AD7475 Analog Devices, AD7475 Datasheet

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AD7475

Manufacturer Part Number
AD7475
Description
1 MSPS, 12-Bit A/D Converter in MSOP-8 or SOIC-8
Manufacturer
Analog Devices
Datasheet

Specifications of AD7475

Resolution (bits)
12bit
# Chan
1
Sample Rate
1MSPS
Interface
Ser
Analog Input Type
SE-Uni
Ain Range
Uni (Vref)
Adc Architecture
SAR
Pkg Type
SOIC,SOP

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FEATURES AND APPLICATIONS
Fast throughput rate: 1 MSPS
Specified for V
Low power:
Wide input bandwidth:
Flexible power/serial clock speed management
No pipeline delays
High speed serial interface:
On-board reference: 2.5 V (AD7495 only)
Standby mode: 1 μA max
8-lead MSOP and SOIC packages
Battery-powered systems
Personal digital assistants
Medical instruments
Mobile communications
Instrumentation and control systems
Data acquisition systems
Optical sensors
GENERAL DESCRIPTION
The AD7475/AD7495
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 part.
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 parts 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.
1
Rev. B
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. Trademarks and
registered trademarks are the property of their respective owners.
Protected by U.S. Patent No. 6,681,332
4.5 mW max at 1 MSPS with 3 V supplies
10.5 mW max at 1 MSPS with 5 V supplies
68 dB SNR at 300 kHz input frequency
SPI™-/QSPI™-/MICROWIRE™-/DSP-compatible
DD
of 2.7 V to 5.25 V
1
are 12-bit, high speed, low power,
PRODUCT HIGHLIGHTS
1.
2.
3.
4.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.461.3113
The AD7475 offers 1 MSPS throughput rates with 4.5 mW
power consumption.
Single-supply operation with V
AD7475/AD7495 operate from a single 2.7 V to 5.25 V
supply. The V
to connect directly to either 3 V or 5 V processor systems
independent of V
Flexible power/serial clock speed management. The con-
version rate is determined by the serial clock, allowing the
conversion time to be reduced through the serial clock
speed increase. The parts also feature shutdown modes to
maximize power efficiency at lower throughput rates. This
allows the average power consumption to be reduced while
not converting. Power consumption is 1 μA when in full
shutdown.
No pipeline delay. The parts feature a standard successive
approximation ADC with accurate control of the sampling
instant via a CS input and once-off conversion control.
REF OUT
REF IN
V
V
IN
IN
FUNCTIONAL BLOCK DIAGRAMS
V
V
REFERENCE
DD
DD
AD7475
AD7495
2.5V
DRIVE
BUF
T/H
T/H
© 2005 Analog Devices, Inc. All rights reserved.
DD
1 MSPS,12-Bit ADCs
function allows the serial interface
.
Figure 1.
GND
GND
APPROXIMATION
APPROXIMATION
AD7475/AD7495
SUCCESSIVE
SUCCESSIVE
CONTROL
CONTROL
LOGIC
LOGIC
12-BIT
12-BIT
ADC
ADC
DRIVE
function. The
www.analog.com
SCLK
SDATA
CS
SCLK
SDATA
CS
V
V
DRIVE
DRIVE

Related parts for AD7475

AD7475 Summary of contents

Page 1

... There are no pipeline delays associated with the part. 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 ...

Page 2

... Updated Outline Dimensions ....................................................... 23 Changes to Ordering Guide .......................................................... 24 Operating Modes............................................................................ 16 Normal Mode.............................................................................. 16 Partial Power-Down Mode ....................................................... 16 Full Power-Down Mode ............................................................ 17 Power vs. Throughput Rate....................................................... 19 Serial Interface ................................................................................ 20 Microprocessor Interfacing........................................................... 21 AD7475/AD7495 to TMS320C5 AD7475/AD7495 to ADSP-21 AD7475/AD7495 to DSP56 AD7475/AD7495 to MC68HC16............................................. 22 Outline Dimensions ....................................................................... 23 Ordering Guide .......................................................................... 24 Rev Page /C54 ................................. ............................................. 21 XX ............................................... 22 XXX ...

