1 MSPS,12-Bit ADCs

AD7475/AD7495

Rev. B

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FEATURES AND APPLICATIONS

Fast throughput rate: 1 MSPS

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

Battery-powered systems

Personal digital assistants

Medical instruments

Mobile communications

Instrumentation and control systems

Data acquisition systems

Optical sensors

GENERAL DESCRIPTION

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.

FUNCTIONAL BLOCK DIAGRAMS

T/H

12-BIT

SUCCESSIVE

APPROXIMATION

ADC

AD7475

GND

SCLK

CS

CONTROL

LOGIC

SDATA

REF IN

T/H

12-BIT

SUCCESSIVE

APPROXIMATION

ADC

AD7495

GND

SCLK

CONTROL

LOGIC

SDATA

BUF

2.5V

REFERENCE

REF OUT

CS

Figure 1.

PRODUCT HIGHLIGHTS

1.

The AD7475 offers 1 MSPS throughput rates with 4.5 mW

power consumption.

2.

AD7475/AD7495 operate from a single 2.7 V to 5.25 V

to connect directly to either 3 V or 5 V processor systems

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.

4.

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.