = 5V, V- = 0V, VCM = 2.5V, RL = Open, TA = +25°C unless otherwise specified.
Boldface limits apply over the operating temperature range, -40°C to +125°C. Temperature data
established by characterization (Continued)
DESCRIPTION
CONDITIONS
MIN
(Note 1)
TYP
4
MAX
(Note 1)
7
9
UNIT
IS,OFF
Quiescent Supply Current, Disabled
(ISL28288)
All channels disabled.
IO+
Short Circuit Sourcing Capability
RL = 10Ω
29
24
31
mA
IO-
Short Circuit Sinking Capability
RL = 10Ω
24
20
26
mA
VSUPPLY
Supply Operating Range
V+ to V-
2.4
VENH
EN Pin High Level (ISL28288)
VENL
EN Pin Low Level (ISL28288)
IENH
EN Pin Input High Current (ISL28288)
VEN = V+
IENL
EN Pin Input Low Current (ISL28288)
VEN = V-
5.0
2
µA
V
V
0.8
V
0.8
1
1.5
µA
0
+0.1
µA
AC SPECIFICATIONS
GBW
Gain Bandwidth Product
AV = 100, RF = 100kΩ, RG = 1kΩ,
RL = 10kΩ to VCM
300
kHz
en
Input Noise Voltage Peak-to-Peak
f = 0.1Hz to 10Hz
5.4
µVP-P
Input Noise Voltage Density
fO = 1kHz
48
nV/√Hz
in
Input Noise Current Density
fO = 1kHz
0.1
pA/√Hz
CMRR @ 60Hz
Input Common Mode Rejection Ratio
VCM = 1VP-P, RL = 10kΩ to VCM
-70
dB
PSRR+ @
120Hz
Power Supply Rejection Ratio (V+)
V+, V- = ±1.2V and ±2.5V,
VSOURCE = 1VP-P, RL = 10kΩ to VCM
-80
dB
PSRR- @
120Hz
Power Supply Rejection Ratio (V-)
V+, V- = ±1.2V and ±2.5V
VSOURCE = 1VP-P, RL = 10kΩ to VCM
-60
dB
TRANSIENT RESPONSE
±0.12
±0.09
±0.14
±0.16
±0.21
V/µs
SR
Slew Rate
tEN
Enable to Output Turn-on Delay Time,
10% EN to 10% Vout, (ISL28288)
VEN = 5V to 0V, AV = -1,
RG = RF = RL = 1k to VCM
2
µs
Enable to Output Turn-off Delay Time,
10% EN to 10% Vout, (ISL28288)
VEN = 0V to 5V, AV = -1,
RG = RF = RL = 1k to VCM
0.1
µs
NOTE:
1. Parts are 100% tested at +25°C. Over temperature limits established by characterization and are not production tested.
3
FN6339.1
June 28, 2007
ISL28288, ISL28488
Typical Performance Curves V+ = 5V, V- = 0V, VCM = 2.5V, RL = Open
+1
45
35
V+, V- = ±1.2V
RL = 10k
30
GAIN (dB)
-2
GAIN (dB)
40
V+, V- = ±1.2V
RL = 1k
V+, V-= ±2.5V
RL = 1k
-1
V+, V- = ±2.5V
RL = 10k
-3
-4
100k
FREQUENCY (Hz)
1M
AV = 100
15 RL = 10kΩ
CL = 3pF
10 R = 100kΩ
F
RG = 1kΩ
5
0
100
5M
80
80
40
40
0
-40
0
-80
100
10k
1k
100k
10k
100k
1M
FIGURE 2. FREQUENCY RESPONSE vs SUPPLY VOLTAGE
1M
-120
10M
200
150
80
PHASE
100
60
50
40
0
20
-80
-40
10
1k
100
PHASE (°)
120
GAIN
-50
0
-100
-20
10
100
10k
1k
100k
-150
1M
FREQUENCY (Hz)
FREQUENCY (Hz)
FIGURE 3. AVOL vs FREQUENCY @ 100kΩ LOAD
FIGURE 4. AVOL vs FREQUENCY @ 1kΩ LOAD
10
10
V+ = 5VDC
VSOURCE = 1VP-P
-10 R = 10kΩ
L
-20 A = +1
V
-30
PSRR -40
0
0
-10
-20
CMRR (dB)
PSRR (dB)
GAIN (dB)
FIGURE 1. FREQUENCY RESPONSE vs SUPPLY VOLTAGE
