Product
Folder
Order
Now
Support &
Community
Tools &
Software
Technical
Documents
BUF634
SBOS030B – SEPTEMBER 2000 – REVISED MARCH 2019
BUF634 250-mA High-Speed Buffer
A newer version of this device is now available: BUF634A
1 Features
3 Description
•
The BUF634 is a high speed, unity-gain open-loop
buffer recommended for a wide range of applications.
The BUF634 can be used inside the feedback loop of
op amps to increase output current, eliminate thermal
feedback, and improve capacitive load drive.
1
•
•
•
•
•
•
•
•
A newer version of this device is now available:
BUF634A
High output current: 250 mA
Slew rate: 2000 V/µs
Pin-selected bandwidth: 30 MHz to 180 MHz
Low quiescent current: 1.5 mA (30 MHz BW)
Wide supply range: ±2.25 to ±18 V
Internal current limit
Thermal shutdown protection
8-pin PDIP, SOIC-8, 5-lead TO-220, 5-lead
DDPAK-TO-263 surface-mount
Output circuitry is fully protected by internal current
limit and thermal shut-down, making the device
rugged and easy to use.
The BUF634 is available in a variety of packages to
suit mechanical and power dissipation requirements.
Types include 8-pin PDIP, SOIC-8 surface-mount, 5lead TO-220, and a 5-lead DDPAK-TO-263 surfacemount plastic power package.
2 Applications
•
•
•
•
•
•
•
•
•
For low power applications, the BUF634 operates on
1.5-mA quiescent current with 250-mA output,
2000-V/µs slew rate, and 30-MHz bandwidth.
Bandwidth can be adjusted from 30 MHz to 180 MHz
by connecting a resistor between V– and the BW Pin.
Valve driver
Solenoid driver
Op amp current booster
Line driver
Headphone driver
Video driver
Motor driver
Test equipment
ATE pin driver
The upgraded device, BUF634A offers a wider
bandwidth (210 MHz) and a higher slew rate
(3750 V/µs) at 40% lower quiescent current. See the
Device Comparison Table for a selection of unitygain, open-loop buffers from Texas Instruments.
Device Information(1)
PART
NUMBER
BUF634
PACKAGE
BODY SIZE (NOM)
SOIC (8)
3.91 mm × 4.90 mm
PDIP (8)
6.35 mm × 9.81 mm
TO-220 (5)
8.51 mm × 10.16 mm
DDPAK/TO-263 (5)
8.42 mm × 10.16 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Boost the Output Current of any Operational Amplifier
1 2
OPA2810
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.
A newer version of this device is now available: BUF634A
BUF634
SBOS030B – SEPTEMBER 2000 – REVISED MARCH 2019
www.ti.com
Table of Contents
1
2
3
4
5
6
7
8
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Device Comparison Table.....................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
3
4
7.1
7.2
7.3
7.4
7.5
7.6
4
4
4
4
5
7
Absolute Maximum Ratings ......................................
ESD Ratings ............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
Detailed Description ............................................ 10
8.1 Overview ................................................................. 10
8.2 Functional Block Diagram ....................................... 10
8.3 Feature Description................................................. 11
8.4 Device Functional Modes........................................ 11
9
Application and Implementation ........................ 12
9.1 Application Information............................................ 12
9.2 Typical Application ................................................. 14
10 Power Supply Recommendations ..................... 15
11 Layout................................................................... 15
11.1 Layout Guidelines ................................................. 15
11.2 Layout Example .................................................... 17
12 Device and Documentation Support ................. 18
12.1
12.2
12.3
12.4
12.5
12.6
12.7
Device Support ....................................................
Documentation Support .......................................
Receiving Notification of Documentation Updates
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
18
18
18
18
19
19
19
13 Mechanical, Packaging, and Orderable
Information ........................................................... 19
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision A (November 2015) to Revision B
Page
•
Added discussion of BUF634A upgrade device to Features and Description sections ......................................................... 1
•
Changed amplifier to OPA2810 and deleted table from Boost the Output Current of any Operational Amplifier figure........ 1
•
Added Device Comparison Table .......................................................................................................................................... 3
Changes from Original (September 2000) to Revision A
•
2
Page
Added ESD Ratings table, Feature Description section, Device Functional Modes, Application and Implementation
section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and
Mechanical, Packaging, and Orderable Information section. ................................................................................................ 1
Submit Documentation Feedback
Copyright © 2000–2019, Texas Instruments Incorporated
Product Folder Links: BUF634
A newer version of this device is now available: BUF634A
BUF634
www.ti.com
SBOS030B – SEPTEMBER 2000 – REVISED MARCH 2019
5 Device Comparison Table
DEVICE
VS± (V)
IQ/CHANNEL
(mA)
BW (MHz)
SLEW RATE
(V/µs)
VOLTAGE NOISE
(nV/√Hz)
BUF634A
±18
1.5 – 8.5
35 – 210
3750
3.4
Unity-gain, open-loop buffer
BUF634
±18
1.5 – 15
30 – 180
2000
4
Unity-gain, open-loop buffer
LMH6321
±18
11
110
1800
2.8
AMPLIFIER DESCRIPTION
Unity-gain, open-loop buffer with
adjustable current limit
6 Pin Configuration and Functions
P and D Packages
8-Pin PDIP and SOIC
Top View
KC Package
5-Pin TO-220
Top View
BW
1
8
NC
NC
2
7
V+
VIN
3
6
VO
V–
4
5
NC
G=1
G=1
1 2 3 4 5
BW V–
V+
VIN VO
KTT Package
5-Pin DDPAK/TO-263
Top View
G=1
1 2 3 4 5
BW V–
V+
VIN VO
Pin Functions
PIN
NAME
NO.
8 PINS
I/O
DESCRIPTION
5 PINS
BW
1
1
I
Bandwidth adjust pin
NC
2, 5, 8
—
–
No internal connection
V+
7
5
I
Positive power supply
VIN
3
2
I
Input
VO
6
4
O
Output
V–
4
3
I
Negative power supply
Submit Documentation Feedback
Copyright © 2000–2019, Texas Instruments Incorporated
Product Folder Links: BUF634
3
A newer version of this device is now available: BUF634A
BUF634
SBOS030B – SEPTEMBER 2000 – REVISED MARCH 2019
www.ti.com
7 Specifications
7.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted)
(1)
MIN
Supply voltage
Input voltage
MAX
UNIT
±18
V
±VS
Output short-circuit (to ground)
Continuous
Operating temperature
–40
125
°C
Junction temperature
150
°C
Lead temperature (soldering, 10 s)
300
°C
125
°C
Storage temperature, Tstg
(1)
–55
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
7.2 ESD Ratings
VALUE
UNIT
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1)
±2500
V
Charged-device model (CDM), per JEDEC specification JESD22-C101 (2)
±1000
V
±2500
V
BUF634F in PDIP and SOIC Packages
V(ESD)
Electrostatic discharge
BUF634F in SOIC-8 Package Only
V(ESD)
Electrostatic discharge,
BUF634F in TO-220 and DDPAK Packages
V(ESD)
(1)
(2)
Electrostatic discharge
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1)
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
7.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
Vs = (V+) - (V-)
Supply voltage
TA
Operating temperature
MIN
NOM
MAX
UNIT
±2.25
(4.5)
±15
(30)
±18
(36)
V
-40
+25
+85
°C
7.4 Thermal Information
BUF634
THERMAL METRIC (1)
RθJA
SOIC
TO-220
DDPAK-TO-263
8 PINS
8 PINS
5 PINS
5 PINS
UNIT
46.5
103.4
32.1
41.8
°C/W
RθJC(top) Junction-to-case (top) thermal resistance
34.8
44.2
25.6
45
°C/W
RθJB
Junction-to-board thermal resistance
23.8
44.5
18.3
24.8
°C/W
ψJT
Junction-to-top characterization parameter
12
5.4
8.5
13.1
°C/W
ψJB
Junction-to-board characterization parameter
23.6
43.8
17.7
23.8
°C/W
RθJC(bot) Junction-to-case (bottom) thermal resistance
n/a
n/a
0.7
2.4
°C/W
(1)
4
Junction-to-ambient thermal resistance
PDIP
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report.
