IC-NT Datasheet, PDF (2/8 Pages) IC-Haus GmbH – LIGHT CHAIN PULSE DRIVER

iC-NT
LIGHT CHAIN PULSE DRIVER
Rev A0, Page 2/8
DESCRIPTION
The iC-NT device is an LED pulse driver for light barrier applications, especially light chain circuitries.
The device, which is controlled by a shift register logic, features an adjustable LED current sink with a set
range of 0.4..1A (at room temperature). For chain circuitries with several transmitters in operation, the
internal set of three flipflops enables a secure beam and data shift control, free of race conditions.
The decrease in LED efficiency with a rise in temperature is almost compensated by a positive temperature
coefficient of the current sink. In order to generate steep light pulses, the LED switch off is actively
supported by the discharge of its junction capacitance. The duration of this LED short-circuiting is
controlled by a monoflop. In the event of a quick follow-up light pulse, a monoflop reset is performed
automatically to protect against cross currents.
The driver stage for the LED output prepares for a light pulse when DIN reads a high signal; synchronized
with the CLK leading edge, the first flipflop transfers the DIN data to Q1 and powers up the LED sink.
Since the chain is loaded with just one single high bit and DIN is given by the output DOUT of the previous
device, input DIN now reads low at the falling edge of CLK. The LED current sink stops the power, at the
same time as an internal data shift from Q1 to Q2 occurs. The LED pulse is well-defined by the time
difference between two leading edges of the clock signal CLK. The second falling edge of CLK triggers the
third flipflop and activates the next device in the chain via DOUT if enabled by SHEN.
Since only one device is activated at a time, several iC-NT drivers may share one resistor, RSET, to define
the LED current value.
The shift register is reset and the LED current sink is turned off in the event of excessive temperature or
undervoltage. Protective diodes to prevent destruction through ESD are also included. The iC-NT device
fulfills safety requirements according to IEC 1496-1. An extended temperature range of -20°C..85°C is also
available as an option.
PACKAGE SO8 to JEDEC Standard
PIN CONFIGURATION SO8
(top view)
PIN FUNCTIONS
No. Name Function
1 DIN Data Input
2 VDD Supply Voltage 5V
3 CLK Clock
4 SHEN Shift Enable
5 ISET Current Adjust, attachement RSET
6 DOUT Data Output
7 GND Ground
8 LED Pulse Output, LED Cathode