IC-NT 参数 Datasheet PDF下载

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

2

3

4

5

6

7

8

DIN

VDD

CLK

SHEN

ISET

DOUT

GND

LED

Data Input

Supply Voltage 5V

Clock

Shift Enable

Current Adjust, attachement RSET

Data Output

Ground

Pulse Output, LED Cathode