ICHAUS IC

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iC-NZN
N-TYPE LASER DIODE DRIVER
Rev B2, Page 1/17
FEATURES
APPLICATIONS
♦ Peak value controlled laser diode driver for operation from CW
up to 155 MHz
♦ Spike-free switching of laser currents of up to 300 mA
♦ Setting of laser power (APC) via external resistor
♦ Optional current control (ACC)
♦ Laser current limitation
♦ LVDS/TTL switching input with TTL monitor output
♦ Low current consumption sleep-mode < 50 µA
♦ Safety shutdown with overtemperature
♦ Error signal output with overtemperature, undervoltage and
overcurrent
♦ All current LD types can be used (N/P/M configurations)
♦ Blue laser diodes supported
♦ Fast soft-start
♦ Strong suppression of transients with small external capacitors
♦ Pulsed and CW laser diode
modules
♦ Laser diode pointers
♦ Laser levels
♦ Bar-code readers
♦ Distance measurement
♦ Blue laser diodes
PACKAGES
QFN24
4 mm x 4 mm
BLOCK DIAGRAM
RVDD
+3..+5.5V
VDD
CVDD
RSI
RSI
NSLP
REGE
CLDA
iC-NZN
LDA MONITOR
100 nF..
0.68.. 9kΩ
LDA
i(RSI)x540
IMON
VDD
&
AVG
..300mA
1
&
VSY
REF
SYN
EP
100 nF..
N
LDK
+
CI
-
LVDS/TTL
ECI
+
EN
CI
x240
-
CIS
..10 nF..
AGND
VDD
TTL
MD
CID
ECI
OUTPUT DRIVER
INPUT INTERFACE
NERR
RMD
OverTemp.
1
GND
OverCurrent
Bandgap, Reference, Overtemp
Low V(LDA)
T.PAD
OUTPUT MONITOR
GND
PMD
RGND
suitable laser diode configurations
N
Copyright © 2012 iC-Haus
M
P
http://www.ichaus.com
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iC-NZN
N-TYPE LASER DIODE DRIVER
Rev B2, Page 2/17
DESCRIPTION
Laser diode pulse driver iC-NZN allows CW operation of laser diodes and spike-free switching with defined current pulses up to 155 MHz. The optical output power of the laser diode is set-up by means of an
external resistor (RMD/PMD). For laser current control without a monitor diode, the laser current monitor at pin IMON is utilised. For high pulse frequencies the device can be switched into controlled burst
mode. A previously settled operating point is maintained throughout the burst phase.
An averaging current monitor can be set by means of
an external resistor at pin RSI. When the current limit
is reached, overcurrent is signalled at NERR and the
current from pin LDA is limited to the pre-set value
but the iC is not shut down. There is an additional
current limitation in pin LDK that prevents the iC from
overpowering the laser diode.
Setting pin NSLP low, the iC enters a low consumption sleep-mode (< 50 µA typ.).
PACKAGES QFN24 4 mm x 4 mm to JEDEC
PIN CONFIGURATION
24
23
PIN FUNCTIONS
No. Name Function
22
21
20
19
1
18
2
17
16
3
NZN
code...
...
4
5
15
14
13
6
7
8
9
10
11
12
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
VDD
AVG
MD
IMON
CID
EP
EN
TTL
VSY
SYN
RGND
RVDD
LDK
AGND
CIS
CI
LDA
Power Supply
Enable Averaging Control
APC setup, monitor input
Laser Current Monitor
Enable Pulldown Current at CI
Positive LVDS/TTL switching input
Negative LVDS switching input
Enable TTL input
Sync Output Supply Voltage
Sync Output
Reference Ground
Reference (P-type laser diodes)
Laser Diode Cathode
Analog ground
Power Control Capacitor sense
Power Control Capacitor
Laser Diode Anode
n/c
RSI
Current Monitor Setup
REGE Control Enable
GND Ground
NSLP Not Sleep-Mode
NERR Error Output
n/c
The Thermal Pad is to be connected to a Ground Plane (GND) on the PCB.
Only pin 1 marking on top or bottom defines the package orientation ( NZN label and coding is subject
to change).
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iC-NZN
N-TYPE LASER DIODE DRIVER
Rev B2, Page 3/17
PACKAGE DIMENSIONS
RECOMMENDED PCB-FOOTPRINT
3.80
2.49
15
R0.