Submit Documentation Feedback
Copyright © 2000–2019, Texas Instruments Incorporated
Product Folder Links: BUF634
A newer version of this device is now available: BUF634A
BUF634
www.ti.com
SBOS030B – SEPTEMBER 2000 – REVISED MARCH 2019
7.5 Electrical Characteristics
at TA = +25°C (1), VS = ±15 V, specifications are for both low quiescent-current mode and wide-bandwidth mode (unless
otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
±30
±100
UNIT
INPUT
Offset Voltage
Offset Voltage vs Temperature
Specified Temperature Range
Offset Voltage vs Power Supply
VS = ±2.25 V (2) to ±18 V
Input Bias Current
Low Quiescent
Current Mode
VIN = 0V
Input Impedance
mV
µV/°C
0.1
1
±0.5
±2
±5
±20
mV/V
µA
Wide Bandwidth
Mode
Low Quiescent
Current Mode
RL = 100 Ω
Noise Voltage
±100
80 || 8
MΩ || pF
Wide Bandwidth
Mode
8 || 8
f = 10 kHz
4
nV/√Hz
GAIN
Gain
RL = 1 kΩ, VO = ±10 V
0.95
0.99
RL = 100 Ω, VO = ±10 V
0.85
0.93
RL = 67 Ω, VO = ±10 V
0.8
0.9
V/V
OUTPUT
Current Output, Continuous
Voltage Output
±250
Positive
IO = 10 mA
(V+) –2.1
(V+) –1.7
Negative
IO = –10 mA
(V–) +2.1
(V–) +1.8
Positive
IO = 100 mA
(V+) –3
(V+) –2.4
Negative
IO = –100 mA
(V–) +4
(V–) +3.5
Positive
IO = 150 mA
(V+) –4
(V+) –2.8
Negative
IO = –150 mA
(V–) +5
(V–) +4
Short-Circuit Current
mA
V
Low Quiescent Current Mode
±350
±550
Wide Bandwidth Mode
±400
±550
mA
DYNAMIC RESPONSE
Low Quiescent
Current Mode
RL = 1 kΩ
Wide Bandwidth
Mode
Bandwidth, –3dB
RL = 100 Ω
Slew Rate
Settling Time
Differential Gain
Differential Phase
(1)
(2)
1%
180
MHz
Low Quiescent
Current Mode
20
Low Quiescent
Current Mode
160
20 Vp-p, RL = 100 Ω
0.1%
30
20-V Step, RL = 100 Ω
Low Quiescent
3.58 MHz, VO = 0.7 V, Current Mode
RL = 150 Ω
Wide Bandwidth
Mode
Low Quiescent
3.58 MHz, VO = 0.7 V, Current Mode
RL = 150 Ω
Wide Bandwidth
Mode
2000
200
50
V/µs
ns
4%
0.4%
2.5
°
0.1
Tests are performed on high speed automatic test equipment, at approximately 25°C junction temperature. The power dissipation of this
product will cause some parameters to shift when warmed up. SeeTypical Characteristics for over-temperature performance.
Limited output swing available at low supply voltage. See Output voltage specifications.
Submit Documentation Feedback
Copyright © 2000–2019, Texas Instruments Incorporated
Product Folder Links: BUF634
5
A newer version of this device is now available: BUF634A
BUF634
SBOS030B – SEPTEMBER 2000 – REVISED MARCH 2019
www.ti.com
Electrical Characteristics (continued)
at TA = +25°C(1), VS = ±15 V, specifications are for both low quiescent-current mode and wide-bandwidth mode (unless
otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
POWER SUPPLY
Specified Operating Voltage
±15
±2.25 (2)
Operating Voltage Range
IQ
Quiescent Current
IO = 0
V
±18
Low Quiescent
Current Mode
±1.5
±2
Wide Bandwidth
Mode
±15
±20
V
mA
TEMPERATURE RANGE
TJ
6
Specification
–40
85
°C
Operating
–40
125
°C
Thermal Shutdown Temperature
175
Submit Documentation Feedback
°C
Copyright © 2000–2019, Texas Instruments Incorporated
Product Folder Links: BUF634
A newer version of this device is now available: BUF634A
BUF634
www.ti.com
SBOS030B – SEPTEMBER 2000 – REVISED MARCH 2019
7.6 Typical Characteristics
at TA = 25°C, VS = ±15 V (unless otherwise noted)
–10
0
–40
Phase (°)
–5
Wide BW
–15
–20
TJ = –40°C
TJ = 25°C
TJ = 125°C
Low IQ
–30
–40
–50
–50
10M
100M
Frequency (Hz)
1G
1M
Figure 1. Gain and Phase vs Frequency vs Quiescent
Current
0
Wide BW
–5
Low IQ
1G
Figure 2. Gain and Phase vs Frequency vs Temperature
RS = 50Ω
VO = 10mV
Gain (dB)
10
RL = 100Ω
VO = 10mV 5
10M
100M
Frequency (Hz)
–5
Wide BW
–20
–30
RS = 0Ω
RS = 50Ω
RS = 100Ω
Low IQ
–40
–15
–10
Phase (°)
Phase (°)
–10
0
–15
–10
Wide BW
–20
RL = 1kΩ
RL = 100Ω
RL = 50Ω
Low IQ
–30
–40
–50
–50
1M
10M
100M
Frequency (Hz)
1G
1M
Figure 3. Gain and Phase vs Frequency vs Source
Resistance
10M
100M
Frequency (Hz)
10
5
0
–5
1G
Figure 4. Gain and Phase vs Frequency vs Load Resistance
RL = 100Ω
RS = 50Ω
VO = 10mV
Gain (dB)
