LMH6555EVAL National Semiconductor, LMH6555EVAL Datasheet - Page 19

• Manufacturer Part Number: LMH6555EVAL
• Manufacturer: National Semiconductor

Specifications of LMH6555EVAL

• Lead Free Status / Rohs Status: Not Compliant

Figures 20, 21, and Figure 22 information summary:
The LMH6555 is capable of driving a variety of National Semi-
conductor Analog to Digital Converters. This is shown in
Table 2, which offers a complete list of possible signal path
ADC+ Amplifier combinations. The use of the LMH6555 to
• Fundamental Test
Frequency
• LMH6555 Output
• Sampling Rate:
• 2
• 3
• 4
• 5
• 6
• THD
• SNR
• Spurious Free Dynamic
• SINAD
• ENOB
FIGURE 22. LMH6555 FFT Result When Used as the
Range (SFDR):
nd
rd
th
th
th
Harmonic
Harmonic
Harmonic
Harmonic
Harmonic
Differential Driver to ADC081500
(Upper Fs/2 Region Magnified)
744 MHz
0.8 V
1.5G samples/ second
−59 dBc @
|1.5 GHz*1– 744 MHz*2|
−57 dBc @
|1.5 GHz*1- 744 MHz *3|
−71 dBc @
|1.5 GHz*2 – 744 MHz *4|
−68 dBc @
|1.5 GHz*2- 744 MHz*5|
−68 dBc @
|1.5 GHz*3- 744 MHz*6|
−51.8 dBc
43.4 dB
57 dB
42.8 dB
6.8 bits
PP
∼
∼
∼
∼
∼
12 MHz or
732 MHz or
24 MHz or
720 MHz or
36 MHz or
20127745
19
drive an ADC is determined by the application and the desired
sampling process (Nyquist operation, sub-sampling or over-
sampling). See application note (AN-236) for more details on
the sampling processes and application note (AN-1393) for
details on “Using High Speed Differential Amplifiers to Drive
ADCs”. For more information regarding a particular ADC, re-
fer to the particular ADC datasheet for details.
EXPOSED PAD LLP PACKAGE
The LMH6555 is in a thermally enhanced package. The ex-
posed pad (device bottom) is connected to the GND pins. It
is recommended, but not necessary, that the exposed pad be
connected to the supply ground plane. The thermal dissipa-
tion of the device is largely dependent on the connection of
this pad. The exposed pad should be attached to as much
copper on the circuit board as possible, preferably external
copper. However, it is very important to maintain good high
speed layout practices when designing a system board.
Here is a link to more information on the National 16-pin LLP
package:
http://www.national.com/packaging/folders/sqa16a.html
EVALUATION BOARD
National Semiconductor suggests the following evaluation
board as a guide for high frequency layout and as an aid in
device testing and characterization.
The evaluation board can be ordered when a device sample
request is placed with National Semiconductor.
Device
LMH6555
ADC Part Number Resolution
TABLE 2. Differential Input ADC’s Compatible with the
ADC08D1000
ADC08D1020
ADC08D1500
ADC08D1520
ADC08B3000
ADC08D500
ADC081000
ADC081500
ADC083000
Package
16-Pin LLP
LMH6555 Driver
(bits)
8
8
8
8
8
8
8
8
8
Evaluation Board
Ordering ID
LMH6555EVAL
Single/
Dual
D
D
D
D
S
S
S
S
S
www.national.com
(MSPS)
Speed
1000
1000
1000
1500
1500
1500
3000
3000
500