1
V+, V- = ±1.0V
FREQUENCY (Hz)
GAIN (dB)
10k
V+, V- = ±1.2V
20
-5 VOUT = 50mVP-P
AV = 1
-6 C = 3pF
L
RF = 0, RG = INF
-7
8
1k
V+, V- = ±2.5V
25
PHASE (°)
0
-50
-60
PSRR +
V+, V- = ±2.5VDC
VSOURCE = 1VP-P
RL = 10kΩ
-30
-40
-50
-60
-70
-70
-80
-80
-90
-90
-100
10
100
1k
10k
100k
FREQUENCY (Hz)
FIGURE 5. PSRR vs FREQUENCY
4
1M
-100
10
100
1k
10k
100k
1M
FREQUENCY (Hz)
FIGURE 6. CMRR vs FREQUENCY
FN6339.1
June 28, 2007
ISL28288, ISL28488
Typical Performance Curves V+ = 5V, V- = 0V, VCM = 2.5V, RL = Open
1k
VOLTAGE NOISE (nV/√Hz)
CURRENT NOISE (pA/√Hz)
10.00
(Continued)
1.00
0.10
0.01
1
10
100
1k
10k
100
10
1
100k
1
10
1k
100
FREQUENCY (Hz)
10k
100k
FREQUENCY (Hz)
FIGURE 7. CURRENT NOISE vs FREQUENCY
FIGURE 8. VOLTAGE NOISE vs FREQUENCY
2.56
VIN
VOLTAGE NOISE (1µV/DIV)
2.54
2.52
VOUT
VOLTS (V)
2.50
2.48
V+ = 5VDC
VOUT = 0.1VP-P
2.46
RL = 1kΩ
2.44
5.4µVP-P
AV = +1
2.42
0
2
4
6
8
TIME (1s/DIV)
10
12
14
16
18
20
TIME (µs)
FIGURE 9. 0.1Hz TO 10Hz INPUT VOLTAGE NOISE
FIGURE 10. SMALL SIGNAL TRANSIENT RESPONSE
5.0
V+ = 5VDC
VOUT = 2VP-P
RL = 1kΩ
AV = -2
3.0
2.0
0
VIN
1.0
VOUT
0.1V/DIV
VOLTS (V)
AV = -1
VIN = 200mVP-P
V+ = 5V
V- = 0V
EN
INPUT
VOUT
1V/DIV
4.0
0
0
50
100
150
200
250
TIME (µs)
FIGURE 11. LARGE SIGNAL TRANSIENT RESPONSE
5
0
10µs/DIV
FIGURE 12. ENABLE TO OUTPUT DELAY TIME
FN6339.1
June 28, 2007
ISL28288, ISL28488
Typical Performance Curves V+ = 5V, V- = 0V, VCM = 2.5V, RL = Open
80
600
60
400
40
I-BIAS (pA)
100
800
VOS (µV)
1000
200
0
-200
-400
-800
-1000
-1
0
1
2
3
VCM (V)
4
-80
5
6
0
1
5
6
n = 12
4.6
MAX
CURRENT (µA)
270
MEDIAN
250
230
MIN
210
4.4
MAX
4.2
MEDIAN
4
3.8
3.6
MIN
3.4
190
-20
0
20
40
60
80
100
3.2
120
-40
-20
0
TEMPERATURE (°C)
FIGURE 15. ISL28488 SUPPLY CURRENT vs TEMPERATURE
V+, V- = ±2.5V ENABLED, RL = INF
N = 1000
20
40
60
80
TEMPERATURE (°C)
100
120
FIGURE 16. ISL28288 SUPPLY CURRENT vs TEMPERATURE
V+, V- = ±2.5V DISABLED, RL = INF
2
MAX
1.5
N = 1000
MAX
1.5
1
1
0.5
VOS (mV)
VOS (mV)
4
4.8
N = 1000
290
2
2
3
VCM (V)
FIGURE 14. INPUT BIAS CURRENT vs COMMON-MODE
INPUT VOLTAGE
310
CURRENT (µA)
0
-20
-100
-1
350
170
-40
20
-60
FIGURE 13. INPUT OFFSET VOLTAGE vs COMMON MODE
INPUT VOLTAGE
330
V+ = 5V
RL = OPEN
RF= 100k, RG = 100
AV = +1000
-40
V+ = 5V
RL = OPEN
RF = 100k, RG = 100
AV = +1000
-600
(Continued)
MEDIAN
0
-0.5
-1
0.5
MEDIAN
0
-0.5
-1
MIN
-1.5
MIN
-1.5
-2
-2
-2.5
-2.5
-40
-20
0
20
40
60
80
100
120
TEMPERATURE (°C)
FIGURE 17. VOS vs TEMPERATURE, VIN = 0V, V+, V- = ±2.5V
6
-40
-20
0
20
40
60
80
100
120
TEMPERATURE (°C)
FIGURE 18. VOS vs TEMPERATURE VIN = 0V, V+, V- = ±1.2V
FN6339.1
June 28, 2007
ISL28288, ISL28488