RL = 100Ω
RS = 50Ω
VO = 10mV
Low IQ Mode
0
–40
Phase (°)
–30
CL = 0
CL = 50pF
CL = 200pF
CL = 1nF
–20
–30
–40
–50
0
–15
–10
CL = 0pF
CL = 50pF
CL = 200pF
CL = 1nF
–20
5
–10
0
–15
–10
10
–5
Wide BW Mode
–10
Phase (°)
5
0
Wide BW
Low IQ
–10
0
10
Gain (dB)
1M
Gain (dB)
Phase (°)
–30
0
–10
IQ = 15mA
IQ = 9mA
IQ = 4mA
IQ = 2.5mA
IQ = 1.5mA
–20
5
–10
0
–15
–10
Wide BW
Low IQ
10
Gain (dB)
–5
RL = 100Ω
RS = 50Ω
VO = 10mV
Gain (dB)
10
RL = 100Ω
5
RS = 50Ω
VO = 10mV 0
–50
1M
10M
100M
Frequency (Hz)
1G
Figure 5. Gain and Phase vs Frequency vs Load
Capacitance
1M
10M
100M
Frequency (Hz)
1G
Figure 6. Gain and Phase vs Frequency vs Load
Capacitance
Submit Documentation Feedback
Copyright © 2000–2019, Texas Instruments Incorporated
Product Folder Links: BUF634
7
A newer version of this device is now available: BUF634A
BUF634
SBOS030B – SEPTEMBER 2000 – REVISED MARCH 2019
www.ti.com
Typical Characteristics (continued)
at TA = 25°C, VS = ±15 V (unless otherwise noted)
100
5
90
0
–5
Low IQ
–10
0
–15
Phase (°)
–10
Wide BW
–20
Low IQ
–30
–40
VS = ±18V
VS = ±12V
VS = ±5V
VS = ±2.25V
Power Supply Rejection (dB)
Wide BW
10
Gain (dB)
RL = 100Ω
RS = 50Ω
VO = 10mV
80
Wide BW
70
60
50
40
Low IQ
30
20
10
–50
0
1M
10M
100M
Frequency (Hz)
1G
1k
10k
100k
1M
10M
Frequency (Hz)
Figure 7. Gain and Phase vs Frequency vs Power Supply
Voltage
20
Figure 8. Power Supply Rejection vs Frequency
500
+15V
18
450
15mA at R = 0
14
BW
12
R
Limit Current (mA)
Quiescent Current (mA)
16
10
8
–15V
6
4
400
Wide Bandwidth Mode
350
Low IQ Mode
300
250
2
1.5mA at R = ∞
0
200
10
100
1k
10k
–50
–25
0
25
50
75
100
125
150
Resistance (Ω)
Junction Temperature (°C)
Figure 9. Quiescent Current vs Bandwidth Control
Resistance
Figure 10. Short-Circuit Current vs Temperature
7
20
Cooling
Low IQ Mode
Quiescent Current (mA)
Quiescent Current (mA)
6
5
4
»10°C
3
2
Thermal Shutdown
15
10
»10°C
Wide BW Mode
5
1
Cooling
Thermal Shutdown
0
0
–50 –25
0
25
50
75
100 125 150 175 200
–50
Figure 11. Quiescent Current vs Temperature
8
–25
0
25
50
75
100
125
150
175
200
Junction Temperature (°C)
Junction Temperature (°C)
Figure 12. Quiescent Current vs Temperature
Submit Documentation Feedback
Copyright © 2000–2019, Texas Instruments Incorporated
Product Folder Links: BUF634
A newer version of this device is now available: BUF634A
BUF634
www.ti.com
SBOS030B – SEPTEMBER 2000 – REVISED MARCH 2019
Typical Characteristics (continued)
at TA = 25°C, VS = ±15 V (unless otherwise noted)
13
13
VIN = 13V
11
VS = ±15V
Low IQ Mode
10
–10
–11
TJ = –40°C
TJ = 25°C
TJ = 125°C
–12
VIN = –13V
VIN = 13V
12
Output Voltage Swing (V)
Output Voltage Swing (V)
12
11
VS = ±15V
Wide BW Mode
10
–10
–11
TJ = –40°C
TJ = 25°C
TJ = 125°C
–12
VIN = –13V
–13
–13
0
50
100
150
200
250
300
0
50
100
|Output Current| (mA)
150
200
Figure 13. Output Voltage Swing vs Output Current
TO-220 and DDPAK
Infinite Heat Sink
ΘJC = 6°C/W
Power Dissipation (W)
Power Dissipation (W)
10
TO-220 and DDPAK
Free Air
ΘJA = 65°C/W
8-Pin DIP
ΘJA = 100°C/W
300
Figure 14. Output Voltage Swing vs Output Current
12
3
2
250
|Output Current| (mA)
1
SO-8
ΘJA = 150°C/W
8
6
TO-220 and DDPAK
Free Air
ΘJA = 65°C/W
4
2
0
0
–50
–25
0
25
50
75
100
125
–50
150
–25
0
25
50
75
100
125
150
Ambient Temperature (°C)
Ambient Temperature (°C)
Figure 15. Maximum Power Dissipation vs Temperature
Input
100mV/div
Figure 16. Maximum Power Dissipation vs Temperature
Input
Wide BW
Mode
Wide BW
Mode
Low IQ
Mode
Low IQ
Mode
20ns/div
RS = 50 Ω, RL = 100 Ω
100mV/div
20ns/div
RS = 50 Ω, RL = 100 Ω
Figure 17. Small-Signal Response
Figure 18. Large-Signal Response
Submit Documentation Feedback
Copyright © 2000–2019, Texas Instruments Incorporated
Product Folder Links: BUF634
9
A newer version of this device is now available: BUF634A
BUF634
SBOS030B – SEPTEMBER 2000 – REVISED MARCH 2019
www.ti.com
8 Detailed Description
8.1 Overview
The BUF634 device is a high speed, unity-gain open-loop buffer recommended for a wide range of applications.
