Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsLinear ICsLinear IC - Op-amp, buffer amplifer Buffer TO 263 7

OUT

GND

G = 1

2 3

4 5

6 7

GND

OUT

LMH6321

www.ti.com

SNOSAL8C –APRIL 2006–REVISED MARCH 2013

LMH6321 300 mA High Speed Buffer with Adjustable Current Limit

Check for Samples: LMH6321

FEATURES

DESCRIPTION

The LMH6321 is a high speed unity gain buffer that

• High Slew Rate 1800 V/μs

slews at 1800 V/µs and has a small signal bandwidth

• Wide Bandwidth 110 MHz

of 110 MHz while driving a 50Ω load. It can drive

• Continuous Output Current ±300 mA

±300 mA continuously and will not oscillate while

driving large capacitive loads.

• Output Current Limit Tolerance ±5 mA ±5%

• Wide Supply Voltage Range 5V to ±15V

The LMH6321 features an adjustable current limit.

The current limit is continuously adjustable from 10

• Wide Temperature Range −40°C to +125°C

mA to 300 ma with a ±5 mA ±5% accuracy. The

• Adjustable Current Limit

current limit is set by adjusting an external reference

• High Capacitive Load Drive

current with a resistor. The current can be easily and

instantly adjusted, as needed by connecting the

• Thermal Shutdown Error Flag

resistor to a DAC to form the reference current. The

sourcing and sinking currents share the same current

APPLICATIONS

limit.

• Line Driver

The LMH6321 is available in a space saving 8-pin SO

• Pin Driver

PowerPAD or a 7-pin DDPAK power package. The

• Sonar Driver

SO PowerPAD package features an exposed pad on

the bottom of the package to increase its heat sinking

• Motor Control

capability. The LMH6321 can be used within the

feedback loop of an operational amplifier to boost the

current output or as a stand alone buffer.

CONNECTION DIAGRAM

A. V

−

pin is connected to tab on back of each package.

Figure 1. 8-Pin SO PowerPAD Figure 2. 7-Pin DDPAK

(A)

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

2All trademarks are the property of their respective owners.

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.

Summary of content (31 pages)

