TSA1204(2006) View Datasheet(PDF) - STMicroelectronics
Part Name
Description
Manufacturer
TSA1204 Datasheet PDF : 31 Pages
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TSA1204
Application information
Table 12. Total power consumption optimization depending on Rpol value
FS (Msps)
10
20
Rpol (kΩ)
120
54
Optimized power (mW)
95
120
8.6
Layout precautions
To use the ADC circuits most efficiently at high frequencies, some precautions have to be
taken for power supplies:
● First of all, the implementation of 4 proper separate supplies and ground planes
(analog, digital, internal and external buffer ones) on the PCB is recommended for high
speed circuit applications to provide low inductance and low resistance common return.
The separation of the analog signal from the digital output part is mandatory to prevent
noise from coupling onto the input signal. The best compromise is to connect AGND,
DGND, GNDBI in a common point whereas GNDBE must be isolated. Similarly, the
AVCC, DVCC and VCCBI power supplies must be separate from the VCCBE power
supply.
● Power supply bypass capacitors must be placed as close as possible to the IC pins in
order to improve high frequency bypassing and reduce harmonic distortion.
● All inputs and outputs must be properly terminated with output termination resistors;
then the amplifier load is resistive only and the stability of the amplifier is improved. All
leads must be wide and as short as possible especially for the analog input in order to
decrease parasitic capacitance and inductance.
● To keep the capacitive loading as low as possible at digital outputs, short lead lengths
of routing are essential to minimize currents when the output changes. To minimize this
output capacitance, use buffers or latches close to the output pins.
● Choose component sizes as small as possible (SMD).
8.7
EVAL1204/BA evaluation board
The EVAL1204/BA is a 4-layer board with high decoupling and grounding level. The
schematic of the evaluation board is shown in Figure 30 and its top overlay view in
Figure 29. The board has been characterized with a fully devoted ADC test bench as shown
in Figure 28.
Figure 28. Analog-to-digital converter characterization bench
HP8644
Sine Wave
Generator
Data
Vin
ADC
evaluation
Logic
Analyzer
PC
board
Clk
Clk
HP8133
Pulse
Generator
Sine Wave
HP8644 Generator
19/31
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