The BUF634 device can be used inside the feedback loop of op amps to increase output current, eliminate
thermal feedback, and improve capacitive load drive.
For low power applications, the BUF634 device operates on 1.5-mA quiescent current with 250-mA output,
2000-V/µs slew rate, and 30-MHz bandwidth. Bandwidth can be adjusted from 30 MHz to 180 MHz by
connecting a resistor between V– and the BW Pin refer to Figure 9 and Figure 1. Output circuitry is fully
protected by internal current limit and thermal shut-down, making it rugged and easy to use.
See the Functional Block Diagram section for a simplified circuit diagram of the BUF634 showing its open-loop
complementary follower design.
8.2 Functional Block Diagram
V+
Thermal
Shutdown
VIN 200Ω
VO
I1(1)
150Ω
4kΩ
BW
V–
Signal path indicated in bold.
Note: (1) Stage currents are set by I1.
10
Submit Documentation Feedback
Copyright © 2000–2019, Texas Instruments Incorporated
Product Folder Links: BUF634
A newer version of this device is now available: BUF634A
BUF634
www.ti.com
SBOS030B – SEPTEMBER 2000 – REVISED MARCH 2019
8.3 Feature Description
8.3.1 Output Current
The BUF634 device can deliver up to ±250-mA continuous output current. Internal circuitry limits output current
to approximately ±350 mA; see Figure 10. For many applications, however, the continuous output current will be
limited by thermal effects.
The output voltage swing capability varies with junction temperature and output current (see Figure 14). Although
all four package types are tested for the same output performance using a high speed test, the higher junction
temperatures with the DIP and SO-8 package types often provide less output voltage swing. Junction
temperature is reduced in the DDPAK surface-mount power package because it is soldered directly to the circuit
board. The TO-220 package used with a good heat sink further reduces junction temperature, allowing maximum
possible output swing.
8.4 Device Functional Modes
The BUF634 is operational when the power-supply voltage is greater than 4.5 V (±2.25 V). The maximum power
supply voltage for the BUF634 is 36 V (±18 V). At low power supply conditions, such as ±2.25 V, the output
swing may be limited. Refer to Electrical Characteristics for additional information.
Submit Documentation Feedback
Copyright © 2000–2019, Texas Instruments Incorporated
Product Folder Links: BUF634
11
A newer version of this device is now available: BUF634A
BUF634
SBOS030B – SEPTEMBER 2000 – REVISED MARCH 2019
www.ti.com
9 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
9.1 Application Information
Figure 19 shows the BUF634 device connected as an open-loop buffer. The source impedance and optional
input resistor, RS, influence frequency response: see Typical Characteristics. Power supplies should be bypassed
with capacitors connected close to the device pins. Capacitor values as low as 0.1 µF assure stable operation in
most applications, but high output current and fast output slewing can demand large current transients from the
power supplies. Solid tantalum 10-µF capacitors are recommended. High frequency open-loop applications may
benefit from special bypassing and layout considerations. See High Frequency Applications for more information.
V+
10µF
DIP/SO-8
Pinout shown
7
VIN
RS
3
BUF634
4
1
6
VO
RL
10µF
Optional connection for
wide bandwidth — see text.
V–
Figure 19. Buffer Connections
9.1.1 High Frequency Applications
The excellent bandwidth and fast slew rate of the BUF634 device are useful in a variety of high frequency openloop applications. When operated open-loop, printed-circuit-board layout and bypassing technique can affect
dynamic performance.
For best results, use a ground plane-type circuit board layout and bypass the power supplies with 0.1-µF ceramic
chip capacitors at the device pins in parallel with solid tantalum 10-µF capacitors. Source resistance affects highfrequency peaking, step-response overshoot and ringing. Best response is usually achieved with a series input
resistor of 25 Ω to 200 Ω, depending on the signal source. Response with some loads (especially capacitive) can
be improved with a resistor of 10 Ω to 150 Ω in series with the output.
Figure 20. High Performance Headphone Driver
12
Submit Documentation Feedback
Copyright © 2000–2019, Texas Instruments Incorporated
Product Folder Links: BUF634
A newer version of this device is now available: BUF634A
BUF634
www.ti.com
SBOS030B – SEPTEMBER 2000 – REVISED MARCH 2019
Application Information (continued)
+24V
C(1)
10kΩ
+
10µF
BUF634
C(1)
10kΩ
+
12V
–
pseudo
ground
+
12V
–
NOTE: (1) System bypass capacitors.
