IC-HTP Datasheet, PDF (33/51 Pages) IC-Haus GmbH – DUAL CW P-TYPE LASER DIODE DRIVER

iC-HTP
DUAL CW P-TYPE
LASER
DIODE
DRIVER
preliminary
Rev B1, Page 33/51
The value in RDCO register needed in order to have
the desired output voltage can be calculated using the
following formula:
RDCO = = = ^{Idco IR2−IR1}
2uA
2uA
0.5
6.7k
−
Vout−0.5
100k
2uA
The resulting value will vary slightly depending on the
tolerances of the selected resistors and DCO current.
The voltage is reduced from 8 V (RDCO = 0) to 2.5 V,
when RDCO = 27.
DC/DC step up operation: regulation at voltages
higher than power supply
A practical application of the present case is the control
of blue lasers. This type of laser present a forward
voltage around 5 V, which demands an LDA voltage
of about 6 V. If the system is supplied with a 3 V LiPo
battery, it is necessary to use a the DC/DC in order
to step up and drive the laser diode and driver with a
sufficient voltage. Figure 19 shows this application:
VB
3V
CVB
1μF
CVDD
1μF
GND
C3
2x10μF
C1
0.1μF
L1
1μH
L1
TPS63060
VIN
EN
VAUX
L2
VOUT
FB
PS/SYNC
GND
PG
PGND
6V
R1
100k
R3
1MEG
R2
6.7k
20μA
DUAL CW LASER DIODE DRIVER
VDD REGULATOR
VB
- ^REF
VDD
+
NCHK
EMC
NCS/A1
MOSI/A0
SCLK/SCL
MISO/SDA
INS/WKR
NSTBY
EC1
EC2
T.PAD
GND
VB UNDERVOLTAGE
VDD UNDERVOLTAGE
CFGTIMO
Check
PODO
OVC
MEMERR
WATCHDOG
OVT
IO DRIVERS
TEMPERATURE
MONITOR 8 Bit
RAM
INTEGRITY
CHECK
0x10 0x30
0x1F 0x3F
RAM
REGISTERS
0x13 REF1(9:8)
0x14 REF1(7:0)
0x11 ILIM1(7:0)
WATCHDOG
TIMER
OSCILLATOR
0x12 RMD1(7:0)
SPI/I2C
SLAVE
LASER
CONTROL
0x03
0x04
ADC1(9:8)
ADC1(7:0)
0x10 ADCC1(2:0)
0x16 ILIM2(7:0)
0x18
0x19
REF2(9:8)
REF2(7:0)
0x05
0x06
ADC2(9:8)
ADC2(7:0)
0x17 RMD2(7:0)
0x02 TEMP(7:0)
10 Bit
D
A
+
-
CI
DCO
ECIE1
VBL1
CIH1
CI1
LDA1
8 Bit
D
A
OVC
VDD
ACC
MRH1
EM C
8 Bit
DISP1
R
0
255
10 Bit
A
D
LDA1
VBL1
VB
A DM DK 1
LASER CHANNEL 1 ^ADFNS1
x1
x2
Signal Level Converter
10 Bit
A
D
LDA2
VBL2
VDD
ADM DK2
APC
MDK1
VBL2
CIH2
CI2
LDA2
MRH2
LASER CHANNEL 2
MDK2
C2
3x22μF
P
Figure 19: Regulation at voltage greater than power supply
Setting register RDCO to 10 it delivers 20 µA and 6 V
are obtained at Vout.
Extension of system working voltage range
iC-HTP must be supplied by a voltage within the thresh-
old values of 2.8 V and 11 V. It is possible to control the
DC/DC output in a voltage range of 2.5 V - 12 V if the
DC/DC converter, controlled by DCO output signal, is
included in the system, as it is shown in figure 20: