ADI ADN8833ACBZ-R7

ADN8833 is a monolithic H-bridge TEC driver integrating 1 A power MOSFETs. It features a linear power stage (LDR output) and a PWM power stage (SW output). Based on the control voltage applied to the CONT input, the ADN8833 drives current through the TEC to bring the temperature of a laser diode or passive component connected to the TEC module to a programmed target temperature. The control voltage applied to the CONT input is generated by a DAC that closes the digital PID loop in the temperature control system.

An internal 2.5 V reference provides a 1% accurate output for biasing voltage divider networks to program the maximum TEC current and voltage limits in both heating and cooling modes. It can also serve as the reference voltage for the DAC and temperature sensing circuitry, including thermistor bridges and ADCs.

The ADN8833 controls an internal FET H-bridge. Current through the TEC can flow in the positive direction (cooling mode), drawing heat away from the object connected to the TEC, or in the negative direction (heating mode), pumping heat into the object connected to the TEC. The target temperature is measured by a thermal sensor connected to the TEC, and the measured temperature (voltage) is fed back to the ADC to close the digital thermal control loop for the TEC. For optimum overall stability, the thermal sensor should be mounted in close proximity to the TEC. In most laser diode modules, the TEC and NTC thermistor are already integrated within the same package to regulate the laser diode temperature.

The TEC is differentially driven in an H-bridge configuration. The ADN8833 drives its internal MOSFET transistors to supply TEC current. To further improve system power efficiency, one side of the H-bridge uses a PWM driver. Only a single inductor and capacitor are required to filter the switching frequency. The other side of the H-bridge uses a linear output, requiring no additional circuitry. This proprietary configuration enables the ADN8833 to achieve >90% efficiency. For most applications, a 1 μH inductor, a 10 μF capacitor, and a 2 MHz switching frequency maintain the worst-case output voltage ripple across the TEC to less than 1%.

• TEC temperature control
• Optical modules
• Fiber amplifiers
• Optical network systems
• Instruments requiring TEC temperature control