Figure 21. Pseudo-Ground Driver
IO = ±200mA
VIN
±2V
OPA177
BUF634
Valve
10Ω
Figure 22. Current-Output Valve Driver
10kΩ
1kΩ
VIN
±1V
10kΩ
9kΩ
1/2
OPA2234
BUF634
Motor
BUF634
1/2
OPA2234
±20V
at 250mA
Figure 23. Bridge-Connected Motor Driver
Submit Documentation Feedback
Copyright © 2000–2019, Texas Instruments Incorporated
Product Folder Links: BUF634
13
A newer version of this device is now available: BUF634A
BUF634
SBOS030B – SEPTEMBER 2000 – REVISED MARCH 2019
www.ti.com
9.2 Typical Application
9.2.1 Boosting Op Amp Output Current
The BUF634 device can be connected inside the feedback loop of most op amps to increase output current (see
Figure 24). When connected inside the feedback loop, the offset voltage of the BUF634 device and other errors
are corrected by the feedback of the op amp.
V+
C1(1)
VO
VIN
OPA
BUF634
BW
NOTE: (1) C1 not required
for most common op amps.
Use with unity-gain stable
high speed op amps.
Wide BW mode
(if required)
V–
OP AMP
RECOMMENDATIONS
OPA177, OPA1013
OPA111, OPA2111
OPA121, OPA234 (1),
OPA130 (1)
Use Low I Q mode. G = 1 stable.
OPA27, OPA2107
OPA602, OPA131 (1)
Low I Q mode is stable. Increasing CL may cause
excessive ringing or instability. Use Wide BW mode.
OPA627, OPA132 (1)
Use Wide BW mode, C1 = 200pF. G = 1 stable.
OPA637, OPA37
Use Wide BW mode. These op amps are not G = 1
stable. Use in G > 4.
NOTE: (1) Single, dual, and quad versions.
Figure 24. Boosting Op Amp Output Current
9.2.1.1 Design Requirements
•
•
•
•
•
•
Boost the output current of an OPA627
Operate from ±15V power supplies
Operate from -40°C to +85°C
Gain = 23.5 V/V
Output current = ±250 mA
Bandwidth greater than 100 kHz
9.2.1.2 Detailed Design Procedure
To assure that the composite amplifier remains stable, the phase shift of the BUF634 device must remain small
throughout the loop gain of the circuit. For a G=+1 op amp circuit, the BUF634 device must contribute little
additional phase shift (approximately 20° or less) at the unity-gain frequency of the op amp. Phase shift is
affected by various operating conditions that may affect stability of the op amp; see Typical Characteristics.
Most general-purpose or precision op amps remain unity-gain stable with the BUF634 device connected inside
the feedback loop as shown. Large capacitive loads may require the BUF634 device to be connected for wide
bandwidth for stable operation. High speed or fast-settling op amps generally require the wide bandwidth mode
to remain stable and to assure good dynamic performance. To check for stability with an op amp, look for
oscillations or excessive ringing on signal pulses with the intended load, and worst-case conditions that affect
phase response of the buffer. Connect the circuit as shown in Figure 24. Choose resistors to provide a voltage
gain of 23.5 V/V. Select the feedback resistor to be 2.7 kΩ. Choose the input resistor to be 120 Ω.
14
Submit Documentation Feedback
Copyright © 2000–2019, Texas Instruments Incorporated
Product Folder Links: BUF634
A newer version of this device is now available: BUF634A
BUF634
www.ti.com
SBOS030B – SEPTEMBER 2000 – REVISED MARCH 2019
Typical Application (continued)
9.2.1.3 Application Curve
Gain (db)
40
20
0
100
1k
10k
Frequency (Hz)
100k
1M
Figure 25. Frequency Response of Composite Amplifier
10 Power Supply Recommendations
The BUF634 is specified for operation from 4.5V to 36 V (±2.25 V to ±18 V). Many specifications apply from
–40°C to +85°C. Parameters that can exhibit significant variance with regard to operating voltage or temperature
are presented in the Typical Characteristics.
11 Layout
11.1 Layout Guidelines
For best operational performance of the device, use good PCB layout practices, including:
• Noise can propagate into analog circuitry through the power pins of the circuit. Bypass capacitors are
used to reduce the coupled noise by providing low-impedance power sources local to the analog circuitry.
– Connect low-ESR, 0.1-µF ceramic bypass capacitors between each supply pin and ground, placed as
close to the device as possible. A single bypass capacitor from V+ to ground is applicable for singlesupply applications.
