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LM8261
SNOS469J – APRIL 2000 – REVISED JANUARY 2015
LM8261 Single RRIO High Output Current & Unlimited Cap Load Op Amp
1 Features
3 Description
•
The LM8261 is a Rail-to-Rail input and output Op
Amp which can operate with a wide supply voltage
range. This device has high output current drive,
greater than Rail-to-Rail input common mode voltage
range, unlimited capacitive load drive capability, and
provides tested and guaranteed high speed and slew
rate while requiring only 0.97 mA supply current. It is
specifically designed to handle the requirements of
flat panel TFT panel VCOM driver applications as well
as being suitable for other low power, and medium
speed applications which require ease of use and
enhanced performance over existing devices.
1
•
•
•
•
•
•
•
•
•
•
•
(VS = 5 V, TA = 25°C, Typical Values Unless
Specified)
GBWP 21 MHz
Wide Supply Voltage Range 2.5 V to 30 V
Slew Rate 12 V/µs
Supply Current 0.97 mA
Cap Load Limit Unlimited
Output Short Circuit Current 53 mA/ −75 mA
±5% Settling Time 400 ns (500 pF, 100 mVPP
Step)
Input Common Mode Voltage 0.3 V Beyond Rails
Input Voltage Noise 15nV/√Hz
Input Current Noise 1pA/√Hz
THD+N < 0.05%
2 Applications
•
•
•
•
TFT-LCD Flat Panel VCOM Driver
A/D Converter Buffer
High Side/low Side Sensing
Headphone Amplifier
Greater than Rail-to-Rail input common mode voltage
range with 50 dB of Common Mode Rejection allows
high side and low side sensing, among many
applications, without concern over exceeding the
range and with no compromise in accuracy.
Exceptionally wide operating supply voltage range of
2.5 V to 30 V alleviates any concerns over
functionality under extreme conditions and offers
flexibility for use in multitude of applications. In
addition, most device parameters are insensitive to
power supply variations; this design enhancement is
yet another step in simplifying its usage. The output
stage has low distortion (0.05% THD+N) and can
supply a respectable amount of current (15 mA) with
minimal headroom from either rail (300 mV).
The LM8261 is offered in the space-saving SOT-23-5
package.
Device Information(1)
PART NUMBER
LM8261
PACKAGE
SOT-23 (5)
BODY SIZE (NOM)
2.9 mm × 1.6 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Output Response with Heavy Capacitive Load
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
LM8261
SNOS469J – APRIL 2000 – REVISED JANUARY 2015
www.ti.com
Table of Contents
1
2
3
4
5
6
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration and Functions .........................
Specifications.........................................................
6.1
6.2
6.3
6.4
6.5
6.6
6.7
6.8
7
1
1
1
2
3
4
Absolute Maximum Ratings ...................................... 4
ESD Ratings.............................................................. 4
Recommended Operating Conditions....................... 4
Thermal Information .................................................. 4
Electrical Characteristics 2.7 V ................................. 5
Electrical Characteristics 5 V .................................... 7
Electrical Characteristics ±15 V ................................ 9
Typical Characteristics ............................................ 11
Application and Implementation ........................ 19
7.1 Block Diagram and Operational Description ........... 19
7.2
7.3
7.4
7.5
Driving Capacitive Loads ........................................
Estimating the Output Voltage Swing .....................
TFT Applications .....................................................
Output Short Circuit Current and Dissipation
Issues.......................................................................
7.6 Other Application Hints ...........................................
8
9
20
22
23
23
24
Power Supply Recommendations...................... 25
Layout ................................................................... 25
9.1 Layout Guidelines ................................................... 25
9.2 Layout Example ...................................................... 26
10 Device and Documentation Support ................. 27
10.1
10.2
10.3
10.4
Documentation Support ........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
27
27
27
27
11 Mechanical, Packaging, and Orderable
Information ........................................................... 27
4 Revision History
Changes from Revision I (March 2013) to Revision J
Page
•
Added, updated, or revised the following sections: Pin Configuration and Functions, Specifications, Detailed
Description , Application and Implementation, Power Supply Recommendations , Layout , Device and
Documentation Support , and Mechanical, Packaging, and Orderable Information section ................................................. 1
•
Changed from -1.0 V to -0.8 V in Specifications ................................................................................................................... 4
Changes from Revision H (March 2013) to Revision I
•
2
Page
Changed layout of National Data Sheet to TI format ............................................................................................................. 1
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SNOS469J – APRIL 2000 – REVISED JANUARY 2015
5 Pin Configuration and Functions
5-Pin SOT-23
Package DBV
(Top View)
Pin Functions
PIN
NUMBER
1
NAME
I/O
DESCRIPTION
Output
O
Output
2
V-
I
Negative Supply
3
IN+
I
Non-inverting input
4
IN-
I
Inverting Input
5
V+
I
Positive Supply
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SNOS469J – APRIL 2000 – REVISED JANUARY 2015
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6 Specifications
6.1 Absolute Maximum Ratings (1)
MIN
VIN Differential
MAX
UNIT
±10
V
32
V
See (2) (3)
Output Short Circuit Duration
Supply Voltage (V+ - V−)
Voltage at Input/Output pins
(2)
(3)
(4)
V
+150
°C
(4)
Soldering Information:
(1)
V,
V −0.8 V
−65
Storage Temperature Range
Junction Temperature
V+ +0.8
−
150
°C
Infrared or Convection (20 sec.)