PAGE 1
LMH6321 www.ti.com SNOSAL8C – APRIL 2006 – REVISED MARCH 2013 LMH6321 300 mA High Speed Buffer with Adjustable Current Limit Check for Samples: LMH6321 FEATURES DESCRIPTION • • • • • • • • • The LMH6321 is a high speed unity gain buffer that slews at 1800 V/µs and has a small signal bandwidth of 110 MHz while driving a 50Ω load. It can drive ±300 mA continuously and will not oscillate while driving large capacitive loads.
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LMH6321 SNOSAL8C – APRIL 2006 – REVISED MARCH 2013 www.ti.com 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. ABSOLUTE MAXIMUM RATINGS (1) (2) ESD Tolerance (3) Human Body Model 2.
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LMH6321 www.ti.com SNOSAL8C – APRIL 2006 – REVISED MARCH 2013 ±15V ELECTRICAL CHARACTERISTICS The following specifications apply for Supply Voltage = ±15V, VCM = 0, RL ≥ 100 kΩ and RS = 50Ω, CL open, unless otherwise noted. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ = 25°C. Symbol AV Parameter Voltage Gain Min Typ RL = 1 kΩ, VIN = ±10V Conditions 0.99 0.98 0.995 RL = 50Ω, VIN = ±10V 0.86 0.84 0.
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LMH6321 SNOSAL8C – APRIL 2006 – REVISED MARCH 2013 www.ti.com ±15V ELECTRICAL CHARACTERISTICS (continued) The following specifications apply for Supply Voltage = ±15V, VCM = 0, RL ≥ 100 kΩ and RS = 50Ω, CL open, unless otherwise noted. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ = 25°C.
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LMH6321 www.ti.com SNOSAL8C – APRIL 2006 – REVISED MARCH 2013 ±5V ELECTRICAL CHARACTERISTICS The following specifications apply for Supply Voltage = ±5V, VCM = 0, RL ≥ 100 kΩ and RS = 50Ω, CL Open, unless otherwise noted. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ = 25°C. Symbol AV Parameter Voltage Gain Min Typ RL = 1 kΩ, VIN = ±3V Conditions 0.99 0.98 0.994 RL = 50Ω, VIN = ±3V 0.86 0.84 0.
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LMH6321 SNOSAL8C – APRIL 2006 – REVISED MARCH 2013 www.ti.com ±5V ELECTRICAL CHARACTERISTICS (continued) The following specifications apply for Supply Voltage = ±5V, VCM = 0, RL ≥ 100 kΩ and RS = 50Ω, CL Open, unless otherwise noted. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ = 25°C.
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LMH6321 www.ti.com SNOSAL8C – APRIL 2006 – REVISED MARCH 2013 TYPICAL PERFORMANCE CHARACTERISTICS Overshoot vs.
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LMH6321 SNOSAL8C – APRIL 2006 – REVISED MARCH 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS (continued) OUTPUT SIGNAL VIN = 200 mVPP RL = 50: VS = ±5V (100 mV/DIV) Small Signal Step Response INPUT SIGNAL OUTPUT SIGNAL INPUT SIGNAL (100 mV/DIV) Small Signal Step Response RL = 50: VS = ±15V TIME (10 ns/DIV) Figure 9. Figure 10.
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LMH6321 www.ti.com SNOSAL8C – APRIL 2006 – REVISED MARCH 2013 TYPICAL PERFORMANCE CHARACTERISTICS (continued) Large Signal Step Response Large Signal Step Response RL = 50: VS = ±5V VS = ±15V VOUT (2V/DIV) VOUT (0.5V/DIV) RL = 1 k: TIME (20 ns/DIV) TIME (20 ns/DIV) Figure 15. Figure 16. Large Signal Step Response Large Signal Step Response RL = 1 k: VS = ±5V VS = ±15V VOUT (2V/DIV) VOUT (0.5V/DIV) RL = 50: TIME (20 ns/DIV) TIME (20 ns/DIV) Figure 17. Figure 18.
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LMH6321 SNOSAL8C – APRIL 2006 – REVISED MARCH 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS (continued) Noise vs. Frequency Harmonic Distortion with 50Ω Load 10000 -30 VS = ±15V 1000 HD2 -45 100 NOISE HD2 & HD3 (dBc) -35 R = 50: L f = 100 kHz -40 -50 10 -55 CURRENT pA/ Hz) HD3 -60 VOLTAGE nV/ Hz) 1.0 -65 -70 0 5 10 15 20 0.1 1.0 25 10 Figure 22. Gain vs. Frequency Gain vs. Frequency 5 0 0 -5 -5 GAIN (dB) GAIN (dB) Figure 21.
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LMH6321 www.ti.com SNOSAL8C – APRIL 2006 – REVISED MARCH 2013 TYPICAL PERFORMANCE CHARACTERISTICS (continued) Supply Current vs. Supply Voltage Output Impedance vs. Sourcing Current 14 5.2 125°C 85°C 25°C 10 5 OUTPUT IMPEDANCE (:) SUPPLY CURRENT (mA) VS = ±5V -40°C 12 -40°C 8 6 4 4.8 125°C 4.6 85°C 25°C 4.4 2 0 1 3 5 7 9 11 13 15 17 4.2 19 5 7 SUPPLY VOLTAGE (±V) 9 11 13 15 17 19 SOURCING CURRENT (mA) Figure 27. Figure 28. Output Impedance vs.
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LMH6321 SNOSAL8C – APRIL 2006 – REVISED MARCH 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS (continued) Output Short Circuit Current—Sinking vs. Program Current Output Short Circuit Current—Sourcing vs. Program Current 400 400 VS = ±5V 300 OUTPUT CURRENT (mA) OUTPUT CURRENT (mA) VS = ±15V 125°C -40°C 85°C 200 25°C 100 0 25 300 125°C -40°C 85°C 200 25°C 100 0 25 125 225 325 425 525 625 725 825 125 225 325 425 525 625 725 825 PROGRAM CURRENT (PA) PROGRAM CURRENT (PA) Figure 33.
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LMH6321 www.ti.com SNOSAL8C – APRIL 2006 – REVISED MARCH 2013 TYPICAL PERFORMANCE CHARACTERISTICS (continued) Negative Output Swing vs. Sinking Current Output Short Circuit Current—Sourcing vs. Supply Voltage -9 1000 VS = ±15V OUTPUT SWING (V) -10 -40°C 25°C CL = OPEN -11 25°C -40°C -12 -13 800 OUTPUT CURRENT (mA) VIN = V - 600 85°C 400 125°C 200 125°C VIN = +3 85°C -14 -500 -400 -300 -200 CL = OPEN -100 0 0 2 4 6 SINKING CURRENT (mA) 10 12 14 Figure 39. Figure 40.
