Datasheet BUF634U, BUF634T, BUF634P, BUF634F-500, BUF634 Datasheet (Burr Brown Corporation)

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Page 1
®
BUF634
BUF634
BUF634
BUF634
250mA HIGH-SPEED BUFFER
FEATURES
HIGH OUTPUT CURRENT: 250mA
SLEW RATE: 2000V/
PIN-SELECTED BANDWIDTH:
LOW QUIESCENT CURRENT:
1.5mA (30MHz BW)
WIDE SUPPLY RANGE:
INTERNAL CURRENT LIMIT
THERMAL SHUTDOWN PROTECTION
8-PIN DIP, SO-8, 5-LEAD TO-220, 5-LEAD
DDPAK SURFACE-MOUNT
µs
±2.25 to ±18V
BUF634
APPLICATIONS
VALVE DRIVER
SOLENOID DRIVER
OP AMP CURRENT BOOSTER
LINE DRIVER
HEADPHONE DRIVER
VIDEO DRIVER
MOTOR DRIVER
TEST EQUIPMENT
ATE PIN DRIVER
DESCRIPTION
The BUF634 is a high speed unity-gain open-loop buffer recommended for a wide range of applications. It 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 operates on 1.5mA quiescent current with 250mA output, 2000V/µs slew rate and 30MHz bandwidth. Band­width can be adjusted from 30MHz to 180MHz by connecting a resistor between V– and the BW Pin.
Output circuitry is fully protected by internal current limit and thermal shut-down making it rugged and easy to use.
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Internet: http://www.burr-brown.com/ • FAXLine: (800) 548-6133 (US/Canada Only) • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132
8-Pin DIP Package
SO-8 Surface-Mount Package
1
BW
2
NC
G = 1
3
V
IN
4
V–
8
NC
7
V+
6
V
O
5
NC
The BUF634 is available in a variety of packages to suit mechanical and power dissipation requirements. Types include 8-pin DIP, SO-8 surface-mount, 5-lead TO-220, and a 5-lead DDPAK surface-mount plastic power package.
5-Lead TO-220
5-Lead DDPAK Surface Mount
G = 1 G = 1
O
5
V+
1234
BW
NOTE: Tabs are connected to V– supply.
5
V–
V+
V
V
IN
O
1234
BW
V–
V
IN
V
©
1993 Burr-Brown Corporation PDS-1206C Printed in U.S.A. June, 1996
Page 2
SPECIFICATIONS
BW
V+
V–
V
O
V
IN
ELECTRICAL
At T
A
= +25°C
(1)
, VS = ±15V, unless otherwise noted.
BUF634P, U, T, F
LOW QUIESCENT CURRENT MODE WIDE BANDWIDTH MODE PARAMETER CONDITION MIN TYP MAX MIN TYP MAX UNITS INPUT
Offset Voltage ±30 ±100 ✻✻ mV
vs Temperature Specified Temperature Range ±100 µV/°C vs Power Supply V
Input Bias Current V
S
Input Impedance R Noise Voltage f = 10kHz 4 nV/Hz
GAIN R
R
L
R
(2)
= ±2.25V
= 1k, VO = ±10V 0.95 0.99 ✻✻ V/V
L
= 100, VO = ±10V 0.85 0.93 ✻✻ V/V
= 67, VO = ±10V 0.8 0.9 ✻✻ V/V
L
to ±18V 0.1 1 ✻✻mV/V
= 0V ±0.5 ±2 ±5 ±20 µA
IN
= 100 80 || 8 8 || 8 M || pF
L
OUTPUT
Current Output, Continuous ±250 mA Voltage Output, Positive I
Negative I Positive I Negative I Positive I Negative I
= 10mA (V+) –2.1 (V+) –1.7 ✻✻ V
O
= –10mA (V–) +2.1 (V–) +1.8 ✻✻ V
O
= 100mA (V+) –3 (V+) –2.4 ✻✻ V
O
= –100mA (V–) +4 (V– ) +3.5 ✻✻ V
O
= 150mA (V+) –4 (V+) –2.8 ✻✻ V
O
= –150mA (V–) +5 (V–) +4 ✻✻ V
O
Short-Circuit Current ±350 ±550 ±400 mA
DYNAMIC RESPONSE
Bandwidth, –3dB R
Slew Rate 20Vp-p, R Settling Time, 0.1% 20V Step, R
1% 20V Step, R Differential Gain Differential Phase
3.58MHz, VO = 0.7V, RL = 150
3.58MHz, VO = 0.7V, RL = 150
