LMH6642Q-Q1_15 Datasheet, PDF (20/34 Pages) Texas Instruments – Low Power, 130 MHz, 75 mA Rail-to-Rail Output Amplifiers

LMH6642Q-Q1, LMH6643Q-Q1
SNOSC61C – JANUARY 2012 – REVISED SEPTEMBER 2014
8 Application and Implementation
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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.
8.1 Circuit Description
The LMH664X family is based on Texas Instruments' proprietary VIP10 dielectrically isolated bipolar process.
This device family architecture features the following:
• Complimentary bipolar devices with exceptionally high f_t (∼8 GHz) even under low supply voltage (2.7 V) and
low bias current.
• A class A-B “turn-around” stage with improved noise, offset, and reduced power dissipation compared to
similar speed devices (patent pending).
• Common Emitter push-push output stage capable of 75mA output current (at 0.5V from the supply rails) while
consuming only 2.7 mA of total supply current per channel. This architecture allows output to reach within
milli-volts of either supply rail.
• Consistent performance over the entire operating supply voltage range with little variation for the most
important specifications (for example, BW, SR, I_OUT, and so forth).
• Significant power saving (∼40%) compared to competitive devices on the market with similar performance.
8.1.1 Application Hints
This Op Amp family is a drop-in replacement for the AD805X family of high speed Op Amps in most applications.
In addition, the LMH664X will typically save about 40% on power dissipation, due to lower supply current, when
compared to competition. All AD805X family’s ensured parameters are included in the list of LMH664X ensured
specifications in order to ensure equal or better level of performance. However, as in most high performance
parts, due to subtleties of applications, it is strongly recommended that the performance of the part to be
evaluated is tested under actual operating conditions to ensure full compliance to all specifications.
With 3V supplies and a common mode input voltage range that extends 0.5V below V^−, the LMH664X find
applications in low voltage/low power applications. Even with 3V supplies, the −3dB BW (@ A_V = +1) is typically
115MHz with a tested limit of 80MHz. Production testing ensures that process variations with not compromise
speed. High frequency response is exceptionally stable confining the typical −3dB BW over the industrial
temperature range to ±2.5%.
As can be seen from the Typical Performance Characteristics, the LMH664X output current capability (∼75mA) is
enhanced compared to AD805X. This enhancement, increases the output load range, adding to the LMH664X’s
versatility.
Because of the LMH664X’s high output current capability attention should be given to device junction
temperature in order not to exceed the Absolute Maximum Rating.
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