Datasheet.kr   

VFC121BP 데이터시트 PDF




Burr-Brown Corporation에서 제조한 전자 부품 VFC121BP은 전자 산업 및 응용 분야에서
광범위하게 사용되는 반도체 소자입니다.


PDF 형식의 VFC121BP 자료 제공

부품번호 VFC121BP 기능
기능 Precision Single Power Supply VOLTAGE-TO-FREQUENCY CONVERTER
제조업체 Burr-Brown Corporation
로고 Burr-Brown Corporation 로고


VFC121BP 데이터시트 를 다운로드하여 반도체의 전기적 특성과 매개변수에 대해 알아보세요.




전체 8 페이지수

미리보기를 사용할 수 없습니다

VFC121BP 데이터시트, 핀배열, 회로
® VFC121
Precision Single Power Supply
VOLTAGE-TO-FREQUENCY CONVERTER
FEATURES
q SINGLE SUPPLY OPERATION:
+4.5V to +36V
q f = 1.5MHz max
O
q LOW NONLINEARITY: 0.03% max at
100kHz, 0.1% max at 1MHz
q HIGH INPUT IMPEDANCE
q VOLTAGE REFERENCE OUTPUT
q THERMOMETER OUTPUT: 1mV/°K
APPLICATIONS
q INTEGRATING A/D CONVERSION
q ANALOG SIGNAL TRANSMISSION
q PHASE-LOCKED LOOP VCO
q GALVANICALLY ISOLATED SYSTEMS
DESCRIPTION
The VFC121 is a monolithic voltage-to-frequency
converter consisting of an integrating amplifier, volt-
age reference, and one-shot charge pump circuitry.
High-frequency complementary NPN/PNP circuitry is
used to implement the charge-balance technique,
achieving speed and accuracy far superior to previous
single power supply VFCs.
The high-impedance input accepts signals from ground
potential to VS – 2.5V. Power supplies from 4.5V to
36V may be used. A 2.6V reference voltage output
may be used to excite sensors or bias external cir-
cuitry. A thermometer output voltage proportional to
absolute temperature (°K) may be used as a tempera-
ture sensor or for temperature compensation of appli-
cations circuits.
Frequency output is an open-collector transistor. A
disable pin forces the output to the high impedance
state, allowing multiple VFCs to share a common
transmission path.
12
VIN = 0 to +2V
11
RBIAS = 8k
(Optional)
RIN = 8k
RTRIM
RIN
CINT = 2700pF
10
Integrator
+5V
+VS
9 13
Comparator
VREF
One
Shot
IREF
VREF
Ground
(Optional)
2
4
63
5
COS = 1200pF
2.6V
VT
VPULL UP
RPULL UP
14
fOUT =
0 to 100kHz
8
International Airport Industrial Park • Mailing Address: PO Box 11400 • Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd. • Tucson, AZ 85706
Tel: (520) 746-1111 • Twx: 910-952-1111 • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132
© 1989 Burr-Brown Corporation
PDS-971A
Printed in U.S.A. March, 1992




VFC121BP pdf, 반도체, 판매, 대치품
TYPICAL PERFORMANCE CURVES
At TA = +25°C, VS = +5V, and RIN = 8k, unless otherwise noted.
JITTER vs FULL SCALE FREQUENCY
700
600
500
400
300
10 4
105 10 6
Full Scale Frequency (Hz)
10 7
0.001%
0.0001%
FREQUENCY COUNT REPEATABILITY
vs COUNTER GATE TIME
f = 100kHz
FS
f = 1MHz
FS
0.00001%
1
10 100
Time (ms)
1000
FULL SCALE FREQUENCY
vs EXTERNAL ONE-SHOT CAPACITOR
10 7
10 6
10 5
10 4
10
100 1000
External One-Shot Capacitor (pF)
10000
NON-LINEARITY
vs FULL-SCALE FREQUENCY
1
0.1
0.01
0.001
10 4
10 5 106
Full-Scale Frequency (Hz)
107
NON-LINEARITY vs INPUT VOLTAGE
0.04
1.5MHz
0.2
0.02
0
1MHz
500kHz
250kHz
0.1
0
–0.02
0
10kHz
0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8
Input Voltage (V)
–0.1
2
2.62
REFERENCE VOLTAGE
vs REFERENCE LOAD CURRENT
2.6
2.58
2.56
NOTE: The VREF output is
short-circuit protected.
2.54
2.52
0
24
6 8 10 12 14 16 18 20
Output Current (mA)
®
VFC121
4

