INCLUDES: Tested Circuit Schematic BOM Description Test Data
Reference Design Ensures Dynamic Output Voltages for a Print-Head Power Supply
By:
Surya Prakash
Mar 19, 2009
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.
Introduction
This 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 Design
The 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 Overview
This 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 Setup
The 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 Plots
Efficiency 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 Results
Converter output voltage and load current are shown in following figures for different input excitations.
Fairchild is a trademark of Fairchild Semiconductor Corporation. Maxim is a registered trademark of Maxim Integrated Products, Inc. ON Semiconductor is a registered trademark and registered service mark of Semiconductor Components Industries, L.L.C. Panasonic is a registered trademark and registered service mark of Panasonic Corporation. Vishay is a registered trademark of Vishay Intertechnology, Inc.
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