3.5- and 4.5-Digit, Single-Chip ADCs with LED Drivers

The MAX1447/MAX1496/MAX1498 low-power, 3.5- and 4.5-digit, analog-to-digital converters (ADCs) with integrated light-emitting diode (LED) drivers operate from a single 2.7V to 5.25V power supply. They include an internal reference, a high-accuracy on-chip oscillator, and a multiplexed LED display driver. An internal charge pump generates the negative supply needed to power the integrated input buffers for single-supply operation. The ADC is configurable for either a ±2V or ±200mV input range and it outputs its conversion results to an LED. The MAX1496 is a 3.5-digit (±1999 count) device and the MAX1447/MAX1498 are 4.5-digit (±19,999 count) devices.

The MAX1447/MAX1496/MAX1498 do not require external precision integrating capacitors, autozero capacitors, crystal oscillators, charge pumps, or other circuitry required with dual-slope ADCs (commonly used in panel meter circuits).

These devices also feature on-chip buffers for the differential signal and reference input, allowing direct interface with high-impedance signal sources. In addition, they use continuous internal offset-calibration and offer >100dB rejection of 50Hz and 60Hz line noise. Other features include data hold and peak detection and overrange/underrange detection. The MAX1447 features on-demand enhanced offset calibration for improved offset performance.

The MAX1447/MAX1498 are available in a 32-pin, 7mm x 7mm TQFP package and the MAX1496 is available in 28-pin SSOP and 28-pin PDIP packages. All devices in this family operate over the -40°C to +85°C extended temperature range.

Applications

* Digital Multimeters * Digital Panel Meters * Digital Voltmeters * Handheld meters

* High Resolution

* MAX1447/MAX1498: 4.5 Digits (±19,999 Count)

* MAX1496: 3.5 Digits (±1999 Count)

* Sigma-Delta ADC Architecture

* No Integrating Capacitors Required

* No Autozeroing Capacitors Required

* >100dB of Simultaneous 50Hz and 60Hz Rejection

* Selectable Input Range of ±200mV or ±2V

* Selectable Voltage Reference: Internal 2.048V or External

* Internal High-Accuracy Oscillator Needs No External Components

* Automatic Offset Calibration

* On-Demand Enhanced Offset Calibration (MAX1447)

* Operate from a Single 2.7V to 5.25V Supply

* Low Power (Exclude LED-Driver Current)

* Maximum 744µA Operating Current (MAX1496)

* Maximum 960µA Operating Current (MAX1447/MAX1498)

* Maximum 325µA Shutdown Current

* Multiplexed Common-Cathode LED Drivers

* Resistor-Programmable Segment Current

* Small 32-Pin, 7mm x 7mm TQFP Package (4.5 Digits), 28-Pin SSOP Package (3.5 Digits)

* Also Available in a PDIP Package (3.5 Digits)