REV. B
3
ADVFC32
UNIPOLAR V/F, POSITIVE INPUT VOLTAGE
When operated as a V/F converter, the transformation from
voltage to frequency is based on a comparison of input signal
magnitude to the 1 mA internal current source.
A more complete understanding of the ADVFC32 requires a
close examination of the internal circuitry of this part. Consider
the operation of the ADVFC32 when connected as shown in
Figure 1. At the start of a cycle, a current proportional to the
Figure 1. Connection Diagram for V/F Conversion,
Positive Input Voltage
input voltage flows through R3 and R1 to charge integration
capacitor C2. As charge builds up on C2, the output voltage of
the input amplifier decreases. When the amplifier output volt-
age (Pin 13) crosses ground (see Figure 2 at time t
1
), the
comparator triggers a one shot whose time period is determined
by capacitor C1. Specifically, the one shot time period (in nano-
seconds) is:
t
OS
 E (C
l
 + 44 pF) ?6.7 k&
Figure 2. Voltage-to-Frequency Conversion Waveforms
During this period, a current of (1 mA  I
IN
) flows out of the
integration capacitor. The total amount of charge depleted
during one cycle is, therefore (1 mA  I
IN
) ?t
OS
. This charge is
replaced during the remainder of the cycle to return the integra-
tor to its original voltage. Since the charge taken out of C2 is
equal to the charge that is put on C2 every cycle,
(1 mA  I
IN
) ?/SPAN> t
OS
 = I
IN
 ?/SPAN>
 
 
1
F
OUT
t
OS
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
or, rearranging terms,
F
OUT
  = 
 
 
I
IN
1mA?SPAN class="pst ADVFC32SH_2632837_9">t
OS
The complete transfer equation can now be derived by substi-
tuting I
IN
 = V
IN
/R
IN
 and the equation relating C1 and t
OS
. The
final equation describing ADVFC32 operation is:
 
 
V
II
N
/R
IN
1mA?SPAN class="pst ADVFC32SH_2632837_9"> C
1
+44pF
(
)
?.7k&
Components should be selected to optimize performance over
the desired input voltage and output frequency range using the
equations listed below:
 
 
3.7?0
7
pF/sec
F
OUTFS
44pF
C
2
 = 
 
 
10
4
Farads/sec
F
OUT FS
1000pFminimum
(
)
R
IN
 =
 
 
V
IN FS
0.25mA
R
2
 e 
 
 
+V
LOGIC
8mA
Both R
IN
 and C
1
 should have very low temperature coefficients
as changes in their values will result in a proportionate change
in the V/F transfer function. Other component values and tem-
perature coefficients are not critical.
Table I. Suggested Values for C
1
, R
IN
 and C
2
V
IN FS
F
OUT FS
C
1
R
IN
C
2
1 V    10 kHz
3650 pF  4.0 k&   0.01 礔
10 V   10 kHz
3650 pF  40 k&    0.01 礔
1 V    100 kHz    330 pF   4.0 k&   1000 pF
10 V   100 kHz    330 pF   40 k&    1000 pF
ORDERING GUIDE
Part
Gain Tempco  Temp Range  Package
Number
1
ppm/C
C
Option
ADVFC32KN  ?5 typ
0 to 70
14-Pin
Plastic DIP
ADVFC32BH   ?00 max
25 to +85   TO-100
ADVFC32SH   ?50 max
55 to +125  TO-100
NOTE
1
For details on grade and package offerings screened in accordance with MIL-STD-883,
refer to the Analog Devices Military Products Databook or current ADVFC32/883B
data sheet.
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000V readily
accumulate on the human body and test equipment and can discharge without detection. Although
the ADVFC32 features proprietary ESD protection circuitry, permanent damage may occur on
devices subjected to high-energy electrostatic discharges. Therefore, proper ESD precautions are
recommended to avoid performance degradation or loss of functionality.
WARNING!
ESD SENSITIVE DEVICE
相关PDF资料
FAN4800ASNY IC CTLR COMBO PFC/PWM 16-DIP
FAN4800AUN IC PWM/PFC CTLR COMBO 16-MDIP
FAN4800CUN IC PWM/PFC CTLR COMBO 16-MDIP
FAN4802MY IC PFC CTRLR AVERAGE CURR 16SOP
FAN4802SNY IC CTLR PFC/PWM COMBO 16-PDIP
FAN6920MRMY IC PWM CTLR PFC/QUASI-RES 16SOP
FAN6921MLMY IC CTLR PFC/FLYBACK 16-SOICN
FAN6921MRMY IC CTLR PFC/FLYBACK 16-SOICN
相关代理商/技术参数
ADVFC32SH/883B 功能描述:电压频率转换及频率电压转换 IC MONO V/F AND F/V CONV RoHS:否 制造商:Texas Instruments 全标度频率:4000 KHz 线性误差:+/- 1 % FSR 电源电压-最大: 电源电压-最小: 最大工作温度:+ 85 C 最小工作温度:- 25 C 安装风格:Through Hole 封装 / 箱体:PDIP-14 封装:Tube
ADVFEEDTHRU001 制造商:AVX Corporation 功能描述:DESIGN KIT FEEDTHROUGH CAPACITORS 制造商:AVX Corporation 功能描述:DESIGN KIT, FEEDTHROUGH CAPACITORS 制造商:AVX Corporation 功能描述:DESIGN KIT, FEEDTHROUGH CAPACITORS; Kit Contents:26 Feedthrough Capacitors ;RoHS Compliant: Yes
A-DVI-1001-01-R 制造商:Assmann Electronics Inc 功能描述:CONN DVI-D MALE SLDR
A-DVI-1001-02-R 制造商:Assmann Electronics Inc 功能描述:CONN DVI MALE SLDR
A-DVI-1002-01-R 制造商:Assmann Electronics Inc 功能描述:CONN DVI MALE SLDR
A-DVI-1002-02-R 制造商:Assmann Electronics Inc 功能描述:CONN DVI MALE SLDR
A-DVI-1003-01-R 制造商:Assmann Electronics Inc 功能描述:DVI CONNECTOR 24+1 MALE, PIN TYPE, G/F, WHITE
A-DVI-1003-02-R 制造商:Assmann Electronics Inc 功能描述:CONN DVI MALE