REV. B
a
AD7470/AD7472
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1.75 MSPS, 4 mW
10-Bit/12-Bit Parallel ADCs
FUNCTIONAL BLOCK DIAGRAM
T/H
10-/12-BIT
SUCCESSIVE
APPROXIMATION
ADC
OUTPUT
DRIVERS
AD7470/AD7472
V
IN
CONVST
AGND DGND
AV
DD
DV
DD
REF IN
V
DRIVE
DB9 (DB11)
DB0
CLK IN
CS
RD
BUSY
CONTROL
LOGIC
AD7470 IS A 10-BIT PART WITH DB0 TO DB9 AS OUTPUTS.
AD7472 IS A 12-BIT PART WITH DB0 TO DB11 AS OUTPUTS.
FEATURES
Specified for V
DD
of 2.7 V to 5.25 V
1.75 MSPS for AD7470 (10-Bit)
1.5 MSPS for AD7472 (12-Bit)
Low Power
AD7470: 3.34 mW Typ at 1.5 MSPS with 3 V Supplies
7.97 mW Typ at 1.75 MSPS with 5 V Supplies
AD7472: 3.54 mW Typ at 1.2 MSPS with 3 V Supplies
8.7 mW Typ at 1.5 MSPS with 5 V Supplies
Wide Input Bandwidth
70 dB Typ SNR at 500 kHz Input Frequency
Flexible Power/Throughput Rate Management
No Pipeline Delays
High Speed Parallel Interface
Sleep Mode: 50 nA Typ
24-Lead SOIC and TSSOP Packages
GENERAL DESCRIPTION
The AD7470/AD7472 are 10-bit/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
1.5 MSPS for the 12-bit AD7472 and up to 1.75 MSPS for the
10-bit AD7470. The parts contain a low noise, wide bandwidth
track-and-hold amplifier that can handle input frequencies in
excess of 1 MHz.
The conversion process and data acquisition are controlled
using standard control inputs, allowing easy interfacing to
microprocessors or DSPs. The input signal is sampled on the
falling edge of CONVST, and conversion is also initiated at
this point. BUSY goes high at the start of conversion and
goes low 531.66 ns after falling edge of CONVST (AD7472
with a clock frequency of 26 MHz) to indicate that the con-
version is complete. There are no pipeline delays associated
with the parts. The conversion result is accessed via standard
CS and RD signals over a high speed parallel interface.
The AD7470/AD7472 use advanced design techniques to
achieve very low power dissipation at high throughput rates. With
3 V supplies and 1.5 MSPS throughput rates, the AD7470
typically consumes, on average, just 1.1 mA. With 5 V supplies
and 1.75 MSPS, the average current consumption is typically
1.6 mA. The part also offers flexible power/throughput rate
management. Operating the AD7470 with 3 V supplies and
500 kSPS throughput reduces the current consumption to 713 µA.
At 5 V supplies and 500 kSPS, the part consumes 944 µA.
It is also possible to operate the parts in an auto sleep mode,
where the part wakes up to do a conversion and automatically
enters sleep mode at the end of conversion. This method allows
very low power dissipation numbers at lower throughput rates.
In this mode, the AD7472 can be operated with 3 V supplies at
100 kSPS, and consume an average current of just 124 µA. At
5 V supplies and 100 kSPS, the average current consumption is
171 µA.
The analog input range for the part is 0 V to REF IN. The 2.5 V
reference is applied externally to the REF IN pin. The conver-
sion rate is determined by the externally-applied clock.
PRODUCT HIGHLIGHTS
1. High Throughput with Low Power Consumption. The
AD7470 offers 1.75 MSPS throughput and the AD7472
offers 1.5 MSPS throughput rates with 4 mW power
consumption.
2. Flexible Power/Throughput Rate Management. The conver-
sion rate is determined by an externally-applied clock allow-
ing the power to be reduced as the conversion rate is reduced.
The part also features an auto sleep mode to maximize power
efficiency at lower throughput rates.
3. No Pipeline Delay. The part features a standard successive
approximation ADC with accurate control of the sampling
instant via a CONVST input and once off conversion control.
