Evaluation Board For The Ad9834 Direct Digital Synthesizer

Description: This document outlines the design of a low-cost 90 W flyback switching power supply intended for use in a multi-sync color monitor. To reduce screen interference caused by switching noise, the power supply can be automatically synchronized to the fixed frequency of the horizontal scanning frequency (ranging from 15 to 32 kHz) of the color monitor. The power supply exhibits excellent line and load regulations. Additionally, a new universal input voltage adapter allows the power supply to function within two input voltage ranges: 90-130 Vac or 180-260 Vac. This design minimizes the ripple current requirement of the input bulk capacitors and reduces stress on the power switch. The design incorporates recently introduced components suitable for a cost-effective power supply. Key components include the state-of-the-art perforated emitter epi-collector bipolar power transistor MJE18004 and the opto-isolator MOC8102. Other components used are MC3423P, UC3842A (for MTP4N90), UC3843A (for MJE18004), TL431CLP, MCR102, MAC229A8, 2N3906, 1N4001, 1N5819, 1N5398, MUR140, MUR180, MBR160, 1N4735A (6.2 V), 1N4740A (10 V for MJE18004), 1N4747A (20 V for MTP4N90), 1N5953A (150 V, optional), and 1N5956A (200 V).

The flyback switching power supply is designed to deliver 90 W of power, specifically tailored for multi-sync color monitors. The synchronization feature at the horizontal scanning frequency is crucial for minimizing electromagnetic interference, which is a common issue in CRT monitors. The ability to operate at two distinct voltage ranges enhances the versatility of the power supply, accommodating various geographical power standards.

The use of the MJE18004 transistor, known for its high efficiency and improved thermal performance, alongside the MOC8102 opto-isolator, ensures reliable isolation and control of the switching process. The MC3423P and UC384x series provide advanced control capabilities, allowing for efficient regulation of output voltage and current, while maintaining low ripple levels.

The design's focus on minimizing ripple current is achieved through careful selection and sizing of the input bulk capacitors, which not only improves the overall efficiency but also enhances the longevity of the components by reducing thermal and electrical stress. The inclusion of various voltage regulation diodes, such as the 1N4735A, 1N4740A, and 1N5953A, provides additional protection against voltage spikes, contributing to the robustness of the power supply design.

Overall, this power supply design represents a significant advancement in cost-effective solutions for powering multi-sync color monitors, integrating modern components to achieve high performance and reliability within a compact form factor.This paper describes the design of a low ’cost 90 W flyback switching power supply for a multi ’sync color monitor. In order to minimize the screen interference from the switching noise, the power supply CAN be automatically synchronized at the fixed frequency of the horizontal scanning frequency (15 to 32 kHz) of the color monitor.

The line and load regulations of the power supply are excellent. Also, a new universal input ’voltage adaptor enables the power supply to operate at two input voltage ranges, 90 ’130 Vac or 180 ’260 Vac. It CAN minimize the ripple current requirement of the input bulk capacitors and the stresses on the power Switch The design demonstrates how to use recently introduced components in a low ’cost power supply.

The state ’of ’the ’art perforated emitter epi ’collector bipolar Power Transistor MJE18004 and opto ’isolator MOC8102 are utilized. MC3423P UC3842A (for MTP4N90) UC3843A (for MJE18004 MC3423P TL431CLP MOC8102 MTP4N90 MCR102 MAC229A8 MJE18004 2N3906 1N4001 1N5819 1N5398 MUR140 MUR180 MBR160 1N4735A 6.

2 V 1N4740A 10 V (for MJE18004 1N4747A 20 V (for MTP4N90) 1N5953A 150 V (optional) 1N5956A 200 V