ICHAUS IC-NT

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 1µs
♦ 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 120Ω 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
+5V
2
iC-NT
VDD
CONTROL INPUTS
1
DOUT
DIN
6µA
3
OUTPUT BUFFER
LOGIC
FF1
D
CLK
C
R
Q
FF2
Q1
D
C
R
Q
6
FF3
Q2
&
D
Q
Q3
LED CURRENT SINK
C
R
VDD
+5V
4
500Ω
6µA
S Dis
SHEN
LED
8
ISET
5
SEND
6µA
1
1
VDD
PDR
TR
ENABLE
A
1:1200
POWER DOWN
RESET
REFERENCE AND
THERMAL SHUTDOWN
VTREF
+
50Ω
RSET
1.8kΩ
GND
7
©1997
Rev A0
iC-Haus GmbH
Integrierte Schaltkreise
Am Kuemmerling 18, 55294 Bodenheim
Tel (+49)6135-9292-0
Fax (+49)6135-9292-192
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
(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
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 1.5kΩ
2
kV
E002 Vd(LED)
ESD Susceptibility at LED
with standard circuitry, HBM 100pF
discharged through 1.5kΩ
2
kV
TG1 Tj
Junction Temperature
-40
150
°C
TG2 Ts
Storage Temperature
-40
150
°C
5
THERMAL DATA
Operating Conditions: VDD= 4.75..5.5V
Item
Symbol
Parameter
T1
Ta
Operating Ambient Temperature
Range
(Extended temperature range
of -20..85°C on request)
T2
Rthja
Thermal Resistance Junction to
Ambient
Conditions
Fig.
Unit
Min.
0
surface mounted without special
cooling areas
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.
Typ.
Max.
70
°C
170
K/W
iC-NT
LIGHT CHAIN PULSE DRIVER
Rev A0, Page 4/8
ELECTRICAL CHARACTERISTICS
Operating Conditions:
VDD= 4.75..5.5V, RSET= 1.8..4.5kΩ, Tj= -20..125°C, unless otherwise noted
Item
Symbol
Parameter
Conditions
Tj
Fig.
°C
Unit
Min.
Typ.
Max.
Total Device
001 VDD
Permissible Supply Voltage
Range
002 I(VDD)
Supply Current in VDD
(Standby)
003 I(VDD)
4.75
5.5
V
Analog section disabled; DIN= lo,
CLK,SHEN= hi or lo,
logic levels: lo= 0..0.45V,
hi= VDD-0.45V..VDD
60
µA
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≥ 1.8kΩ,
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≥ 1.8kΩ,
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
008 VDDhys
Hysteresis
VDDhys= VDDon-VDDoff
100
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
V
mV
LED Current Sink
101 V(ISET)
Reference Voltage at ISET
-20
27
85
Toff
102 TC(ISET) Temperature Coefficient of
Reference Voltage at ISET
1.27
1.50
1.79
0
27
0.30
0.33
V
V
V
V
0.36
%/K
103 CR()
Current Ratio I(LED) / -I(ISET)
104 I(LED)
LED Pulse Current
duty cycle I(LED)≤ 1%,
RSET= 1.8kΩ,
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= 4.5kΩ,
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
400
ns
108 tdis(LED) LED Discharge Duration
1200
LED shutdown, switch Sdis
closed
iC-NT
LIGHT CHAIN PULSE DRIVER
Rev A0, Page 5/8
ELECTRICAL CHARACTERISTICS
Operating Conditions:
VDD= 4.75..5.5V, RSET= 1.8..4.5kΩ, Tj= -20..125°C, unless otherwise noted
Item
Symbol
Parameter
Conditions
Tj
Fig.
°C
Unit
Min.
Typ.
Max.
LED Current Sink (continued)
109 Ir(LED)
LED Discharge Current
V(VDD/LED)= 1.5V
200
110 Rpu(LED) Pull-up Resistor at LED
300
500
mA
850
Ω
78
%VDD
Control Inputs DIN, SHEN, CLK
201 Vt()hi
Threshold Voltage hi
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
µA
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
-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
Ω
306 tr()
Rise Time
CL(DOUT)≤ 50pF
20
60
ns
307 tf()
Fall Time
CL(DOUT)≤ 50pF
20
60
ns
-100
Switching Characteristics
401 tphl(CLK LED Pulse Turn-on Delay
-LED)
DIN= hi, CLK lo→hi until
I(LED)= 10% set value
4
100
ns
402 tplh(CLK LED Pulse Turn-off Delay
-LED)
DIN= lo, CLK lo→hi until
I(LED)= 90% set value
4
80
ns
403 tplh(CLK- DOUT Switch Delay hi
DOUT)
CL(DOUT)≤ 50pF,
CLK hi→lo
2
25
60
ns
404 tphl(CLK- DOUT Switch Delay lo
DOUT)
CL(DOUT)≤ 50pF,
CLK hi→lo
2
25
60
ns
iC-NT
LIGHT CHAIN PULSE DRIVER
Rev A0, Page 6/8
OPERATING REQUIREMENTS: Logic
Operating Conditions: VDD= 4.75..5.5V, Ta= 0..70°C, CL()= 50pF,
input levels lo= 0..0.45V, hi= VDD-0.45V..VDD, see Fig. 1 for reference levels and waveforms
Item Symbol
Parameter
Conditions
Fig.
