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IC-NZ 参数 Datasheet PDF下载

IC-NZ图片预览
型号: IC-NZ
PDF下载: 下载PDF文件 查看货源
内容描述: 故障保护激光二极管驱动器 [FAIL-SAFE LASER DIODE DRIVER]
分类和应用: 驱动器二极管激光二极管
文件页数/大小: 20 页 / 509 K
品牌: ICHAUS [ IC-HAUS GMBH ]
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iC-NZ  
FAIL-SAFE LASER DIODE DRIVER  
Rev B2, Page 10/20  
1. Enabling the system  
Possible sources of error  
Before iC-NZ is put into operation for the first time the  
external circuitry should be checked for the following  
(see block diagram):  
• V(NERR) remains at low:  
Check the current in NERR. Is the impedance  
of the pull-up resistor too high?  
Too high a current is flowing through pin NERR:  
An error has occurred during the device self-test.  
Check the following:  
• Resistor RSMD should be of low impedance. It may  
not, however, be lower than 250 , otherwise the in-  
ternal iC check will generate an error message.  
Is ENCAL lo?  
Is RSMD of too low an impedance? RSMD  
may not be lower than 250 .  
Is pin SMD open or has it directly short-  
circuited with VCC?  
Is there a direct connection between pin LDK  
and ground?  
• The resistors at pins RMDL, RMDM and RMDH  
should be of high impedance (low output).  
• Inputs LENL, LENM and LENH should be switched  
to low (the driver stages switched off).  
Is there a low-impedance connection between  
pin LDA and ground?  
Have all CIx capacitors (x: L, M, H) been prop-  
erly soldered and placed close to the iC?  
Is VCC properly back upped?  
So that iC-NZ can be switched on pin EN must be  
set to high and pin ENCAL to low. A current in the  
milliampere range (Electrical Characteristics No. 501)  
now flows into pin NERR. This indicates that the de-  
vice is now in its start-up phase. The voltage at pin  
RSI is set to 0.5 V and capacitor CLDA charged at pin  
LDA. Once voltage V(LDA) has reached its final value  
the control unit and safety monitor diode are checked,  
if the latter is in use (see also Operation without a  
second monitor diode). Following this check the cur-  
rent into pin NERR is lowered (Electrical Characteris-  
tics No. 502). The residual current still remaining (ca.  
500 µA) indicates that the control unit is not yet in oper-  
ation (N-type: V(MDL) < 0.5 V, P-type: VDD – V(MDL)  
< 0.5 V). The entire process is described in Figure 6.  
2. Calibrating the low and middle channels  
So that the optical power can be regulated pin REGEN  
must be set to high. The level at pin ENCAL is of no  
consequence when setting the low and middle chan-  
nels.  
Setting the low output level  
Pin LENL is first switched from low to high. The in-  
tegration capacitor at CIL is then charged. Until the  
control unit has settled a small amount of current flows  
in pin NERR. Following this the voltage at pin MDL is  
0.5 V for an N-type diode and VDD – 0.5 V for a P-type  
diode. The required optical power can now be set at  
resistor RML.  
V(EN)  
V(LDA)  
VCHK  
Demo board  
By way of example, three output levels of 1 mW, 3 mW  
and 5 mW are to be set. With an optical power of 1 mW  
laser diode HL6339G has a typical monitor current (IM)  
of 15 µA. The following value is then obtained for the  
resistor at pin MDL (RMLn = PML + RML):  
V(SMD)  
VREF  
V(MDL)  
V(NERR)  
V(MDL) 0.5V  
RMLn =  
=
= 33.34kΩ  
IM  
15µA  
Figure 6: Signal pattern when the system is enabled  
Setting the middle channel  
Pin LENL must remain at high and LENM be switched  
from low to high. Following the settling of the control  
Demo board  
Before the demo board is put into operation trimmers unit at CIM (N-type: V(MDL) < 0.5 V; P-type: VDD –  
PSMDL, PML, PMM and PMH should be set to the left V(MDL) < 0.5 V) the required optical power can be set  
and trimmer PSMDH to its centre setting.  
at resistor RMM.