AD654JR-REEL7 Analog Devices Inc, AD654JR-REEL7 Datasheet - Page 9
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AD654JR-REEL7
Manufacturer Part Number
AD654JR-REEL7
Description
IC,Voltage-to-Frequency Converter,BIPOLAR,SOP,8PIN
Manufacturer
Analog Devices Inc
Type
Voltage to Frequencyr
Datasheet
1.AD654JRZ-REEL.pdf
(11 pages)
Specifications of AD654JR-REEL7
Rohs Status
RoHS non-compliant
Frequency - Max
500kHz
Full Scale
±50ppm/°C
Linearity
±0.2%
Mounting Type
Surface Mount
Package / Case
8-SOIC (0.154", 3.90mm Width)
Converter Function
VFC
Full Scale Frequency
500
Power Supply Requirement
Single/Dual
Single Supply Voltage (typ)
5/9/12/15/18/24/28V
Single Supply Voltage (max)
36V
Single Supply Voltage (min)
4.5V
Dual Supply Voltage (typ)
±9/±12/±15V
Dual Supply Voltage (min)
±5V
Dual Supply Voltage (max)
±18V
Operating Temperature (min)
-40C
Operating Temperature (max)
85C
Operating Temperature Classification
Industrial
Package Type
SOIC N
Lead Free Status / Rohs Status
Not Compliant
Other names
AD654JR-REEL7TR
REV. B
(0V TO 1V)
+
–
V
IN
1k
D
Figure 11. AD654 VFC as an ADC
A
825
1%
500
20pF
20pF
1
2
3
4
AD654
1 F
10k
6MHz
(0V TO 10V)
NC
V
8
7
6
5
IN
ALE PSEN PROG WR RD
XTAL1
XTAL2
RESET
EA
SS
INT
T0
T1
5V
8.06k
R1
1000pF
V
5V
CC
NC
2k
1k
R2
V
R3
DD
8048
NC
GND
V
R
1k
SS
NC = NO CONNECT
T
DB0
DB7
Figure 12. Frequency Doubler
P10
P17
P20
P27
AD654
TRANSISTOR
PORT 1
PORT 2
BUS
PORT
A
B
C
OFF
–9–
DRIVER
ON
500pF
OSC/
V
V
0
0
5
0
C
T
FREQUENCY DOUBLING
Since the AD654’s output is a square-wave rather than a pulse
train, information about the input signal is carried on both
halves of the output waveform. The circuit in Figure 12 converts
the output into a pulse train, effectively doubling the output
frequency, while preserving the better low frequency linearity of
the AD654. This circuit also accommodates an input voltage
that is greater than the AD654 supply voltage.
Resistors R1–R3 are used to scale the 0 V to +10 V input voltage
down to 0 V to +1 V as seen at Pin 4 of the AD654. Recall that
V
The timing resistor and capacitor are selected such that this 0 V
to +1 V signal seen at Pin 4 results in a 0 kHz to 200 kHz output
frequency.
The use of R4, C1 and the XOR gate doubles this 200 kHz
output frequency to 400 kHz. The AD654 output transistor is
basically used as a switch, switching capacitor C1 between a
charging mode and a discharging mode of operation. The voltages
seen at the input of the 74LS86 are shown in the waveform dia-
gram. Due to the difference in the charge and discharge time
constants, the output pulse widths of the 74LS86 are not equal.
The output pulse is wider when the capacitor is charging due to
its longer rise time than fall time. The pulses should therefore be
counted on their rising, rather than falling, edges.
IN
must be less than V
WAVEFORM DIAGRAM
5V
1000pF
R
2.87k
PU
C1
R4
1k
A
B
SUPPLY
74LS86
FS = 400MHz
V/F OUTPUT
–4 V, or in this case less than 1 V.
C
AD654