• Separate grounding for analog and digital portions of circuitry is one of the simplest and most-effective
methods of noise suppression. One or more layers on multilayer PCBs are usually devoted to ground
planes. A ground plane helps distribute heat and reduces EMI noise pickup. Make sure to physically
separate digital and analog grounds paying attention to the flow of the ground current. For more detailed
information refer to Circuit Board Layout Techniques, SLOA089.
• In order to reduce parasitic coupling, run the input traces as far away from the supply or output traces as
possible. If these traces cannot be kept separate, crossing the sensitive trace perpendicular is much
better as opposed to in parallel with the noisy trace.
• Place the external components as close to the device as possible. As illustrated in Figure 27
• Keep the length of input traces as short as possible. Always remember that the input traces are the most
sensitive part of the circuit.
• Cleaning the PCB following board assembly is recommended for best performance.
• Any precision integrated circuit may experience performance shifts due to moisture ingress into the
plastic package. Following any aqueous PCB cleaning process, baking the PCB assembly is
recommended to remove moisture introduced into the device packaging during the cleaning process. A
low temperature, post cleaning bake at 85°C for 30 minutes is sufficient for most circumstances.
Submit Documentation Feedback
Copyright © 2000–2019, Texas Instruments Incorporated
Product Folder Links: BUF634
15
A newer version of this device is now available: BUF634A
BUF634
SBOS030B – SEPTEMBER 2000 – REVISED MARCH 2019
www.ti.com
Layout Guidelines (continued)
Power dissipated in the BUF634 device causes the junction temperature to rise. A thermal protection circuit in
the BUF634 device disables the output when the junction temperature reaches approximately 175°C. When the
thermal protection is activated, the output stage is disabled, allowing the device to cool. Quiescent current is
approximately 6 mA during thermal shutdown. When the junction temperature cools to approximately 165°C, the
output circuitry is again enabled. This can cause the protection circuit to cycle on and off with a period ranging
from a fraction of a second to several minutes or more, depending on package type, signal, load and thermal
environment.
The thermal protection circuit is designed to prevent damage during abnormal conditions. Any tendency to
activate the thermal protection circuit during normal operation is a sign of an inadequate heat sink or excessive
power dissipation for the package type.
The TO-220 package provides the best thermal performance. When the TO-220 is used with a properly sized
heat sink, output is not limited by thermal performance. See Application Bulletin AB-037 for details on heat sink
calculations. The DDPAK also has excellent thermal characteristics. Its mounting tab should be soldered to a
circuit board copper area for good heat dissipation. Figure 26 shows typical thermal resistance from junction to
ambient as a function of the copper area. The mounting tab of the TO-220 and DDPAK packages is electricallyconnected to the V– power supply.
The DIP and SO-8 surface-mount packages are excellent for applications requiring high output current with low
average power dissipation. To achieve the best possible thermal performance with the DIP or SO-8 packages,
solder the device directly to a circuit board. Because much of the heat is dissipated by conduction through the
package pins, sockets will degrade thermal performance. Use wide circuit board traces on all the device pins,
including pins that are not connected. With the DIP package, use traces on both sides of the printed circuit board
if possible.
THERMAL RESISTANCE vs
CIRCUIT BOARD COPPER AREA
Thermal Resistance, ΘJA (°C/W)
60
Circuit Board Copper Area
BUF634F
Surface Mount Package
1oz copper
50
40
30
20
BUF634F
Surface Mount Package
10
0
1
2
3
4
5
Copper Area (inches2)
Figure 26. Thermal Resistance vs Circuit Board Copper Area
11.1.1 Power Dissipation
Power dissipation depends on power supply voltage, signal, and load conditions. With DC signals, power
dissipation is equal to the product of output current times the voltage across the conducting output transistor,
VS – VO. Power dissipation can be minimized by using the lowest possible power supply voltage necessary to
assure the required output voltage swing.
For resistive loads, the maximum power dissipation occurs at a DC output voltage of one-half the power supply
voltage. Dissipation with AC signals is lower. Application Bulletin SBOS022 explains how to calculate or measure
power dissipation with unusual signals and loads.
Any tendency to activate the thermal protection circuit indicates excessive power dissipation or an inadequate
heat sink. For reliable operation, junction temperature should be limited to 150°C, maximum. To estimate the
margin of safety in a complete design, increase the ambient temperature until the thermal protection is triggered.
The thermal protection should trigger more than 45°C above the maximum expected ambient condition of your
application.
