AN2014 datasheet(34/65 Pages) STMICROELECTRONICS

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Hardware considerations

AN2014

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DocID10701 Rev 10

4.3.3

Organization Select (ORG)

ORG is not a CMOS input. If left floating, it is interpreted internally as being High. It is

strongly recommended to connect it directly to the VCC or VSS pin of the device. Driving it

dynamically implies that application software can handle specific MICROWIRE dual

organization and switch from Single data byte management to word data management.

The input pin leakage is negligible, in standby mode, typically a few nA. The input schematic,

including the protection circuit, does not offer any open path to the VSS or VCC. (See

Figure 29)

Figure 29. Organization input ORG

1. The pull-up resistor is only active for a short period of time (right after the device selection) to latch the level

read on the ORG pin when it’s left floating.

4.3.4

Serial Data output (Q)

It is a push-pull tri-state output buffer. As the Serial Data Output is often in the High-

impedance state and connected to a Master input pin, it may be useful to connect a pull-up

resistor to set a default value (corresponding to the Ready state) on the bus and thus

prevent the Master input from toggling. Application designers must be aware that

connecting several devices on Serial Data Output (Q) increases the capacitive load of the

line. Access time of M93C ST EEPROM is tested with 100pF load (see Figure 25: Output

pin tri-state buffer)

4.3.5

Don’t use (DU)

Pin does not contribute to the normal operation of the device. It is reserved for use by

STMicroelectronics during test sequences. The pin may be left unconnected or may be

connected to VCC or VSS. No other connection is allowed. Direct connection of DU to VSS is

recommended for the lowest standby power consumption mode.

Ai11089

ORG pin

ESD/EOS Protection

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AN2014 Datenblatt(PDF) 34 Page - STMicroelectronics