= 1k 30 180 MHz
L
R
= 100 20 160 MHz
L
= 100 2000 V/µs
L
= 100 200 ns
L
= 100 50 ns
L
4 0.4 %
2.5 0.1 °
POWER SUPPLY
Specified Operating Voltage ±15 V Operating Voltage Range ±2.25 Quiescent Current, I
Q
IO = 0 ±1.5 ± 2 ±15 ±20 mA
(2)
±18 ✻✻V
TEMPERATURE RANGE
Specification –40 +85 ✻✻°C Operating –40 +125 ✻✻°C Storage –55 +125 ✻✻°C Thermal Shutdown
Temperature, T
Thermal Resistance,
J
θ
JA
θ
JA
θ
JA
θ
JC
θ
JA
θ
JC
“P” Package “U” Package “T” Package
“T” Package 6 °C/W
“F” Package
“F” Package 6 °C/W
(3) (3) (3)
(3)
175 °C 100 °C/W 150 °C/W
65 °C/W
65 °C/W
V+
V
IN
V
O
V–
Specifications the same as Low Quiescent Mode. NOTES: (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. See typical performance curves for over-temperature performance. (2) Limited output swing available at low supply voltage. See Output voltage specifications. (3) Typical when all leads are soldered to a circuit board. See text for recommendations.
The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN assumes no responsibility for the use of this information, and all use of such information shall be entirely at the user’s own risk. Prices and specifications are subject to change without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not authorize or warrant any BURR-BROWN product for use in life support devices and/or systems.
®
BUF634
2
Page 3
PIN CONFIGURATION
Top View 8-Pin Dip Package
1
BW
2
NC
G = 1
3
V
IN
4
V–
SO-8 Surface-Mount Package
8
NC
7
V+
6
V
O
5
NC
NC = No Connection
ABSOLUTE MAXIMUM RATINGS
Supply Voltage ..................................................................................... ±18V
Input Voltage Range ...............................................................................±V
Output Short-Circuit (to ground) .................................................Continuous
Operating Temperature .....................................................–40°C to +125°C
Storage Temperature ........................................................ –55°C to +125°C
Junction Temperature ....................................................................... +150°C
Lead Temperature (soldering,10s) .................................................... +300°C
PACKAGE/ORDERING INFORMATION
PACKAGE DRAWING TEMPERATURE
PRODUCT PACKAGE NUMBER
BUF634P 8-Pin Plastic DIP 006 –40°C to +85°C BUF634U SO-8 Surface-Mount 182 –40°C to +85°C BUF634T 5-Lead TO-220 315 –40°C to +85°C BUF634F 5-Lead DDPAK 325 –40°C to +85°C
NOTE: (1) For detailed drawing and dimension table, please see end of data sheet, or Appendix C of Burr-Brown IC Data Book.
(1)
RANGE
Top View
5-Lead TO-220
5-Lead DDPAK Surface Mount
G = 1 G = 1
O
5
V+
1234
BW
V–
V
IN
5
V+
V
O
NOTE: Tab electrically connected to V–.
1234
S
BW
V–
V
V
IN
ELECTROSTATIC DISCHARGE SENSITIVITY
Any integrated circuit can be damaged by ESD. Burr-Brown 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 published specifications.
®
3
BUF634
Page 4
TYPICAL PERFORMANCE CURVES
At TA = +25°C, VS = ±15V, unless otherwise noted.