Typical Performance Curves V+ = 5V, V- = 0V, VCM = 2.5V, RL = Open
(Continued)
200
500
n = 1000
n = 1000
0
0
IBIAS- (pA)
IBIAS+ (pA)
-200
-500
MAX
-1000
-1500
-2000
-20
0
20
40
60
80
-800
MEDIAN
-1200
MIN
-40
MAX
-600
-1000
MEDIAN
-2500
-400
100
-1400
120
MIN
-40
-20
0
TEMPERATURE (°C)
FIGURE 19. IBIAS+ vs TEMPERATURE V+, V- = ±2.5V
40
60
80
n = 1000
0
0
-200
IBIAS- (pA)
-500
MAX
-1000
-1500
MAX
-400
-600
-800
MEDIAN
-2000
MEDIAN
-1000
MIN
-40
-20
0
20
40
60
80
MIN
100
-1200
-40
120
-20
0
TEMPERATURE (°C)
20
40
60
80
100
120
TEMPERATURE (°C)
FIGURE 22. IBIAS- vs TEMPERATURE V+, V- = ±-1.2V
FIGURE 21. IBIAS+ vs TEMPERATURE V+, V- = ±1.2V
200
650
n = 1000
600
0
AVOL (V/mV)
-400
MAX
-600
-800
500
450
400
MEDIAN
350
300
MEDIAN
-1000
MAX
n = 1000
550
-200
IOS (pA)
120
200
n = 1000
-2500
100
FIGURE 20. IBIAS- vs TEMPERATURE V+, V- = ±2.5V
500
IBIAS+ (pA)
20
TEMPERATURE (°C)
250
-1200
-1400
-40
200
MIN
-20
0
20
40
60
80
100
TEMPERATURE (°C)
FIGURE 23. IOS vs TEMPERATURE V+, V- = ±2.5V
7
120
150
MIN
-40
-20
0
20
40
60
80
100
120
TEMPERATURE (°C)
FIGURE 24. AVOL vs TEMPERATURE V+, V- = ±2.5V, RL=100k
FN6339.1
June 28, 2007
ISL28288, ISL28488
Typical Performance Curves V+ = 5V, V- = 0V, VCM = 2.5V, RL = Open
90
(Continued)
135
80
MAX
n = 1000
n = 1000
125
70
CMRR (dB)
AVOL (V/mV)
MAX
MEDIAN
60
50
30
-40
-20
0
20
105
MEDIAN
95
MIN
MIN
40
115
85
40
60
80
100
75
120
-40
-20
0
20
40
60
80
100
120
TEMPERATURE (°C)
TEMPERATURE (°C)
FIGURE 25. AVOL vs TEMPERATURE, V+, V- = ±2.5V, RL=1k
FIGURE 26. CMRR vs TEMPERATURE VCM = +2.5V TO -2.5V,
V+, V- = ±2.5V
4.91
140
n = 1000
n = 1000
MAX
MAX
4.90
130
110
VOUT (V)
PSRR (dB)
4.89
120
MEDIAN
100
MEDIAN
4.87
4.86
MIN
MIN
90
80
4.88
4.85
-40
-20
0
20
40
60
80
100
4.84
-40
120
-20
0
TEMPERATURE (°C)
FIGURE 27. PSRR vs TEMPERATURE, V+, V- = ±1.2V TO ±2.75V
100
120
100
120
160
MAX
150
4.9976
VOUT (mV)
VOUT (V)
80
n = 1000
MAX
4.9978
4.9972
60
170
n = 12
4.9980
4.9974
40
FIGURE 28. VOUT HIGH vs TEMPERATURE,
V+, V- = ±2.5V, RL= 1k
4.9984
4.9982
20
TEMPERATURE (°C)
MEDIAN
MIN
4.9970
MEDIAN
130
120
4.9968
MIN
110
4.9966
4.9964
-40
140
-20
0
20
40
60
80
TEMPERATURE (°C)
FIGURE 29. VOUT HIGH vs TEMPERATURE,
V+, V- = ±2.5V, RL= 100k
8
100
120
100
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
FIGURE 30. VOUT LOW vs TEMPERATURE,
V+, V- = ±2.5V, RL= 1k
FN6339.1
June 28, 2007
ISL28288, ISL28488
4.3
+OUTPUT SHORT CIRCUIT CURRENT
(mA)
Typical Performance Curves V+ = 5V, V- = 0V, VCM = 2.5V, RL = Open
n = 12
4.2
4.1
VOUT (mV)
4.0
3.9
MAX
MEDIAN
3.8
3.7
MIN
3.6
3.5
3.4
-40
-20
0
20
40
60
80
100
(Continued)
39
n = 1000
37
35
MAX
33
