确保打印头电源动态输出电压的参考设计,Reference D

Reference Design Ensures Dynamic Output Voltages for a Print-Head Power Supply

Abstract: This arTIcle describes some important design parameters for managing power in a printer. The reference design shows how to use a MAX15005 power-supply controller as a SEPIC circuit to obtain a high-variable output voltage for a print-head power supply. The circuit schemaTIcs, bill of materials (BOM), test measurements, and results are provided.

IntroducTIonThis reference design is a soluTIon for obtaining a high-variable output voltage for a printer-head power supply. The design includes the complete circuit schematic, bill of materials (BOM), efficiency measurements, and test results.

Some Basics of Printer DesignThe increasing speed of printers has led to higher power dissipation and higher temperatures in the print head. If the temperature in the printer becomes sufficiently high, the ink will smudge. When the temperature is low, the ink becomes illegible. Consequently, thermal management of the print head is critical to ensuring high-quality printing. A microcontroller is required to adjust the printing speed and thus maintain the operating temperature between these two limits. The printer's motor speed is adjusted by applying variable DC voltages.

Reference Design OverviewThis reference design features the MAX15005 power-supply controller and provides a dynamic DC voltage (up to 45V) to the printer's motor. The output voltage can be varied by applying a PWM signal from the microcontroller to the SS pin of MAX15005 through a RC filter. During startup, the printer's motor draws more current to magnetize its field. The MAX15005A is particularly useful now because it offers hiccup-mode protection. The MAX15005 can enter hiccup mode and supply power at a reduced rate to protect all circuit components. Once magnetization is over, the motor draws normal current and the converter operates in regulation mode.

Specifications and Design SetupThe reference design meets the following specifications:

• Input voltage: 32V to 45V
• Output voltage: 25V to 45V (varied externally from the microcontroller)
• Output current: 0 to 2A
• Output ripple: ±0.5V
• Input ripple: ±100mV
• Efficiency: > 93% with full load
• Switching frequency: 400kHz

The schematic for the above specifications is shown in Figure 1. In this design the MAX15005 is used in the SEPIC configuration when output is below or above the input voltage.


Figure 1. Schematic of the MAX15005A SEPIC converter for FSW = 400kHz.

The bill of materials (BOM) for this reference design is given in Table 1.

Table 1. BOM for Print-Head Power Supply Designator Description Comment Footprint Manufacturer Quantity Value C1, C6 Electrolytic capacitor EEVFK1H331Q 12.5mm x 13.5mm Panasonic® 2 330µF/50V C2, C4, C5, C7, C8, C9 Capacitor GRM32ER71H475KA88L 1210 Murata® 6 4.7µF/50V C3 Capacitor GRM31MR71H105KA88L 1206 Murata 1 1µF/50V C10, C12 Capacitor GRM188R71C105KA12D 603 Murata 2 1µF/16V C11 Capacitor GRM1885C1H181JA01D 603 Murata 1 180pF C13 Capacitor GRM1885C1H101JA01D 603 Murata 1 100pF C14 Capacitor GRM1885C1H271JA01D 603 Murata 1 270pF C15 Capacitor GRM188R71E474KA12D 603 Murata 1 0.47µF C16 Capacitor GRM188R71H102KA01D 603 Murata 1 1000pF C17 Capacitor GRM188R71H104KA93D 603 Murata 1 100nF C18 Capacitor GRM1885C1H331JA01D 603 Murata 1 330pF D1 Zener diode MMSZ10T1 SOD-123 ON Semiconductor® 1 10V, 500mW Zener D2 Schottky rectifier FEPB6BT D²PAK Vishay® 1 100V/6A Schottky L1, L2 Inductor D05040H-683MLD D05040 Coil Craft 2 68µH Q1, Q2 n-Channel MOSFET HUF76609D3S DPAK Fairchild Semiconductor® 2 100V/10A MOSFET R1 Resistor SMD 1% Resistor 603 Vishay 1 475kΩ R2 Resistor SMD 1% Resistor 603 Vishay 1 20kΩ R3 Resistor SMD 1% Resistor 603 Vishay 1 100kΩ R4 Resistor SMD 1% Resistor 603 Vishay 1 2.61kΩ R5 Resistor SMD 1% Resistor 603 Vishay 1 2.2Ω R6 Resistor SMD 1% Resistor 603 Vishay 1 1kΩ R7 Resistor SMD 1% Resistor 603 Vishay 1 7.87kΩ R8, R9 Resistor LRCLR201001R075F 2010 IRC 2 0.075Ω/1W R10 Resistor SMD 1% Resistor 603 Vishay 1 774.8Ω R11 Resistor SMD 1% Resistor 603 Vishay 1 15kΩ R12 Resistor SMD 1% Resistor 603 Vishay 1 5kΩ R13 Resistor ERJ-1TYJ5R0 2512 Panasonic 1 5Ω/1W R14 Resistor SMD 1% Resistor 603 Vishay 1 10Ω U1 PWM controller MAX15005A TSSOP-16-EP Maxim® 1 –
Efficiency PlotsEfficiency VS load-current plots are given in Figures 2 and 3. The input voltage was VOUT = 25V in Figure 2 and VOUT = 45V in Figure 3.


Figure 2. Load current vs. converter efficiency for VOUT = 25V.


Figure 3. Load current vs. converter efficiency for VOUT = 45V.

Experimental ResultsConverter output voltage and load current are shown in following figures for different input excitations.

Test conditions: VIN = 45V and VOUT = 45V.

Ch1: output voltage; Ch2: input voltage; Ch3: MOSFET drain voltage; Ch4: output current.


Test conditions: VIN = 32V and VOUT = 45V.

Ch1: output voltage; Ch2: input voltage; Ch3: MOSFET gate voltage; Ch4: output current.


Test conditions: VIN = 45V and VOUT = 45V.

Ch1: output voltage; Ch2: input voltage; Ch3: MOSFET gate voltage; Ch4: output current.


Test conditions: VIN= 45V and VOUT= 25V.

Ch1: output voltage; Ch2: input voltage; Ch3: MOSFET gate voltage; Ch4: output current.

Fairchild is a registered trademark of Fairchild Semiconductor Corporation.
Maxim is a registered trademark of Maxim Integrated Products, Inc.
Murata is a registered trademark of Murata Manufacturing Co., Ltd.
On Semiconductor is a registered service mark of Semiconductor Components Industries, LLC.
Panasonic is a registered trademark of Matsushita Electric Industrial Co., Ltd.
Vishay is a registered trademark of Vishay Intertechnology, Inc.