4페이지










VFC121BP 전자부품, 판매, 대치품
repeatedly reduced during the one-shot period. The size of
the bucket (the capacitor value) is not critical, since it
primarily determines how far below VREF the output of the
integrator ramps during the one-shot period. At the same
time, the capacitor used must not leak since capacitor leak-
age or dielectric absorption can affect the linearity and offset
of the transfer function. High-quality ceramic capacitors can
be used for values less than 0.01µF, but caution should be
used with higher value ceramic capacitors. High-k ceramic
capacitors may have voltage non-linearities which can de-
grade overall linearity. Polystyrene, polycarbonate, or mylar
film capacitors are superior for higher capacitance values.
During the one-shot period, the output of the integrator is
ramping down. To prevent the integrating op amp from
being saturated at its minimum output of 0.8V, CINT should
be kept at least 1.7 x COS.
OUTPUT FREQUENCY ADJUSTMENT
The full scale output frequency of the VFC121 can be
adjusted using a trim-pot, RTRIM in Figure 3, in series with
RIN. For optimum drift vs temperature, a low temperature
coefficient fixed resistor of approximately 90% of the calcu-
lated RIN requirement should be used in series with a trim-
pot approximately 20% of the size of the calculated RIN. The
low-drift fixed resistor contributes most of the final RIN
resistance, so that the effect of higher drift from the trim-pot
is attenuated in the total RIN.
PULL-UP RESISTOR
The VFC121’s frequency output is an open-collector transis-
tor. A pull-up resistor should be connected from fOUT to the
logic supply, +VL. The output transistor is On during the
one-shot period, causing the output to be logic Low. The
current flowing in this resistor should be limited to 10mA to
assure a 0.4V maximum logic Low. The value chosen for the
pull-up resistor may depend on the full-scale frequency and
capacitance on the output line. Excessive capacitance on
fOUT will cause a slow, rounded rising edge at the end of an
output pulse. This effect can be minimized by using a pull-
up resistor which sets the output current to its maximum of
10mA. The logic power supply can be any positive voltage
up to +36V.
ENABLE PIN
If left unconnected, the Enable input will assume a logic
Low level, enabling the output stage, Alternatively, the
Enable input may be connected directly to ground. This pin
can also be driven by standard TTL or CMOS logic.
A logic High at the Enable input causes output pulses to
cease. This is accomplished by interrupting the signal path
through the one-shot circuitry. While disabled, all circuitry
remains active and quiescent current is unchanged. Since no
reset current pulses can occur while disabled, any positive
input voltage will cause the integrator op amp to ramp
positive and saturate at its most positive output swing of
approximately VREF + 0.7V.
When the Enable input receives a logic Low (less than
0.8V), a reset current cycle is initiated, (causing fOUT to go
Low). The integrator ramps negatively and normal operation
is established. The time required for the output frequency to
stabilize is equal to approximately one cycle of the final
output frequency plus 1µs.
Using the Enable input, the outputs from several VFCs can
be connected to a single line. All disabled VFCs will have a
high output impedance; one active VFC can then transmit on
the line. Since disabled VFCs are not oscillating, they cannot
interfere or “lock” with the operating VFC. Locking can
occur when one VFC operates at nearly the same frequency,
or a multiple, as a nearby VFC. Coupling between the two
may cause them to lock to the same frequency or an exact
multiple. It then takes a small incremental input voltage
change on one of the VFCs to unlock them. Locking cannot
occur when unneeded VFCs are disabled.
APPLICATION INFORMATION
OPERATION FROM 10kHz TO 210kHz
The VFC121 is designed to provide an output frequency
starting at 0Hz for a 0V input and increasing linearly to the
full scale output frequency, fFS, at the full scale input
voltage, VFS. For applications where low level inputs, near
0V, are critical, it may be inconvenient to have an output
frequency approaching 0Hz. Figure 4 shows a circuit which
transforms a 0V to 2V input level into output frequencies
from 10kHz to 210kHz, by placing a resistor divider net-
work between the input source and the VREF output of the
VFC121. This produces a positive voltage at +VIN when the
input to the circuit is grounded. This circuit makes use of the
high input impedance at +VIN.
The transfer function of this circuit is:
VIN =
fOUT – 10kHz
100kHz
V
To trim the circuit, first apply 2V to the analog input, and
adjust R1 to give a full scale output frequency of 210kHz. Then
apply 0V to the analog input, and adjust R2 until the output
frequency is 10kHz. For absolute precision, it may be neces-
sary to make several iterations trimming R1 and R2. In most
cases, one iteration will be enough, since the effect of R2 on
0V to 2V
4.99k
C INT =
2200pF
+V IN
–V IN
10kHz to
210kHz
f OUT
R2
10k
121k
R1
1k
4.53k
2.6V
Integrator
Out
Comparator
In
COS
V REF
VFC121
COS =
1000pF
NOTE: Use 1% metal film fixed resistors, Cermet® trim pots, and NPO
ceramic capacitors.
FIGURE 4. Offsetting the Output Frequency.
7 VFC121
®

7페이지


구       성 총 8 페이지수
다운로드[ VFC121BP.PDF 데이터시트 ]

당사 플랫폼은 키워드, 제품 이름 또는 부품 번호를 사용하여 검색할 수 있는

포괄적인 데이터시트를 제공합니다.


구매 문의
일반 IC 문의 : 샘플 및 소량 구매
-----------------------------------------------------------------------

IGBT, TR 모듈, SCR 및 다이오드 모듈을 포함한
광범위한 전력 반도체를 판매합니다.

전력 반도체 전문업체

상호 : 아이지 인터내셔날

사이트 방문 :     [ 홈페이지 ]     [ 블로그 1 ]     [ 블로그 2 ]



관련 데이터시트

부품번호상세설명 및 기능제조사
VFC121BP

Precision Single Power Supply VOLTAGE-TO-FREQUENCY CONVERTER

Burr-Brown Corporation
Burr-Brown Corporation

DataSheet.kr       |      2020   |     연락처      |     링크모음      |      검색     |      사이트맵