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AD7450
Differential Input, 1 MSPS
12-Bit ADC in SOIC-8 and SO-8
SPI and QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corporation.
FEATURES
Fast Throughput Rate: 1 MSPS
Specified for V
DD
of 3 V and 5 V
Low Power at Max Throughput Rate:
3.75 mW Max at 833 kSPS with 3 V Supplies
9 mW Max at 1 MSPS with 5 V Supplies
Fully Differential Analog Input
Wide Input Bandwidth:
70 dB SINAD at 300 kHz Input Frequency
Flexible Power/Serial Clock Speed Management
No Pipeline Delays
High-Speed Serial Interface—SPI
TM
/QSPI
TM
MICROWIRE
TM
/DSP Compatible
Power-Down Mode: 1 A Max
8-Lead SOIC and SOIC Packages
APPLICATIONS
Transducer Interface
Battery-Powered Systems
Data Acquisition Systems
Portable Instrumentation
Motor Control
Communications
FUNCTIONAL BLOCK DIAGRAM
12-BIT SUCCESSIVE
APPROXIMATION
ADC
CONTROL
LOGIC
AD7450
V
IN+
SCLK
CS
SDATA
V
IN–
V
REF
GND
V
DD
T/H
GENERAL DESCRIPTION
The AD7450 is a 12-bit, high-speed, low power, successive
approximation (SAR) analog-to-digital converter that features a
fully
differential analog input. It operates from a single 3 V or 5 V
power
supply and features throughput rates up to 833 kSPS or
1 MSPS,
respectively.
This part contains a low noise, wide bandwidth, differential track
-
and-hold amplifier (T/H) that can handle input frequencies in
excess of 1 MHz with the –3 dB point typically being 20 MHz.
The reference voltage for the AD7450 is applied externally to the
V
REF
pin and can be varied from 100 mV to 3.5 V, depending
on the power supply and what suits the application. The value of
the
reference voltage determines the common-mode voltage
range of
the part. With this truly differential input structure and
variable reference input, the user can select a variety of input
ranges and bias points.
The conversion and data acquisition processes are controlled
using
CS and the serial clock, allowing the device to interface
with microprocessors or DSPs. The input signals are sampled
on the
falling edge of CS, and the conversion is also initiated at
this point.
The SAR architecture of this part ensures that there are no
pipeline delays.
The AD7450 uses advanced design techniques to achieve low
power dissipation at high throughput rates.
PRODUCT HIGHLIGHTS
1. Operation with either 3 V or 5 V power supplies.
2. High throughput with low power consumption. With a 3 V
supply, the AD7450 offers 3.75 mW max power consumption
for 833 kSPS throughput.
3. Fully differential analog input.
4. Flexible power/serial clock speed management. The conversion
rate is determined by the serial clock, allowing the power
to be reduced as the conversion time is reduced through
the serial clock speed increase. This part also features a
shutdown mode to maximize power efficiency at lower
throughput rates.
5. Variable voltage reference input.
6. No pipeline delay.
7. Accurate control of the sampling instant via a CS input and
once-off conversion control.
8. ENOB > 8 bits typically with 100 mV reference.
