ST72321R7-Auto datasheet(225/243 Pages) STMICROELECTRONICS

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ST72321xx-Auto

Device configuration and ordering information

Doc ID 13829 Rev 1

225/243

Note:

On the chip, each I/O port has up to eight pads. Pads that are not bonded to external pins

are in input pull-up configuration after reset. The configuration of these pads must be kept at

reset state to avoid added current consumption.

Table 142.

Option byte 1 bit description

Bit

Name

Function

OPT7

PKG1

Package selection bit 1

This option bit, with the PKG0 bit, selects the package (see Table 143:

Package selection (OPT7)).

OPT6

RSTC

RESET clock cycle selection

This option bit selects the number of CPU cycles applied during the

RESET phase and when exiting Halt mode. For resonator oscillators,

it is advised to select 4096 due to the long crystal stabilization time.

0: Reset phase with 4096 CPU cycles

1: Reset phase with 256 CPU cycles

OPT5:4

OSCTYPE[1:0]

Oscillator type

These option bits select the ST7 main clock source type.

00: Clock source = Resonator oscillator

01: Reserved

10: Clock source = Internal RC oscillator

11: Clock source = External source

OPT3:1 OSCRANGE[2:0]

Oscillator range

When the resonator oscillator type is selected, these option bits select

the resonator oscillator current source corresponding to the frequency

range of the resonator used. Otherwise, these bits are used to select

the normal operating frequency range.

000: Typ. frequency range = LP (1 ~ 2 MHz)

001: Typ. frequency range = MP (2 ~ 4 MHz)

010: Typ. frequency range = MS (4 ~ 8 MHz)

011: Typ. frequency range = HS (8 ~ 16 MHz)

OPT0

PLLOFF

PLL activation

This option bit activates the PLL which allows multiplication by two of

the main input clock frequency. The PLL must not be used with the

internal RC oscillator or with external clock source. The PLL is

guaranteed only with an input frequency between 2 and 4 MHz.

0: PLL x2 enabled

1: PLL x2 disabled

Caution: The PLL can be enabled only if the OSCRANGE (OPT3:1) bits

are configured to “MP 2 ~ 4 MHz”. Otherwise, the device functionality is

not guaranteed.

Table 143.

Package selection (OPT7)

Version

Selected package

PKG1

PKG0

(A)R

LQFP64

JLQFP44

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