TOP
0.30
0.70
0.50
0.25
0.40
3.80
0.90
2.49
SIDE
BOTTOM
2.45
4
2.45
4
0.50
dra_qfn24-1_pack_1, 10:1
All dimensions given in mm.
iC-NZN
N-TYPE LASER DIODE DRIVER
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Rev B2, Page 4/17
ABSOLUTE MAXIMUM RATINGS
Beyond these values damage may occur; device operation is not guaranteed.
Item
No.
Symbol
Parameter
Conditions
Unit
Min.
Max.
G001 VDD
Voltage at VDD
-0.7
6
V
G002 I(VDD)
Current in VDD
DC current
-2
1200
mA
G003 I(CI)
Current in CI
V(LDA) = 0
-2
5
mA
G004 I(NERR)
Current in NERR
-2
20
mA
G005 I(MD)
Current in MD
-2
20
mA
G006 I()dig
Current in EP, EN, TTL, REGE, NSLP,
AVG, CID
-2
20
mA
G007 I(LDK)
Current in LDK
DC current
-2
1200
mA
G008 I(LDA)
Current in LDA
DC current
-2
1200
mA
G009 I(RSI)
Current in RSI
-2
20
mA
G010 I(VSY)
Current in VSYNC
-2
50
mA
G011 I(SYN)
Current in SYNC
-2
50
mA
G012 I(IMON)
Current in IMON
-2
20
mA
G013 V()c
Voltage at RSI, VSY, SYN, EP, EN,
TTL, REGE, AVG, CID, RGND, MD, CI,
IMON, RVDD, LDA, NERR, NSLP
-0.7
6
V
G014 V()h
Voltage at LDK
-0.7
15
V
G015 Vd()
ESD Susceptibility at all pins
2
kV
G016 Tj
Operating Junction Temperature
-40
190
°C
G017 Ts
Storage Temperature Range
-40
190
°C
HBM, 100 pF discharged through 1.5 kΩ
THERMAL DATA
Operating Conditions: VDD = 3...5.5 V
Item
No.
Symbol
Parameter
Conditions
Unit
Min.
T01
Ta
Operating Ambient Temperature Range
T02
Rthja
Thermal Resistance Chip/Ambient
Typ.
-20
surface mounted, thermal pad soldered to ca.
2 cm² heat sink
All voltages are referenced to ground unless otherwise stated.
All currents flowing into the device pins are positive; all currents flowing out of the device pins are negative.
30
Max.
85
°C
40
K/W
iC-NZN
N-TYPE LASER DIODE DRIVER
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Rev B2, Page 5/17
ELECTRICAL CHARACTERISTICS
Operating Conditions: VDD = 3...5.5 V, VSY = 0 V...VDD, Tj = -20...125 °C, NSLP = hi, CID = lo; unless otherwise stated
Item
No.
Symbol
Parameter
Conditions
Unit
Min.
Typ.
Max.
Total Device
001
VDD
Permissible Supply Voltage
002
VSY
Permissible Supply Voltage at
VSY
VSY ≤ VDD
003
Ioff(VDD)
Supply Current in VDD
NSLP = lo, all other input pins set to lo
5
50
µA
004
Idc(VDD)
Supply Current in VDD
RSI ≥ 680 Ω
10
15
mA
005
I(VSY)
Supply Current in VSY
SYN pin open
10
µA
006
Tab
Thermal Shutdown Threshold
130
196
°C
007
VDDon
Power-On Threshold
1.7
2.8
V
008
Vc()hi
Clamp Voltage hi at RSI, TTL,
REGE, MD, CI, LDA, NSLP,
IMON
0.3
1.5
V
009
Vc()hi
Clamp Voltage hi to VSY at SYN I() = 1 mA, other pins open, VSY = 0
0.3
1.5
V
010
Vc()hi
Clamp Voltage hi at LDK
I() = 1 mA, other pins open
12
011
Vc()lo
