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PDF ADS7805U Data sheet ( Hoja de datos )
| Número de pieza | ADS7805U | |
| Descripción | 16-Bit 10ms Sampling CMOS ANALOG-to-DIGITAL CONVERTER | |
| Fabricantes | Burr-Brown Corporation | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de ADS7805U (archivo pdf) en la parte inferior de esta página. Total 12 Páginas | ||
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® ADS7805
DEMO BOARD
AVAILABLE
See Appendix A
16-Bit 10µs Sampling CMOS
ANALOG-to-DIGITAL CONVERTER
FEATURES
q 100kHz min SAMPLING RATE
q STANDARD ±10V INPUT RANGE
q 86dB min SINAD WITH 20kHz INPUT
q ±3.0 LSB max INL
q DNL: 16-bits “No Missing Codes”
q SINGLE +5V SUPPLY OPERATION
q PIN-COMPATIBLE WITH 12-BIT ADS7804
q USES INTERNAL OR EXTERNAL
REFERENCE
q FULL PARALLEL DATA OUTPUT
q 100mW max POWER DISSIPATION
q 28-PIN 0.3" PLASTIC DIP AND SOIC
DESCRIPTION
The ADS7805 is a complete 16-bit sampling A/D
using state-of-the-art CMOS structures. It contains a
complete 16-bit, capacitor-based, SAR A/D with S/H,
reference, clock, interface for microprocessor use, and
three-state output drivers.
The ADS7805 is specified at a 100kHz sampling rate,
and guaranteed over the full temperature range. Laser-
trimmed scaling resistors provide an industry-
standard ±10V input range, while the innovative de-
sign allows operation from a single +5V supply, with
power dissipation under 100mW.
The 28-pin ADS7805 is available in a plastic 0.3" DIP
and in an SOIC, both fully specified for operation over
the industrial –25°C to +85°C range.
Clock
Successive Approximation Register and Control Logic
R/C
CS
BYTE
BUSY
±10V Input
20kΩ
10kΩ 4kΩ
CAP
REF
CDAC
Buffer
4kΩ
Internal
+2.5V Ref
Comparator
Output
Latches
and
Three
State
Drivers
Three
State
Parallel
Data
Bus
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
Internet: http://www.burr-brown.com/ • FAXLine: (800) 548-6133 (US/Canada Only) • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132
©1992 Burr-Brown Corporation
PDS-1157E
Printed in U.S.A. August, 1996
1 page  
TYPICAL PERFORMANCE CURVES
TA = +25°C, fS = 100kHz, VDIG = VANA = +5V, using internal reference and fixed resistors shown in Figure 6b, unless otherwise specified.
0
–20
–40
–60
–80
–100
–120
–140
0.0
FREQUENCY SPECTRUM
(8192 Point FFT; fIN = 20kHz, 0dB)
12.5 25.0 37.5
Frequency (kHz)
50.0
0
–20
–40
–60
–80
–100
–120
–140
0.0
FREQUENCY SPECTRUM
(8192 Point FFT; fIN = 45kHz, 0dB)
12.5 25.0 37.5
Frequency (kHz)
50.0
90
80
70
60
50
40
30
20
10
0
0
SIGNAL-TO-(NOISE + DISTORTION)
vs INPUT FREQUENCY AND INPUT AMPLITUDE
0dB
–20dB
–60dB
5 10 15 20 25 30 35 40 45
Input Signal Frequency (kHz)
SIGNAL-TO-(NOISE + DISTORTION) vs TEMPERATURE
100.0
(fIN = 20kHz, 0dB; fS = 50kHz, 100kHz)
95.0
90.0
50kHz
85.0
100kHz
80.0
75.0
–50 –25
0
25 50 75
Temperature (°C)
100 125 150
A.C. PARAMETERS vs TEMPERATURE
(fIN = 20kHz, 0dB)
110 –80
105
SFDR
100
–85
–90
95
THD
–95
90
85
80
–50 –25
0
SNR
–100
SINAD
25 50 75 100 125
Temperature (°C)
–105
–110
150
3
2
1
0
–1
–2
–3
0
All Codes INL
8192 16384 24576 32768 40960 49152 57344 65535
Decimal Code
3
2 All Codes DNL
1
0
–1
–2
–3
0
8192 16384 24576 32768 40960 49152 57344 65535
Decimal Code
®
5 ADS7805
5 Page 
Digital
Output
7FFF
–10V –9.99983V –9.9998V
–50mV
–15mV
9.9997V 9.999815V +10V
Analog
Input
Ideal Transfer Function
With External Resistors
Range of Transfer Function
Without External Resistors
8000
FIGURE 7. Full Scale Transfer Function.
REFERENCE
The ADS7805 can operate with its internal 2.5V reference or
an external reference. By applying an external reference to
pin 5, the internal reference can be bypassed. The reference
voltage at REF is buffered internally with the output on CAP
(pin 4).
The internal reference has an 8 ppm/°C drift (typical) and
accounts for approximately 20% of the full scale error
(FSE = ±0.5% for low grade, ±0.25% for high grade).
REF
REF (pin 3) is an input for an external reference or the output
for the internal 2.5V reference. A 2.2µF capacitor should be
connected as close to the REF pin as possible. The capacitor
and the output resistance of REF create a low pass filter to
bandlimit noise on the reference. Using a smaller value
capacitor will introduce more noise to the reference degrad-
ing the SNR and SINAD. The REF pin should not be used
to drive external AC or DC loads.
The range for the external reference is 2.3V to 2.7V and
determines the actual LSB size. Increasing the reference
voltage will increase the full scale range and the LSB size of
the converter which can improve the SNR.
CAP
CAP (pin 4) is the output of the internal reference buffer. A
2.2µF capacitor should be placed as close to the CAP pin as
possible to provide optimum switching currents for the
CDAC throughout the conversion cycle and compensation
for the output of the internal buffer. Using a capacitor any
smaller than 1µF can cause the output buffer to oscillate and
may not have sufficient charge for the CDAC. Capacitor
values larger than 2.2µF will have little affect on improving
performance.
The output of the buffer is capable of driving up to 2mA of
current to a DC load. DC loads requiring more than 2mA of
current from the CAP pin will begin to degrade the linearity
of the ADS7805. Using an external buffer will allow the
internal reference to be used for larger DC loads and AC
loads. Do not attempt to directly drive an AC load with the
output voltage on CAP. This will cause performance degra-
dation of the converter.
®
11 ADS7805
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet ADS7805U.PDF ] | |
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