HC705JJ7GRSSLASHD datasheet(114/230 Pages) NXP

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Analog Subsystem

General Release Specification

MC68HC705JJ7/MC68HC705JP7 — Rev. 3.0

Analog Subsystem

CP2EN

The CP2EN enable bit controls power to voltage comparator 2 in the

analog subsystem. Powering down a comparator will drop the supply

current by about 100

µA. This bit is cleared by a reset of the device.

1 = Writing a logical one powers up voltage comparator 2

0 = Writing a logical zero powers down voltage comparator 2

NOTE:

Voltage comparators power up slower than digital logic; and their

outputs may go through indeterminate states which might set their

respective flags (CPF1, CPF2). It is therefore recommended to power up

the charge current source first (ISEN); then to power up any

comparators, and finally clear the flag bits by writing a logic one to the

respective CPFR1 or CPFR2 bits in the ACR.

CP1EN

The CP1EN enable bit will power down the voltage comparator 1 in

the analog subsystem. Powering down a comparator will drop the

supply current by about 100

µA. This bit is cleared by a reset of the

device.

1 = Writing a logical one powers up voltage comparator 1

0 = Writing a logical zero powers down voltage comparator 1

ISEN

The ISEN enable bit will power down the charge current source and

disable the discharge device in the analog subsystem. Powering

down the current source will drop the supply current by about 200

µA.

This bit is cleared by a reset of the device.

1 = Writing a logical one powers up the ramping current source and

enables the discharge device on the PB0/AN0 pin.

0 = Writing a logical zero powers down the ramping current source

and disables the discharge device on the PB0/AN0 pin.

NOTE:

The analog subsystem has support circuitry which draws about 80

µA of

current. This current will be powered down if both comparators and the

charge current source are powered down (ISEN, CP1EN, and CP2EN

all cleared). Powering up either comparator or the charge current source

will activate the support circuitry.

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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