cxa1166k Sony Electronics, cxa1166k Datasheet - Page 10

• Manufacturer Part Number: cxa1166k
• Description: 8-bit 250 Msps Flash A/d Converter
• Manufacturer: Sony Electronics

Notes on Operation
• The CXA1166K is an ultra-high speed A/D converter featuring ECL level of input/output for the logic block. In
• The outputs are designed to drive a load terminated to –2V at 50 . An excellent transmission characteristic
• The power supply and ground pattern greatly affect the characteristics of the converter. The higher the
• When mounting the A/D converter on the socket, use the one of shortest leads. The QFP socket, the type
• The V
• Connect all four V
• The voltage at the V
• Provide adequate by-pass capacitors for V
order to derive the most from its high-speed performance, the characteristic impedance should be matched
properly.
can be yielded by designing the printed circuit board with a 50 characteristic impedance.
Yielding its top performance is difficult on the printed circuit board with a characteristic impedance of 100 or
more.
frequency, the more important these connections become. The general precautions are as follows.
– Make the pattern of the power supply and ground as wide as possible. Using a ground plane inner layer by
– lsolate the AGND, DGND pins and the AV
name IC61-0684-048, manufactured by YAMAICHI ELECTRONICS CO., LTD. is recommended.
circuits. In order to drive them with an excellent frequency response, it is necessary to safeguard against any
deterioration in performance resulting from parasitic capacitance and parasitic inductance by using a high-
capacity drive circuit, keeping the wiring as short as possible, and using chip parts as resistors and
capacitors, for instance. The drive circuit shown in the Application Circuit has a virtually flat frequency
response up to approximately 170MHz. C89, R11 and C15 have been inserted mainly to expand the
bandwidth, while R10 has been inserted mainly to suppress operational amplifier oscillation and block
peaking of the frequency response. Since the optimal values of these elements differ depending on the
printed circuit board pattern and mounting condition of the A/D converter socket used, they must be
determined on the basis of experimentation.
resistance of several ohms for each pin.
slightly due to residual resistance. V
The overrange reference voltage is 1/2 LSB down from V
code changes is 1/2 LSB up from V
V
0.1µF), make the by-pass from V
suppressing the oscillation of the reference voltage generation circuit.
RT
using a multilayer printed circuit board is recommended.
against interaction. Connect the AGND and DGND pins at one place using a ferrite-bead filter to prevent
DC offset. The same processing is requited for the AV
is connected to AGND of an inner layer of the printed circuit board. Using a chip capacitor (approximately
IN
analog input pins have somewhat large input capacitance (approximately 18pF) for high-frequency
IN
pins directly and as short as possible. Unlike the CXA1176, it is not necessary to insert
RT
and V
RB
RB
reference voltage pins and the reference voltage inside these pins differ
RBS
RTS
to AGND as short as possible. C22 (1µF), in the Application Circuit is for
.
and V
RT
EE,
RBS
and V
DV
are provided to detect the reference voltage inside the pins.
– 10 –
EE
RB
from one another on the pattern in order to safeguard
to protect them from high-frequency noise. Normally,
EE
and DV
RTS
; the lowest input voltage at which the output
EE
pins.
CXA1166K