Clamp Voltage lo at VDD, AVG,
MD, IMON, CID, EP, EN, TTL,
VSY, SYN, RGND, RVDD, LDK,
AGND, CI, LDA, RSI, REGE,
NSLP, NERR
I() = 1 mA, other pins open
-1.5
012
Vc()hi
Clamp Voltage hi at VSY, EP, EN I() = 1 mA, other pins open, VDD = 0
I() = 0.1 mA, other pins open, VDD = 0
3
5.5
V
3
5.5
V
V
-0.65
-0.3
V
6
V
580
mV
9
9
kΩ
kΩ
630
mV
880
630
mA
mA
Current Monitor RSI, LDA
101
102
V(RSI)
Voltage at RSI
RSI
Permissable Resistor at RSI
VDD = 3...3.5 V
VDD = 4.5...5.5 V
2.5
0.68
103
104
VLDA
LDA Voltage Monitor Threshold
VDD − V(LDA), V(RSI) = VDD
400
Ierr(LDA)
Maximum Unlimited current from V(RSI) = VDD;
VDD = 4.5...5.5 V
LDA without error signaling
VDD = 3...3.5 V
105
Cmin(LDA) Minimum capacitor needed at
LDA
106
rILDA
107
rILDK
Current Ratio I(LDA)max / I(RSI)
Current Ratio I(LDK)max / I(RSI)
108
i(ldk)
109
Rdis(LDA) Discharge Resistor at LDA
Maximum limited current
430
520
500
400
260
100
nF
V(LDA) = 0 V
VDD = 4.5...5.5 V
VDD = 3...3.5 V
470
430
610
610
V(LDK) = V(REGE) = V(TTL) = V(EP) = VDD,
V(MD) = 0 V
VDD = 4.5...5.5 V
VDD = 3...3.5 V
400
480
960
870
RSI = 0.68 KΩ VDD = 5.5 V
NSLP = lo, V(LDA) = VDD
1
630
mA
20
kΩ
560
mV
Reference
201
V(MD)
V(MD) − V(RGND),
closed control loop
V(RVDD) − V(MD) for P-type LD
or ACC
202
dV(MD)
Temperature Drift of Voltage at
MD
closed control loop
203
V(MD)
V(MD) − V(RGND)
V(EP) = 0 V, V(AVG) = 0 V, N-type LD
460
460
510
120
510
µV/°C
560
mV
VDD −
1.4
V
Digital Inputs/Outputs
301
Vin()
Input Voltage Range at EP, EN
TTL = lo, VDD = 3.0...5.5 V
0.6
302
Vd()
Input Differential Voltage at EP,
EN
TTL = lo, Vd() = |V(EP) − V(EN)|
200
303
R()
Differential Input Impedance at
EP, EN
TTL = lo
V(EP), V(EN) < VDD − 1.5 V
0.6
304
Vt(EP)hi
Input Threshold Voltage hi at EP TTL = hi, EN = open
305
Vt(EP)lo
Input Threshold Voltage lo at EP TTL = hi, EN = open
0.8
mV
3
kΩ
2
V
V
iC-NZN
N-TYPE LASER DIODE DRIVER
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Rev B2, Page 6/17
ELECTRICAL CHARACTERISTICS
Operating Conditions: VDD = 3...5.5 V, VSY = 0 V...VDD, Tj = -20...125 °C, NSLP = hi, CID = lo; unless otherwise stated
Item
No.
Symbol
Parameter
Conditions
Unit
Min.
306
Vhys(EP)
Hysteresis at EP
TTL = hi, EN = open
40
307
Ipd(EP)
Pull-Down Current at EP
TTL = hi, EN = open, V() = 1 V...VDD
0.5
308
Vt()hi
Input Threshold Voltage hi at
TTL, REGE, NSLP, AVG, CID
309
Vt()lo
Input Threshold Voltage lo at
TTL, REGE, NSLP, AVG, CID
0.8
310
Vhys()
Hysteresis at TTL, REGE, NSLP,
AVG, CID
140
311
Ipu()
Pull-Up Current at TTL, REGE
312
Ipd()
Pull-Down Current at NSLP, AVG, V() = 1 V...VDD
CID
313
Vs()hi
Saturation voltage hi at SYN
314
Vs()lo
315
V() = 0...VDD − 1.2 V
Typ.