235
°C
Wave Soldering (10 sec.)
260
°C
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Rating indicate conditions for
which the device is intended to be functional, but specific performance is not guaranteed. For guaranteed specifications and the test
conditions, see Electrical Characteristics 2.7 V.
Applies to both single-supply and split-supply operation. Continuous short circuit operation at elevated ambient temperature can result in
exceeding the maximum allowed junction temperature of 150°C.
Allowable Output Short Circuit duration is infinite for VS ≤ 6 V at room temperature and below. For VS > 6 V, allowable short circuit
duration is 1.5 ms.
The maximum power dissipation is a function of TJ(max), RθJA, and TA. The maximum allowable power dissipation at any ambient
temperature is PD = (TJ(MAX) - TA)/ RθJA. All numbers apply for packages soldered directly onto a PC board.
6.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
(3)
Electrostatic discharge
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001
(1) (2)
UNIT
±2000
Machine model (MM) (3)
V
±200
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. Manufacturing with
less than 2000-V HBM is possible with the necessary precautions. Pins listed as ±200 V may actually have higher performance.
Human Body Model is 1.5 kΩ in series with 100 pF.
Machine Model, 0 Ω is series with 200 pF.
6.3 Recommended Operating Conditions
MIN
MAX
Supply Voltage (V+ - V−)
2.5
30
V
Temperature Range (1)
−40
+85
°C
(1)
UNIT
The maximum power dissipation is a function of TJ(max), RθJA, and TA. The maximum allowable power dissipation at any ambient
temperature is PD = (TJ(MAX) - TA)/ RθJA. All numbers apply for packages soldered directly onto a PC board.
6.4 Thermal Information
THERMAL METRIC (1) (2)
RθJA
(1)
(2)
4
Junction-to-ambient thermal resistance
DBV
(5 PINS)
325
UNIT
°C/W
For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.
The maximum power dissipation is a function of TJ(max), RθJA, and TA. The maximum allowable power dissipation at any ambient
temperature is PD = (TJ(MAX) - TA)/ RθJA. All numbers apply for packages soldered directly onto a PC board.
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SNOS469J – APRIL 2000 – REVISED JANUARY 2015
6.5 Electrical Characteristics 2.7 V
Unless otherwise specified, all limits guaranteed for TA = 25°C, V+ = 2.7 V, V− = 0 V, VCM = 0.5 V, VO = V+/2, and RL > 1 MΩ
to V−. (1)
PARAMETER
TEST CONDITIONS
VOS
Input Offset Voltage
VCM = 0.5 V & VCM = 2.2 V
TC VOS
Input Offset Average Drift
VCM = 0.5 V & VCM = 2.2 V (4)
Common Mode Rejection
Ratio
VCM = 0.5 V & VCM = 2.2 V
CMVR
Positive Power Supply
Rejection Ratio
Input Common-Mode
Voltage Range
−65°C ≤ TJ ≤ +150°C
+/−2
V+ = 2.7 V to 5 V
CMRR > 50 dB
−65°C ≤ TJ ≤ +150°C
Output Swing Low
ISC
(1)
(2)
(3)
(4)
(5)
(6)
(7)
Output Short Circuit Current
78
−0.3
−0.1
63
−65°C ≤ TJ ≤ +150°C
3.0
2.8
78
70
73
67
2.59
2.49
2.53
2.45
90
100
2.7
−65°C ≤ TJ ≤ +150°C
RL = 10K to V−
104
0.0
VO = 0.5 to 2.2 V,
RL = 2K to V−
RL = 2K to V
dB
58
74
2.46
−
VO
nA
76
70
−65°C ≤ TJ ≤ +150°C
−65°C ≤ TJ ≤ +150°C
µA
50
67
Output Swing High
250
100
−65°C ≤ TJ ≤ +150°C
RL = 10K to V−
+1.00
60
VO = 0.5 to 2.2 V,
RL = 10K to V−
Large Signal Voltage Gain
µV/C
400
100
−65°C ≤ TJ ≤ +150°C
mV
+1.60
−65°C ≤ TJ ≤ +150°C
−65°C ≤ TJ ≤ +150°C
UNIT
−2.00
−2.70
20
−65°C ≤ TJ ≤ +150°C
AVOL
+/−7
VCM stepped from 1.7 V to 2.7 V
VCM stepped from
0 V to 2.7 V
+PSRR
+/−5
−65°C ≤ TJ ≤ +150°C
VCM stepped from
0 V to 1.0 V
CMRR
+/−0.7
+0.49
VCM = 2.2 V (5)
Input Offset Current
MAX (3)
−65°C ≤ TJ ≤ +150°C
Input Bias Current
IOS
TYP (2)
−1.20
VCM = 0.5 V (5)
IB
MIN
dB
V
V
dB
dB
V
2.41
−65°C ≤ TJ ≤ +150°C
120
Sourcing to V−
VID = 200 mV (6) (7)
−65°C ≤ TJ ≤ +150°C
20
Sinking to V+
VID = −200 mV (6) (7)
−65°C ≤ TJ ≤ +150°C
30
48
30
65
50
mV
mA
mA
Electrical Table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions result in very
limited self-heating of the device such that TJ = TA. No guarantee of parametric performance is indicated in the electrical tables under
conditions of internal self heating where TJ > TA.
