AD7475 Datasheet, PDF (1/16 Pages) Analog Devices – 1 MSPS, 12-Bit ADCs

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1 MSPS,
12-Bit ADCs
AD7475/AD7495
FEATURES
Fast Throughput Rate: 1 MSPS
Specified for V_DD 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 ␮A Max
8-Lead ␮SOIC and SOIC Packages
APPLICATIONS
Battery-Powered Systems
Personal Digital Assistants
Medical Instruments
Mobile Communications
Instrumentation and Control Systems
Data Acquisition Systems
High-Speed Modems
Optical Sensors
GENERAL DESCRIPTION
The AD7475/AD7495 are 12-bit high-speed, low-power,
successive-approximation ADCs. The parts operate from a single
2.7 V to 5.25 V power supply and feature throughput rates up to
1 MSPS. The parts contain a low-noise, wide bandwidth track/hold
amplifier that can handle input frequencies in excess of 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 also initiated at this point.
There are no pipelined 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 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 part 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. The conver-
sion time is determined by the SCLK frequency.
MICROWIRE is a trademark of National Semiconductor Corporation.
SPI and QSPI are trademarks of Motorola, Inc.
REV. A
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. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices.
FUNCTIONAL BLOCK DIAGRAMS
V_DD
V_IN
REF IN
T/H
12-BIT
SUCCESSIVE
APPROXIMATION
ADC
AD7475
V_DD
CONTROL
LOGIC
GND
SCLK
SDATA
CS
V_DRIVE
V_IN
REF OUT
T/H
BUF
2.5V
REFERENCE
AD7495
12-BIT
SUCCESSIVE
APPROXIMATION
ADC
CONTROL
LOGIC
SCLK
SDATA
CS
V_DRIVE
GND
PRODUCT HIGHLIGHTS
1. High throughput with low power consumption. The
AD7475 offers 1 MSPS throughput rates with 4.5 mW
power consumption.
2. Single-supply operation with V_DRIVE function. The AD7475/
AD7495 operate from a single 2.7 V to 5.25 V supply. The
V_DRIVE function allows the serial interface to connect directly
to either 3 V or 5 V processor systems independent of V_DD.
3. 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 part also features shutdown modes to maximize
power efficiency at lower throughput rates. This allows the
average power consumption to be reduced while not convert-
ing. Power consumption is 1 µA when in full shutdown.
4. No pipeline delay. The part features a standard successive-
approximation ADC with accurate control of the sampling
instant via a CS input and once off conversion control.
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© Analog Devices, Inc., 2001