• High signal-to-noise ratio over a large analog input
frequency range (7.4 effective bits at 4.43 MHz full-scale
input and at f
= 50 MHz)
clk
• Binary 3-state TTL outputs
• Overflow/underflow 3-state TTL output
• TTL compatible digital inputs
• Low-level AC clock input signal allowed
• Stable internal reference voltage regulator included
• Power dissipation only 380 mW (typical)
• Low analog input capacitance, no buffer amplifier
required
• No sample-and-hold circuit required.
QUICK REFERENCE DATA
APPLICATIONS
• General purpose high-speed analog-to-digital
conversion for extended temperature applications
• Automotive
• RF, satellite and GPS (Global Positioning System)
• Medical
• General industrial
• Digital video (VCR, TV and satellite).
GENERAL DESCRIPTION
The TDF8704T is an 8-bit high-speed analog-to-digital
converter (ADC) for general industrial applications. It
converts the analog input signal into 8-bit binary-coded
digital words at a maximum sampling rate of 50 MHz. All
digital inputs and outputs are TTL compatible, although a
low-level AC clock input signal is allowed.
SYMBOLPARAMETERCONDITIONSMIN.TYP.MAX.UNIT
V
V
V
I
CCA
I
CCD
I
CCO
CCA
CCD
CCO
analog supply voltage4.755.05.25V
digital supply voltage4.755.05.25V
output stages supply voltage4.755.05.25V
analog supply current−3746mA
digital supply current−2335mA
output stages supply current−1621mA
ILEDC integral linear error−±0.4±1LSB
DLEDC differential linearity error−±0.2±0.5LSB
AILEAC integral linearity errornote 1−−±2LSB
f
D11data output; bit 1
D02data output; bit 0 (LSB)
n.c.3not connected
V
RB
DEC5decoupling input (internal
AGND6analog ground
V
CCA
V
I
V
RT
n.c.10not connected
O/UF11overflow/underflow data output
D712data output; bit 7 (MSB)
D613data output; bit 6
D514data output; bit 5
D415data output; bit 4
CLK16clock input
DGND17digital ground
V
CCD
V
CCO1
OGND20output ground
V
CCO2
CE22chip enable input (TTL level input,
D323data output; bit 3
D224data output; bit 2
4reference voltage BOTTOM
(decoupling)
stabilization loop decoupling)
7analog supply voltage (+5 V)
8analog input voltage
9reference voltage TOP (decoupling)
18digital supply voltage (+5 V)
19supply voltage for output stages 1
In accordance with the Absolute Maximum Rating System (IEC134).
SYMBOLPARAMETERCONDITIONSMIN.MAX.UNIT
V
CCA
V
CCD
V
CCO
∆V
∆V
∆V
V
I
V
clk(p-p)
I
O
T
stg
T
amb
T
j
CC
CC
CC
analog supply voltage−0.3+7.0V
digital supply voltage−0.3+7.0V
output stages supply voltage−0.3+7.0V
supply voltage differences between V
supply voltage differences between V
supply voltage differences between V
CCA
CCO
CCA
and V
and V
and V
CCD
CCD
CCO
−1.0+1.0V
−1.0+1.0V
−1.0+1.0V
input voltagereferenced to AGND−0.3+7.0V
AC input voltage for switching (peak-to-peak value)referenced to DGND−V
CCD
V
output current−10mA
storage temperature−55+150°C
operating ambient temperature−40+85°C
junction temperature−+150°C
HANDLING
Inputs and outputs are protected against electrostatic discharges in normal handling. However, to be totally safe, it is
desirable to take normal precautions appropriate to handling integrated circuits.
THERMAL CHARACTERISTICS
SYMBOLPARAMETERVALUEUNIT
R
th j-a
thermal resistance from junction to ambient in free air75K/W
1. In addition to a good layout of the digital and analog ground, it is recommended that the rise and fall times of the clock
must be less than 1 ns.