GAIN and PHASE vs FREQUENCY
vs QUIESCENT CURRENT
0 –10 –20 –30
Phase (°)
–40
IQ = 15mA
= 9mA
I
Q
= 4mA
I
Q
= 2.5mA
I
Q
= 1.5mA
I
Q
–50
1M 10M 100M 1G
Frequency (Hz)
GAIN and PHASE vs FREQUENCY
vs SOURCE RESISTANCE
Wide BW
Low I
Q
0 –10 –20 –30
Phase (°)
–40
Low I
Q
Wide BW
RS = 0
= 50
R
S
= 100
R
S
–50
1M 10M 100M 1G
Frequency (Hz)
RL = 100
= 50
R
S
= 10mV
V
O
RL = 100
= 10mV
V
O
10 5 0 –5 –10 –15
10 5 0 –5 –10 –15
Gain (dB)
Gain (dB)
GAIN and PHASE vs FREQUENCY
vs TEMPERATURE
Low I
Q
0
Wide BW
Wide BW
–10 –20 –30
Phase (°)
–40
Low I
Q
TJ = –40°C
= 25°C
T
J
= 125°C
T
J
–50
1M 10M 100M 1G
Frequency (Hz)
GAIN and PHASE vs FREQUENCY
vs LOAD RESISTANCE
Wide BW
Low I
Q
0 –10 –20 –30
Phase (°)
–40
Low I
Q
Wide BW
RL = 1k
= 100
R
L
= 50
R
L
–50
1M 10M 100M 1G
Frequency (Hz)
RL = 100
= 50
R
S
= 10mV
V
O
RS = 50
= 10mV
V
O
10 5 0 –5 –10 –15
10 5 0 –5 –10 –15
Gain (dB)
Gain (dB)
GAIN and PHASE vs FREQUENCY
vs LOAD CAPACITANCE
Low IQ Mode
0 –10 –20 –30
Phase (°)
–40
CL = 0pF
= 50pF
C
L
= 200pF
C
L
= 1nF
C
L
–50
1M 10M 100M 1G
Frequency (Hz)
®
BUF634
RL = 100
= 50
R
S
= 10mV
V
O
10 5 0 –5 –10 –15
Gain (dB)
4
GAIN and PHASE vs FREQUENCY
vs LOAD CAPACITANCE
Wide BW Mode
0 –10 –20 –30
Phase (°)
–40
CL = 0
= 50pF
C
L
= 200pF
C
L
= 1nF
C
L
–50
1M 10M 100M 1G
Frequency (Hz)
RL = 100
= 50
R
S
= 10mV
V
O
1 5 0 –5 –10 –15
0
Gain (dB)
Page 5
QUIESCENT CURRENT vs TEMPERATURE
20
15
10
5
0
Junction Temperature (°C)
–50 –25 0 25 50 75 100 125 150 175 200
Thermal Shutdown
10°C
Cooling
Wide BW Mode
Quiescent Current (mA)
TYPICAL PERFORMANCE CURVES (CONT)
q
)
SHORT CIRCUIT CURRENT vs TEMPERATURE
500
450
400
350
300
250
200
–50 –25 0 25 50 75 100 125 150
Junction Temperature (°C)
Wide Bandwidth Mode
Low IQ Mode
Limit Current (mA)
At TA = +25°C, VS = ±15V, unless otherwise noted.
GAIN and PHASE vs FREQUENCY
vs POWER SUPPLY VOLTAGE
Wide BW
Low I
Q
0 –10 –20 –30
Phase (°)
–40
Low I
Q
Wide BW
VS = ±18V
= ±12V
V
S
= ±5V
V
S
= ±2.25V
V
S
–50
1M 10M 100M 1G
Frequency (Hz)
QUIESCENT CURRENT
vs BANDWIDTH CONTROL RESISTANCE
20 18 16 14
15mA at R = 0
12 10
8 6
Quiescent Current (mA)
4 2 0
10 100 1k 10k
1.5mA at R =
Resistance ()
RL = 100
= 50
R
S
= 10mV
V
O
+15V
BW
R
–15V
10 5 0 –5 –10 –15
Gain (dB)
100
POWER SUPPLY REJECTION vs FREQUENCY
90 80 70
Wide BW
60 50 40
Low I
30 20
Power Supply Rejection (dB)
10
Q
0
1k 10k 100k 1M 10M
uency (Hz
Fre
7
QUIESCENT CURRENT vs TEMPERATURE
6
Low IQ Mode
5
4
3
2
Quiescent Current (mA)
1
0
–50 –25 0 25 50 75 100 125 150 175 200
Junction Temperature (°C)
Cooling
10°C
Thermal Shutdown
®
5
BUF634
Page 6
TYPICAL PERFORMANCE CURVES (CONT)
At TA = +25°C, VS = ±15V, unless otherwise noted.
