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AD7495 Schematic ( PDF Datasheet ) - Analog Devices

Teilenummer AD7495
Beschreibung 1 MSPS / 12-Bit ADCs
Hersteller Analog Devices
Logo Analog Devices Logo 




Gesamt 24 Seiten
AD7495 Datasheet, Funktion
Data Sheet
FEATURES
Fast throughput rate: 1 MSPS
Specified for VDD of 2.7 V to 5.25 V
Low power
4.5 mW max at 1 MSPS with 3 V supplies
10.5 mW max at 1 MSPS with 5 V supplies
Wide input bandwidth: 68 dB SNR at 300 kHz input frequency
Flexible power/serial clock speed management
No pipeline delays
High speed serial interface
SPI-/QSPI™-/MICROWIRE-/DSP-compatible
On-board reference: 2.5 V (AD7495 only)
Standby mode: 1 μA max
8-lead MSOP and SOIC packages
APPLICATIONS
Battery-powered systems
Personal digital assistants
Medical instruments
Mobile communications
Instrumentation and control systems
Data acquisition systems
Optical sensors
GENERAL DESCRIPTION
The AD7475/AD74951 are 12-bit, high speed, low power,
successive-approximation ADCs that operate from a single
2.7 V to 5.25 V power supply with throughput rates up to 1 MSPS.
They contain a low noise, wide bandwidth track-and-hold
amplifier that can handle input frequencies above 1 MHz.
The conversion process and data acquisition are controlled
using CS and the serial clock, allowing the devices to interface
with microprocessors or DSPs. The input signal is sampled on
the falling edge of CS and conversion is initiated at this point.
The conversion time is determined by the SCLK frequency.
There are no pipeline delays associated with the device.
The AD7475/AD7495 use advanced design techniques to
achieve very low power dissipation at high throughput rates.
With 3 V supplies and a 1 MSPS throughput rate, the AD7475
consumes just 1.5 mA, while the AD7495 consumes 2 mA. With
5 V supplies and 1 MSPS, the current consumption is 2.1 mA
for the AD7475 and 2.6 mA for the AD7495.
The analog input range for the devices is 0 V to REF IN. The
2.5 V reference for the AD7475 is applied externally to the REF IN
pin, while the AD7495 has an on-board 2.5 V reference.
1Protected by U.S. Patent No. 6,681,332
Rev. C
Document Feedback
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.
1 MSPS,12-Bit ADCs
AD7475/AD7495
FUNCTIONAL BLOCK DIAGRAM
VDD
VIN
REF IN
T/H 12-BIT
SUCCESSIVE
APPROXIMATION
ADC
AD7475
VDD
CONTROL
LOGIC
GND
SCLK
SDATA
CS
VDRIVE
VIN
REF OUT
T/H
BUF
2.5V
REFERENCE
AD7495
12-BIT
SUCCESSIVE
APPROXIMATION
ADC
CONTROL
LOGIC
SCLK
SDATA
CS
VDRIVE
GND
Figure 1.
PRODUCT HIGHLIGHTS
1. The AD7475 offers 1 MSPS throughput rates with 4.5 mW
power consumption.
2. Single-supply operation with VDRIVE function. The
AD7475/AD7495 operate from a single 2.7 V to 5.25 V
supply. The VDRIVE function allows the serial interface to
connect directly to either 3 V or 5 V processor systems
independent of VDD.
3. Flexible power/serial clock speed management. The
conversion rate is determined by the serial clock, allowing
the conversion time to be reduced through the serial clock
speed increase. The devices also feature shutdown modes
to maximize power efficiency at lower throughput rates.
This allows the average power consumption to reduce while
not converting. Power consumption is 1 μA when in full
shutdown.
4. No pipeline delay. The devices feature a standard successive
approximation ADC with accurate control of the sampling
instant via a CS input and once-off conversion control.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 ©2001-2015 Analog Devices, Inc. All rights reserved.
Technical Support
www.analog.com






AD7495 Datasheet, Funktion
AD7475/AD7495
Data Sheet
Parameter
POWER REQUIREMENTS
VDD
VDRIVE
IDD
Normal Mode (Static)
Normal Mode (Operational)
Partial Power-Down Mode
Partial Power-Down Mode
Full Power-Down Mode
Power Dissipation3
Normal Mode (Operational)
Partial Power-Down (Static)
Full Power-Down
A Version1
2.7/5.25
2.7/5.25
1
2.6
2
650
230
1
13
6
1.15
690
5
3
1 Temperature ranges for A, B versions: −40°C to +85°C.
2 Guaranteed by initial characterization.
3 See the Power vs. Throughput Rate section.
B Version1
2.7/5.25
2.7/5.25
1
2.6
2
650
230
1
13
6
1.15
690
5
3
Unit
V min/max
V min/max
mA typ
mA max
mA max
µA typ
µA max
µA max
mW max
mW max
mW max
µW max
µW max
µW max
Test Conditions/Comments
Digital inputs = 0 V or VDRIVE
VDD = 2.7 V to 5.25 V, SCLK on or off
VDD = 4.75 V to 5.25 V, fSAMPLE = 1 MSPS
VDD = 2.7 V to 3.6 V, fSAMPLE = 1 MSPS
fSAMPLE = 100 kSPS
Static
Static, SCLK on or off
VDD = 5 V, fSAMPLE = 1 MSPS
VDD = 3 V, fSAMPLE = 1 MSPS
VDD = 5 V
VDD = 3 V
VDD = 5 V
VDD = 3 V
Rev. C | Page 6 of 24

6 Page









AD7495 pdf, datenblatt
AD7475/AD7495
Data Sheet
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 7 shows a typical FFT plot for the AD7475 at a 1 MHz sample rate and a 100 kHz input frequency. Figure 8 shows a typical FFT
plot for the AD7495 at a 1 MHz sample rate and a 100 kHz input frequency. Figure 9 shows the SINAD performance vs. input frequency
for various supply voltages while sampling at 1 MSPS with an SCLK of 20 MHz.
71.0
8192 POINT FFT
fSAMPLE = 1MSPS
–15
fIN = 100kHz
SINAD = 70.46dB
70.5
VDD = VDRIVE = 4.75V
THD = –87.7dB
VDD = VDRIVE = 3.60V
–35 SFDR = –89.5dB
70.0
–55
VDD = VDRIVE = 2.70V
69.5
–75 VDD = VDRIVE = 5.25V
–95 69.0
–115
0
50 100 150 200 250 300 350 400 450 500
FREQUENCY (kHz)
Figure 7. AD7475 Dynamic Performance
68.5
10
100
INPUT FREQUENCY (kHz)
1000
Figure 9. AD7495 SINAD vs. Input Frequency at 1 MSPS
8192 POINT FFT
–15
fSAMPLE = 1MSPS
fIN = 100kHz
SINAD = 69.95dB
THD = –89.2dB
–35 SFDR = –91.2dB
–55
–75
–95
–115
0
50 100 150 200 250 300 350 400 450 500
FREQUENCY (kHz)
Figure 8. AD7495 Dynamic Performance
Rev. C | Page 12 of 24

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