New Products MB88R157A Spread Spectrum Clock Generator Capable of Freely Setting the Output Clock Frequency MB88R157A We have added MB88R157A with built-in FRAM to our lineup of spread spectrum clock generator (SSCG) products that are effective measures against EMI noise. The output frequency can be set at the user ,s discretion between 1MHz and 134MHz for the input frequency of 10MHz to 50MHz. * SSCG: Spread Spectrum Clock Generator * FRAM: Ferroelectric Random Access Memory (nonvolatile memory utilizing ferroelectric) Introduction In recent years, electronic devices have adopted higher performance (speed) and smaller sizes (higher density) and, as a result, their noise emission has been growing steadily. Noise problems are often the final challenge to overcome prior to the mass production of a product following the trial and error of product design and evaluation. As electrical signals (the clock frequency that operates a system) and noise are intrinsically the same, it is important to take noise countermeasures into consideration at the board system design stage of a product. This product not only simplifies noise countermeasures but also dramatically saves on the time spent developing noise countermeasures later, thereby minimizing the cost and evaluation time. Our SSCG controls the clock frequency in an ideal fashion by applying our proprietary digitally controlled (current D/A converter) “frequency modulation technology” and “composite modulation technology.” It achieves − 19dB (measurement value by FUJITSU, 1.5％ modulation degree used), which corresponds Photo 1 External View What is SSCG? SSCG is a product that reduces the emission of unnecessary noise by slightly fluctuating (modulating) the clock frequency that is the source of noise in a range that does not affect the system operation. 2010 No.3 FIND Vol.28 New Products MB88R157A to 1/100 in power. The noise emitted from electrical devices (EMI) is regulated by various international standards, including CISPR, as it has negative effects (e.g., it can cause other electronic devices to malfunction). Our SSCG digitally controls the clock frequency that is the source of EMI noise. In this way, it is possible to avoid unexpected noise generation and to easily satisfy international standards. Figure 1 presents a diagram of the spread spectrum, and Figure 2 the EMI reduction effect on an actual board. Product Features MB88R157A we have developed is not dependent on the input frequency and the output frequency can be set at the user’s discretion. It is thus possible to generate a unique clock frequency within digital devices such as TVs, DVD players and audio devices that can simultaneously be utilized as a noise countermeasure. The major advantages of SSCG include the following: Our proprietary digital control technology delivers a high noise reduction effect; it is possible to evaluate the actual noise with the product built onto the board. ● Figure 1 Spread Spectrum -17.451dBm 40.11MHz -27.136dBm 39.39MHz −13dB Conventional method Our proprietary method Figure 2 EMI Reduction Effect in Actual Boards Electromagnetic field map −19dB Figure 3 Pin Assignments Large EMI reduction effect is facilitated depending on the degree of modulation Small XOUT XIN OE PEX MB88R157A （TOP VIEW） VSS Measurement range Modulation OFF 1.0% modulation NC VDD OUT 1.5% modulation 2010 No.3 FIND Vol.28 New Products MB88R157A A dramatic reduction in the number of conventional noise countermeasure parts, such as shields, beads and capacitors, can be realized. Time and man-hours can be reduced dramatically compared to conventional noise countermeasures that use parts (which require evaluation and measure/layout change/building and re-measurement). Figure 3 presents the pin assignments, Table 1 the pin functions and Table 2 the parameters that can be set through the program. ● ● Evaluation Board and FRAM Writing Environment For this product, we offer an evaluation board and writing environment with a built-in LSI to simplify single unit evaluation and property check. We also offer a GUI program to enable the simple calculation of the parameter data to be programmed as the FRAM writing environment. Figure 4 presents an example of a connection to a writing environment. Table 1 Pin Functions Pin code I/O 端子番号 Description of function XOUT O 1 Connection terminal for crystal oscillator OE I 2 Output enable terminal SP I/O 3 Serial program terminal VSS − 4 GND terminal OUT O 5 Clock output terminal VF I 6 Variable function terminal ＊M odulation enable, power down control, Hi or Low output can be set depending on the setting in the memory. VDD − 7 Power supply voltage terminal XIN I 8 Connection terminal/clock input for crystal oscillator Table 2 Main Setup Functions Functions set by the program Function details M/N/K divider parameter The multiplication rate for output clock frequency can be set. L divider parameter Modulation cycle can be set. Charge pump current/gain An optimal value can be set for PLL oscillation frequency. Modulation degree setting The degree of modulation can be selected in units of 0.25% from modulation off, ±0.25% to ±1.75% . OUT terminal level OUT terminal status can be set at L output or Hi-Z when OE terminal = L. Clock output drive capacity The drive capacity for OUT terminal can be selected (2 stages). XIN/XOUT terminal oscillation stability capacity value The built-in oscillation stability capacity can be set in units of 0.039pF from 5pF to 10pF each. SS/PLL mode Whether or not SS functions are used or the highly precise PLL mode is used can be selected. ※A PC GUI software program to calculate the optimal parameter values in the table is available. 2010 No.3 FIND Vol.28 New Products MB88R157A Lineup After adding this programmable product (single output) to the existing lineup of single output products, we will continue to expand the lineup in the future to address the needs of our customers. Figure 5 presents the lineup of our clock generator products. ✱ Figure 4 Connection Example to a Writing Environment GUI screen DC power supply 3.3V Crystal oscillator （10 to 50MHz） USB cable PC OE（SW1） Connection cable JP1 VDD SP（SW2） VSS VF（SW3） Writing tool I.S.P-310 MB88R157A evaluation board Figure 5 Product Lineup In mass production New product In development Multi-output product Programmable Output×6 Differential output Serial I/F program QFN-24-pin （W2.5mm×L3.5mm） Internal voltage 1.8V External voltage 2.6V Output×5 In planning MB88182 32.768kHz master oscillation MB8818× Output×3 （W2.5mm×L3.5mm） MB88185 Programmable Single output products TSSOP-8-pin （W4.4mm×L3.1mm） 3.3V±0.3V SOP-8 （W3.9mm×L5.05mm） 3.3V±0.3V MB88151A MB88152A MB88R157A Miniaturization Low voltage operation TSSOP-8-pin （W4.4mm×L3.1mm） 3.3V±0.3V SON-8-pin （W2.0mm×L2.0mm） 1.8V±0.15V MB88155 MB88163 MB88153A MB88154A 2010 No.3 FIND Vol.28