1 MSPS,12-Bit ADCs
AD7475/AD7495
FUNCTIONAL BLOCK DIAGRAMS
FEATURES AND APPLICATIONS
Fast throughput rate: 1 MSPS
V
DD
Specified for VDD of 2.7 V to 5.25 V
12-BIT
SUCCESSIVE
APPROXIMATION
ADC
Low power:
T/H
V
IN
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:
REF IN
SCLK
SDATA
CS
68 dB SNR at 300 kHz input frequency
Flexible power/serial clock speed management
No pipeline delays
CONTROL
LOGIC
V
DRIVE
High speed serial interface:
AD7475
SPI™-/QSPI™-/MICROWIRE™-/DSP-compatible
On-board reference: 2.5 V (AD7495 only)
Standby mode: 1 μA max
GND
V
DD
8-lead MSOP and SOIC packages
12-BIT
SUCCESSIVE
APPROXIMATION
ADC
T/H
V
IN
Battery-powered systems
Personal digital assistants
Medical instruments
Mobile communications
Instrumentation and control systems
Data acquisition systems
Optical sensors
REF OUT
BUF
2.5V
SCLK
SDATA
CS
CONTROL
LOGIC
REFERENCE
V
DRIVE
AD7495
GND
GENERAL DESCRIPTION
Figure 1.
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.
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
The conversion process and data acquisition are controlled
using
and the serial clock, allowing the devices to interface
CS
with microprocessors or DSPs. The input signal is sampled on
the falling edge of and conversion is initiated at this point.
CS
independent of VDD
.
The conversion time is determined by the SCLK frequency.
There are no pipeline delays associated with the part.
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 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.
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.
4. No pipeline delay. The parts feature a standard successive
approximation ADC with accurate control of the sampling
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.
instant via a
input and once-off conversion control.
CS
1Protected by U.S. Patent No. 6,681,332
Rev. B
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