OUTPUT VOLTAGE SWING vs OUTPUT CURRENT
13
VIN = 13V
12
11
VS = ±15V
10
–10
Low I
Mode
Q
–11
Output Voltage Swing (V)
–12
VIN = –13V
–13
0 50 100 150 200 250 300
TJ = –40°C
= 25°C
T
J
= 125°C
T
J
|Output Current| (mA)
MAXIMUM POWER DISSIPATION vs TEMPERATURE
3
2
8-Pin DIP
θ
= 100°C/W
JA
TO-220 and DDPAK Free Air
θ
= 65°C/W
JA
1
Power Dissipation (W)
SO-8
= 150°C/W
θ
JA
0
–50 –25 0 25 50 75 100 125 150
Ambient Temperature (°C)
OUTPUT VOLTAGE SWING vs OUTPUT CURRENT
13
VIN = 13V
12
11
VS = ±15V
10
Wide BW Mode
–10
–11
Output Voltage Swing (V)
–12
VIN = –13V
–13
0 50 100 150 200 250 300
TJ = –40°C
= 25°C
T
J
= 125°C
T
J
|Output Current| (mA)
MAXIMUM POWER DISSIPATION vs TEMPERATURE
12
10
TO-220 and DDPAK Infinite Heat Sink
θ
= 6°C/W
JC
8
6
4
Power Dissipation (W)
TO-220 and DDPAK Free Air
θ
= 65°C/W
JA
2
0
–50 –25 0 25 50 75 100 125 150
Ambient Temperature (°C)
Input
Wide BW
Mode
Low I
Mode
SMALL-SIGNAL RESPONSE
RS = 50, RL = 100
LARGE-SIGNAL RESPONSE
R
= 50, RL = 100
S
Input
100mV/div 10V/div
Wide BW
Mode
Q
Low I
Mode
Q
20ns/div 20ns/div
®
BUF634
6
Page 7
APPLICATION INFORMATION
Figure 1 is a simplified circuit diagram of the BUF634 showing its open-loop complementary follower design.
V+
Thermal
Shutdown
200
V
IN
(1)
I
1
150
4k
BW
Signal path indicated in bold. Note: (1) Stage currents are set by I
V–
.
1
FIGURE 1. Simplified Circuit Diagram.
Figure 2 shows the BUF634 connected as an open-loop buffer. The source impedance and optional input resistor, RS, influence frequency response—see typical curves. Power supplies should be bypassed with capacitors connected close to the device pins. Capacitor values as low as 0.1µF will 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 10µF capacitors are recommended.
High frequency open-loop applications may benefit from special bypassing and layout considerations—see “High Frequency Applications” at end of applications discussion.
V+
10µF
DIP/SO-8 Pinout shown
10µF
3
BUF634
7
6
1
4
Optional connection for wide bandwidth — see text.
V–
V
O
R
L
R
V
S
IN
FIGURE 2. Buffer Connections.
V
O
OUTPUT CURRENT
The BUF634 can deliver up to ±250mA continuous output current. Internal circuitry limits output current to approxi­mately ±350mA—see typical performance curve “Short Circuit Current vs Temperature”. 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 typical curves “Output Voltage Swing vs Output Current.” 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 will 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.
THERMAL PROTECTION
Power dissipated in the BUF634 will cause the junction temperature to rise. A thermal protection circuit in the BUF634 will disable 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 6mA 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.
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 3 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 electrically connected 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. Since 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.
7
BUF634
®
Page 8
THERMAL RESISTANCE vs
60
50
(°C/W)
JA
40
30
20
Thermal Resistance, θ
10
012345
CIRCUIT BOARD COPPER AREA
BUF634F
Surface Mount Package
1oz copper
2
Copper Area (inches
)
FIGURE 3. Thermal Resistance vs Circuit Board Copper Area.
Circuit Board Copper Area
BUF634F
Surface Mount Package
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, V
– VO. Power
S
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 AB-039 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.