2. Full-scale sine wave (fi = 4.43 MHz; f
= 50 MHz).
clk
3. Determined by beat frequency method on a reconstructed sine wave signal for no missing codes and no glitches.
4. The analog input settling time is the minimum time required for the input signal to be stabilized after a sharp full-scale
input (square-wave signal) in order to sample the signal and obtain correct output data.
5. Effective bits are obtained via a Fast Fourier Transform (FFT) treatment taking 4K acquisition points per period. The
calculation takes into account all harmonics and noise up to half of the clock frequency (NYQUIST frequency).
Conversion to signal-to-noise ratio: S/N = EB × 6.02 + 1.76 dB.
6. Intermodulation measured relative to either tone with analog input frequencies of 4.43 MHz and 4.53 MHz. The two
input signals have the same amplitude and the total amplitude of both signals provides full scale to the converter.
7. Measurement taken using video analyser VM700A.
8. Output data acquisition: the output data is available after the maximum delay time of td.
The analog and digital supplies should be separated and decoupled.
(1) VRB and VRT are decoupling pins for the internal reference ladder; do not draw current from these pins in order to achieve good linearity.
(2) Pins 3 and 10 should be connected to DGND in order to prevent noise influence.
B
During placement and before soldering, the component
must be fixed with a droplet of adhesive. After curing the
adhesive, the component can be soldered. The adhesive
can be applied by screen printing, pin transfer or syringe
dispensing.
Maximum permissible solder temperature is 260 °C, and
maximum duration of package immersion in solder bath is
10 s, if allowed to cool to less than 150 °C within 6 s.
Typical dwell time is 4 s at 250 °C.
A modified wave soldering technique is recommended
using two solder waves (dual-wave), in which a turbulent
wave with high upward pressure is followed by a smooth
laminar wave. Using a mildly-activated flux eliminates the
need for removal of corrosive residues in most
applications.
Y SOLDER PASTE REFLOW
B
Reflow soldering requires the solder paste (a suspension
of fine solder particles, flux and binding agent) to be
applied to the substrate by screen printing, stencilling or
pressure-syringe dispensing before device placement.
Several techniques exist for reflowing; for example,
thermal conduction by heated belt, infrared, and
vapour-phase reflow. Dwell times vary between 50 and
300 s according to method. Typical reflow temperatures
range from 215 to 250 °C.
Preheating is necessary to dry the paste and evaporate
the binding agent. Preheating duration: 45 min at 45 °C.
EPAIRING SOLDERED JOINTS (BY HAND-HELD SOLDERING
R
IRON OR PULSE
-HEATED SOLDER TOOL)
Fix the component by first soldering two, diagonally
opposite, end pins. Apply the heating tool to the flat part of
the pin only. Contact time must be limited to 10 s at up to
300 °C. When using proper tools, all other pins can be
soldered in one operation within 2 to 5 s at between 270
and 320 °C. (Pulse-heated soldering is not recommended
for SO packages.)
For pulse-heated solder tool (resistance) soldering of VSO
packages, solder is applied to the substrate by dipping or
by an extra thick tin/lead plating before package
placement.
DEFINITIONS
Data sheet status
Objective specificationThis data sheet contains target or goal specifications for product development.
Preliminary specificationThis data sheet contains preliminary data; supplementary data may be published later.
Product specificationThis data sheet contains final product specifications.
Limiting values
Limiting values given are in accordance with the Absolute Maximum Rating System (IEC 134). Stress above one or
more of the limiting values may cause permanent damage to the device. These are stress ratings only and operation
of the device at these or at any other conditions above those given in the Characteristics sections of the specification
is not implied. Exposure to limiting values for extended periods may affect device reliability.
Application information
Where application information is given, it is advisory and does not form part of the specification.
LIFE SUPPORT APPLICATIONS
These products are not designed for use in life support appliances, devices, or systems where malfunction of these
products can reasonably be expected to result in personal injury. Philips customers using or selling these products for
use in such applications do so at their own risk and agree to fully indemnify Philips for any damages resulting from such
improper use or sale.
June 199418
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