Datasheet

LMH6574
SNCS103C –NOVEMBER 2004–REVISED SEPTEMBER 2005 www.ti.com
POWER DISSIPATION
The LMH6574 is optimized for maximum speed and performance in the small form factor of the standard SOIC
package. To ensure maximum output drive and highest performance, thermal shutdown is not provided.
Therefore, it is of utmost importance to make sure that the T
JMAX
is never exceeded due to the overall power
dissipation.
Follow these steps to determine the Maximum power dissipation for the LMH6574:
1. Calculate the quiescent (no-load) power.
P
AMP
= I
CC
* (V
S
)
where
• V
S
= V
+
- V
−
(1)
2. Calculate the RMS power dissipated in the output stage:
P
D
(rms) = rms ((V
S
- V
OUT
) * I
OUT
)
where
• V
OUT
is the voltage across the external load
• I
OUT
is the current through the external load
• V
S
is the total supply voltage (2)
3. Calculate the total RMS power: P
T
= P
AMP
+ P
D
.
The maximum power that the LMH6574 package can dissipate at a given temperature can be derived with the
following equation:
P
MAX
= (150° – T
AMB
)/ θ
JA
where
• T
AMB
= Ambient temperature (°C)
• θ
JA
= Thermal resistance, from junction to ambient, for a given package (°C/W) (3)
For the SOIC package θ
JA
is 130 °C/W.
ESD PROTECTION
The LMH6574 is protected against electrostatic discharge (ESD) on all pins. The LMH6574 will survive 2000V
Human Body model and 200V Machine model events. Under normal operation the ESD diodes have no effect on
circuit performance. There are occasions, however, when the ESD diodes will be evident. If the LMH6574 is
driven by a large signal while the device is powered down the ESD diodes will conduct . The current that flows
through the ESD diodes will either exit the chip through the supply pins or will flow through the device, hence it is
possible to power up a chip with a large signal applied to the input pins. Using the shutdown mode is one way to
conserve power and still prevent unexpected operation.
EVALUATION BOARDS
Texas Instruments provides the following evaluation boards as a guide for high frequency layout and as an aid in
device testing and characterization. Many of the data sheet plots were measured with this board.
Device Package Evaluation Board
LMH6574 SOIC LMH730276
An evaluation board can be shipped when a sample request is placed with Texas Instruments. Samples can be
ordered on the TI web page.
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