Reference design to ensure dynamic output voltage of printhead power supply

introduction

This reference design provides an adjustable high-voltage output to power the printhead. The design includes complete schematics, bill of materials (BOM), efficiency measurements and test results.

Basic Printer Design Considerations

The increase in printer speed increases the power consumed by the print head and increases the temperature of the print head. If the printer temperature is too high, the ink will be easily contaminated; if the temperature is too low, the ink will become blurry. Therefore, in order to obtain high print quality, thermal management of the print head is very critical. A microcontroller is usually required to adjust the printing speed to ensure that the operating temperature is between two temperature thresholds, and the speed of the printer motor is adjusted by the variable DC voltage acting on the motor.

Introduction to reference designs

The reference design uses the MAX15005 power supply controller, which can provide dynamically changing DC voltage (up to 45V) to the printer motor. The PWM output generated by the microcontroller is RC filtered and connected to the SS pin of the MAX15005. The output voltage can be adjusted by changing the PWM signal. When the printer starts up, the motor requires a large excitation current, and the MAX15005 has hiccup protection, which is ideal in this application. The MAX15005 can enter hiccup mode, limiting the power output to a reduced rate to protect all circuit components. After excitation ends, the motor will draw regular operating current and the converter enters normal operating mode.

Specifications and Design Circuit

The reference design meets the following specifications:

• Input voltage: 32V to 45V

• Output voltage: 25V to 45V (externally adjusted via microcontroller)

• Output current: 0 to 2A

• Output ripple: ±0.5V

• Input ripple: ±100mV

• Efficiency: >93% (at full load)

• Switching frequency: 400kHz