Typical Values represent the most likely parametric norm.
All limits are guaranteed by testing or statistical analysis.
Offset voltage average drift determined by dividing the change in VOS at temperature extremes into the total temperature change.
Positive current corresponds to current flowing into the device.
Production Short Circuit test is a momentary test. See Note 7.
Allowable Output Short Circuit duration is infinite for VS ≤ 6V at room temperature and below. For VS > 6V, allowable short circuit
duration is 1.5 ms.
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Electrical Characteristics 2.7 V (continued)
Unless otherwise specified, all limits guaranteed for TA = 25°C, V+ = 2.7 V, V− = 0 V, VCM = 0.5 V, VO = V+/2, and RL > 1 MΩ
to V−.(1)
PARAMETER
TEST CONDITIONS
MIN
TYP (2)
MAX (3)
0.95
1.20
UNIT
IS
Supply Current
No load,
VCM = 0.5 V
SR
Slew Rate (8)
AV = +1,VI = 2 VPP
fu
Unity Gain-Frequency
VI = 10 mV, RL = 2 KΩ to V+/2
GBWP
Gain Bandwidth Product
f = 50 KHz
Phim
Phase Margin
VI = 10 mV
50
Deg
en
Input-Referred Voltage
Noise
f = 2 KHz, RS = 50 Ω
15
nV/ √Hz
in
Input-Referred Current
Noise
f = 2 KHz
1
pA/ √Hz
fMAX
Full Power Bandwidth
ZL = (20 pF || 10 KΩ) to V+/2
1
MHz
(8)
6
−65°C ≤ TJ ≤ +150°C
1.50
9
V/µs
10
MHz
21
−65°C ≤ TJ ≤ +150°C
mA
14
15.5
MHz
Slew rate is the slower of the rising and falling slew rates. Connected as a Voltage Follower.
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6.6 Electrical Characteristics 5 V (1)
Unless otherwise specified, all limited guaranteed for TA = 25°C, V+ = 5 V, V− = 0 V, VCM = 1 V, VO = V+/2, and RL > 1 MΩ to
V −.
PARAMETER
TEST CONDITIONS
Input Offset Voltage
VCM = 1 V & VCM = 4.5 V
TC VOS
Input Offset Average Drift
VCM = 1 V & VCM = 4.5 V (4)
IB
Input Bias Current
VCM = 4.5 V (5)
IOS
Input Offset Current
VCM = 1 V & VCM = 4.5 V
VCM stepped from
0 V to 3.3 V
CMRR
+PSRR
CMVR
Common Mode Rejection Ratio
Positive Power Supply Rejection
Ratio
Input Common-Mode Voltage
Range
RL = 10 K to V−
Sourcing to V−
VID = 200 mV (6) (7)
(1)
(2)
(3)
(4)
(5)
(6)
(7)
Output Short Circuit Current
−65°C ≤ TJ ≤ +150°C
Sinking to V+
VID = −200 mV (6) (7)
µV/°C
+1.00
250
400
110
64
104
78
−0.3
−0.1
0.0
−65°C ≤ TJ ≤ +150°C
5.0
−65°C ≤ TJ ≤ +150°C
70
−65°C ≤ TJ ≤ +150°C
66
−65°C ≤ TJ ≤ +150°C
4.72
5.3
5.1
84
74
80
70
4.87
4.75
4.81
4.70
86
125
dB
V
V
dB
V
4.66
−65°C ≤ TJ ≤ +150°C
−65°C ≤ TJ ≤ +150°C
dB
80
−65°C ≤ TJ ≤ +150°C
−65°C ≤ TJ ≤ +150°C
nA
84
100
−65°C ≤ TJ ≤ +150°C
µA
72
74
RL = 2 K to V−
mV
+1.60
20
−65°C ≤ TJ ≤ +150°C
Output Swing High
ISC
−65°C ≤ TJ ≤ +150°C
V+ = 2.7 V to 5 V,
VCM = 0.5 V
RL = 10 K to V−
Output Swing Low
+0.49
UNIT
−2.00
−2.70
61
VO = 0.5 to 4.5 V,
RL = 2 K to V−
VO
−65°C ≤ TJ ≤ +150°C
−65°C ≤ TJ ≤ +150°C
Large Signal Voltage Gain
+/−5
+/−2
−1.18
−65°C ≤ TJ ≤ +150°C
MAX (3)
+/− 7
VCM stepped from
0 V to 5 V
VO = 0.5 to 4.5 V,
RL = 10 K to V−
AVOL
−65°C ≤ TJ ≤ +150°C
VCM stepped from
4 V to 5 V
CMRR > 50 dB
TYP (2)
+/−0.7
VOS
VCM = 1 V (5)
MIN
135
53
35
75
60
20
mV
mA
50
Electrical Table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions result in very
limited self-heating of the device such that TJ = TA. No guarantee of parametric performance is indicated in the electrical tables under
conditions of internal self heating where TJ > TA.