16
Submit Documentation Feedback
Copyright © 2000–2019, Texas Instruments Incorporated
Product Folder Links: BUF634
A newer version of this device is now available: BUF634A
BUF634
www.ti.com
SBOS030B – SEPTEMBER 2000 – REVISED MARCH 2019
11.2 Layout Example
Optional: Use for
wide bandwidth
applications
Place all passive
components close to
the device to reduce
parasitic errors
VS+
Run the input trace
as far away from
the supply lines
as possible
BW
BUF634 SOIC
Package
NC
NC
V+
VIN
VO
V±
NC
10 µF
GND
RS
VIN
Output
Use low-ESR, ceramic
bypass capacitor
10 µF
Use low-ESR,
ceramic bypass
capacitor
GND
VS±
Ground (GND) plane on another layer
Figure 27. BUF634 Layout Example
Submit Documentation Feedback
Copyright © 2000–2019, Texas Instruments Incorporated
Product Folder Links: BUF634
17
A newer version of this device is now available: BUF634A
BUF634
SBOS030B – SEPTEMBER 2000 – REVISED MARCH 2019
www.ti.com
12 Device and Documentation Support
12.1 Device Support
12.1.1 TINA-TI™ (Free Software Download)
TINA™ is a simple, powerful, and easy-to-use circuit simulation program based on a SPICE engine. TINA-TI is a
free, fully-functional version of the TINA software, preloaded with a library of macro models in addition to a range
of both passive and active models. TINA-TI provides all the conventional dc, transient, and frequency domain
analysis of SPICE, as well as additional design capabilities.
Available as a free download from the Analog eLab Design Center, TINA-TI offers extensive post-processing
capability that allows users to format results in a variety of ways. Virtual instruments offer the ability to select
input waveforms and probe circuit nodes, voltages, and waveforms, creating a dynamic quick-start tool.
NOTE
These files require that either the TINA software (from DesignSoft™) or TINA-TI software
be installed. Download the free TINA-TI software from the TINA-TI folder.
12.1.2 TI Precision Designs
The BUF634 is featured in several TI Precision Designs, available online at http://www.ti.com/. TI Precision
Designs are analog solutions created by TI’s precision analog applications experts and offer the theory of
operation, component selection, simulation, complete PCB schematic and layout, bill of materials, and measured
performance of many useful circuits.
12.2 Documentation Support
12.2.1 Related Documentation
For related documentation see the following:
• Texas Instruments, Circuit board layout techniques application report
• Texas Instruments, Combining an amplifier with the BUF634 application note
• Texas Instruments, Add current limit to the BUF634 application note
• Texas Instruments, Power amplifier stress and power handling limitations application note
• Texas Instruments, Shelf-Life Evaluation of Lead-Free Component Finishes application report
12.3 Receiving Notification of Documentation Updates
To receive notification of documentation updates, navigate to the device product folder on ti.com. In the upper
right corner, click on Alert me to register and receive a weekly digest of any product information that has
changed. For change details, review the revision history included in any revised document.
12.4 Community Resources
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
18
Submit Documentation Feedback
Copyright © 2000–2019, Texas Instruments Incorporated
Product Folder Links: BUF634
A newer version of this device is now available: BUF634A
BUF634
www.ti.com
SBOS030B – SEPTEMBER 2000 – REVISED MARCH 2019
12.5 Trademarks
E2E is a trademark of Texas Instruments.
TINA-TI is a trademark of Texas Instruments, Inc and DesignSoft, Inc.
TINA, DesignSoft are trademarks of DesignSoft, Inc.
All other trademarks are the property of their respective owners.
12.6 Electrostatic Discharge Caution
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
12.7 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
13 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.
Submit Documentation Feedback
Copyright © 2000–2019, Texas Instruments Incorporated
Product Folder Links: BUF634
19
PACKAGE OPTION ADDENDUM
www.ti.com
14-Oct-2022
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
BUF634F/500
NRND
DDPAK/
TO-263
KTT
5
500
RoHS & Green
Call TI | SN
Level-2-260C-1 YEAR
-40 to 125
BUF634F
BUF634F/500E3
NRND
DDPAK/
TO-263
KTT
5
500
RoHS & Green
SN
Level-2-260C-1 YEAR
-40 to 125
BUF634F
BUF634FKTTT
NRND
DDPAK/
TO-263
KTT
5
250
RoHS & Green
Call TI | SN
Level-2-260C-1 YEAR
-40 to 125
BUF634F
BUF634FKTTTE3
NRND
DDPAK/
TO-263
KTT
5
250
RoHS & Green
SN
Level-2-260C-1 YEAR
-40 to 125
BUF634F
BUF634T
NRND
TO-220
KC
5
49
RoHS & Green
Call TI | SN
N / A for Pkg Type
-40 to 125
BUF634T
BUF634TG3
NRND
TO-220
KC
5
49
RoHS & Green
SN
N / A for Pkg Type
-40 to 125
BUF634T
BUF634U
NRND
SOIC
D
8
75
RoHS & Green
NIPDAU
Level-3-260C-168 HR
-40 to 125
BUF
634U
BUF634U/2K5
NRND
SOIC
D
8
2500
RoHS & Green
NIPDAU
Level-3-260C-168 HR
-40 to 125
BUF
634U
(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
工商网监
湘ICP备2023018690号
