ADC-318 Просмотр технического описания (PDF) - DATEL Data Acquisition products
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ADC-318 Datasheet PDF : 8 Pages
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ADC-318, ADC-318A
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®
the reference input voltages given to VRT and VRB. Keep
the ranges of V within values shown in this data sheet.
Standard settings are VRT = +4.0V, V input range from
+2 to +4V. This setting can be varied to VRT = +3.5V,
VRB = +2V and 1.5V p-p analog input range, depending
on your selection of amplifiers which may provide less
than +4V output.
5. The ADC-318 and ADC-318A have resistor matrix taps at
VRM1 (pin 4), VRM2 (pin 7) and VRM3 (pin 9). These pins
provide ¼, ½ and ¾ full scale of VRT-VRB voltage respec-
tively. These outputs may be used to adjust the integral
non-linearity. Bypass these pins to GND with 0.1uF ceramic
chip capacitors.
6. A/D CLK input and RSET/RSET inputs are TTL or ECL,
PECL (Positive ECL) compatible. Pins are provided
individually. TTL or PECL is available with +5V single power
applied. ECL is available with ±5V dual power applied. The
connections of –DVs (pin 1) and DGND3 (pin12) are
different depending on the power supply mode used. Refer
to Figures 2-1 and 2-2.
a. For +5V single power (TTL or PECL) –DVs (pin 1) is
connected to DGND. DGND3 (pin 12) is connected
to +5V power.
b. For ±5V dual power (ECL) –DVs (pin 1) is connected
to –5V power. DGND3 (pin 12) is connected to DGND.
7. When the A/D CLK is driven with ECL or PECL, A/D CLK
(pin 13) and A/D CLK (pin 14) are to be driven by differen-
tial logic inputs to avoid unstable performance at critically
high speeds. If a risk of unstable performance is accept-
able, single logic input can be used opening A/D CLK (pin
14). The A/D CLK pin should be bypassed to DGND with a
0.1uF ceramic capacitor. When connected this way there
will be a voltage of DGND –1.2V on the A/D CLK pin. This
voltage can not be used as a threshold voltage for ECL or
PECL. Input the A/D CLK pulse to pin 15 when TTL is
selected.
8. The ADC-318 and ADC-318A have RSET/RSET input pins.
An internal frequency half divider can be initialized with
inputs to these pins. With ECL or PECL, differential inputs
are given to RSET (pin 48) and RSET (pin 47). This
function can be achieved with a single input, leaving pin 47
open and bypassing to DGND with a 0.1uF ceramic chip
capacitor. The voltage level of pin 47 is the threshold
voltage of ECL or PECL. Use RSET (pin 46) for TTL.
9. SELECT (pin 45) is used to set output mode. Connection of
this pin to DGND selects the straight output mode and
connection to +DVs selects the 1:2 de-multiplexed output
mode. The maximum sampling rates are 100MHz for straight
mode (For both models, ADC-318 and ADC-318A) and
120MHz (ADC-318) and 140MHz (ADC-318A) for de-
multiplexed mode. Refer to figure 2-4. There is an applica-
tion where a multiple number of ADC-318/318A's are used
with a common A/D CLK and outputs are in de-multiplexed
mode. In this case, the initial conditions of the frequency half
divider of each A/D Converter are not synchronized and it is
possible that each converter may have one clock maximum
of timing lag. This lag can be avoided by giving a common
RSET pulse to all converters at power ON. (See Figure 3-3
and 3-4, timing diagrams.)
10.The ADC-318 and ADC-318A have a TTL compatible CLK
OUT (pin 43). Since the rising edge of this pulse can provide
Setup and Hold time of output data, regardless of the output
mode, this signal can be used as synchronization pulse for
external circuits. Data output timing is different for the
straight mode and the de-multiplexed mode. See the timing
chart Figure 3.
11. INV (pin 44) is used to invert polarity of the TTL compatible
output data from both A and B ports. Leaving this pin open
or connected to +DVs makes the output positive true and
connection to DGND makes it negative true logic. See
input/output code table, Table 4.
Table 3: Logic Input Level vs. Power Supply Settings
DIGITAL INPUT
LEVEL
–DVS
DGND3
SUPPLY
VOLTAGES
TTL
0V
+5V
+5V
PECL
0V
+5V
+5V
ECL
–5V
0V
±5V
Table 4: Digital Output Coding
SIGNAL
INPUT
VOLTAGE
VRT
VRM2
VRB
DIGITAL OUTPUT CODE (A,B OUTPUT)
INV=1
INV=0
LSB
MSB LSB
MSB
11111111
00000000
10000000
01111111
01111111
10000000
00000000
11111111
11
ADC-318
ADC-318A
12
13 14 15 16 17 18
TTL LEVEL CLOCK INPUT
A/D CLOCK
A/D CLOCK
A/D CLOCK
ECL, PECL LEVEL CLOCK INPUTS
Figure 2-3: A/D Clock Input Connection
TTL LEVEL RESET INPUT
RSET
RSET
RSET
ECL, PECL LEVEL
RESET INPUTS
5V(D)
A/D CONVERSION MODE
DEMULTIPLEXED DATA OUT
STRAIGHT DATA OUT
5V(D)
OUTPUT CODING
STRAIGHT BINARY
COMPLEMENTARY BINARY
48 47 46 45 44 43 42
1
ADC-318
ADC-318A
2
TTL CLOCK OUT
Figure 2-4: Digital Input/Output Connections
4
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