Max.
mV
5
µA
2
V
V
230
mV
-60
-2
µA
2
130
µA
Vs(SYN)hi = VSY − V(SYN), I() = -1 mA,
VSY = VDD, EP = TTL = High, EN = open
0.4
V
Saturation voltage lo at SYN
I() = 1 mA, TTL = High, VSY = VDD, EP = Low,
EN = open
0.4
V
Isc()hi
Short-circuit Current hi at SYN
EP = TTL = High, EN = open, V(SYN) = 0 V,
VSY = VDD
-40
-3
mA
316
Isc()lo
Short-circuit Current lo at SYN
EP = TTL = High, EN = open, V(SYN) = 0 V,
VSY = VDD
3
25
mA
317
I(NERR)
Current in NERR
V(NERR) > 0.6 V, error
1
318
Vs()lo
Saturation Voltage lo at NERR
I() = 1 mA, error
Laser Driver LDK, CI, IMON
401 Vs(LDK)lo Saturation Voltage lo at LDK
I(LDK) = 300 mA, RSI = 680 Ω, VDD=4.5...5.5 V
I(LDK) = 100 mA, RSI = 680 Ω VDD=4.5...5.5 V
I(LDK) = 60 mA, RSI = 2.5 kΩ VDD=3...3.5 V
1.6
1.2
0.8
20
mA
600
mV
3
2
1.3
V
V
V
mA
402
Idc(LDK)
Permissible DC Current in LDK
300
403
Vo()
Permissible Voltage at LDK
12
404
405
C(CI)
Required Capacitor at CI
|I(CI)|
Charge Current from CI
0
iC active, REGE = hi, V(CI) = 1 V, CID = 0 V
iC active, REGE = hi, V(CI) = 1 V, CID = VDD
10
V
nF
20
0
65
µA
µA
406
Ipd(CI)
Pull-Down Current in CI
iC active, REGE = lo, CID = hi, V(CI) = 1 V,
VDD = 3...5.5 V
0.3
2.6
µA
407
Imon()
Current at IMON
V(IMON) = VDD − 0.5 V, I(LDK) < 300 mA,
VDD = 4.5...5.5 V
1/280
1/200
I(LDK)
408
Imin(LDK) Minimum permissible current
pulse
0.5
mA
409
Imax(LDK) Maximum obtainable current from V(REGE) = V(TTL) = V(EP) = VDD,
the driver
V(MD) = 0 V;
VDD = 4.5...5.5 V
VDD = 3...4.5 V
300
90
mA
mA
Timing
501
twu
Time to Wakeup:
NSLP lo → hi to system enable
CLDA = 1 µF, RSI = 680 Ω
300
µs
502
tr
Laser Current Rise Time
VDD = 5 V see Fig. 2
1.5
ns
503
tf
Laser Current Fall Time
VDD = 5 V see Fig. 2
1.5
ns
504
tp
Propagation Delay
V(EPx, ENx) → I(LDKx)
VDD = 5 V
10
ns
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iC-NZN
N-TYPE LASER DIODE DRIVER
Rev B2, Page 7/17
ELECTRICAL CHARACTERISTICS: DIAGRAMS
I(LED)
tr
tf
I pk
V
90% I pk
Input/Output
VDD−0.45V
Vt()hi
Vt()lo
0.45V
1
t
10% I pk
t
0
Figure 1: Reference levels
Figure 2: Laser current pulse
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iC-NZN
N-TYPE LASER DIODE DRIVER
Rev B2, Page 8/17
DESCRIPTION OF FUNCTIONS
iC-NZN is a laser diode pulse driver. The device features the following functions:
• Peak or averaging control
• Optical power (APC) or current control (ACC)
• Pulses of up to 155 MHz in controlled burst mode
• Laser current limitation
• Operation of blue laser diodes possible
• Error signalling for overcurrent
• Sleep mode with less than 50 µA consumption
OPTICAL POWER CONTROL
The iC-NZN supports the control of the laser diode’s
optical output power for all common laser diode pin
configurations (N, P and M). The control is enabled
with pin REGE set to high. With AVG set to low, the
peak power control is enabled. The laser power level
is selected by means of the resistor RMON (= RMD +
PMD). This control mode can be used for frequencies
up to ca. 4 Mhz. For higher frequencies the averaging control (AVG = high) or the burst mode have to be
used. Tables 4 and 5 show how to set the inputs for
laser control depending on the input interface selected
(TTL or LVDS).
Laser control in TTL mode (TTL = high/open)
EP
EN
NSLP
REGE
SYN Mode
low/open Power-save mode
low/open open high
low LDA charged, laser off
high
open high
high/open high LDA charged, laser on, peak control
high
open high
low
high LDA charged, laser on, burst mode
Table 4: Laser control in TTL mode
Laser control in LVDS mode (TTL = low)
EP
EN
NSLP
REGE
SYN
low/open < EN > EP high
low
> EN < EP high
high/open high
> EN < EP high
low
high
Mode
Power-save mode
LDA charged, laser off
LDA charged, laser on, peak control
LDA charged, laser on, burst mode
Table 5: Laser control in LVDS mode
RMON dimensioning
Peak control (AVG = low): In order to calculate the right
value of RMON, the value of IM (monitor current with
respect to optical output power) of the laser diode must
be known. RMON must be chosen in a way that the
monitor current generated by the desired output power
creates a voltage drop across RMON of 500 mV (cf.