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LMH6321 SNOSAL8C – APRIL 2006 – REVISED MARCH 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS (continued) Negative Output Swing vs. Supply Voltage Input Offset Voltage of Amplifier vs. Common Mode Voltage -3 15 VS = ±5V INPUT OFFSET VOLTAGE (mV) RL = 1 k: OUTPUT SWING (V) -5 -40°C -7 25°C 85°C -9 125°C -11 -13 10 -40°C 5 25°C 0 125°C 85°C -5 -15 5 7 9 11 13 15 2 Figure 46. Input Offset Voltage of Amplifier vs. Common Mode Voltage Input Bias Current of Amplifier vs.
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LMH6321 www.ti.com SNOSAL8C – APRIL 2006 – REVISED MARCH 2013 APPLICATION HINTS BUFFERS Buffers are often called voltage followers because they have largely unity voltage gain, thus the name has generally come to mean a device that supplies current gain but no voltage gain. Buffers serve in applications requiring isolation of source and load, i.e., high input impedance, low output impedance (high output current drive). In addition, they offer gain flatness and wide bandwidth.
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LMH6321 SNOSAL8C – APRIL 2006 – REVISED MARCH 2013 www.ti.com V R1 10 k: TP1 EF + V C2 0.1 PF R3 R2 10 k: 1% 10 k: 1% + EF INPUT CL VOUT LMH6321 CIN - V C1 1 nF GND 50: COAXIAL CABLE | VIN VCL R4 50: OUTPUT R6 50: C3 0.1 PF V - Figure 52.
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LMH6321 www.ti.com SNOSAL8C – APRIL 2006 – REVISED MARCH 2013 BANDWIDTH AND STABILITY As can be seen in the schematic of Figure 52, a small capacitor is inserted in parallel with the series input resistors. The reason for this is to compensate for the natural band-limiting effect of the 1st order filter formed by this resistor and the input capacitance of the buffer. With a typical CIN of 3.5 pF (Figure 52), a pole is created at fp2 = 1/(2πR1CIN) = 4.
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LMH6321 SNOSAL8C – APRIL 2006 – REVISED MARCH 2013 REXTERNAL VCL www.ti.com IEXT 25 PA to 750 PA VPROG V/I CONVERTER A1 GND + | + NPN OUTPUT XTR + V IOUT SENSE XTR IDRIVE AMP2 QSENSE TO INPUT STAGE R3 2: SHORT CIRCUIT PROTECTION ±VDIFF RSENSE 200: ILOAD + V - CONNECT TO GROUND (FOR DUAL SUPPLIES) OR MID RAIL FOR SINGLE SUPPLY RSC 400: ISENSE IPROG 50 PA to 1.5 mA OUTPUT TO LOWER OUTPUT STAGE Only the NPN output ISC protection is shown.
PAGE 19
LMH6321 www.ti.com SNOSAL8C – APRIL 2006 – REVISED MARCH 2013 Determining Copper Area One can determine the required copper area by following a few basic guidelines: 1. Determine the value of the circuit’s power dissipation, PD 2. Specify a maximum operating ambient temperature, TA(MAX).
PAGE 20
LMH6321 SNOSAL8C – APRIL 2006 – REVISED MARCH 2013 www.ti.com Examining Figure 54, we see that we cannot attain this low of a thermal resistance for one layer of 1 oz copper. It will be necessary to derate the part by decreasing either the ambient temperature or the power dissipation. Other solutions are to use two layers of 1 oz foil, or use 2 oz copper (see Table 1), or to provide forced air flow. One should allow about an extra 15% heat sinking capability for safety margin.
PAGE 21
LMH6321 www.ti.com SNOSAL8C – APRIL 2006 – REVISED MARCH 2013 As seen in the previous example, buffer dissipation in DC circuit applications is easily computed. However, in AC circuits, signal wave shapes and the nature of the load (reactive, non-reactive) determine dissipation. Peak dissipation can be several times the average with reactive loads. It is particularly important to determine dissipation when driving large load capacitance.
PAGE 22
LMH6321 SNOSAL8C – APRIL 2006 – REVISED MARCH 2013 www.ti.com + V LMH6321 + GND V V - - R1 OP AMP + R2 Figure 56. Using an Op Amp to Bias the GND Pin to ½ V+ for Single Supply Operation In Figure 56, the op amp circuit pre-biases the GND pin of the buffer for single supply operation. The GND pin can be driven by an op amp configured as a constant voltage source, with the output voltage set by the resistor voltage divider, R1 and R2.
PAGE 23
LMH6321 www.ti.com SNOSAL8C – APRIL 2006 – REVISED MARCH 2013 and rapidly changing output voltages will require large output load currents. For example if the part is required to slew at 1000 V/μs with a load capacitance of 1 nF the current demand from the LMH6321 would be 1A. Therefore, fast slew rate is incompatible with large CL. Also, since CL is in parallel with the load, the peak current available to the load decreases as CL increases.
PAGE 24
LMH6321 SNOSAL8C – APRIL 2006 – REVISED MARCH 2013 www.ti.com REVISION HISTORY Changes from Revision B (March 2013) to Revision C • 24 Page Changed layout of National Data Sheet to TI format ..........................................................................................................
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE OPTION ADDENDUM www.ti.com 10-Nov-2013 (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish value exceeds the maximum column width. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided.
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PACKAGE MATERIALS INFORMATION www.ti.com 23-Sep-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant LMH6321MRX/NOPB SO Power PAD DDA 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 LMH6321TSX/NOPB DDPAK/ TO-263 KTW 7 500 330.0 24.4 10.75 14.85 5.0 16.0 24.
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PACKAGE MATERIALS INFORMATION www.ti.com 23-Sep-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LMH6321MRX/NOPB SO PowerPAD DDA 8 2500 367.0 367.0 35.0 LMH6321TSX/NOPB DDPAK/TO-263 KTW 7 500 367.0 367.0 45.
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MECHANICAL DATA DDA0008B MRA08B (Rev B) www.ti.
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MECHANICAL DATA KTW0007B TS7B (Rev E) BOTTOM SIDE OF PACKAGE www.ti.
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