MSP430F6433IPZ datasheet(49/106 Pages) TI1

49 / 106 page

MSP430F643x

www.ti.com

SLAS720B – AUGUST 2010 – REVISED AUGUST 2012

Crystal Oscillator, XT1, Low-Frequency Mode

(1)

over recommended ranges of supply voltage and operating free-air temperature (unless otherwise noted)

PARAMETER

TEST CONDITIONS

VCC

MIN

TYP

MAX

UNIT

fOSC = 32768 Hz, XTS = 0,

XT1BYPASS = 0, XT1DRIVEx = 1,

0.075

TA = 25°C

Differential XT1 oscillator crystal

fOSC = 32768 Hz, XTS = 0,

ΔIDVCC,LF

current consumption from lowest

XT1BYPASS = 0, XT1DRIVEx = 2,

3 V

0.170

µA

drive setting, LF mode

TA = 25°C

fOSC = 32768 Hz, XTS = 0,

XT1BYPASS = 0, XT1DRIVEx = 3,

0.290

TA = 25°C

XT1 oscillator crystal frequency,

fXT1,LF0

XTS = 0, XT1BYPASS = 0

32768

LF mode

XT1 oscillator logic-level square-

fXT1,LF,SW

XTS = 0, XT1BYPASS = 1(2) (3)

32.768

kHz

wave input frequency, LF mode

XTS = 0,

XT1BYPASS = 0, XT1DRIVEx = 0,

210

fXT1,LF = 32768 Hz, CL,eff = 6 pF

Oscillation allowance for

OALF

Ω

LF crystals(4)

XTS = 0,

XT1BYPASS = 0, XT1DRIVEx = 1,

300

fXT1,LF = 32768 Hz, CL,eff = 12 pF

XTS = 0, XCAPx = 0(6)

XTS = 0, XCAPx = 1

5.5

Integrated effective load

CL,eff

capacitance, LF mode(5)

XTS = 0, XCAPx = 2

8.5

XTS = 0, XCAPx = 3

12.0

XTS = 0, Measured at ACLK,

Duty cycle, LF mode

fXT1,LF = 32768 Hz

Oscillator fault frequency,

fFault,LF

XTS = 0(8)

10000

LF mode(7)

fOSC = 32768 Hz, XTS = 0,

XT1BYPASS = 0, XT1DRIVEx = 0,

1000

TA = 25°C,

CL,eff = 6 pF

tSTART,LF

Startup time, LF mode

3 V

fOSC = 32768 Hz, XTS = 0,

XT1BYPASS = 0, XT1DRIVEx = 3,

500

TA = 25°C,

CL,eff = 12 pF

(1)

To improve EMI on the XT1 oscillator, the following guidelines should be observed.

(a) Keep the trace between the device and the crystal as short as possible.

(b) Design a good ground plane around the oscillator pins.

(d) Avoid running PCB traces underneath or adjacent to the XIN and XOUT pins.

(e) Use assembly materials and praxis to avoid any parasitic load on the oscillator XIN and XOUT pins.

(f) If conformal coating is used, ensure that it does not induce capacitive/resistive leakage between the oscillator pins.

(2)

When XT1BYPASS is set, XT1 circuit is automatically powered down. Input signal is a digital square wave with parametrics defined in

the Schmitt-trigger Inputs section of this datasheet.

(3)

Maximum frequency of operation of the entire device cannot be exceeded.

(4)

Oscillation allowance is based on a safety factor of 5 for recommended crystals. The oscillation allowance is a function of the

XT1DRIVEx settings and the effective load. In general, comparable oscillator allowance can be achieved based on the following

guidelines, but should be evaluated based on the actual crystal selected for the application:

(a) For XT1DRIVEx = 0, CL,eff ≤ 6 pF.

(b) For XT1DRIVEx = 1, 6 pF

≤ CL,eff ≤ 9 pF.

≤ CL,eff ≤ 10 pF.

(d) For XT1DRIVEx = 3, CL,ef f ≥ 6 pF.

(5)

Includes parasitic bond and package capacitance (approximately 2 pF per pin).

Since the PCB adds additional capacitance, it is recommended to verify the correct load by measuring the ACLK frequency. For a

correct setup, the effective load capacitance should always match the specification of the used crystal.

(6)

Requires external capacitors at both terminals. Values are specified by crystal manufacturers.

(7)

Frequencies below the MIN specification set the fault flag. Frequencies above the MAX specification do not set the fault flag.

Frequencies in between might set the flag.

(8)

Measured with logic-level input frequency but also applies to operation with crystals.

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