Electrical Characteristics No. 201).
Averaging control (AVG = high): In this mode the calculation is the same as in peak control, only the result
has to be divided by the duty cycle of the laser pulses,
D = Tτ . At a duty cycle of e.g. 50% D = 21 . This requires an external averaging capacitor of sufficient size
at pin CI though.
Control modes
Averaging Operation mode RMON calculation
AVG = 0
Peak control
RMON =
AVG = 1
Averaging control RMON =
V (MD)
IM
V (MD)
IM×D
Table 6: RMON dimensioning
Example
By way of example, an output level of 1 mW is to be
set. With an optical power of 1 mW e.g. laser diode
HL6339G has a typical monitor current (IM) of 15 µA.
The following value is then obtained for the resistor at
pin MD (RMON = PMD + RMD, where RMD is a fixed
resistor and PMD a potentiometer.):
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iC-NZN
N-TYPE LASER DIODE DRIVER
Rev B2, Page 9/17
External capacitor mode
In applications where an external capacitor is required
(see best performance recommendations below), the
external capacitor mode must be enabled (pin CID =
high). This connects the capacitor to the control circuit and additionally enables a pull-down current at pin
CI to prevent this capacitor from being charged due
to residual currents (cf. Electrical Characteristics No.
406).
lead to an unstable control circuit under certain conditions such as inadequate PCB layout or laser diodes
with very low monitor current. In these cases, an optional capacitor can be connected as close as possible
to the chip, across pin CI and CIS. This will prevent
instability of the control circuit. For averaging control
a 10 nF capacitor at CI is recommended. Special care
must be taken in PCB layout when laying out the path
from the laser diode’s cathode via pin LDK to AGND.
This path must be kept as short as possible to avoid
parasitic inductances. A sbubber network across the
laser diode helps to compensate for these parasitic inductances.
Best performance recommendations
The operating point for the laser diode is stored in an
on-chip capacitor. This permits a fast start-up but can
Figures 3, 4 and 5 show the typical set-up for the different N, P and M-type diode configurations.
V (MD)
0.5 V
RMON =
=
= 33.34 kΩ
IM
15 µA
N-type diodes
RVDD
+3..+5.5V
VDD
CVDD
RSI
RSI
NSLP
REGE
CLDA
iC-NZN
LDA MONITOR
100 nF..
0.68.. 9kΩ
LDA
i(RSI)x540
IMON
VDD
&
AVG
..300mA
1
&
VSY
REF
SYN
EP
100 nF..
N
LDK
+
CI
-
LVDS/TTL
ECI
+
EN
CI
x240
-
CIS
..10 nF..
AGND
VDD
TTL
MD
CID
ECI
OUTPUT DRIVER
INPUT INTERFACE
NERR
RMD
OverTemp.
1
GND
T.PAD
OverCurrent
Bandgap, Reference, Overtemp
Low V(LDA)
GND
OUTPUT MONITOR
PMD
RGND
Figure 3: Circuit example for N-type laser diodes
P-type diodes
Althought this kind of laser diodes are supported by iCNZN, it’s strongly recommended to use iC-NZP instead
since in this configuration, all the pulses at LDK will
be coupled directly to pin MD due to monitor diode’s
internal capacitance, thus making an accurate control
much more difficult. Moreover, applications with P-type
laser diode case grounded are possible with iC-NZP
only.
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iC-NZN
N-TYPE LASER DIODE DRIVER
Rev B2, Page 10/17
RVDD
+3..+5.5V
VDD
CVDD
RSI
NSLP
0.68.. 9kΩ
REGE
100 nF..
LDK
AVG
..300mA
1
&
VSY
REF
SYN
+
CI
x240
CI
-
LVDS/TTL
ECI
+
-
EN
TTL
P
IMON
VDD
&
EP
CLDA
iC-NZN
LDA MONITOR
100 nF..
RMD
LDA
i(RSI)x540
RSI
PMD
CIS
..10 nF..
AGND
VDD
MD
CID
ECI
OUTPUT DRIVER
INPUT INTERFACE
NERR
OverTemp.