INPUT CHARACTERISTICS
Internal circuitry is protected with a diode clamp connected from the input to output of the BUF634—see Figure 1. If the output is unable to follow the input within approximately 3V (such as with an output short-circuit), the input will conduct increased current from the input source. This is limited by the internal 200 resistor. If the input source can be dam­aged by this increase in load current, an additional resistor can be connected in series with the input.
BANDWIDTH CONTROL PIN
The –3dB bandwidth of the BUF634 is approximately 30MHz in the low quiescent current mode (1.5mA typical). To select this mode, leave the bandwidth control pin open (no connec­tion).
Bandwidth can be extended to approximately 180MHz by connecting the bandwidth control pin to V–. This increases
®
BUF634
the quiescent current to approximately 15mA. Intermediate bandwidths can be set by connecting a resistor in series with the bandwidth control pin—see typical curve "Quiescent Current vs Resistance" for resistor selection. Characteristics of the bandwidth control pin can be seen in the simplified circuit diagram, Figure 1.
The rated output current and slew rate are not affected by the bandwidth control, but the current limit value changes slightly. Output voltage swing is somewhat improved in the wide bandwidth mode. The increased quiescent current when in wide bandwidth mode produces greater power dissipation during low output current conditions. This quiescent power is equal to the total supply voltage, (V+) + |(V–)|, times the quiescent current.
BOOSTING OP AMP OUTPUT CURRENT
The BUF634 can be connected inside the feedback loop of most op amps to increase output current—see Figure 4. When connected inside the feedback loop, the BUF634’s offset voltage and other errors are corrected by the feedback of the op amp.
To assure that the op amp remains stable, the BUF634’s phase shift must remain small throughout the loop gain of the circuit. For a G=+1 op amp circuit, the BUF634 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 Gain and Phase curves.
Most general-purpose or precision op amps remain unity­gain stable with the BUF634 connected inside the feedback loop as shown. Large capacitive loads may require the BUF634 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.
8
Page 9
HIGH FREQUENCY APPLICATIONS
The BUF634’s excellent bandwidth and fast slew rate make it useful in a variety of high frequency open-loop applications. When operated open-loop, 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 0.1µF ceramic chip
V+
(1)
C
1
V
V
IN
NOTE: (1) C for most common op amps. Use with unity-gain stable high speed op amps.
OPA
not required
1
BUF634
BW
V–
O
Wide BW mode (if required)
FIGURE 4. Boosting Op Amp Output Current.
capacitors at the device pins in parallel with solid tantalum 10µF capacitors. Source resistance will affect high-frequency peaking and step response overshoot and ringing. Best response is usually achieved with a series input resistor of 25 to 200, depending on the signal source. Response with some loads (especially capacitive) can be improved with a resistor of 10 to 150 in series with the output.
OP AMP RECOMMENDATIONS
OPA177, OPA1013 Use Low I OPA111, OPA2111 OPA121, OPA234 OPA130
OPA27, OPA2107 Low IQ mode is stable. Increasing CL may cause OPA602, OPA131
OPA627, OPA132 OPA637, OPA37 Use Wide BW mode. These op amps are not G = 1
NOTE: (1) Single, dual, and quad versions.
(1)
(1)
,
(1)
excessive ringing or instability. Use Wide BW mode.
(1)
Use Wide BW mode, C1 = 200pF. G = 1 stable.
stable. Use in G > 4.
mode. G = 1 stable.
Q
G = +21
250
1µF
V
IN
OPA132
100k
FIGURE 5. High Performance Headphone Driver.
+24V
10k
+
10µF
BUF634
10k
NOTE: (1) System bypass capacitors.
(1)
C
(1)
C
FIGURE 6. Pseudo-Ground Driver.
+
12V
12V
+ –
5k
pseudo ground
V+
BW
Drives headphones or small speakers.
RL = 100
f
1kHz
20kHz
V
IN
±2V
THD+N
0.015%
0.02%
OPA177
BUF634
V–
FIGURE 7. Current-Output Valve Driver.
10k
BUF634
= ±200mA
I
O
Valve
10
1k
1/2
V
±1V
IN
OPA2234
FIGURE 8. Bridge-Connected Motor Driver.
9k
BUF634
Motor
±20V
at 250mA
9
BUF634
10k
1/2
OPA2234
®
BUF634
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