Typical Values represent the most likely parametric norm.
All limits are guaranteed by testing or statistical analysis.
Offset voltage average drift determined by dividing the change in VOS at temperature extremes into the total temperature change.
Positive current corresponds to current flowing into the device.
Production Short Circuit test is a momentary test. See Note 7.
Allowable Output Short Circuit duration is infinite for VS ≤ 6V at room temperature and below. For VS > 6V, allowable short circuit
duration is 1.5ms.
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Electrical Characteristics 5 V(1) (continued)
Unless otherwise specified, all limited guaranteed for TA = 25°C, V+ = 5 V, V− = 0 V, VCM = 1 V, VO = V+/2, and RL > 1 MΩ to
V −.
PARAMETER
TEST CONDITIONS
TYP (2)
MIN
0.97
MAX (3)
1.25
UNIT
IS
Supply Current
No load, VCM = 1 V
SR
Slew Rate (8)
AV = +1, VI = 5 VPP
fu
Unity Gain Frequency
VI = 10 mV,
RL = 2 KΩ to V+/2
GBWP
Gain-Bandwidth Product
f = 50 KHz
Phim
Phase Margin
VI = 10 mV
53
Deg
en
Input-Referred Voltage Noise
f = 2 KHz, RS = 50 Ω
15
nV/ √hZ
in
Input-Referred Current Noise
f = 2 KHz
1
pA/ √hZ
−65°C ≤ TJ ≤ +150°C
1.75
12
−65°C ≤ TJ ≤ +150°C
10
7
10.5
21
−65°C ≤ TJ ≤ +150°C
+
15
mA
V/µs
MHz
16
MHz
fMAX
Full Power Bandwidth
ZL = (20 pF || 10 kΩ) to V /2
900
KHz
tS
Settling Time (±5%)
100 mVPP Step, 500 pF load
400
ns
THD+N
Total Harmonic Distortion +
Noise
RL = 1 KΩ to V+/2
f = 10 KHz to AV= +2, 4 VPP swing
(8)
8
0.05%
Slew rate is the slower of the rising and falling slew rates. Connected as a Voltage Follower.
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6.7 Electrical Characteristics ±15 V (1)
Unless otherwise specified, all limited guaranteed for TA = 25°C, V+ = 15 V, V− = −15 V, VCM = 0 V, VO = 0 V, and RL > 1 MΩ
to 0 V.
PARAMETER
TEST CONDITIONS
VOS
Input Offset Voltage
VCM = −14.5 V & VCM =
14.5 V
TC VOS
Input Offset Average Drift
VCM = −14.5 V & VCM = 14.5 V (4)
VCM = −14.5 V (5)
IB
Input Bias Current
VCM = 14.5 V (5)
IOS
Input Offset Current
CMRR
Common Mode Rejection Ratio
Negative Power Supply Rejection
V− = −12 V to −15 V
Ratio
CMVR
Input Common-Mode Voltage
Range
CMRR > 50 dB
VO = 0 V to ±13 V,
RL = 10 KΩ
Large Signal Voltage Gain
VO = 0 V to ±13 V,
RL = 2 KΩ
RL = 10 KΩ
Output Swing High
RL = 2 KΩ
VO
RL = 10 KΩ
Output Swing Low
RL = 2 KΩ
Sourcing to ground
VID = 200 mV (6) (7)
ISC
Output Short Circuit Current
Sinking to ground
VID = 200 mV (6) (7)
(1)
(2)
(3)
(4)
(5)
(6)
(7)
+/− 9
+/−2
−65°C ≤ TJ ≤ +150°C
275
µA
nA
84
100
dB
88
74
100
70
100
70
−15.3
−15.1
72
66
−65°C ≤ TJ ≤ +150°C
66
−65°C ≤ TJ ≤ +150°C
−15.0
−65°C ≤ TJ ≤ +150°C
15.0
−65°C ≤ TJ ≤ +150°C
74
−65°C ≤ TJ ≤ +150°C
66
−65°C ≤ TJ ≤ +150°C
14.61
15.3
15.1
85
78
79
72
14.83
14.65
14.73
14.60
−14.91
−14.75
dB
dB
V
V
dB
V
14.55
−65°C ≤ TJ ≤ +150°C
−14.65
−14.83
−65°C ≤ TJ ≤ +150°C
−65°C ≤ TJ ≤ +150°C
+1.00
80
−65°C ≤ TJ ≤ +150°C
−65°C ≤ TJ ≤ +150°C
µV/°C
550
100
−65°C ≤ TJ ≤ +150°C
mV
+1.50
30
−65°C ≤ TJ ≤ +150°C
UNIT
−2.00
−2.80
VCM stepped from 14 V to 15 V
−PSRR
+/−7
+0.49
−65°C ≤ TJ ≤ +150°C
V+ = 12 V to 15 V
+/−0.7
−65°C ≤ TJ ≤ +150°C
VCM stepped from −15 V
to 13 V
Positive Power Supply Rejection
Ratio
MAX (3)
−1.05
−65°C ≤ TJ ≤ +150°C
+PSRR
TYP (2)
−65°C ≤ TJ ≤ +150°C
VCM = −14.5 V & VCM =
14.5 V
VCM stepped from −15 V
to 15 V
AVOL
MIN
−14.65
V
−14.60
60
40
100
70
25
mA
60
Electrical Table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions result in very
limited self-heating of the device such that TJ = TA. No guarantee of parametric performance is indicated in the electrical tables under
conditions of internal self heating where TJ > TA.
