551600074-001 National Semiconductor, 551600074-001 Datasheet - Page 2

• Manufacturer Part Number: 551600074-001
• Description: BOARD FOR SOIC LMH6612/19
• Manufacturer: National Semiconductor
• Series: WEBENCH® Buildit Boardr

Specifications of 551600074-001

• Channels Per Ic: 2 - Dual
• Amplifier Type: General Purpose
• Board Type: Bare (Unpopulated)
• Utilized Ic / Part: LMH6612, LMH6619
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Operating Temperature: -
• Output Type: -
• Current - Output / Channel: -
• Voltage - Supply, Single/dual (±): -
• -3db Bandwidth: -
• Slew Rate: -
• Current - Supply (main Ic): -

www.national.com
A sample Bill of Material (BOM) for a single to single ADC
driver board is given in the table below. The ADC driver will
have a cutoff frequency of 500 kHz and a gain of -1.
Single to Differential ADC Driver
The single to differential ADC driver board schematic in Fig-
ure 2 utilizes a dual op amp to buffer a single-ended source
to drive an ADC with differential inputs. One of the op amps,
U1A, is configured as a unity gain buffer that drives the in-
verting (IN−) input of the op amp U1B and the non-inverting
(IN+) input of the ADC. U1B inverts the input signal and drives
the inverting input of the ADC. The ADC driver is configured
for a gain of +2 to reduce the noise without sacrificing THD
performance. The common mode voltage of 2.5V is supplied
at the non-inverting inputs of both op amps U1A and U1B.
This configuration produces differential ±2.5 V
Designator
C
C
C
C
C
C
C
C
J1
J2
J4, J5
R
R
R
R
R
U1
1
2
3
4
5
6
7
8
1
3
4
8
IN
, R
, R
2
5
Description
0805 Capacitor
0805 Capacitor
0805 Capacitor
0603 Capacitor
Tantalum Capacitor
0805 Capacitor
0805 Capacitor
0805 Capacitor
SMA Connector
SMA Connector
Test Point
0805 Capacitor
0805 Capacitor
0805 Capacitor
0805 Capacitor
0805 Capacitor
6-Pin SOT23
PP
output sig-
2
nals, when the single-ended input signal of 0 to VREF is AC
coupled into the non-inverting terminal of the op amp and
each non-inverting terminal of the op amp is biased at the mid-
scale of 2.5V. The two output RC anti-aliasing filters are used
between the outputs of both U1A and U1B and the inputs of
the ADC to minimize the effect of undesired high frequency
noise coming from the input source. Each RC filter’s cutoff
frequency is found from the equation:
Comment
1 µF
150 pF
1 nF
0.1 µF
6.8 µF
5.6 µF
0.1 µF
220 pF
IN+
OUT
Test Point
549
1.24k
14.3k
22
50
LMH6611/LMH6618