31
MEDIAN
29
MIN
27
25
120
-40
-20
0
TEMPERATURE (°C)
40
60
80
100
120
FIGURE 32. +OUTPUT SHORT CIRCUIT CURRENT vs
TEMPERATURE VIN = +2.5V, RL = 10,
V+, V- = ±2.5V
FIGURE 31. VOUT LOW vs TEMPERATURE,
V+, V- = ±2.5V, RL= 100k
-OUTPUT SHORT CIRCUIT CURRENT
(mA)
20
TEMPERATURE (°C)
-21
n = 1000
-23
MAX
-25
-27
MEDIAN
-29
MIN
-31
-33
-40
-20
0
20
40
60
80
100
120
TEMPERATURE (°C)
FIGURE 33. -OUTPUT SHORT CIRCUIT CURRENT vs TEMPERATURE VIN = -2.5V, RL = 10, V+, V- = ±2.5V
Pin Descriptions
ISL28288
ISL28488
(10 LD MSOP) (16 LD QSOP)
1
3
2
3
13
4
PIN NAME
EQUIVALENT
CIRCUIT
IN+_A
Circuit 1
Amplifier A non-inverting input
EN_A
Circuit 2
Amplifier A enable pin internal pull-down; Logic “1” selects the disabled state;
Logic “0” selects the enabled state.
V-
Circuit 4
Negative power supply
EN_B
Circuit 2
Amplifier B enable pin with internal pull-down; Logic “1” selects the disabled state;
Logic “0” selects the enabled state.
DESCRIPTION
5
5
IN+_B
Circuit 1
Amplifier B non-inverting input
6
6
IN-_B
Circuit 1
Amplifier B inverting input
7
7
OUT_B
Circuit 3
Amplifier B output
8
4
V+
Circuit 4
Positive power supply
9
1
OUT_A
Circuit 3
Amplifier A output
10
2
IN-_A
Circuit 1
Amplifier A inverting input
9
FN6339.1
June 28, 2007
ISL28288, ISL28488
Pin Descriptions (Continued)
ISL28288
ISL28488
(10 LD MSOP) (16 LD QSOP)
PIN NAME
EQUIVALENT
CIRCUIT
10
OUT_C
Circuit 3
Amplifier C output
11
IN-_C
Circuit 1
Amplifier C inverting input
12
IN+_C
Circuit 1
Amplifier C non-inverting input
14
IN+_D
Circuit 1
Amplifier D non-inverting input
15
IN-_D
Circuit 1
Amplifier D inverting input
16
OUT_D
Circuit 3
Amplifier D output
8, 9
NC
-
DESCRIPTION
No internal connection
V+
V+
IN-
IN+
V+
LOGIC
PIN
V-
VCIRCUIT 2
Applications Information
Introduction
The ISL28288 and ISL28488 are dual and quad CMOS
rail-to-rail input, output (RRIO) micropower operational
amplifiers. These devices are designed to operate from a
single supply (2.4V to 5.0V) or dual supplies (±1.2V to
±2.5V) while drawing only 120μA of supply current. This
combination of low power and precision performance makes
these devices suitable for solar and battery power
applications.
Rail-to-Rail Input
Many rail-to-rail input stages use two differential input pairs,
a long-tail PNP (or PFET) and an NPN (or NFET). Severe
penalties have to be paid for this circuit topology. As the
input signal moves from one supply rail to another, the
operational amplifier switches from one input pair to the
other causing drastic changes in input offset voltage and an
undesired change in magnitude and polarity of input offset
current.