Typical Values represent the most likely parametric norm.
All limits are guaranteed by testing or statistical analysis.
Offset voltage average drift determined by dividing the change in VOS at temperature extremes into the total temperature change.
Positive current corresponds to current flowing into the device.
Production Short Circuit test is a momentary test. See Note 7.
Allowable Output Short Circuit duration is infinite for VS ≤ 6 V at room temperature and below. For VS > 6 V, allowable short circuit
duration is 1.5 ms.
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Electrical Characteristics ±15 V(1) (continued)
Unless otherwise specified, all limited guaranteed for TA = 25°C, V+ = 15 V, V− = −15 V, VCM = 0 V, VO = 0 V, and RL > 1 MΩ
to 0 V.
PARAMETER
TEST CONDITIONS
IS
Supply Current
No load, VCM = 0 V
SR
Slew Rate (8)
AV = +1, VI = 24 VPP
fu
Unity Gain Frequency
VI = 10 mV, RL = 2 KΩ
MIN
TYP (2)
MAX (3)
1.30
1.50
−65°C ≤ TJ ≤ +150°C
1.90
15
−65°C ≤ TJ ≤ +150°C
10
8
14
24
UNIT
mA
V/µs
MHz
18
GBWP
Gain-Bandwidth Product
f = 50 KHz
Phim
Phase Margin
VI = 10 mV
58
Deg
en
Input-Referred Voltage Noise
f = 2 KHz, RS = 50 Ω
15
nV/ √hZ
in
Input-Referred Current Noise
f = 2 KHz
1
pA/ √hZ
fMAX
Full Power Bandwidth
ZL = 20 pF || 10 KΩ
160
ts
Settling Time (±1%, AV = +1)
Positive Step, 5 VPP
320
Negative Step, 5 VPP
600
THD+N
Total Harmonic Distortion +Noise
(8)
10
−65°C ≤ TJ ≤ +150°C
RL = 1 KΩ, f = 10 KHz,
AV = +2, 28VPP swing
16
MHz
KHz
ns
0.01%
Slew rate is the slower of the rising and falling slew rates. Connected as a Voltage Follower.
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6.8 Typical Characteristics
TA = 25°C, Unless Otherwise Noted
Figure 1. VOS vs. VCM for 3 Representative Units
Figure 2. VOS vs. VCM for 3 Representative Units
Figure 3. VOS vs. VCM for 3 Representative Units
Figure 4. VOS vs. VS for 3 Representative Units
Figure 5. VOS vs. VS for 3 Representative Units
Figure 6. VOS vs. VS for 3 Representative Units
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Typical Characteristics (continued)
TA = 25°C, Unless Otherwise Noted
12
Figure 7. IB vs. VCM
Figure 8. IB vs. VS
Figure 9. IS vs. VCM
Figure 10. IS vs. VCM
Figure 11. IS vs. VCM
Figure 12. IS vs. VS (PNP side)
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Typical Characteristics (continued)
TA = 25°C, Unless Otherwise Noted
Figure 13. IS vs. VS (NPN side)
Figure 14. Gain/Phase vs. Frequency
Figure 15. Unity Gain Frequency vs. VS
Figure 16. Phase Margin vs. VS
Figure 17. Unity Gain Freq. and Phase Margin vs. VS
Figure 18. Unity Gain Frequency vs. Load
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Typical Characteristics (continued)
TA = 25°C, Unless Otherwise Noted
14
Figure 19. Phase Margin vs. Load
Figure 20. Unity Gain Freq. and Phase Margin vs. CL
Figure 21. CMRR vs. Frequency
Figure 22. +PSRR vs. Frequency
Figure 23. −PSRR vs. Frequency
Figure 24. Output Voltage vs. Output Sourcing Current
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Typical Characteristics (continued)
TA = 25°C, Unless Otherwise Noted
Figure 25. Output Voltage vs. Output Sourcing Current
Figure 26. Output Voltage vs. Output Sinking Current
Figure 27. Max Output Swing vs. Load
Figure 28. Max Output Swing vs. Frequency
Figure 29. % Overshoot vs. Cap Load
Figure 30. ±5% Settling Time vs. Cap Load
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Typical Characteristics (continued)
TA = 25°C, Unless Otherwise Noted
Figure 31. +SR vs. Cap Load
Figure 32. −SR vs. Cap Load
16
Figure 33. +SR vs. Cap Load
Figure 34. −SR vs. Cap Load
Figure 35. Settling Time vs. Error Voltage
Figure 36. Settling Time vs. Error Voltage
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Typical Characteristics (continued)
TA = 25°C, Unless Otherwise Noted
Figure 37. Input Noise Voltage/Current vs. Frequency
Figure 38. Input Noise Voltage for Various VCM
Figure 39. Input Noise Current for Various VCM
Figure 40. Input Noise Voltage vs. VCM
Figure 41. Input Noise Current vs. VCM
Figure 42. THD+N vs. Frequency
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Typical Characteristics (continued)
TA = 25°C, Unless Otherwise Noted
18
Figure 43. THD+N vs. Frequency
Figure 44. THD+N vs. Frequency
Figure 45. THD+N vs. Amplitude