OverCurrent
Low V(LDA)
1
T.PAD
GND
Bandgap, Reference, Overtemp
OUTPUT MONITOR
GND
RGND
Figure 4: Circuit example for P-type laser diodes.
M-type diodes
RVDD
+3..+5.5V
VDD
CVDD
0.68.. 9kΩ
CLDA
iC-NZN
LDA MONITOR
100 nF..
RSI
LDA
i(RSI)x540
RSI
NSLP
100 nF..
LDK
REGE
&
AVG
..300mA
1
&
VSY
REF
SYN
EP
M
IMON
VDD
+
CI
-
LVDS/TTL
ECI
+
EN
CI
x240
-
CIS
..10 nF..
AGND
VDD
TTL
MD
CID
ECI
OUTPUT DRIVER
INPUT INTERFACE
NERR
RMD
OverTemp.
1
GND
T.PAD
OverCurrent
Bandgap, Reference, Overtemp
Low V(LDA)
GND
OUTPUT MONITOR
PMD
RGND
Figure 5: Circuit example for M-type laser diodes
Althought this type of laser diode are supported by iCNZN, it’s strongly recommended to use iC-NZP instead
since in this configuration, all the pulses at LDK will be
coupled directly to pin MD due to monitor diode’s in-
ternal capacitance, thus making an accurate control
much more difficult. Moreover, applications with Mtype laser diode case grounded are possible with iCNZP only.
iC-NZN
N-TYPE LASER DIODE DRIVER
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Rev B2, Page 11/17
LASER CURRENT LIMITATION
RSI @ VDD
LDA
VDD
CLDA
CVDD
i(RSI)x540
100 nF..
RSI
RSI
100 nF..
0.5V
0.68..9 kΩ
When dimensioning resistor RSI the following applies
(cf. Electrical Characteristics No. 106):
+
-
VDD-0.5V
LDA current limitation
iC-NZN monitors the average laser current flowing
from pin LDA (Figure 6). The DC current limit is set
by means of a resistor at pin RSI.
Imax (LDA) = 540 ×
0.5 V
RSI
The current limitation can be disabled by connecting
pin RSI to VDD.
NSLP
NERR
Overcurrent
1
OverTemp.
Figure 6: iC-NZN LDA current limitation
iC-NZN features two different current limitations, limiting the average current flowing from pin LDA plus the
current flowing into pin LDK.
Short pulses at LDA with higher currents are possible as only the DC current is monitored and capacitor
CLDA supplies the current for short pulses.
LDK current limitation
The control circuit also monitors the laser current in pin
LDK and limits this current when reaching the threshold also defined by RSI. The following applies (cf. Electrical Characteristics No. 107):
Imax (LDK ) = 520 ×
0.5 V
RSI
BURST MODE
In controlled burst mode iC-NZN can pulse with up to
155 MHz. Controlled here means that a pre-set operating point is maintained during the burst phase.
Therefore an operating point is settled first, for which
pin REGE has to be high and the laser diode must
be switched on. Once the operating point has been
reached the laser diode can be switched off again. The
operating point is stored in an on-chip capacitor and
when pin REGE is set to low, the burst mode is activated. The pre-set operating point is maintained.
For a longer burst mode, an external capacitor can
be connected to pin CI. To prevent the laser current
from rising due to residual currents, the capacitor is
discharged then with a maximum of 2.6 µA (cf. Electrical Characteristics No. 406). As the capacitor is discharged gradually, the output level must be re-settled
again after a certain period, depending on the admissible degradation of the laser output power.
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iC-NZN
N-TYPE LASER DIODE DRIVER
Rev B2, Page 12/17
CURRENT CONTROL
The iC-NZN also supports laser current control, when
no monitor diode is present. For that purpose, a fraction of the current flowing trough the laser diode is provided at IMON pin (ILDK / 240, cf. Electrical Charac-
teristics No. 407). Tables 7 and 8 show how to set the
inputs for laser control depending on the input interface
selected (TTL or LVDS).
Laser control in TTL mode (TTL = high/open)
EP
EN
NSLP
AVG REGE
SYN
low/open low/open open high
low
high
open high
high high/open high
Mode
Power save mode
LDA charged, laser off
LDA charged, laser on, regulated
Table 7: Laser control in TTL mode
Laser control in LVDS mode (TTL = Low)
EP
EN
NSLP
AVG REGE
SYN
low/open < EN > EP high
low
> EN < EP high
high high/open high
Mode
Power save mode
LDA charged, laser off
LDA charged, laser on, regulated
Table 8: Laser control in LVDS mode
The laser current is set by means of resistor RMON
(= RMD + PMD).
