AD7478 Datasheet

• Fast Throughput Rate: 1 MSPS
• Specified for V_DD of 2.35 V to 5.25 V
• Low Power:
  3.6 mW Typ at 1 MSPS with 3 V Supplies
  15 mW Typ at 1 MSPS with 5 V Supplies
• Wide Input Bandwidth: 70 dB SNR at 100 kHz Input Frequency
• Flexible Power/Serial Clock Speed Management
• No Pipeline Delays
• High Speed Serial Interface
  SPI^®/QSPI^™/MICROWIRE^™/DSP Compatible
• Standby Mode: 1 µA Max
• 6-Lead SOT-23 Package

• Battery-powered systems
  Personal digital assistants
  Medical instruments
  Mobile communications
• Instrumentation and control systems
• Data acquisition systems
• High speed modems
• Optical sensors

The AD7478 are, respectively, 8-bit, high speed, low power, successive approximation ADCs. The parts operate from a single 2.35 V to 5.25 V power supply and feature throughput rates up to 1 MSPS. Each part contains a low noise, wide bandwidth track-and-hold amplifier that can handle input frequencies in excess of 6 MHz.

The conversion process and data acquisition are controlled using CS the serial clock, allowing the devices to interface with microprocessors or DSPs. The input signal is sampled on the falling edge of CS and the conversion is initiated at this point. There are no pipeline delays associated with these parts.

The AD7478 use advanced design techniques to achieve very low power dissipation at high throughput rates. The reference for the parts is taken internally from V_DD. This allows the widest dynamic input range to the ADC. Thus, the analog input range for the parts are 0 V to V_DD. The conversion rate is determined by the SCLK.

PRODUCT HIGHLIGHTS

1. First 8-Bit ADCs in SOT-23 Packages.
2. High Throughput with Low Power Consumption.
3. Flexible Power/Serial Clock Speed Management. The conversion rate is determined by the serial clock, allowing the conversion time to be reduced through the serial clock speed increase. This allows the average power consumption to be reduced while not converting. The parts also feature a shutdown mode to maximize power efficiency at lower throughput rates. Current consumption is 1 μA maximum when in shutdown mode.
4. Reference Derived from the Power Supply.
5. 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.