Figure 46. THD+N vs. Amplitude
Figure 47. Small Signal Step Response
Figure 48. Large Signal Step Response
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7 Application and Implementation
7.1 Block Diagram and Operational Description
7.1.1
A) Input Stage
Figure 49. Simplified Schematic Diagram
As seen in Figure 49, the input stage consists of two distinct differential pairs (Q1-Q2 and Q3-Q4) in order to
accommodate the full Rail-to-Rail input common mode voltage range. The voltage drop across R5, R6, R7, and
R8 is kept to less than 200 mV in order to allow the input to exceed the supply rails. Q13 acts as a switch to
steer current away from Q3-Q4 and into Q1-Q2, as the input increases beyond 1.4 V of V+. This in turn shifts the
signal path from the bottom stage differential pair to the top one and causes a subsequent increase in the supply
current.
In transitioning from one stage to another, certain input stage parameters (VOS, Ib, IOS, en, and in) are determined
based on which differential pair is "on" at the time. Input Bias current, IB, will change in value and polarity as the
input crosses the transition region. In addition, parameters such as PSRR and CMRR which involve the input
offset voltage will also be effected by changes in VCM across the differential pair transition region.
The input stage is protected with the combination of R9-R10 and D1, D2, D3, and D4 against differential input
over-voltages. This fault condition could otherwise harm the differential pairs or cause offset voltage shift in case
of prolonged over voltage. As shown in Figure 50, if this voltage reaches approximately ±1.4 V at 25°C, the
diodes turn on and current flow is limited by the internal series resistors (R9 and R10). The Absolute Maximum
Rating of ±10 V differential on VIN still needs to be observed. With temperature variation, the point were the
diodes turn on will change at the rate of 5 mV/°C.
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Block Diagram and Operational Description (continued)
Figure 50. Input Stage Current vs. Differential Input Voltage
7.1.2 B) Output Stage
The output stage Figure 49 is comprised of complementary NPN and PNP common-emitter stages to permit
voltage swing to within a VCE(SAT) of either supply rail. Q9 supplies the sourcing and Q10 supplies the sinking
current load. Output current limiting is achieved by limiting the VCE of Q9 and Q10; using this approach to current
limiting, alleviates the draw back to the conventional scheme which requires one VBE reduction in output swing.
The frequency compensation circuit includes Miller capacitors from collector to base of each output transistor
(see Figure 49, Ccomp9 and Ccomp10). At light capacitive loads, the high frequency gain of the output transistors is
high, and the Miller effect increases the effective value of the capacitors thereby stabilizing the Op Amp. Large
capacitive loads greatly decrease the high frequency gain of the output transistors thus lowering the effective
internal Miller capacitance - the internal pole frequency increases at the same time a low frequency pole is
created at the Op Amp output due to the large load capacitor. In this fashion, the internal dominant pole
compensation, which works by reducing the loop gain to less than 0dB when the phase shift around the feedback
loop is more than 180°C, varies with the amount of capacitive load and becomes less dominant when the load
capacitor has increased enough. Hence the Op Amp is very stable even at high values of load capacitance
resulting in the uncharacteristic feature of stability under all capacitive loads.
7.2 Driving Capacitive Loads
The LM8261 is specifically designed to drive unlimited capacitive loads without oscillations (See Figure 30). In
addition, the output current handling capability of the device allows for good slewing characteristics even with
large capacitive loads (see Slew Rate vs. Cap Load plots, Figure 31 through Figure 34). The combination of
these features is ideal for applications such as TFT flat panel buffers, A/D converter input amplifiers, and so
forth.
However, as in most Op Amps, addition of a series isolation resistor between the Op Amp and the capacitive
load improves the settling and overshoot performance.