The ISL28288 achieves input rail-to-rail without sacrificing
important precision specifications and degrading distortion
performance. The devices’ input offset voltage exhibits a
smooth behavior throughout the entire common-mode input
range. The input bias current versus the common-mode
voltage range gives us an undistorted behavior from typically
100mV below the negative rail and 10% higher than the V+
rail (0.5V higher than V+ when V+ equals 5V).
Input Protection
All input terminals have internal ESD protection diodes to both
positive and negative supply rails, limiting the input voltage to
10
CAPACITIVELY
COUPLED
ESD CLAMP
OUT
V-
CIRCUIT 1
V+
VCIRCUIT 3
CIRCUIT 4
within one diode beyond the supply rails. There is an
additional pair of back-to-back diodes across the input
terminals. For applications where the input differential voltage
is expected to exceed 0.5V, external series resistors must be
used to ensure the input currents never exceed 5mA.
Rail-to-Rail Output
A pair of complementary MOSFET devices are used to achieve
the rail-to-rail output swing. The NMOS sinks current to swing
the output in the negative direction. The PMOS sources current
to swing the output in the positive direction. The ISL28288 with
a 100kΩ load will swing to within 4mV of the positive supply rail
and within 3mV of the negative supply rail.
Enable/Disable Feature
The ISL28288 offers an EN pin that disables the device
when pulled up to at least 2.0V. In the disabled state (output
in a high impedance state), the part consumes typically 4µA.
By disabling the part, multiple ISL28288 parts can be
connected together as a MUX. In this configuration, the
outputs are tied together in parallel and a channel can be
selected by the EN pin. The loading effects of the feedback
resistors of the disabled amplifier must be considered when
multiple amplifier outputs are connected together. The EN
pin also has an internal pull down. If left open, the EN pin will
pull to the negative rail and the device will be enabled by
default.
Using Only One Channel
The ISL28288 is a dual op amp. If the application only
requires one channel, the user must configure the unused
channel to prevent it from oscillating. The unused channel
will oscillate if the input and output pins are floating. This will
result in higher than expected supply currents and possible
FN6339.1
June 28, 2007
ISL28288, ISL28488
noise injection into the channel being used. The proper way
to prevent this oscillation is to short the output to the
negative input and ground the positive input (as shown in
Figure 34).
.
R4
100kΩ
R3
10kΩ
R2
10kΩ
K TYPE
THERMOCOUPLE
ISL28288
+
V+
+
ISL28X88
V-
410µV/°C
+
5V
R1
FIGURE 34. PREVENTING OSCILLATIONS IN UNUSED
CHANNELS
100kΩ
FIGURE 36. THERMOCOUPLE AMPLIFIER
Proper Layout Maximizes Performance
To achieve the maximum performance of the high input
impedance and low offset voltage of the ISL28288, care
should be taken in the circuit board layout. The PC board
surface must remain clean and free of moisture to avoid
leakage currents between adjacent traces. Surface coating
of the circuit board will reduce surface moisture and provide
a humidity barrier, reducing parasitic resistance on the
board. When input leakage current is a concern, the use of
guard rings around the amplifier inputs will further reduce
leakage currents. Figure 35 shows a guard ring example for
a unity gain amplifier that uses the low impedance amplifier
output at the same voltage as the high impedance input to
eliminate surface leakage. The guard ring does not need to
be a specific width, but it should form a continuous loop
around both inputs. For further reduction of leakage
currents, components can be mounted to the PC board
using Teflon standoff insulators.
V+
HIGH IMPEDANCE INPUT
Current Limiting
The ISL28288 has no internal current-limiting circuitry. If the
output is shorted, it is possible to exceed the Absolute
Maximum Rating for output current or power dissipation,
potentially resulting in the destruction of the device.