Page 3

... AD7475 SPECIFICATIONS 5.25 V, REF DRIVE Table 1. Parameter DYNAMIC PERFORMANCE Signal-to-Noise and Distortion Ratio (SINAD) Total Harmonic Distortion (THD) Peak Harmonic or Spurious Noise (SFDR) Intermodulation Distortion (IMD) Second-Order Terms Third-Order Terms Aperture Delay Aperture Jitter Full Power Bandwidth ...

Page 4

... AD7475/AD7495 Parameter POWER REQUIREMENTS DRIVE Normal Mode (Static) Normal Mode (Operational) Partial Power-Down Mode Partial Power-Down Mode Full Power-Down Mode Power Dissipation Normal Mode (Operational) Partial Power-Down (Static) Full Power-Down 1 Temperature ranges for A, B versions: −40°C to +85°C. ...

Page 5

... Straight (Natural) Binary 800 800 ns max 300 300 ns max 325 325 ns max 1 1 MSPS max Rev Page AD7475/AD7495 Test Conditions/Comments f = 300 kHz sine wave MSPS IN SAMPLE f = 300 kHz sine wave MSPS IN SAMPLE f = 300 kHz sine wave MSPS ...

Page 6

... AD7475/AD7495 Parameter POWER REQUIREMENTS DRIVE I DD Normal Mode (Static) Normal Mode (Operational) Partial Power-Down Mode Partial Power-Down Mode Full Power-Down Mode 3 Power Dissipation Normal Mode (Operational) Partial Power-Down (Static) Full Power-Down 1 Temperature ranges for A, B versions: −40°C to +85°C. ...

Page 7

... TIMING SPECIFICATIONS 5.25 V, REF IN = 2.5 V (AD7475 DRIVE Table 3. Parameter Limit MIN SCLK × t CONVERT SCLK 800 t 100 QUIET 0 SCLK t 0 SCLK POWER-UP ...

Page 8

... AD7475/AD7495 TIMING EXAMPLE 1 With MHz and a throughput of 1 MSPS, the cycle SCLK time 12.5(1 μs. With t 2 SCLK ACQ is 365 ns. The 365 ns satisfies the requirement of 300 ns for t In Figure 3, t comprises 2.5(1 ACQ SCLK 45 ns. This allows a value of 195 ns for t minimum requirement of 100 ns ...

Page 9

... 0.3 V device reliability. DD −0 0.3 V DRIVE −0 0 ±10 mA −40°C to +85°C −65°C to +150°C 150°C 450 mW 157°C/W (SOIC) 205.9°C/W (MSOP) 56°C/W (SOIC) 43.74°C/W (MSOP) 215°C 220° Rev Page AD7475/AD7495 ...

Page 10

... Pin No. Mnemonic Function 1 (AD7475) REF IN Reference Input for the AD7475. An external reference must be applied to this input. The voltage range for the external reference is 2.5 V ± 1% for specified performance. A cap of a least 0.1 μF should be placed on the REF IN pin. 1 (AD7495) REF OUT Reference Output for the AD7495. A minimum 100 nF capacitance is required from this pin to GND. The internal reference can be taken from this pin, but buffering is required before it is applied elsewhere in a system ...

Page 11

... The AD7475/AD7495 are tested using the CCIF standard where two input frequencies near the top end of the input bandwidth are used. In this case, the second-order terms are usually ...

Page 12

... AD7475/AD7495 TYPICAL PERFORMANCE CURVES Figure 7 shows a typical FFT plot for the AD7475 MHz sample rate and a 100 kHz input frequency. –15 –35 –55 –75 –95 –115 0 50 100 150 200 250 300 FREQUENCY (kHz) Figure 7. AD7475 Dynamic Performance Figure 8 shows a typical FFT plot for the AD7495 MHz sample rate and a 100 kHz input frequency. – ...

Page 13

... V reference. The serial clock input accesses data from the part but also provides the clock source for the successive-approximation ADC. The analog input range REF IN for the AD7475 and REF OUT for the AD7495. The AD7475/AD7495 also feature power-down options to allow power saving between conversions ...

