ST AN2122 Application note

	AN2122
®	APPLICATION NOTE

TV Hardware Design Rules:

PCB Compatibility with ST92196/186

Introduction

The purpose of this application note is to:

1.	Describe how to design a printed circuit board (PCB) with optimum performance and
	compatiblity between ST92E196 or ST92T196 (SDIP56 package), and ST92186 (SDIP32 and
	SDIP42 packages) microcontrollers.
2.	Describe the external filters and components needed for the ST92186 family of
	microcontrollers (MCU).	Product(s)
3.
	Provide advice on how to develop applications for ST92186 microcontrollers in SDIP32 or

SDIP42 packages using ST92E196 / ST92T196 devices.

-Obsolete

Product(s) Obsolete

AN2122/0205

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						AN2122
		Table of Contents
	Introduction						1
	Chapter 1 Ground Plane and Power Supply Lines . . . . . . . . .				. . . . . . . . . . . . . . . . .	. . . . .	. 3
1.1		Ground Plane .......................................................................................................................					3
1.2		Power Supply Lines ..............................................................................................................					3
1.2.1		Digital and Analog Power Supplies ......................................................................................................................					3
	Chapter 2	Tied Pins . . . . . . . . . . . . . .	. .	. . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . . . . .	. . . . .	. 5
2.1		Unused Pins ........................................................................................................................					5
2.2		I²C Pull-up Resistors .............................................................................................................			Product(s)		5
	Chapter 3	External Components					6
			. . .	. . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . . . . .	. . . . .
3.1		PLL .......................................................................................................................................					6
3.2		Crystal Oscillator ..................................................................................................................		Obsolete			6
	Chapter 4	Reference Layout					8
			. . .	. . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . . . . .	. . . . .
	Chapter 5 CVBS and HSYNC Signals . .			. . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . . . . .	. . . . .	10
5.1		CVBS Signal on ST92196 ..................................................................................................	-				10
5.2		HSYNC Signal					10
		Product(s)					10
	Chapter 6 PCB Compatibility between ST92196 and ST92186 MCUs . . . . . . . . . .					. . . . .
6.1		SDIP56/42 Mounting Instructions .......................................................................................					10
6.2		SDIP56/32 Mounting instructions .......................................................................................					11
Obsolete							12
	Chapter 7 Developing Applications for ST92186 using ST92x196 . . . . . . . . . . . . .					. . . . .

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● one Analog power supply line for VDDA pin.

1.2.1 Digital and Analog Power Supplies

AN2122

Ground Plane and Power Supply Lines

1 Ground Plane and Power Supply Lines

1.1Ground Plane

A local ground plane must be placed under the entire area of the ST92196/186 component and connected using the widest possible line to the PCB ground as shown in Figure 1, Figure 2 and Figure 3. This plane and its associated lines are dedicated to the ST92196/186 microcontroller. It is strongly recommended not to connect any other lines from components not already connected to the ST92196/186 to this plane. This is to avoid adding any impedance or analog disturbances which could cause the IC ground to float.

All ground pins for the ST92196/186 (VSS1 and VSS2) and external components (PLL, oscillator, etc.) must be connected to this ground plane.

Ground pins VSS1 and VSS2 must be connected as close as possible to each other on the printed circuit board.

1.2Power Supply Lines

Two different power supply lines are required for the ST92196/186:Product(s) one Digital power supply line (pins VDD1 and VDD2 (only on ST92196)).

Those 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, Figure 2 and Figure 3. Decoupling capacitors must be set as close as possible to the IC supply pins.

● Obsolete

An inductive component, with a low serial resistance, must be placed close to the decoupling capacitors to provide high impedance and-to improve noise filtering. This component is required on both:

●the VDDA power supply pin to prevent noise disturbances from the PCB power source,

●the VDD power supply pins in order to prevent disturbances being sent towards the PCB power source and other ICs.

The VDD andProduct(s)VDDA lines must be dedicated to the ST92196/186. Any other connections between other IC supply pins and VDD and/or VDDA lines are not recommended. This does

Obsoletenot include MCU Reset circuitry. (See Figure 1, Figure 2 and Figure 3).

All other components must be connected to the +5V power supply and not to the ST92196/186 VDD or VDDA lines.

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Ground Plane and Power Supply Lines

AN2122

Figure 1: Ground Plane and Power Supply Lines for ST92196

	GND	+5V
			Other connections possible
			VDD
			10uH
			VDDA (Other connections not recommended)
			10uH
				10uF	10uF
				+		+
				100nF	100nF
ST92196		56 55	41	32	30	29
Device	VPPTEST0		VSS2	VDDA VSS1 VDD1

1

VDD2

Product(s)

16

100nF

GND Plane

10u

F

(under device)

+

Obsolete

Note: For ST92196 family devices, there is an internal connection between the VDD1 and VDD2 pins.

Nevertheless, for better current distribution, it is highly advised to externally connect both VDD1 and

VDD2 pins to digital +5V power supply.

Figure 2: Ground Plane and-Power Supply Lines for ST92186 SDIP42 Packages

Product(s)

+5V

GND

VDD

Other connections possible

Obsolete Device

100nF

100nF

10uH

VDDA (Other connections not recommended)

10uH

10uF

10uF

ST92186 SDIP42

+

+

	42	34	25	23	22
		VSS2	VDDA VSS1 VDD1
GND Plane
(under device)	TEST0
	1 2

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Tied Pins

2

AN2122

Tied Pins

Figure 3: Ground Plane and Power Supply Lines for ST92186 SDIP32 Package

		GND +5V
						Other connections possible
			VDD
			10uH
			VDDA (Other connections not recommended)
			10uH
			10uF		10uF
			+			+
	ST92186 SDIP32		100nF		100nF
	Device
		32	20	18		17
	GND Plane		VDDA VSS1 VDD1
		TEST0
	(under device)	1 2

Product(s)

2.1Unused Pins

		Table 1: Rules for Connecting Unused Pins
				Obsolete
		Pin Name	-		Rule
		TEST0			Tie to VDD
		VPP (only on ST92196)			Tie to VDD
Note:	All unused I/O pins must be initialized as Bidirectional Weak Pull Up (default state after reset - set
		Product(s)
	by hardware), associated with a ‘0’ in their data register. This prevents uncontrolled levels and
	reduces power consumption.
2.2	I²C Pull-up Resistors
	All the pull-up resistors (1.7 kΩ)of the ST92196/186 I²C line must be connected to the +5V power
Obsolete
	supply line (and not to the VDDA or VDD pins).

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