Power Dissipation
It is possible to exceed the +150°C maximum junction
temperatures under certain load and power-supply
conditions. It is therefore important to calculate the
maximum junction temperature (TJMAX) for all applications
to determine if power supply voltages, load conditions, or
package type need to be modified to remain in the safe
operating area. These parameters are related in Equation 1:
T JMAX = T MAX + ( θ JA xPD MAXTOTAL )
(EQ. 1)
where:
• PDMAXTOTAL is the sum of the maximum power
dissipation of each amplifier in the package (PDMAX)
IN
• PDMAX for each amplifier is calculated in Equation 2:
V OUTMAX
PD MAX = 2*V S × I SMAX + ( V S - V OUTMAX ) × ---------------------------R
L
(EQ. 2)
FIGURE 35. GUARD RING EXAMPLE FOR UNITY GAIN
AMPLIFIER
where:
• TMAX = Maximum ambient temperature
Example Application
Thermocouples are the most popular temperature-sensing
device because of their low cost, interchangeability, and
ability to measure a wide range of temperatures. The
ISL28288 (Figure 36) is used to convert the differential
thermocouple voltage into single-ended signal with 10X gain.
The ISL28288's rail-to-rail input characteristic allows the
thermocouple to be biased at ground and the amplifier to run
from a single 5V supply.
11
• θJA = Thermal resistance of the package
• PDMAX = Maximum power dissipation of 1 amplifier
• VS = Supply voltage (Magnitude of V+ and V-)
• IMAX = Maximum supply current of 1 amplifier
• VOUTMAX = Maximum output voltage swing of the
application
• RL = Load resistance
FN6339.1
June 28, 2007
ISL28288, ISL28488
Quarter Size Outline Plastic Packages Family (QSOP)
MDP0040
A
QUARTER SIZE OUTLINE PLASTIC PACKAGES FAMILY
D
(N/2)+1
N
INCHES
SYMBOL QSOP16 QSOP24 QSOP28 TOLERANCE NOTES
E
PIN #1
I.D. MARK
E1
1
(N/2)
A
0.068
0.068
0.068
Max.
-
A1
0.006
0.006
0.006
±0.002
-
A2
0.056
0.056
0.056
±0.004
-
b
0.010
0.010
0.010
±0.002
-
c
0.008
0.008
0.008
±0.001
-
D
0.193
0.341
0.390
±0.004
1, 3
E
0.236
0.236
0.236
±0.008
-
E1
0.154
0.154
0.154
±0.004
2, 3
e
0.025
0.025
0.025
Basic
-
L
0.025
0.025
0.025
±0.009
-
L1
0.041
0.041
0.041
Basic
-
N
16
24
28
Reference
-
B
0.010
C A B
e
H
C
SEATING
PLANE
0.007
0.004 C
b
C A B
Rev. F 2/07
NOTES:
L1
A
1. Plastic or metal protrusions of 0.006” maximum per side are not
included.
2. Plastic interlead protrusions of 0.010” maximum per side are not
included.
c
SEE DETAIL "X"
3. Dimensions “D” and “E1” are measured at Datum Plane “H”.
4. Dimensioning and tolerancing per ASME Y14.5M-1994.
0.010
A2
GAUGE
PLANE
L
A1
4°±4°
DETAIL X
12
FN6339.1
June 28, 2007
ISL28288, ISL28488
Mini SO Package Family (MSOP)
0.25 M C A B
D
MINI SO PACKAGE FAMILY
(N/2)+1
N
E
MDP0043
A
E1
MILLIMETERS
PIN #1
I.D.
1
B
(N/2)
e
H
C
SEATING
PLANE
0.10 C
N LEADS
SYMBOL
MSOP8
MSOP10
TOLERANCE
NOTES
A
1.10
1.10
Max.
-
A1
0.10
0.10
±0.05
-
A2
0.86
0.86
±0.09
-
b
0.33
0.23
+0.07/-0.08
-
c
0.18
0.18
±0.05
-
D
3.00
3.00
±0.10
1, 3
E
4.90
4.90
±0.15
-
E1
3.00
3.00
±0.10
2, 3
e
0.65
0.50
Basic
-
L
0.55
0.55
±0.15
-
L1
0.95
0.95
Basic
-
N
8
10
Reference
-
0.08 M C A B
b
Rev. D 2/07
NOTES:
1. Plastic or metal protrusions of 0.15mm maximum per side are not
included.
L1
2. Plastic interlead protrusions of 0.25mm maximum per side are
not included.
A
3. Dimensions “D” and “E1” are measured at Datum Plane “H”.
4. Dimensioning and tolerancing per ASME Y14.5M-1994.
c
SEE DETAIL "X"
A2
GAUGE
PLANE
L
A1
0.25
3° ±3°
DETAIL X
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Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without
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13
FN6339.1
June 28, 2007