GENERAL DESCRIPTION

The AD7490 is a 12-bit high speed, low power, 16-channel, successive approximation ADC. The part operates from a single 2.7 V to 5.25 V power supply and features throughput rates up to 1 MSPS. The part contains 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 CS and the serial clock signal, allowing the device to easily interface with microprocessors or DSPs. The input signal is sampled on the falling edge of CS, and conversion is also initiated at this point. There are no pipeline delays associated with the part.
The AD7490 uses advanced design techniques to achieve very low power dissipation at high throughput rates. For maximum throughput rates, the AD7490 consumes just 1.8 mA with 3 V supplies, and 2.5 mA with 5 V supplies.
By setting the relevant bits in the control register, the analog input range for the part can be selected to be a 0 V to REFIN input or a 0 V to 2 × REFIN input, with either straight binary or twos complement output coding. The AD7490 features 16 single-ended analog inputs with a channel sequencer to allow a preprogrammed selection of channels to be converted sequentially. The conversion time is determined by the SCLK frequency because this is also used as the master clock to control the conversion.
The AD7490 is available in a 32-lead LFCSP and a 28-lead TSSOP package.

 

FEATURES

Fast throughput rate: 1 MSPS
Specified for VDD of 2.7 V to 5.25 V
Low power at maximum throughput rates
-5.4 mW maximum at 870 kSPS with 3 V supplies
-12.5 mW maximum at 1 MSPS with 5 V supplies
16 (single-ended) inputs with sequencer
Wide input bandwidth: 69.5 dB SNR at 50 kHz input frequency
Flexible power/serial clock speed management
No pipeline delays
High speed serial interface, SPI/QSPI™/MICROWIRE™/ DSP compatible
Full shutdown mode: 0.5 µA maximum
28-lead TSSOP and 32-lead LFCSP packages
AEC-Q100 qualified for automotive applications

 

APPLICATIONS

Multichannel system monitoring
Battery-powered equipment
Power line monitoring
Data acquisition, instrumentation, and process control

 

More Information

PRODUCT HIGHLIGHTS

1.The AD7490 offers up to 1 MSPS throughput rates. At maximum throughput with 3 V supplies, the AD7490 dissipates just 5.4 mW of power.
2.A sequence of channels can be selected, through which the AD7490 cycles and converts.
3.The AD7490 operates 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 independent of VDD.
4.The conversion rate is determined by the serial clock, allowing the conversion time to be reduced through the serial clock speed increase. The part also features various shutdown modes to maximize power efficiency at lower throughput rates. Power consumption is 0.5 µA, maximum, when in full shutdown.
5.The part features a standard successive approximation ADC with accurate control of the sampling instant via a CS input and once off conversion control.

Channel-to-Channel Isolation

Channel-to-channel isolation is a measure of the level of crosstalk between channels. It is measured by applying a fullscale 400 kHz sine wave signal to all 15 nonselected input channels and determining how much that signal is attenuated in the selected channel with a 50 kHz signal.

PSR (Power Supply Rejection)

Variations in power supply affect the full scale transition, but not the converter linearity. Power supply rejection is the maximum change in the full-scale transition point due to a change in power supply voltage from the nominal value.

Track-and-Hold Acquisition Time

The track-and-hold amplifier returns into track on the 14th SCLK falling edge. Track-and-hold acquisition time is the minimum time required for the track-and-hold amplifier to remain in track mode for its output to reach and settle to within ±1 LSB of the applied input signal, given a step change to the input signal.