- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄373890 > AD654 (Analog Devices, Inc.) Low Cost Monolithic Voltage-to-Frequency Converter(低成本單片電壓-頻率轉(zhuǎn)換器) PDF資料下載
參數(shù)資料
| 型號： | AD654 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | Low Cost Monolithic Voltage-to-Frequency Converter(低成本單片電壓-頻率轉(zhuǎn)換器) |
| 中文描述： | 低成本單片電壓頻率轉(zhuǎn)換器（低成本單片電壓-頻率轉(zhuǎn)換器） |
| 文件頁數(shù)： | 6/8頁 |
| 文件大小： | 307K |
| 代理商： | AD654 |
AD654
REV. A
–6–
Figure 9. Optoisolator Interface
At the receiver side, the output transistor is operated in the
photo-transistor mode; that is with the base lead (Pin 6) open.
This allows the highest possible output current. For reasonable
speed in this mode, it is imperative that the load impedance be
as low as possible. This is provided by the single transistor stage
current-to-voltage converter, which has a dynamic load imped-
ance of less than 10 ohms and interfaces with TTL at the output.
USING A STAND-ALONE FREQUENCY COUNTER/LED
DISPLAY DRIVER FOR VOLTMETER APPLICATIONS
Figure 10 shows the AD654 used with a stand-alone frequency
counter/LED display driver. With C
T
= 1000 pF and R
T
= 1 k
the AD654 produces an FS frequency of 100 kHz when V
IN
=
+1 V. This signal is fed into the ICM7226A, a universal counter
system that drives common anode LEDs. With the FUNC-
TION pin tied to D1 through a 10 k
resistor the ICM7226A
counts the frequency of the signal at A
IN
. This count period is
selected by the user and can be 10 ms, 100 ms, 1s, or 10 seconds,
as shown on Pin 21. The longer the period selected, the more
resolution the count will have. The ICM7226A then displays
the frequency on the LEDs, driving them directly as shown. Re-
freshing of the LEDs is handled automatically by the ICM7226.
The entire circuit operates on a single +5 V supply and gives a
meter with 3, 4, or 5 digit resolution.
Figure 10. AD654 With Stand-Alone Frequency Counter/
LED Display Driver
As the V/F oscillates, additional switched current is drawn
through R
L
when Pin 1 goes low. The peak level of this addi-
tional current causes Q1 to saturate, and thus regenerates the
AD654’s output square wave at the collector. The supply volt-
age to the AD654 then consists of a dc level, less the resistive
line drop, plus a one V
BE
p-p square wave at the output
frequency of the AD654. This ripple is reduced by the diode/
capacitor combination.
To set up the receiver circuit for a given voltage, the R
S
and R
L
resistances are selected as shown in Table I. CMOS logic stages
can be driven directly from the collector of Q1, and a single
TTL load can be driven from the junction of R
S
and R6.
Table I.
+V
S
R
S
R
L
10 V
15 V
270
680
1.8k
2.7k
Table II.
(+V
S
) R1
R2
R3
R4
R5
K
10 V
15 V
–
–
–
–
–
–
100k 127k
100k 127k
F = 10 Hz/K
°
C
10 V
15 V
6.49k
12.7k
4.02k
4.02k
1k
1k
95.3k 22.6k
78.7k 36.5k
F = 10 Hz/
°
C
°
F
10 V
15 V
6.49k
12.7k
4.42k
4.42k
1k
1k
154k 22.6k
105k 36.5k
F = 5.55 Hz/
°
F
At the V/F end, the AD592C temperature transducer is inter-
faced with the AD654 in such a manner that the AD654 output
frequency is proportional to temperature. The output frequency
can be sealed and offset from K to
°
C or
°
F using the resistor
values shown in Table II. Since temperature is the parameter of
interest, an NPO ceramic capacitor is used as the timing capaci-
tor for low V/F TC.
When scaling per K, resistors R1–R3 and the AD589 voltage
reference are not used. The AD592 produces a 1
μ
A/K current
output which drives Pin 3 of the AD654. With the timing
capacitor of 0.01
μ
F this produces an output frequency scaled to
10 Hz/K. When scaling per
°
C and
°
F, the AD589 and resistors
R1–R3 offset the drive current at Pin 3 by 273.2
μ
A for scaling
per
°
C and 255.42
μ
A for scaling per
°
F. This will result in fre-
quencies sealed at 10 Hz/
°
C and 5.55 Hz/
°
F, respectively.
OPTOISOLATOR COUPLING
A popular method of isolated signal coupling is via optoelec-
tronic isolators, or optocouplers. In this type of device, the sig-
nal is coupled from an input LED to an output photo-transistor,
with light as the connecting medium. This technique allows dc
to be transmitted, is extremely useful in overcoming ground
loop problems between equipment, and is applicable over a wide
range of speeds and power.
Figure 9 shows a general purpose isolated V/F circuit using a
low cost 4N37 optoisolator. A +5 V power supply is assumed
for both the isolated (+5 V isolated) and local (+5 V local) sup-
plies. The input LED of the isolator is driven from the collector
output of the AD654, with a 9 mA current level established by
R1 for high speed, as well as for a 100% current transfer ratio.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| AD6600 | Dual Channel, Gain-Ranging ADC with RSSI |
| AD6600AST | Dual Channel, Gain-Ranging ADC with RSSI |
| AD6600PCB | Dual Channel, Gain-Ranging ADC with RSSI |
| AD6600ST | Dual Channel, Gain-Ranging ADC with RSSI |
| AD660AN | Monolithic 16-Bit Serial/Byte DACPORT |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AD654JCHIPS | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Voltage-to-Frequency Converter |
| AD654JN | 功能描述:IC V-F CONVERTER MONO 8-DIP RoHS:否 類別:集成電路 (IC) >> PMIC - V/F 和 F/V 轉(zhuǎn)換器 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 類型:頻率至電壓 頻率 - 最大:10kHz 全量程:- 線性:±0.3% 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 供應(yīng)商設(shè)備封裝:8-SOIC 包裝:Digi-Reel® 其它名稱:LM2917MX-8/NOPBDKR |
| AD654JN/+ | 制造商:Rochester Electronics LLC 功能描述:IC - LOW COST V/F CONV. - Bulk |
| AD654JNZ | 功能描述:IC V-F CONVERTER MONO 8-DIP RoHS:是 類別:集成電路 (IC) >> PMIC - V/F 和 F/V 轉(zhuǎn)換器 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 類型:頻率至電壓 頻率 - 最大:10kHz 全量程:- 線性:±0.3% 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 供應(yīng)商設(shè)備封裝:8-SOIC 包裝:Digi-Reel® 其它名稱:LM2917MX-8/NOPBDKR |
| AD654JNZ/+ | 功能描述:IC CONV VOLT-FREQ 500KHZ 8DIP RoHS:是 類別:集成電路 (IC) >> PMIC - V/F 和 F/V 轉(zhuǎn)換器 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 類型:頻率至電壓 頻率 - 最大:10kHz 全量程:- 線性:±0.3% 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 供應(yīng)商設(shè)備封裝:8-SOIC 包裝:Digi-Reel® 其它名稱:LM2917MX-8/NOPBDKR |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。