AMC7820_15 Datasheet, PDF (18/32 Pages) Texas Instruments – ANALOG MONITORING AND CONTROL

SW2_DISABLE
Unipolar_Bipolar_CTR
2.5V
SOFT_START_CTR
DAC0
(12 Bits)
R
R
OPA7
DAC0_OUT 6
DAC0_OUT_SET 7
OPA7_IN+ 48
OPA7_OUT 47
EN
Bip
Uni _SW3
SW2_OUT 1
SW2
OPA7_IN– 46
To TEC
DRIVER
C
R
ON _SW4
OFF
TEC
Soft-Start
Controller
SOFT_START_ENABLE
OPA9
2
T_SENSE_Voltage
FIGURE 6. Soft Start Function.
APPLICATION
The AMC7820 can be used to control one CW type laser
diode (or pump laser diode) current and one TEC cooler, two
TEC coolers, or two laser diodes. See Figure 7 for a typical
application to control one pump laser diode and one TEC. A
similar approach can be used to control other CW type laser
diodes.
TEC CONTROL
The TEC control loop is made up of the thermistor current
source, a unity-gain buffer, a thermostat DAC (DAC0), the
TEC integrator (OPA7), the internal TEC SOFT_START_
CONTROLLER, an external thermistor, and an external
TEC Power Current Driver.
The external thermistor is driven by the current from the
thermistor current source. The voltage across the thermistor
represents the actual TEC temperature, and is fed into the
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AMC7820
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SBAS231B