ams.com

db09284e_V3.01_preliminary_2017-07-06

Page 3 of 30

AS89020

V3.01

1 GENERAL DESCRIPTION

Transimpedance amplifiers (TIA) used as current-voltage converters ensure continuous signal processing

at high signal frequencies, thus meeting the demands of e.g. automated processes. They are best suited

to synchronous measuring procedures in the kilohertz range, where fast converters are required to scan

optical signals. Examples include sensors for quality testing in inline manufacturing processes or those in

touchless handheld devices. ams Sensors Germany offers several multichannel TIAs with digital and analog

interface.

The AS89020 is a 12 bit, 4 channel, current input analog-to-digital converter (ADC). It combines current-

to-voltage (TIA) and analog-to-digital (AD) conversion, so that 4 separate current output devices

(e.g. photodiodes) can be directly connected to its inputs and digitized.

For each of the 4 inputs the AS89020 provides an input amplifier with a track and hold circuit. The outputs

of the track and hold stages are serial converted to 12 bit digital words using an analog-to-digital converter

(ADC).

The 12 bit conversion results are available via SPI at a frequency up to 16 MHz and a conversion time as

low as 1 µs per channel.

The input amplifier is separately programmable for each channel in 17 stages. This results in a

programmable full-scale range for the ADC from 11.7 nA to 12 µA and a sensitivity up to 2.8 pA/LSB.

Input currents of both polarities can be fed to each of the input amplifiers. The adjustment is realized by

digital programming of each channel separately via standard SPI-interface.

All reference voltages are implemented internally; only some external passive devices are needed to

complete their operating mode.

The AS89020 supports Power Down functions for low power solutions.

Based on the high flexibility the AS89020 is suitable as a converter for a wide range of multi-channel

optoelectronic sensors (UV, VIS, NIR, IR) or other sensors with current output. The device achieves a high

dynamic range.

The combination of ams Sensors Germany’s color sensors with AS89020 is excellently suited especially for

fast color measurement and control in printing and automation, for mobile color measurement devices but

also for photometry applications (brightness, color coordinate and/or color temperature), for determining

current values for control of spectrally mixed LED light sources or as sensors for display and (back)light

calibration and mobile devices for light measurement.

The sensor compact signal IC is available in a SSOP20 package and or as bar die on request.