1 MSPS,12-Bit ADCs
Data Sheet
AD7475/AD7495
Rev. C Document Feedback
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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 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/AD7495
1
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.
1
Protected by U.S. Patent No. 6,681,332
FUNCTIONAL BLOCK DIAGRAM
T/H
12-BIT
SUCCESSIVE
APPROXIMATION
ADC
AD7475
V
IN
GND
V
DD
SCLK
CS
CONTROL
LOGIC
SDATA
V
DRIVE
REF IN
T/H
12-BIT
SUCCESSIVE
APPROXIMATION
ADC
AD7495
V
IN
GND
V
DD
SCLK
CONTROL
LOGIC
SDATA
V
DRIVE
BUF
2.5V
REFERENCE
REF OUT
CS
01684-B-001
Figure 1.
PRODUCT HIGHLIGHTS
1. 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
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.