Page 14

... AD7475 and AD7495, respectively. In both setups the GND pin is connected to the analog ground plane of the system. In Figure 13, REF IN is connected to a decoupled 2.5 V supply from a reference source, the AD780, to provide an analog input range 2.5 V. Although the AD7475 is connected the serial interface is connected micro- DD processor ...

Page 15

... V. (See the Absolute Maximum Ratings section.) IN Reference Section An external reference source should be used to supply the 2.5 V reference to the AD7475. Errors in the reference source result in gain errors in the AD7475 transfer function and add the specified full-scale errors on the part. The AD7475 voltage f = 100kHz IN reference input, REF IN, has a dynamic input impedance ...

Page 16

... This mode is intended for fastest throughput rate performance, because the user does not have to worry about any power-up times with the AD7475/AD7495 remaining fully powered all the time. Figure 19 shows the general diagram of the AD7475/ AD7495 operating in this mode. The conversion is initiated on the falling edge described in the Serial Interface section ...

Page 17

... QUIET, goes back into three-state after the dummy conversion to the next falling edge When running MSPS throughput rate, the AD7475/AD7495 power up and acquire a signal within ±0.5 LSB in one dummy cycle, 1 μs. THE PART BEGINS TO POWER UP ...

Page 18

... For the AD7495, enough time should be allowed for the internal reference buffer to charge the reference capacitor. Then, to place the AD7475/ AD7495 in normal mode, a dummy cycle, 1 μs, should be initiated. If the first valid conversion is then performed directly after the dummy conversion, ensure that adequate acquisition time has been allowed ...

Page 19

... V and 3 V supplies for both the AD7475 and AD7495. For the AD7475, partial power- down current is lower than that of the AD7495. Full power-down mode is intended for use in applications with ...

Page 20

... THREE-STATE FOUR LEADING ZEROS Sixteen serial clock cycles are required to perform the con- version process and to access data from the AD7475/AD7495. CS going low provides the first leading zero to be read in by the microcontroller or DSP. The remaining data is then clocked out by subsequent SCLK falling edges beginning with the second leading zero ...

Page 21

... AD7475/AD7495 TO ADSP-21 The ADSP-21xx family of DSPs is interfaced directly to the AD7475/AD7495 without any glue logic required. The V pin of the AD7475/AD7495 takes the same supply voltage as that of the ADSP-21xx. This allows the ADC to operate at a higher voltage than the serial interface, that is, ADSP-21xx, if ...

Page 22

... SCLKs between interrupts is a whole integer figure of N, equidistant sampling is implemented by the DSP. AD7475/AD7495 TO DSP56 XXX The connection diagram in Figure 30 shows how the AD7475/ AD7495 can be connected to the synchronous serial interface (SSI) of the DSP56xxx family of devices from Motorola. The SSI is operated in synchronous mode (SYN bit in CRB = 1) with internally generated 1-bit clock period frame sync for both Tx and Rx (Bits FSL1 = 1 and FSL0 = 0 in CRB) ...

Page 23

... Dimensions shown in millimeters and (inches) 3.00 BSC 8 5 3.00 4.90 BSC BSC 1 4 PIN 1 0.65 BSC 1.10 MAX 0.15 0.00 0.38 0.23 0.22 0.08 COPLANARITY SEATING 0.10 PLANE COMPLIANT TO JEDEC STANDARDS MO-187-AA Figure 33. 8-Lead Mini Small Outline Package [MINI_SO] (RM-8) Dimensions shown in millimeters Rev Page AD7475/AD7495 0.50 (0.0196) × 45° 0.25 (0.0099) 8° 1.27 (0.0500) 0° 0.40 (0.0157) 0.80 8° 0.60 0° 0.40 ...

Page 24

... AD7475ARM −40°C to +85°C AD7475ARM-REEL −40°C to +85°C AD7475ARM-REEL7 −40°C to +85°C AD7475BRM −40°C to +85°C AD7475BRM-REEL −40°C to +85°C AD7475BRM-REEL7 −40°C to +85°C 3 AD7475BRMZ −40°C to +85°C 3 AD7475BRMZ-REEL −40°C to +85°C 3 AD7475BRMZ-REEL7 − ...

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