MC34708 datasheet(27/159 Pages) FREESCALE

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Analog Integrated Circuit Device Data



Freescale Semiconductor

MC34708

Functional Block Description

7.3.2

SRTC Support

When configured for DRM mode (SPI bit DRM = 1), the CLK32KMCU driver will be kept enabled through all operational states

to ensure that the SRTC module always has its reference clock. If DRM = 0, the CLK32KMCU driver will not be maintained in the

Off state.

It is also necessary to provide a means for the processor to do an RTC initiated wake-up of the system if it has been programmed

for such capability. This can be accomplished by connecting an open drain NMOS driver to the PWRON pin of the MC34708

PMIC, so that it is in effect, a parallel path for the power key. The MC34708 PMIC will not be able to discern the turn on event

from a normal power key initiated turn on, but the processor should have the knowledge, since the RTC initiated turn on is

generated locally.

Table 15. Oscillator and Clock Main Electrical Specifications

Characteristics noted under conditions BP = 3.6 V, VBUS = 5.0 V, -40 C  TA  85 C, unless otherwise noted. Typical values

at BP = 3.6 V and TA = 25 °C under nominal conditions, unless otherwise noted.

Symbol

Characteristic

Min

Typ

Max

Unit

Notes

OSCILLATOR AND CLOCK OUTPUT

VINRTC

Operating Voltage

• Oscillator and RTC Block from BP

• Oscillator and RTC Block from LICELL

1.8

4.5

3.6

IINRTC

Operating Current Crystal Oscillator and RTC Module

• All blocks disabled, no main battery attached, coin cell is attached

to LICELL

2.0

5.0

A

tSTART-RTC RTC oscillator startup time

• Upon application of power

1.0

sec

VRTCLO

Output Low

• CLK32K Output sink 100

A

• CLK32KMCU Output source 50

A

0.0

0.2

VRTCHI

Output High

• CLK32K Output source 100

A

• CLK32KMCU Output sink 50

A

CLK32K

VCC -0.2

VSRTC-0.2

CLK32K

VCC

VSRTC

tCLK32KET CLK32K Rise and Fall Time, CL = 50 pF

• CLK32KDRV [1:0] = 00

• CLK32KDRV [1:0] = 01 (default)

• CLK32KDRV [1:0] = 10

• CLK32KDRV [1:0] = 11

6.0

2.5

3.0

2.0

tCKL32K

MCUET

CLK32KMCU Rise and Fall Time

•CL = 12 pF

CLK32KDC/

CLK32K

MCUDC

CLK32K and CLK32KMCU Output Duty Cycle

• Crystal on XTAL1, XTAL2 pins

RMS Output Jitter

• 1 Sigma for Gaussian distribution

RMS

MC34708 Datasheet(PDF) 27 Page - Freescale Semiconductor, Inc

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