iC-NT
LIGHT CHAIN PULSE DRIVER
FEATURES
APPLICATIONS
Adjustable LED pulse operation, set range of 0.4..1A
Controlled current slew rate enables short light pulses
down to 1
s
LED efficiency degradation compensated by positive current
temperature coefficient
Low standby current; circuit activation by input data
Low power requirement for external set resistor
Control logic with 3-step shift register
Compatible to CMOS levels
Data output buffer with built-in 120
wave impedance
adaption
Single 5V supply
Thermal shutdown and power-down reset
ESD protection
Small outline package SO8
Suited for high-risk applications according to IEC 1496-1
Option: Extended temperature range of -20
C..85
C
Electro-sensitive protective
equipment (ESPE)
Light curtain LED driver
Light barrier LED driver
PACKAGES
SO8
BLOCK DIAGRAM
1997
Rev A0
A
FF3
RESET
REFERENCE AND
THERMAL SHUTDOWN
CONTROL INPUTS
LOGIC
ENABLE
OUTPUT BUFFER
LED CURRENT SINK
iC-NT
POWER DOWN
D
C
R
Q
Q1
FF1
D
C
R
Q
Q2
FF2
D
C
R
Q
Q3
-
+
ISET
DIN
VDD
GND
PDR
TR
VTREF
VDD
SEND
DOUT
+5V
CLK
SHEN
+5V
VDD
S
LED
6
1:1200
50
500
5
RSET
1.8k
3
1
8
2
7
1
&
1
6
A
6
A
6
A
4
Dis
iC-Haus GmbH
Tel
(+49)6135-9292-0
Integrierte Schaltkreise
Fax (+49)6135-9292-192
Am Kuemmerling 18, 55294 Bodenheim
http://www.ichaus.com
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
PIN FUNCTIONS
(top view)
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
iC-NT
LIGHT CHAIN PULSE DRIVER
Rev A0, Page 3/8
ABSOLUTE MAXIMUM RATINGS
Values beyond which damage may occur; device operation is not guaranteed.
Item
Symbol
Parameter
Conditions
Fig.
Unit
Min.
Max.
G001 VDD
Supply Voltage
-0.5
7
V
G002 V()
Voltage at Inputs DIN, CLK, SHEN
-0.5
VDD+0.5
V
G003 V()
Voltage at DOUT, ISET, LED
-0.5
VDD+0.5
V
E001 Vd()
ESD Susceptibility at VDD, ISET and
digital inputs/outputs
MIL-STD-883, HBM 100pF
discharged through 1.5k
2
kV
E002 Vd(LED)
ESD Susceptibility at LED
with standard circuitry, HBM 100pF
discharged through 1.5k
5
2
kV
TG1 Tj
Junction Temperature
-40
150
C
TG2 Ts
Storage Temperature
-40
150
C
THERMAL DATA
Operating Conditions: VDD= 4.75..5.5V
Item
Symbol
Parameter
Conditions
Fig.
Unit
Min.
Typ.
Max.
T1
Ta
Operating Ambient Temperature
Range
(Extended temperature range
of -20..85
C on request)
0
70
C
T2
Rthja
Thermal Resistance Junction to
Ambient
surface mounted without special
cooling areas
170
K/W
All voltages are referenced to ground unless otherwise noted.
All currents into the device pins are positive; all currents out of the device pins are negative.
iC-NT
LIGHT CHAIN PULSE DRIVER
Rev A0, Page 4/8
ELECTRICAL CHARACTERISTICS
Operating Conditions:
VDD= 4.75..5.5V, RSET= 1.8..4.5k
, Tj= -20..125
C, unless otherwise noted
Item
Symbol
Parameter
Conditions
Tj
Fig.
Unit
C
Min.
Typ.
Max.
