Motor de Búsqueda de Datasheet de Componentes Electrónicos
  Spanish  ▼
ALLDATASHEET.ES

X  

AD7741 Datasheet(PDF) 9 Page - Analog Devices

No. de pieza AD7741
Descripción Electrónicos  Single and Multichannel, Synchronous Voltage-to-Frequency Converters
Download  12 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Fabricante Electrónico  AD [Analog Devices]
Página de inicio  http://www.analog.com
Logo AD - Analog Devices

AD7741 Datasheet(HTML) 9 Page - Analog Devices

Back Button AD7741 Datasheet HTML 4Page - Analog Devices AD7741 Datasheet HTML 5Page - Analog Devices AD7741 Datasheet HTML 6Page - Analog Devices AD7741 Datasheet HTML 7Page - Analog Devices AD7741 Datasheet HTML 8Page - Analog Devices AD7741 Datasheet HTML 9Page - Analog Devices AD7741 Datasheet HTML 10Page - Analog Devices AD7741 Datasheet HTML 11Page - Analog Devices AD7741 Datasheet HTML 12Page - Analog Devices  
Zoom Inzoom in Zoom Outzoom out
 9 / 12 page
background image
REV. 0
AD7741/AD7742
–9–
AD7741/AD7742
CLKOUT
CLKIN
C1
C2
TO OTHER
CIRCUITRY
5M
Figure 8. On-Chip Oscillator
The on-chip oscillator circuit also has a start-up time associated
with it before it oscillates at its correct frequency and correct
voltage levels. The typical start-up time for the circuit is 5 ms
(with a 6.144 MHz crystal).
The AD7741/AD7742 master clock appears on the CLKOUT
pin of the device. The maximum recommended load on this pin
is one CMOS load. When using a crystal to generate the AD7741/
AD7742 clock it may be desirable to then use this clock as the
clock source for the system. In this case it is recommended that
the CLKOUT signal be buffered with a CMOS buffer before
being applied to the rest of the circuit.
Reference Input
The AD7741/AD7742 performs conversion relative to an applied
reference voltage that allows easy interfacing to ratiometric
systems. This reference may be applied using the internal 2.5 V
bandgap reference. For the AD7741, this is done by simply
leaving REFIN/OUT unconnected. For the AD7742, REFIN is
tied to REFOUT. Alternatively, an external reference, e.g.,
REF192 or AD780, may be used. For the AD7741, this is con-
nected to REFIN/OUT and will overdrive the internal refer-
ence. For the AD7742, it is connected directly to the REFIN
pin.
While the internal reference will be adequate for most applica-
tions, power supply rejection and overall regulation may be
improved through the use of an external precision reference.
The process of selecting an external voltage reference should
include consideration of drive capability, initial error, noise and
drift characteristics. A suitable choice would be the AD780 or
REF192.
Power-Down Mode
The low power standby mode is initiated by taking the
PD pin
low, which shuts down most of the analog and digital circuitry.
This reduces the power consumption to 185
µW max.
The digital data that represents the analog input voltage is con-
tained in the duty cycle of the pulse train appearing at the out-
put of the comparator. The output is a fixed-width pulse whose
frequency depends on the analog input signal. The input voltage
is offset internally so that a full-scale input gives an output fre-
quency of 0.45 fCLKIN and zero-scale input gives an output fre-
quency of 0.05 fCLKIN. The output allows simple interfacing to
either standard logic families or opto-couplers. The clock high
period controls the pulsewidth of the frequency output. The
pulse is initiated by the edge of the clock signal. The delay time
between the edge of the clock and the edge of the frequency
output is typically 9 ns. Figure 7 shows the waveform of this
frequency output.
After power-up, or if there is a step change in input voltage,
there is a settling time that must elapse before valid data is
obtained. This is typically 2 CLKIN cycles on the AD7742 and
10 CLKIN cycles on the AD7741.
6 TCLK
7 TCLK
AVERAGE fOUT IS fCLKIN *3/20 BUT THE ACTUAL PULSE STREAM
VARIES BETWEEN fCLKIN/6 AND fCLKIN/7
fCLKIN
fOUT = fCLKIN/4
VIN = VREF/2
fOUT = fCLKIN/10
VIN = VREF/8
fOUT = fCLKIN*3/20
VIN = VREF/4
Figure 7. AD7741/AD7742 Frequency Output Waveforms
Clock Generation
As distinct from the asynchronous VFCs which rely on the stability
of an external capacitor to set their full-scale frequency, the
AD7741/AD7742 uses an external clock to define the full-scale
output frequency. The result is a more stable, more linear trans-
fer function and also allows the designer to determine the sys-
tem stability and drift based upon the external clock selected. A
crystal oscillator may also be used if desired.
The AD7741/AD7742 requires a master clock input, which may
be an external CMOS-compatible clock signal applied to the
CLKIN pin (CLKOUT not used). Alternatively, a crystal of the
correct frequency can be connected between CLKIN and
CLKOUT, when the clock circuit will function as a crystal
controlled oscillator. Figure 8 shows a simple model of the on-
chip oscillator.


