iC-NE SO8

Description

The iC-NE device is a light-grid receiver IC. Typical applications cover light cur tains, light barriers and electro-sensitive protective equipment in general. Integrated on a single silicon chip the iC-NE contains a bandpass amplifier with a center frequency of typically 300 kHz, a differential current-signal output plus control logic to activate the amplifier and the output. Deactivated, the current consumption is very low and the current-signal outputs SN and SP are switched to high impedance (zero current). The logic consists of a three-stage shift register in which the first two stages are triggered by the rising edge of the clock input CLK. The third flipflop is triggered with the falling clock edge, which produces an artificial delay in order to avoid race conditions when shifting the input data via the serial output to the next device in the chain. The bandpass amplifier is activated when DIN reads a logical 1. The output stage still remains disabled (zero current) until the output of the first flip-flop changes to 1. This activates the bias for the complete signal path from light detection to the differential current output. The differential outputs SP and SN are powered up to an equal current, as far as the attached photodiode does not receive any changes in light. The rising edge of a received light pulse (which produces an increase of photocurrent), causes the output current at SP to increase and at SN to decrease by an equal value. The sum of I(SP) + I(SN) is kept constant. For light cur tain applications in which only one device is activated at a time, the outputs SN and SP can be attached to a two-wire bus. After processing the serial input data at DIN, the activated amplifier and output automatically return to standby mode, when the clock input receives the second rising edge. Therefore, a chain circuitr y with multiple beams has to be set up with just a single data bit within a shift cycle. The IC contains protective diodes to prevent destruction by ESD. Logic input pins feature Schmitt-trigger characteristics for high noise immunity. All pins are short-circuit proof.

Features