Unit
Min.
Max.
I1
ten
Activation Time (standby to operation):
DIN lo→hi before CLK lo→hi
4
5
µs
I2
tset1
Setup time:
DIN stable before CLK lo→hi
2
50
ns
I3
thold1
Hold time:
DIN stable after CLK lo→hi
2
50
ns
I4
tset2
Setup time:
SHEN stable before CLK hi→lo
2
50
ns
I5
thold2
Hold time:
SHEN stable after CLK hi→lo
2
50
ns
I6
tw
LED Pulse time:
1st to 2nd CLK lo→hi
4
1.0
µs
Fig. 1: Reference levels
Fig. 2: Timing characteristics
Fig. 3: LED Current Pulse
Fig. 4: Chain configuration (SHEN= hi),
LED pulse definition by clock signal
iC-NT
LIGHT CHAIN PULSE DRIVER
Rev A0, Page 7/8
APPLICATIONS INFORMATION
Light curtain
The circuit in Figure 5 shows iC-NT chained to a light curtain where consecutive LEDs emit clock-driven light
pulses.
When discussing the function of iC-NT, it is assumed that all flipflops in IC1..ICn have been reset, for example
after the operating voltage has been switched on. The signal DIN1= hi activates the IC1 current sink which is
switched to LED1 with the CLK rising edge. With DIN1= lo, the next CLK rising edge resets FF1, turns off the
LED and deactivates the current sink in IC1. Simultaneously, FF1 sends the stored information to FF2. FF3 also
accepts this information via the CLK trailing edge (provided that SHEN= hi) and activates the current sink in the
next component, IC2, via the output driver. The pulse diagram in Figure 6 is also valid for the subsequent
components in the chain, i.e. the ICs switched as a light curtain make up a clock-driven shift register which
passes on the input information.
The typical timing of a CLK signal, shown in Figure 6, is characterized by two successive pulses which
determine the length of a light pulse tw from 1..3µs, followed by a longer activation time of ten ≥5µs. In general,
the CLK pulse interval is determined and lengthened by the activation time required by the receiver or by more
extensive, system-set default options.
Because of the high LED pulse currents, the PCB layout of the light curtain sender must be designed to avoid
large voltage drops on the supply lines. The high, short-term pulse current is provided by back-up capacitors
C1..Cn at the pulse driver ICs; these should have a low inductance due to the high current increase rate. The
leads to the LED anode and to iC-NT’s GND pin should be as short as possible. The capacitors selected should
ensure that the voltage drop caused by the light pulse is less than 1V, i.e. that C1..Cn= 1µF for a light pulse of
1A x 1µs, for example. In practice, the voltage at the IC drops much less during a light pulse, as charge from
the back-up capacitors of neighboring ICs also flows into the chip. A low-inductance capacitance distribution can
be achieved more economically by placing further smaller capacitors in parallel.
Since only one device is activated at a time within one section of a light curtain, several iC-NTs may share the
external resistor RSET, needed to set the pulse current. This parallel chain circuit should be limited to ca. 5 ICs
due to the increasing capacitive loading at pin ISET.
Fig. 5: Schematic of a Chain Configuration
iC-NT
LIGHT CHAIN PULSE DRIVER
Rev A0, Page 8/8
Fig. 6: Signals of the Chain Configuration of Figure 5
ORDERING INFORMATION
Type
Package
Order designation
iC-NT
SO8
iC-NT-SO8
For information about prices, terms of delivery, options for other case types, etc., please contact:
iC-Haus GmbH
Am Kuemmerling 18
D-55294 Bodenheim
GERMANY
Tel (+49)6135-9292-0
Fax (+49)6135-9292-192
http://www.ichaus.com
This specification is for a newly developed product. iC-Haus therefore reserves the right to modify data without further notice. Please contact
us to ascertain the current data. The data specified is intended solely for the purpose of product description and is not to be deemed
guaranteed in a legal sense. Any claims for damage against us - regardless of the legal basis - are excluded unless we are guilty of
premeditation or gross negligence.
We do not assume any guarantee that the specified circuits or procedures are free of copyrights of third parties.
Copying - even as an excerpt - is only permitted with the approval of the publisher and precise reference to source.