Número de pieza similar - AD7741

Fabricante ElectrónicoNo. de piezaDatasheetDescripción Electrónicos
logo
Analog Devices
AD7741 AD-AD7741 Datasheet
131Kb / 12P
   Single and Multichannel, Synchronous Voltage-to-Frequency Converters
REV. 0
AD7741BN AD-AD7741BN Datasheet
131Kb / 12P
   Single and Multichannel, Synchronous Voltage-to-Frequency Converters
REV. 0
AD7741BN AD-AD7741BN Datasheet
135Kb / 12P
   Single and Multichannel, Synchronous Voltage-to-Frequency Converters
REV. 0
AD7741BN AD-AD7741BN Datasheet
135Kb / 12P
   Single and Multichannel, Synchronous Voltage-to-Frequency Converters
REV. 0
AD7741BR AD-AD7741BR Datasheet
131Kb / 12P
   Single and Multichannel, Synchronous Voltage-to-Frequency Converters
REV. 0
More results

Descripción similar - AD7741

Fabricante ElectrónicoNo. de piezaDatasheetDescripción Electrónicos
logo
Analog Devices
AD7741 AD-AD7741 Datasheet
131Kb / 12P
   Single and Multichannel, Synchronous Voltage-to-Frequency Converters
REV. 0
AD7742 AD-AD7742_15 Datasheet
135Kb / 12P
   Single and Multichannel, Synchronous Voltage-to-Frequency Converters
REV. 0
AD7741 AD-AD7741_15 Datasheet
135Kb / 12P
   Single and Multichannel, Synchronous Voltage-to-Frequency Converters
REV. 0
EVAL-AD7741-42EBZ AD-EVAL-AD7741-42EBZ Datasheet
135Kb / 12P
   Single and Multichannel, Synchronous Voltage-to-Frequency Converters
REV. 0
AD7742YRZ AD-AD7742YRZ Datasheet
135Kb / 12P
   Single and Multichannel, Synchronous Voltage-to-Frequency Converters
REV. 0
AD7741BRZ AD-AD7741BRZ Datasheet
135Kb / 12P
   Single and Multichannel, Synchronous Voltage-to-Frequency Converters
REV. 0
logo
Microchip Technology
TC9400 MICROCHIP-TC9400 Datasheet
504Kb / 20P
   Voltage-to-Frequency/Frequency-to-Voltage Converters
2002
logo
TelCom Semiconductor, I...
TC9400 TELCOM-TC9400 Datasheet
154Kb / 13P
   VOLTAGE-TO-FREQUENCY/FREQUENCY-TO-VOLTAGE CONVERTERS
logo
Microchip Technology
TC9400 MICROCHIP-TC9400_06 Datasheet
691Kb / 24P
   Voltage-to-Frequency/Frequency-to-Voltage Converters
2006
logo
Texas Instruments
LM2917P TI1-LM2917P Datasheet
96Kb / 7P
[Old version datasheet]   FREQUENCY-TO-VOLTAGE CONVERTERS
More results


Html Pages

1 2 3 4 5 6 7 8 9 10 11 12


Datasheet Descarga

Go To PDF Page


Enlace URL




Política de Privacidad
ALLDATASHEET.ES
¿ALLDATASHEET es útil para Ud.?  [ DONATE ] 

Todo acerca de Alldatasheet   |   Publicidad   |   Contáctenos   |   Política de Privacidad   |   Intercambio de Enlaces   |   Lista de Fabricantes
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz
Family Site : ic2ic.com  |   icmetro.com