551600075-001 National Semiconductor, 551600075-001 Datasheet - Page 23

• Manufacturer Part Number: 551600075-001
• Description: BOARD FOR SOIC LMH6612/19
• Manufacturer: National Semiconductor
• Series: WEBENCH® Buildit Boardr

Specifications of 551600075-001

• 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): -

SINGLE-ENDED TO DIFFERENTIAL ADC DRIVER
The single-ended to differential ADC driver in Figure 3 utilizes
an LMH6612 dual op amp to buffer a single-ended source to
drive an ADC with differential inputs. One of the op amps is
configured as a unity gain buffer that drives the inverting
(IN−) input of the op amp U2 and non-inverting (IN+) input of
the ADC121S625. U2 inverts the input signal and drives the
inverting input of the ADC121S625. The ADC driver is con-
figured for a gain of +2 to reduce the noise without sacrificing
THD performance. The common mode voltage of 2.5V is set
FIGURE 6. Single-Ended to Differential ADC Driver
FIGURE 5. LMH6611 and ADC121S101 Layout
23
up at the non-inverting inputs of both op amps U1 and U2.
This configuration produces differential ±2.5 V
nals, when the single-ended input signal of 0 to V
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 both the outputs of U1 and U2 and the input of the
ADC121S625 to minimize the effect of undesired high fre-
quency noise coming from the input source. Each RC filter
has the cutoff frequency of approximately 22 MHz.
30033640
PP
www.national.com
output sig-
REF
30033680
is AC