IC-HTP Datasheet, PDF (37/51 Pages) IC-Haus GmbH – DUAL CW P-TYPE LASER DIODE DRIVER

iC-HTP
DUAL CW P-TYPE
LASER
DIODE
DRIVER
preliminary
Rev B1, Page 37/51
TEMPERATURE MONITOR AND PROTECTION
iC-HTP includes an 8 bit temperature monitor that al-
lows to measure the internal chip temperature going
from -40 °C to 125 °C. The resolution is 1 °C/LSB. The
internal temperature can be obtained by reading TEMP
register. The TEMP register is a read-only register.
TEMP
Addr. 0x02; bit 7:0
R
0x00
Minimum temperature
...
0xFF
Maximum temperature
Table 76: Chip temperature
Absolute read values may differ from one chip to an-
other. An individual initial calibration of the temper-
ature monitor is recommended. The TEMP register
must be read at a known temperature. Using the reso-
lution value of 1 °C/LSB, the internal temperature can
be calculated.
The temperature monitor can be used to compensate
temperature effects on the laser diode. The microcon-
troller can use a laser diode characteristic formula or a
look-up table combined with the temperature value mea-
sured through TEMP register. The reference voltage
can be configured accordingly in order to compensate
temperature effects.
iC-HTP is protected against overtemperature. In iC-WK
mode, if the internal temperature value exceeds the
overtemperature threshold an OVT error event will be
triggered and signaled through pin NCHK. Both laser
channels will be disabled. Pin NCHK will keep signaling
the error although the internal temperature goes down
to a safe value below the overtemperature threshold
value. If the temperature has exceeded the overtem-
perature threshold value, pins EC1 and EC2 have to be
pulled lo in order to stop signaling the error. Setting pin
ECx back hi will re-enable the corresponding channel.
In microcontroller mode, if the internal temperature
exceeds a safety value an overtemperature error bit
(OVT) will be set to 1. If OVT = 1, both channels will be
disabled and the error event will be signaled through
NCHK pin. If the internal temperature goes down to a
safe value below the overtemperature threshold value,
OVT will remain at value 1. Reading the OVT bit stop
signaling error through pin NCHK. Reading OVT bit will
set it back to 0. Setting ECx pin lo and then back hi will
allow re-enabling the corresponding channel.
The overtemperature threshold value can not be config-
ured.
OVT
0
1
Addr. 0x00; bit 3
R
No overtemperature event has occurred since last
read
Overtemperature event has occurred. Cleared on
read
Table 77: Overtemperature
In microcontroller mode it is possible to simulate an
overtemperature event using SOVT bit. Setting SOVT
to 1, the overtemperature error flag OVT will be set to
1. iC-HTP will remain in error state until SOVT is set
back to 0.
SOVT
0
1
Addr. 0x1D; bit 4
No overtemperature event is simulated
Overtemperature event simulated
R/W 0
Table 78: Simulate overtemperature