RMON =
V (RVDD) − V (MD)
IMON
Figure 7 shows the typical set-up for current control.
External capacitor mode
In applications where an external capacitor is required
(see best performance recommendations below), the
external capacitor mode must be enabled (pin CID =
high). This connects the capacitor to the control circuit and additionally enables a pull-down current at pin
CI to prevent this capacitor from being charged due
to residual currents (cf. Electrical Characteristics No.
406).
Best performance recommendations
The operating point for the laser diode is stored in
an on-chip capacitor. This permits a fast start-up but
can make the regulated system unstable under certain conditions such as inadequate PCB layout. In
these cases, an optional capacitor can be connected
as close as possible to the chip, across pins CI and
CIS.
Special care must be taken in PCB layout when laying
out the path from the laser diode’s cathode via pin LDK
to AGND. This path must be kept as short as possible to avoid parasitic inductances. A snubber network
across the laser diode also helps to compensate for
these parasitic inductances.
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iC-NZN
N-TYPE LASER DIODE DRIVER
Rev B2, Page 13/17
PMD RMD
RVDD
+3..+5.5V
VDD
CVDD
LDA
i(RSI)x540
RSI
RSI
NSLP
0.68.. 9kΩ
REGE
CLDA
iC-NZN
LDA MONITOR
100 nF..
100 nF..
IMON
VDD
LDK
&
AVG
..300mA
1
&
+
VSY
REF
SYN
CI
-
LVDS/TTL
EP
..10 nF..
CIS
ECI
+
EN
CI
x240
-
AGND
VDD
TTL
MD
CID
ECI
OUTPUT DRIVER
INPUT INTERFACE
NERR
OverTemp.
OverCurrent
1
Bandgap, Reference, Overtemp
Low V(LDA)
T.PAD
GND
OUTPUT MONITOR
GND
Figure 7: Example set-up for current control
BLUE LASER DIODES
required for the blue laser diodes. Nevertheless, the
current limitation protection in pin LDK (cf. Electrical
Characteristics No. 107) is still active. Figure 8 shows
a typical set-up for blue laser diodes with APC and figure 9 with ACC.
With the iC-NZN also blue laser diodes can be driven.
Due to the high forward voltage of these laser diodes,
an appropriate supply voltage must be provided. The
current limitation at pin LDA cannot be used then, since
only pin LDK is capable of handling the higher voltage
..12V
CL
100 nF..
RVDD
+3..+5.5V
VDD
CVDD
RSI
RSI
0.68.. 9kΩ
iC-NZN
LDA MONITOR
100 nF..
NSLP
IMON
VDD
LDK
REGE
&
AVG
..300mA
1
&
VSY
REF
SYN
EP
M
LDA
i(RSI)x540
+
LVDS/TTL
CI
ECI
+
EN
CI
x240
-
CIS
..10 nF..
AGND
VDD
TTL
MD
CID
ECI
INPUT INTERFACE
OUTPUT DRIVER
NERR
RMD
OverTemp.
1
GND
T.PAD
GND
OverCurrent
Low V(LDA)
Bandgap, Reference, Overtemp
OUTPUT MONITOR
PMD
RGND
Figure 8: Set-up for blue laser diodes with APC
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iC-NZN
N-TYPE LASER DIODE DRIVER
Rev B2, Page 14/17
..12V
CL
RVDD
+3..+5.5V
VDD
CVDD
i(RSI)x540
RSI
RSI
0.68.. 9kΩ
iC-NZN
LDA MONITOR
100 nF..
NSLP
100 nF..
IMON
VDD
LDK
REGE
&
AVG
..300mA
1
&
VSY
REF
SYN
EP
PMD RMD
LDA
+
CI
-
LVDS/TTL
ECI
+
EN
CI
x240
-
CIS
..10 nF..
AGND
VDD
TTL
MD
CID
ECI
OUTPUT DRIVER
INPUT INTERFACE
NERR
OverTemp.
