AD783JR Analog Devices Inc, AD783JR Datasheet - Page 8

• Manufacturer Part Number: AD783JR
• Description: Audio Power Amplifier IC Package/Case:8-SOIC
• Manufacturer: Analog Devices Inc

Specifications of AD783JR

• Leaded Process Compatible: No
• Bandwidth: 80MHz
• Features: Very High Speed
• Mounting Type: Surface Mount
• Operating Temp. Max: 85 C
• Operating Temp. Min: -40 C
• Output Current: 5mA
• Rohs Status: RoHS non-compliant
• Amplifier Type: Sample and Hold
• Number Of Circuits: 1
• -3db Bandwidth: 15MHz
• Current - Input Bias: 100nA
• Current - Supply: 9.5mA
• Current - Output / Channel: 5mA
• Voltage - Supply, Single/dual (±): ±4.75 V ~ 5.25 V
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Output Type: -
• Slew Rate: -
• Gain Bandwidth Product: -
• Voltage - Input Offset: -
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

AD783
AD783 TO AD670 INTERFACE
The 15 MHz small signal bandwidth of the AD783 makes it a
good choice for undersampling applications. Figure 8 shows
the interface between the AD783 and the AD670 ADC, where
the AD783 samples the incoming IF signal. For this particular
application, the IF carrier was 10.7 MHz and the information
signal was a 5 kHz FSK-modulated tone. The sample-and-hold
signal is applied to the 8-bit AD670 ADC and then digitally
processed for analysis.
The CLKIN signal is connected directly to the S/H pin of the
AD783 and must comply with the acquisition and settling re-
quirements of the SHA. A delayed version of CLKIN is applied
to the R/W input of the AD670 in order to accommodate the
hold-mode settling requirements of the AD783. The 10 s con-
version speed of the AD670 combined with the 150 ns hold-
mode settling time of the AD783 result in a total system
throughput of 10.15 s.
By keeping the 10.7 MHz IF input to the AD783 at a low
amplitude, 255 mV p-p, the resultant distortion and jitter-
induced noise result in approximately 45 dB of dynamic range.
The AD670 can be conveniently configured such that its full-
scale input range is 255 mV in order to retain the full 8-bit
dynamic range of the converter. The maximum sample rate of
the AD670 is 10 s; therefore, to comply with the Nyquist
criteria the maximum information bandwidth is 50 kHz.
AD783 to AD671 (12-Bit, 500 ns ADC) Interface
The AD783 to AD671 interface requires an op amp, a dual
flip-flop, and a monostable multivibrator or “one-shot.” The
op amp amplifies the 2.5 V output of the AD783 to the
full-scale input of the AD671. Appropriate op amps include the
AD841 and AD845 (see the AD671 data sheet for additional
information). The flip-flops and one-shot are used to generate
the AD671 ENCODE pulse and the appropriately timed
AD783 S/H pulse.
A master sampling clock is tied to the clock input of flip-flop1
and the input of the one-shot. The D1 input of flip-flop1
should be tied high and the one-shot should be configured to
generate a pulse on a rising edge of the sampling clock. The ris-
ing edge of the sampling clock causes the Q1 output of the
flip-flop to go low placing the AD783 into hold mode. Simulta-
neously, a low going pulse is generated at the one-shot output.
The length of this pulse would usually be made long enough to
allow the output of the AD783 to settle (hold-mode settling
time), but because of the error-correcting ability of the AD671,
the length of this pulse may be reduced to approximately 200 ns.
255mV p-p
10.7MHz
Figure 8. AD783 to AD670 Interface
ANALOG
CLK IN
INPUT
50
2
AD783
7
ONE -
SHOT
8
10k
18
19
17
16
21
+V
–V
+V
–V
R/W
AD670
IN
IN
IN
IN
HI
LOW
HI
LOW
–8–
The low going one-shot output is connected to the clock input
of flip-flop2. The D2 input of flip-flop2 is tied high. The rising
edge of the low going pulse toggles the Q2 output of flip-flop2 to
a high state. This output, which is tied to the ENCODE input of
the AD671, initiates a conversion of the buffered output signal
of the AD783. The AD671 issues the signal DAV when the con-
version is complete. The DAV signal is tied to the asynchronous
CLR1 and CLR2 inputs of both flip-flops. When DAV goes low,
the Q1 output goes high returning the AD783 to the sample or
acquisition mode. The Q2 output (ENCODE) returns low until
it is again triggered by the rising edge of the one-shot output.
0.011 (0.275)
0.005 (0.125)
CLOCK
V
IN
0.023 (0.58)
0.014 (0.36)
0.050 (1.27)
0.070 (1.78)
0.030 (0.76)
(5.08)
0.200
MAX
BSC
8
1
SHOT
ONE-
+5V
0.198 (5.03)
0.188 (4.77)
Figure 9. AD783 to AD671 Interface
Dimensions shown in inches and (mm).
1
8
8-Pin Cerdip (Q-8) Package
0.405 (10.29)
OUTLINE DIMENSIONS
8-Pin SOIC (R-8) Package
D2
5
4
D1
0.107 (2.72)
0.089 (2.26)
MAX
0.100 (2.54)
0.022 (0.56)
0.014 (0.36)
0.158 (4.01)
0.150 (3.81)
CLR2
CLR1
BSC
Q2
Q1
4
5
AD783
0.248 (6.29)
0.224 (5.69)
0.310 (7.87)
0.015 (0.38)
0.220 (5.59)
0.060 (1.52)
0.015 (0.38)
0.007 (0.18)
0.150
(3.81)
MIN
AD84X
0.205 (5.21)
0.195 (4.95)
0.015 (0.381)
0.008 (0.204)
0.320 (8.13)
0.290 (7.37)
AIN
DAV
ENCODE
AD671
0.034 (0.86)
0.018 (0.46)
REV. A