Total Device
001
VDD
Permissible Supply Voltage
Range
4.75
5.5
V
002
I(VDD)
Supply Current in VDD
(Standby)
Analog section disabled; DIN= lo,
CLK,SHEN= hi or lo,
logic levels: lo= 0..0.45V,
hi= VDD-0.45V..VDD
60
A
003
I(VDD)
Supply Current in VDD
Analog section disabled; DIN= lo
CLK, SHEN hi or lo,
logic levels: lo= 22%VDD,
hi= 78%VDD
1
mA
004
I(VDD)
Supply Current in VDD
Analog section enabled;
RSET
1.8k
,
LED current sink off
-20
27
85
Toff
7.5
7.5
8.5
1.0
mA
mA
mA
mA
005
I(VDD)
Supply Current in VDD
Analog section enabled;
RSET
1.8k
,
LED current sink on
-20
27
85
Toff
25
25
26
1.0
mA
mA
mA
mA
006
VDDon
Turn-on Threshold VDD
(Power-on Release)
4.3
V
007
VDDoff
Undervoltage Threshold at VDD
(Power-down Reset)
decreasing voltage VDD
2.7
V
008
VDDhys
Hysteresis
VDDhys= VDDon-VDDoff
100
mV
009
Vc()hi
Clamp Voltage hi at DIN, CLK,
SHEN, DOUT, ISET, LED
Vc()hi= V()-VDD,
I()= 10mA
0.4
1.25
V
010
Vc()lo
Clamp Voltage lo at DIN, CLK,
SHEN, DOUT, ISET, LED
I()= -10mA, VDD= 0V
other pins open
-1.25
-0.4
V
011
Toff
Shutdown Temperature
110
150
C
LED Current Sink
101
V(ISET)
Reference Voltage at ISET
-20
27
85
Toff
1.27
1.50
1.79
0
V
V
V
V
102
TC(ISET) Temperature Coefficient of
Reference Voltage at ISET
27
0.30
0.33
0.36
%/K
103
CR()
Current Ratio I(LED) / -I(ISET)
1200
104
I(LED)
LED Pulse Current
duty cycle I(LED)
1%,
RSET= 1.8k
,
V(LED)= 1.0V..VDD
-20
27
85
Toff
0.65
0.82
0.93
0.85
1.00
1.2
0
1.06
1.18
1.48
A
A
A
A
105
I(LED)
LED Pulse Current
duty cycle I(LED)
1%,
RSET= 4.5k
,
V(LED)= 0.85V..VDD
-20
27
85
Toff
0.26
0.33
0.37
0.34
0.40
0.48
0
0.44
0.48
0.61
A
A
A
A
106
tr(LED)
LED Current Rise Time
3
150
ns
107
tf(LED)
LED Current Fall Time
3
150
ns
108
tdis(LED) LED Discharge Duration
LED shutdown, switch Sdis
closed
400
ns
iC-NT
LIGHT CHAIN PULSE DRIVER
Rev A0, Page 5/8
ELECTRICAL CHARACTERISTICS
Operating Conditions:
VDD= 4.75..5.5V, RSET= 1.8..4.5k
, Tj= -20..125
C, unless otherwise noted
Item
Symbol
Parameter
Conditions
Tj
Fig.
Unit
C
Min.
Typ.
Max.
LED Current Sink (continued)
109
Ir(LED)
LED Discharge Current
V(VDD/LED)= 1.5V
200
mA
110
Rpu(LED) Pull-up Resistor at LED
300
500
850
Control Inputs DIN, SHEN, CLK
201
Vt()hi
Threshold Voltage hi
78
%VDD
202
Vt()lo
Threshold Voltage lo
22
%VDD
203
Vhys()
Schmitt-Trigger Input
Hysteresis
400
mV
204
Ipd()
Pull-Down Current
V()= 5.0V
3
6
12
A
Output Buffer DOUT
301
Vs()hi
Saturation Voltage hi
Vs(DOUT)hi= VDD-V(DOUT),
I(DOUT)= -4mA
0.4
V
302
Vs()lo
Saturation Voltage lo
I(DOUT)= 4mA
0.4
V
303
Isc()hi
Short-Circuit Current hi
V(DOUT)= 0V
-100
-40
-20
mA
304
Isc()lo
Short-Circuit Current lo
V(DOUT)= VDD
20
40
100
mA
305
Rout()
Output Resistance
VDD= 5.0V, V(DOUT)= 2.5V
80
120
190
306
tr()
Rise Time
CL(DOUT)
50pF
20
60
ns
307
tf()
Fall Time
CL(DOUT)
50pF
20
60
ns
Switching Characteristics
401
tphl(CLK
-LED)
LED Pulse Turn-on Delay
DIN= hi, CLK lo
hi until
I(LED)= 10% set value
4
100
ns
402
tplh(CLK
-LED)
LED Pulse Turn-off Delay
DIN= lo, CLK lo
hi until
I(LED)= 90% set value
4
80
ns
403
tplh(CLK-
DOUT)
DOUT Switch Delay hi
CL(DOUT)
50pF,
CLK hi
lo
2
25
60
ns
404
tphl(CLK-
DOUT)
DOUT Switch Delay lo
CL(DOUT)
50pF,
CLK hi
lo
2
25
60
ns
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