February 2002
LMH6645/46/47
2.7V, 650µA, 55MHz, Rail-to-Rail Input and Output
Amplifiers with Shutdown Option
General Description
Features
The LMH6645 (single) and LMH6646 (dual), rail-to-rail input
and output voltage feedback amplifiers, offer high speed
(55MHz), and low voltage operation (2.7V) in addition to
micro-power shutdown capability (LMH6647, single).
(VS = 2.7V, TA = 25˚C, RL = 1kΩ to V+/2, AV = +1. Typical
values unless specified).
n −3dB BW
n Supply voltage range
n Slew rate
n Supply current
n Output short circuit current
n Linear output current
n Input common mode voltage
n Output voltage swing
n Input voltage noise
n Input current noise
55MHz
2.5V to 12V
22V/µs
Input common mode voltage range exceeds either supply by
0.3V, enhancing ease of use in multitude of applications
where previously only inferior devices could be used. Output
voltage range extends to within 20mV of either supply rails,
allowing wide dynamic range especially in low voltage appli-
cations. Even with low supply current of 650µA/amplifier,
650µA/channel
42mA
±
20mA
0.3V beyond rails
20mV from rails
17nV/
±
output current capability is kept at a respectable 20mA for
driving heavier loads. Important device parameters such as
BW, Slew Rate and output current are kept relatively inde-
pendent of the operating supply voltage by a combination of
process enhancements and design architecture.
0.75pA/
Applications
n Active filters
n High speed portable devices
n Multiplexing applications (LMH6647)
n Current sense buffer
In portable applications, the LMH6647 provides shutdown
capability while keeping the turn-off current to less than
50µA. Both turn-on and turn-off characteristics are well be-
haved with minimal output fluctuations during transitions.
This allows the part to be used in power saving mode, as
well as multiplexing applications. Miniature packages
(SOT23, MSOP-8, and SO-8) are further means to ease the
adoption of these low power high speed devices in applica-
tions where board area is at a premium.
n High speed transducer amp
Connection Diagrams
SOT23-5 (LMH6645)
SOT23-6 (LMH6647)
SOIC-8 (LMH6645)
20020260
20020259
20020261
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© 2002 National Semiconductor Corporation
DS200202
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