Output current drive is an important parameter when driving capacitive loads. This parameter will determine how
fast the output voltage can change. Referring to the Slew Rate vs. Cap Load Plots (Figure 31 through Figure 34),
two distinct regions can be identified. Below about 10,000pF, the output Slew Rate is solely determined by the
Op Amp's compensation capacitor value and available current into that capacitor. Beyond 10nF, the Slew Rate is
determined by the Op Amp's available output current. Note that because of the lower output sourcing current
compared to the sinking one, the Slew Rate limit under heavy capacitive loading is determined by the positive
transitions. An estimate of positive and negative slew rates for loads larger than 100nF can be made by dividing
the short circuit current value by the capacitor.
20
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Driving Capacitive Loads (continued)
For the LM8261, the available output current increases with the input overdrive. As seen in Figure 51 and
Figure 52, both sourcing and sinking short circuit current increase as input overdrive increases. In a closed loop
amplifier configuration, during transient conditions while the fed back output has not quite caught up with the
input, there will be an overdrive imposed on the input allowing more output current than would normally be
available under steady state condition. Because of this feature, the Op Amp's output stage quiescent current can
be kept to a minimum, thereby reducing power consumption, while enabling the device to deliver large output
current when the need arises (such as during transients).
Figure 51. Output Short Circuit Sourcing Current vs. Input Overdrive
Figure 52. Output Short Circuit Sinking Current vs. Input Overdrive
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Driving Capacitive Loads (continued)
Figure 53 shows the output voltage, output current, and the resulting input overdrive with the device set for AV =
+1 and the input tied to a 1VPP step function driving a 47nF capacitor. During the output transition, the input
overdrive reaches 1 V peak and is more than enough to cause the output current to increase to its maximum
value (see Figure 51 and Figure 52). Because the larger output sinking current is compared to the sourcing one,
the output negative transition is faster than the positive one.
Figure 53. Buffer Amplifier Scope Photo
7.3 Estimating the Output Voltage Swing
It is important to keep in mind that the steady state output current will be less than the current available when
there is an input overdrive present. For steady state conditions, Figure 24 through Figure 26 in Typical
Characteristics can be used to predict the output swing. Figure 54 and Figure 55 show this performance along
with several load lines corresponding to loads tied between the output and ground. In each cases, the
intersection of the device plot at the appropriate temperature with the load line would be the typical output swing
possible for that load. For example, a 1-KΩ load can accommodate an output swing to within 250 mV of V− and
to 330 mV of V+ (VS = ±15 V) corresponding to a typical 29.3 VPP unclipped swing.
Figure 54. Output Sourcing Characteristics with Load Lines
Figure 55. Output Sinking Characteristics with Load Lines
22
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7.4 TFT Applications
Figure 56 below, shows a typical application where the LM8261 is used as a buffer amplifier for the VCOM signal
employed in a TFT LCD flat panel:
Figure 56. VCOM Driver Application Schematic
Figure 57 shows the time domain response of the amplifier when used as a VCOM buffer/driver with VREF at
ground. In this application, the Op Amp loop will try and maintain its output voltage based on the voltage on its
non-inverting input (VREF) despite the current injected into the TFT simulated load. As long as this load current is
within the range tolerable by the LM8261 (45 mA sourcing and 65 mA sinking for ±5 V supplies), the output will
settle to its final value within less than 2 µs.
Figure 57. VCOM Driver Performance Scope Photo
7.5 Output Short Circuit Current and Dissipation Issues
The LM8261 output stage is designed for maximum output current capability. Even though momentary output
shorts to ground and either supply can be tolerated at all operating voltages, longer lasting short conditions can
cause the junction temperature to rise beyond the absolute maximum rating of the device, especially at higher
supply voltage conditions. Below supply voltage of 6 V, output short circuit condition can be tolerated indefinitely.
With the Op Amp tied to a load, the device power dissipation consists of the quiescent power due to the supply
current flow into the device, in addition to power dissipation due to the load current. The load portion of the
power itself could include an average value (due to a DC load current) and an AC component. DC load current
would flow if there is an output voltage offset, or the output AC average current is non-zero, or if the Op Amp
operates in a single supply application where the output is maintained somewhere in the range of linear
operation. Therefore:
PTOTAL = PQ + PDC + PAC
(1)
Op Amp Quiescent Power Dissipation:
PQ = IS · VS
(2)
DC Load Power:
PDC = IO · (VR - VO)
(3)
AC Load Power:
PAC = (outlined in table below)
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Output Short Circuit Current and Dissipation Issues (continued)
where
•
•
•
•
•
IS is Supply Current
VS is Total Supply Voltage (V+ - V−)
IO is Average Load Current
VO is Average Output Voltage
VR is V+ for sourcing and V− for sinking current
(4)
Table 1 shows the maximum AC component of the load power dissipated by the Op Amp for standard
Sinusoidal, Triangular, and Square Waveforms:
Table 1. Normalized AC Power Dissipated in the Output Stage for Standard Waveforms
PAC (W.Ω/V2)
Sinusoidal
Triangular
Square
50.7 x 10−3
46.9 x 10−3
62.5 x 10−3
The table entries are normalized to VS2/ RL. To calculate the AC load current component of power dissipation,
simply multiply the table entry corresponding to the output waveform by the factor VS2/ RL. For example, with ±15
V supplies, a 600-Ω load, and triangular waveform power dissipation in the output stage is calculated as:
PAC= (46.9 x 10−3) · [302/600]= 70.4 mW
(5)
7.6 Other Application Hints
The use of supply decoupling is mandatory in most applications. As with most relatively high speed/high output
current Op Amps, best results are achieved when each supply line is decoupled with two capacitors; a small
value ceramic capacitor (∼0.01 µF) placed very close to the supply lead in addition to a large value Tantalum or
Aluminum (> 4.7 µF). The large capacitor can be shared by more than one device if necessary. The small
ceramic capacitor maintains low supply impedance at high frequencies while the large capacitor will act as the
charge "bucket" for fast load current spikes at the Op Amp output. The combination of these capacitors will
provide supply decoupling and will help keep the Op Amp oscillation free under any load.
