Part # Application Note Television ST92195 ST92R195C ST92T195 8-bit MCU for TV AN1862 datasheet

Part Manufacturer: ST Microelectronics

ST Microelectronics

Part Description: TV Chassis Hardware Design Rules for ST92x195 Microcontrollers

Part Details:

AN1862 APPLICATION NOTE TV CHASSIS HARDWARE DESIGN RULES FOR ST92X195 MICROCONTROLLERS 1 INTRODUCTIONThe aim of this note is to present the different rules required to obtain the optimum perfor-mance from any of the ST92x195 microcontroller devices when designing a TV chassis. The following recommendations apply to all ST92x195 family devices. 2 GROUND PLANE & POWER SUPPLY LINES 2.1 Ground Plane A local ground plane must be placed under the entire area of the ST92x195 component andconnected using the widest possible line to the PCB ground as shown in Figure 1 This planeand its associated line are dedicated to the ST92x195. It is strongly recommended not to con-nect any other lines from components not already connected to the ST92x195 to this plane.This is to avoid adding any impedance or analog disturbance which could cause the IC groundto float. All ground pins for the ST92x195 (GND, AGND) and external components (PLL, crystal oscil-lator, etc....) must be connected to this ground plane. 2.2 Power Supply Lines 2.2.1 Digital Power Supply and Analog Power Supply Two different power supply lines are required for the ST92x195: ­ one Analog power supply line (AVDD), which groups the AVDD1, AVDD2 and AVDD3 pins. ­ one Digital power supply line (VDD). These power supply levels must be within the +5V ±10% range with |VDD-AVDD| < 600 mV. The supply pins must be decoupled as shown in Figure 1. Decoupling capacitors must be setas close as possible to the IC supply pins. An inductive component, with a low serial resistance, must be placed close to the decouplingcapacitors to provide a high impedance and to improve noise filtering. This component is re-quired on both: ­ AVDD power supply pins to avoid noise disturbances from the PCB power source. ­ VDD power supply pins in order to prevent disturbances from being sent towards the PCB power source and other ICs. Rev. 2 AN1862/0704 1/14 AN1862 - APPLICATION NOTE The VDD and AVDD lines must be dedicated to the ST92x195. Any other connectionsbetween other IC supply pins and VDD and/or AVDD lines are not recommended. Thisdoes not include MCU Reset circuitry. (See Figure 1). All other components must be connected to the +5V power supply and not to the ST92x195VDD or AVDD lines. 2.2.2 External Memory Power Supply for ROMless Device Only (ST92R195) An additional supply pin (VDDM) is present on the ST92R195 package (ROMless device). Thispin is used to supply the ST92R195 pads which are toggled during external memory access. A dedicated external memory power supply line is required (not connected to any other powersupply line). The VDDM power supply pin must be decoupled, as with the other power supplypins. Refer to Section 2.2.1. Figure 1. Ground Plane and Power Supply Lines GND +5V Other connections possible AVDD (Other connections not recommended) 10 µH 10uF 10 µH + 100nF 100nF 56 39 37 36 35 31 AVDD1 GNDAGND AVDD2 See note below. VDD AVDD3 1 21 25

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Application Note Television ST92195 ST92R195C ST92T195 8-bit MCU for TV AN1862.pdf Datasheet