1
GND
T.PAD
OverCurrent
Bandgap, Reference, Overtemp
Low V(LDA)
GND
OUTPUT MONITOR
RGND
Figure 9: Set-up for blue laser diodes with ACC
SLEEP MODE
The iC-NZN has a very low consumption sleep mode,
e.g. for battery powered applications. With pin NSLP
set to low the chip enters the sleep mode and discon-
nects pin LDA from the supply. The wake-up time from
this sleep mode is about 300 µs.
J1-LVDS_N
11
JP11
JP12
J1-LVDS_P
9
J1-TTL
3
J1-GND6
12
J1-GND5
10
J1-GND4
8
J1-GND3
5
J1-GND2
4
J1-GND1
2
J1-GND
1
J1-V5D
6
1
2
JP9
BURST
R4
opt
JP8
AVG
19 RSI
1 VDD
U1
iC-NZN
GND
21 GND
23 NERR
5 CID
8 TTL
7 EN
6 EP
VDD
+
-
&
1
Low V(LDA)
OverTemp.
OverCurrent
INPUT INTERFACE
LVDS/TTL
VDD
i(RSI)x540
LDA MONITOR
1
OUTPUT DRIVER
x240
OUTPUT MONITOR
Bandgap, Reference, Overtemp
SUB
EPAD
REF
&
iC-NZN
RGND 11
MD 3
AGND 14
CIS 15
CI 16
LDK 13
IMON 4
LDA 17
RVDD 12
C5
10nF
1
2
C
1
N-Type
M-Type
(default)
3
3
P-Type
ACC
2
L
R
10K
P1
R1
5.1K
2
3
LDC MDA
LDA
(default)
ACC APC
D1
JP1 1
R6
opt
JP2
CIS
C6
opt
CI
C8
opt
R7
opt
(default)
IMON
JP3
R5
opt
N
2
1
2
1
3
3
LDC MDA
LDA
LDC
LDAMDC
M D2
P
C3
100nF
opt
C4
MD
GND
LDK
LDA
N-TYPE LASER DIODE DRIVER
GND2
NERR
CID
TTL
EN
JP10
LVDS
9 VSY
VSY
10 SYN
2 AVG
AVG
EP
3
JP7
ON
20 REGE
C7
100nF
JP6
Cext
22 NSLP
R2
2.74k
JP4
ILIM
OFF
REGE
JP5
VSY
NSLP
2
1
R3
1k
D3
RD
SYN
C2
opt
3
C1
100nF
VDD
iC-NZN
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Rev B2, Page 15/17
EVALUATION BOARD
iC-NZN comes with an evaluation board for test purpose. Figures 10 and 11 show both the schematic and the
component side of the evaluation board.
Figure 10: Schematic of the evaluation board
iC-NZN
N-TYPE LASER DIODE DRIVER
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Rev B2, Page 16/17
Figure 11: Evaluation board (component side)
iC-Haus expressly reserves the right to change its products and/or specifications. An info letter gives details as to any amendments and additions made to the
relevant current specifications on our internet website www.ichaus.de/infoletter; this letter is generated automatically and shall be sent to registered users by
email.
Copying – even as an excerpt – is only permitted with iC-Haus’ approval in writing and precise reference to source.
iC-Haus does not warrant the accuracy, completeness or timeliness of the specification and does not assume liability for any errors or omissions in these
materials.
The data specified is intended solely for the purpose of product description. No representations or warranties, either express or implied, of merchantability, fitness
for a particular purpose or of any other nature are made hereunder with respect to information/specification or the products to which information refers and no
guarantee with respect to compliance to the intended use is given. In particular, this also applies to the stated possible applications or areas of applications of
the product.
iC-Haus conveys no patent, copyright, mask work right or other trade mark right to this product. iC-Haus assumes no liability for any patent and/or other trade
mark rights of a third party resulting from processing or handling of the product and/or any other use of the product.
iC-NZN
N-TYPE LASER DIODE DRIVER
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Rev B2, Page 17/17
ORDERING INFORMATION
Type
Package
Order Designation
iC-NZN
QFN24 4 mm x 4 mm
Evaluation Board
iC-NZN QFN24
iC-NZN EVAL NZN1D
For technical support, information about prices and terms of delivery please contact:
iC-Haus GmbH
Am Kuemmerling 18
D-55294 Bodenheim
GERMANY
Tel.: +49 (61 35) 92 92-0
Fax: +49 (61 35) 92 92-192
Web: http://www.ichaus.com
E-Mail: [email protected]
Appointed local distributors: http://www.ichaus.com/sales_partners