7.6.1 LM8261 Advantages
Compared to other Rail-to-Rail Input/Output devices, the LM8261 offers several advantages such as:
• Improved cross over distortion.
• Nearly constant supply current throughout the output voltage swing range and close to either rail.
• Consistent stability performance for all input/output voltage and current conditions.
• Nearly constant Unity gain frequency (fu) and Phase Margin (Phim) for all operating supplies and load
conditions.
• No output phase reversal under input overload condition.
24
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8 Power Supply Recommendations
The LM8261 can operate off a single supply or with dual supplies. The input CM capability of the parts (CMVR)
extends covers the entire supply voltage range for maximum flexibility. Supplies should be decoupled with low
inductance, often ceramic, capacitors to ground less than 0.5 inches from the device pins. The use of ground
plane is recommended, and as in most high speed devices, it is advisable to remove ground plane close to
device sensitive pins such as the inputs.
9 Layout
9.1 Layout Guidelines
Generally, a good high frequency layout will keep power supply and ground traces away from the inverting input
and output pins. Parasitic capacitances on these nodes to ground will cause frequency response peaking and
possible circuit oscillations. Texas Instruments suggests the following evaluation boards as a guide for high
frequency layout and as an aid in device testing and characterization. See Table 2 for details. The LM8261
evaluation board(s) is a good example of high frequency layout techniques as a reference. General high-speed,
signal-path layout suggestions include:
• Continuous ground planes are preferred for signal routing with matched impedance traces for longer runs.
However, open up both ground and power planes around the capacitive sensitive input and output device
pins as shown in Figure 58. After the signal is sent into a resistor, parasitic capacitance becomes more of a
bandlimiting issue and less of a stability issue.
• Use good, high-frequency decoupling capacitors (0.1 μF) on the ground plane at the device power pins as
shown in Figure 58. Higher value capacitors (2.2 μF) are required, but may be placed further from the device
power pins and shared among devices. For best high-frequency decoupling, consider X2Y supply-decoupling
capacitors that offer a much higher self-resonance frequency over standard capacitors.
• When using differential signal routing over any appreciable distance, use microstrip layout techniques with
matched impedance traces.
• The input summing junction is very sensitive to parasitic capacitance. Connect any Rf, and Rg elements into
the summing junction with minimal trace length to the device pin side of the resistor, as shown in Figure 59.
The other side of these elements can have more trace length if needed to the source or to ground.
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9.2 Layout Example
Figure 58. LM8261 Evaluation Board Layer 1
Figure 59. LM8261 Evaluation Board Layer 2
Table 2. Evaluation Board Comparison
26
DEVICE
PACKAGE
EVALUATION BOARD PART NUMBER
LM8261M5
SOT-23
LMH730216
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10 Device and Documentation Support
10.1 Documentation Support
10.1.1 Related Documentation
For related documentation, see IC Package Thermal Metrics Application Report, SPRA953
10.2 Trademarks
All trademarks are the property of their respective owners.
10.3 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
10.4 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
11 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
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PACKAGE OPTION ADDENDUM
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6-Feb-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
Lead/Ball Finish
MSL Peak Temp
(2)
(6)
(3)
Op Temp (°C)
Device Marking
(4/5)
LM8261M5
NRND
SOT-23
DBV
5
1000
TBD
Call TI
Call TI
-40 to 85
A45A
LM8261M5/NOPB
ACTIVE
SOT-23
DBV
5
1000
Green (RoHS
& no Sb/Br)
SN
Level-1-260C-UNLIM
-40 to 85
A45A
LM8261M5X
NRND
SOT-23
DBV
5
3000
TBD
Call TI
Call TI
-40 to 85
A45A
LM8261M5X/NOPB
ACTIVE
SOT-23
DBV
5
3000
Green (RoHS
& no Sb/Br)
SN
Level-1-260C-UNLIM
-40 to 85
A45A
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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